/src/middleware/stb_vorbis/stb_vorbis.c

#include "stb_vorbis.h"



#ifndef STB_VORBIS_HEADER_ONLY



// global configuration settings (e.g. set these in the project/makefile),

// or just set them in this file at the top (although ideally the first few

// should be visible when the header file is compiled too, although it's not

// crucial)



// STB_VORBIS_NO_PUSHDATA_API

//     does not compile the code for the various stb_vorbis_*_pushdata()

//     functions

// #define STB_VORBIS_NO_PUSHDATA_API



// STB_VORBIS_NO_PULLDATA_API

//     does not compile the code for the non-pushdata APIs

// #define STB_VORBIS_NO_PULLDATA_API



// STB_VORBIS_NO_STDIO

//     does not compile the code for the APIs that use FILE *s internally

//     or externally (implied by STB_VORBIS_NO_PULLDATA_API)

// #define STB_VORBIS_NO_STDIO



// STB_VORBIS_NO_INTEGER_CONVERSION

//     does not compile the code for converting audio sample data from

//     float to integer (implied by STB_VORBIS_NO_PULLDATA_API)

// #define STB_VORBIS_NO_INTEGER_CONVERSION



// STB_VORBIS_NO_FAST_SCALED_FLOAT

//      does not use a fast float-to-int trick to accelerate float-to-int on

//      most platforms which requires endianness be defined correctly.

//#define STB_VORBIS_NO_FAST_SCALED_FLOAT





// STB_VORBIS_MAX_CHANNELS [number]

//     globally define this to the maximum number of channels you need.

//     The spec does not put a restriction on channels except that

//     the count is stored in a byte, so 255 is the hard limit.

//     Reducing this saves about 16 bytes per value, so using 16 saves

//     (255-16)*16 or around 4KB. Plus anything other memory usage

//     I forgot to account for. Can probably go as low as 8 (7.1 audio),

//     6 (5.1 audio), or 2 (stereo only).

#ifndef STB_VORBIS_MAX_CHANNELS

#define STB_VORBIS_MAX_CHANNELS    16  // enough for anyone?

#endif



// STB_VORBIS_PUSHDATA_CRC_COUNT [number]

//     after a flush_pushdata(), stb_vorbis begins scanning for the

//     next valid page, without backtracking. when it finds something

//     that looks like a page, it streams through it and verifies its

//     CRC32. Should that validation fail, it keeps scanning. But it's

//     possible that _while_ streaming through to check the CRC32 of

//     one candidate page, it sees another candidate page. This #define

//     determines how many "overlapping" candidate pages it can search

//     at once. Note that "real" pages are typically ~4KB to ~8KB, whereas

//     garbage pages could be as big as 64KB, but probably average ~16KB.

//     So don't hose ourselves by scanning an apparent 64KB page and

//     missing a ton of real ones in the interim; so minimum of 2

#ifndef STB_VORBIS_PUSHDATA_CRC_COUNT

#define STB_VORBIS_PUSHDATA_CRC_COUNT  4

#endif



// STB_VORBIS_FAST_HUFFMAN_LENGTH [number]

//     sets the log size of the huffman-acceleration table.  Maximum

//     supported value is 24. with larger numbers, more decodings are O(1),

//     but the table size is larger so worse cache missing, so you'll have

//     to probe (and try multiple ogg vorbis files) to find the sweet spot.

#ifndef STB_VORBIS_FAST_HUFFMAN_LENGTH

#define STB_VORBIS_FAST_HUFFMAN_LENGTH   10

#endif



// STB_VORBIS_FAST_BINARY_LENGTH [number]

//     sets the log size of the binary-search acceleration table. this

//     is used in similar fashion to the fast-huffman size to set initial

//     parameters for the binary search



// STB_VORBIS_FAST_HUFFMAN_INT

//     The fast huffman tables are much more efficient if they can be

//     stored as 16-bit results instead of 32-bit results. This restricts

//     the codebooks to having only 65535 possible outcomes, though.

//     (At least, accelerated by the huffman table.)

#ifndef STB_VORBIS_FAST_HUFFMAN_INT

#define STB_VORBIS_FAST_HUFFMAN_SHORT

#endif



// STB_VORBIS_NO_HUFFMAN_BINARY_SEARCH

//     If the 'fast huffman' search doesn't succeed, then stb_vorbis falls

//     back on binary searching for the correct one. This requires storing

//     extra tables with the huffman codes in sorted order. Defining this

//     symbol trades off space for speed by forcing a linear search in the

//     non-fast case, except for "sparse" codebooks.

// #define STB_VORBIS_NO_HUFFMAN_BINARY_SEARCH



// STB_VORBIS_DIVIDES_IN_RESIDUE

//     stb_vorbis precomputes the result of the scalar residue decoding

//     that would otherwise require a divide per chunk. you can trade off

//     space for time by defining this symbol.

// #define STB_VORBIS_DIVIDES_IN_RESIDUE



// STB_VORBIS_DIVIDES_IN_CODEBOOK

//     vorbis VQ codebooks can be encoded two ways: with every case explicitly

//     stored, or with all elements being chosen from a small range of values,

//     and all values possible in all elements. By default, stb_vorbis expands

//     this latter kind out to look like the former kind for ease of decoding,

//     because otherwise an integer divide-per-vector-element is required to

//     unpack the index. If you define STB_VORBIS_DIVIDES_IN_CODEBOOK, you can

//     trade off storage for speed.

//#define STB_VORBIS_DIVIDES_IN_CODEBOOK



// STB_VORBIS_CODEBOOK_SHORTS

//     The vorbis file format encodes VQ codebook floats as ax+b where a and

//     b are floating point per-codebook constants, and x is a 16-bit int.

//     Normally, stb_vorbis decodes them to floats rather than leaving them

//     as 16-bit ints and computing ax+b while decoding. This is a speed/space

//     tradeoff; you can save space by defining this flag.

#ifndef STB_VORBIS_CODEBOOK_SHORTS

#define STB_VORBIS_CODEBOOK_FLOATS

#endif



// STB_VORBIS_DIVIDE_TABLE

//     this replaces small integer divides in the floor decode loop with

//     table lookups. made less than 1% difference, so disabled by default.



// STB_VORBIS_NO_INLINE_DECODE

//     disables the inlining of the scalar codebook fast-huffman decode.

//     might save a little codespace; useful for debugging

// #define STB_VORBIS_NO_INLINE_DECODE



// STB_VORBIS_NO_DEFER_FLOOR

//     Normally we only decode the floor without synthesizing the actual

//     full curve. We can instead synthesize the curve immediately. This

//     requires more memory and is very likely slower, so I don't think

//     you'd ever want to do it except for debugging.

// #define STB_VORBIS_NO_DEFER_FLOOR









//////////////////////////////////////////////////////////////////////////////



#ifdef STB_VORBIS_NO_PULLDATA_API

   #define STB_VORBIS_NO_INTEGER_CONVERSION

   #define STB_VORBIS_NO_STDIO

#endif



#if defined(STB_VORBIS_NO_CRT) && !defined(STB_VORBIS_NO_STDIO)

   #define STB_VORBIS_NO_STDIO 1

#endif



#ifndef STB_VORBIS_NO_INTEGER_CONVERSION

#ifndef STB_VORBIS_NO_FAST_SCALED_FLOAT



   // only need endianness for fast-float-to-int, which we don't

   // use for pushdata



   #ifndef STB_VORBIS_BIG_ENDIAN

     #define STB_VORBIS_ENDIAN  0

   #else

     #define STB_VORBIS_ENDIAN  1

   #endif



#endif

#endif





#ifndef STB_VORBIS_NO_STDIO

#include <stdio.h>

#endif



#ifndef STB_VORBIS_NO_CRT

#include <stdlib.h>

#include <string.h>

#include <assert.h>

#include <math.h>

#include <malloc.h>

#else

#define NULL 0

#endif



#ifndef _MSC_VER

   #if __GNUC__

      #define __forceinline inline

   #else

      #define __forceinline

   #endif

#endif



#if STB_VORBIS_MAX_CHANNELS > 256

#error "Value of STB_VORBIS_MAX_CHANNELS outside of allowed range"

#endif



#if STB_VORBIS_FAST_HUFFMAN_LENGTH > 24

#error "Value of STB_VORBIS_FAST_HUFFMAN_LENGTH outside of allowed range"

#endif





#define MAX_BLOCKSIZE_LOG  13   // from specification

#define MAX_BLOCKSIZE      (1 << MAX_BLOCKSIZE_LOG)





typedef unsigned char  uint8;

typedef   signed char   int8;

typedef unsigned short uint16;

typedef   signed short  int16;

typedef unsigned int   uint32;

typedef   signed int    int32;



#ifndef TRUE

#define TRUE 1

#define FALSE 0

#endif



#ifdef STB_VORBIS_CODEBOOK_FLOATS

typedef float codetype;

#else

typedef uint16 codetype;

#endif



// @NOTE

//

// Some arrays below are tagged "//varies", which means it's actually

// a variable-sized piece of data, but rather than malloc I assume it's

// small enough it's better to just allocate it all together with the

// main thing

//

// Most of the variables are specified with the smallest size I could pack

// them into. It might give better performance to make them all full-sized

// integers. It should be safe to freely rearrange the structures or change

// the sizes larger--nothing relies on silently truncating etc., nor the

// order of variables.



#define FAST_HUFFMAN_TABLE_SIZE   (1 << STB_VORBIS_FAST_HUFFMAN_LENGTH)

#define FAST_HUFFMAN_TABLE_MASK   (FAST_HUFFMAN_TABLE_SIZE - 1)



typedef struct

{

   int dimensions, entries;

   uint8 *codeword_lengths;

   float  minimum_value;

   float  delta_value;

   uint8  value_bits;

   uint8  lookup_type;

   uint8  sequence_p;

   uint8  sparse;

   uint32 lookup_values;

   codetype *multiplicands;

   uint32 *codewords;

   #ifdef STB_VORBIS_FAST_HUFFMAN_SHORT

    int16  fast_huffman[FAST_HUFFMAN_TABLE_SIZE];

   #else

    int32  fast_huffman[FAST_HUFFMAN_TABLE_SIZE];

   #endif

   uint32 *sorted_codewords;

   int    *sorted_values;

   int     sorted_entries;

} Codebook;



typedef struct

{

   uint8 order;

   uint16 rate;

   uint16 bark_map_size;

   uint8 amplitude_bits;

   uint8 amplitude_offset;

   uint8 number_of_books;

   uint8 book_list[16]; // varies

} Floor0;



typedef struct

{

   uint8 partitions;

   uint8 partition_class_list[32]; // varies

   uint8 class_dimensions[16]; // varies

   uint8 class_subclasses[16]; // varies

   uint8 class_masterbooks[16]; // varies

   int16 subclass_books[16][8]; // varies

   uint16 Xlist[31*8+2]; // varies

   uint8 sorted_order[31*8+2];

   uint8 neighbors[31*8+2][2];

   uint8 floor1_multiplier;

   uint8 rangebits;

   int values;

} Floor1;



typedef union

{

   Floor0 floor0;

   Floor1 floor1;

} Floor;



typedef struct

{

   uint32 begin, end;

   uint32 part_size;

   uint8 classifications;

   uint8 classbook;

   uint8 **classdata;

   int16 (*residue_books)[8];

} Residue;



typedef struct

{

   uint8 magnitude;

   uint8 angle;

   uint8 mux;

} MappingChannel;



typedef struct

{

   uint16 coupling_steps;

   MappingChannel *chan;

   uint8  submaps;

   uint8  submap_floor[15]; // varies

   uint8  submap_residue[15]; // varies

} Mapping;



typedef struct

{

   uint8 blockflag;

   uint8 mapping;

   uint16 windowtype;

   uint16 transformtype;

} Mode;



typedef struct

{

   uint32  goal_crc;    // expected crc if match

   int     bytes_left;  // bytes left in packet

   uint32  crc_so_far;  // running crc

   int     bytes_done;  // bytes processed in _current_ chunk

   uint32  sample_loc;  // granule pos encoded in page

} CRCscan;



typedef struct

{

   uint32 page_start, page_end;

   uint32 after_previous_page_start;

   uint32 first_decoded_sample;

   uint32 last_decoded_sample;

} ProbedPage;



struct stb_vorbis

{

  // user-accessible info

   unsigned int sample_rate;

   int channels;



   unsigned int setup_memory_required;

   unsigned int temp_memory_required;

   unsigned int setup_temp_memory_required;



  // input config

#ifndef STB_VORBIS_NO_STDIO

   FILE *f;

   uint32 f_start;

   int close_on_free;

#endif

#ifdef STB_VORBIS_USE_CALLBACKS

	STREAM_DATA_CLLBACK data_callback;

	STREAM_RESET_CLLBACK reset_callback;

	void* user_data;

	uint32 cb_offset;

#endif



   uint8 *stream;

   uint8 *stream_start;

   uint8 *stream_end;



   uint32 stream_len;



   uint8  push_mode;



   uint32 first_audio_page_offset;



   ProbedPage p_first, p_last;



  // memory management

   stb_vorbis_alloc alloc;

   int setup_offset;

   int temp_offset;



  // run-time results

   int eof;

   enum STBVorbisError error;



  // user-useful data



  // header info

   int blocksize[2];

   int blocksize_0, blocksize_1;

   int codebook_count;

   Codebook *codebooks;

   int floor_count;

   uint16 floor_types[64]; // varies

   Floor *floor_config;

   int residue_count;

   uint16 residue_types[64]; // varies

   Residue *residue_config;

   int mapping_count;

   Mapping *mapping;

   int mode_count;

   Mode mode_config[64];  // varies



   uint32 total_samples;



  // decode buffer

   float *channel_buffers[STB_VORBIS_MAX_CHANNELS];

   float *outputs        [STB_VORBIS_MAX_CHANNELS];



   float *previous_window[STB_VORBIS_MAX_CHANNELS];

   int previous_length;



   #ifndef STB_VORBIS_NO_DEFER_FLOOR

   int16 *finalY[STB_VORBIS_MAX_CHANNELS];

   #else

   float *floor_buffers[STB_VORBIS_MAX_CHANNELS];

   #endif



   uint32 current_loc; // sample location of next frame to decode

   int    current_loc_valid;



  // per-blocksize precomputed data

   

   // twiddle factors

   float *A[2],*B[2],*C[2];

   float *window[2];

   uint16 *bit_reverse[2];



  // current page/packet/segment streaming info

   uint32 serial; // stream serial number for verification

   int last_page;

   int segment_count;

   uint8 segments[255];

   uint8 page_flag;

   uint8 bytes_in_seg;

   uint8 first_decode;

   int next_seg;

   int last_seg;  // flag that we're on the last segment

   int last_seg_which; // what was the segment number of the last seg?

   uint32 acc;

   int valid_bits;

   int packet_bytes;

   int end_seg_with_known_loc;

   uint32 known_loc_for_packet;

   int discard_samples_deferred;

   uint32 samples_output;



  // push mode scanning

   int page_crc_tests; // only in push_mode: number of tests active; -1 if not searching

#ifndef STB_VORBIS_NO_PUSHDATA_API

   CRCscan scan[STB_VORBIS_PUSHDATA_CRC_COUNT];

#endif



  // sample-access

   int channel_buffer_start;

   int channel_buffer_end;

};



extern int my_prof(int slot);

//#define stb_prof my_prof



#ifndef stb_prof

#define stb_prof(x)  0

#endif



#if defined(STB_VORBIS_NO_PUSHDATA_API)

   #define IS_PUSH_MODE(f)   FALSE

#elif defined(STB_VORBIS_NO_PULLDATA_API)

   #define IS_PUSH_MODE(f)   TRUE

#else

   #define IS_PUSH_MODE(f)   ((f)->push_mode)

#endif



typedef struct stb_vorbis vorb;



static int error(vorb *f, enum STBVorbisError e)

{

   f->error = e;

   if (!f->eof && e != VORBIS_need_more_data) {

      f->error=e; // breakpoint for debugging

   }

   return 0;

}





// these functions are used for allocating temporary memory

// while decoding. if you can afford the stack space, use

// alloca(); otherwise, provide a temp buffer and it will

// allocate out of those.



#define array_size_required(count,size)  (count*(sizeof(void *)+(size)))



#define temp_alloc(f,size)              (f->alloc.alloc_buffer ? setup_temp_malloc(f,size) : alloca(size))

#ifdef dealloca

#define temp_free(f,p)                  (f->alloc.alloc_buffer ? 0 : dealloca(size))

#else

#define temp_free(f,p)                  0

#endif

#define temp_alloc_save(f)              ((f)->temp_offset)

#define temp_alloc_restore(f,p)         ((f)->temp_offset = (p))



#define temp_block_array(f,count,size)  make_block_array(temp_alloc(f,array_size_required(count,size)), count, size)



// given a sufficiently large block of memory, make an array of pointers to subblocks of it

static void *make_block_array(void *mem, int count, int size)

{

   int i;

   void ** p = (void **) mem;

   char *q = (char *) (p + count);

   for (i=0; i < count; ++i) {

      p[i] = q;

      q += size;

   }

   return p;

}



static void *setup_malloc(vorb *f, int sz)

{

   sz = (sz+3) & ~3;

   f->setup_memory_required += sz;

   if (f->alloc.alloc_buffer) {

      void *p = (char *) f->alloc.alloc_buffer + f->setup_offset;

      if (f->setup_offset + sz > f->temp_offset) return NULL;

      f->setup_offset += sz;

      return p;

   }

   return sz ? malloc(sz) : NULL;

}



static void setup_free(vorb *f, void *p)

{

   if (f->alloc.alloc_buffer) return; // do nothing; setup mem is not a stack

   free(p);

}



static void *setup_temp_malloc(vorb *f, int sz)

{

   sz = (sz+3) & ~3;

   if (f->alloc.alloc_buffer) {

      if (f->temp_offset - sz < f->setup_offset) return NULL;

      f->temp_offset -= sz;

      return (char *) f->alloc.alloc_buffer + f->temp_offset;

   }

   return malloc(sz);

}



static void setup_temp_free(vorb *f, void *p, size_t sz)

{

   if (f->alloc.alloc_buffer) {

      f->temp_offset += (sz+3)&~3;

      return;

   }

   free(p);

}



#define CRC32_POLY    0x04c11db7   // from spec



static uint32 crc_table[256];

static void crc32_init(void)

{

   int i,j;

   uint32 s;

   for(i=0; i < 256; i++) {

      for (s=i<<24, j=0; j < 8; ++j)

         s = (s << 1) ^ (s >= (1<<31) ? CRC32_POLY : 0);

      crc_table[i] = s;

   }

}



static __forceinline uint32 crc32_update(uint32 crc, uint8 byte)

{

   return (crc << 8) ^ crc_table[byte ^ (crc >> 24)];

}





// used in setup, and for huffman that doesn't go fast path

static unsigned int bit_reverse(unsigned int n)

{

  n = ((n & 0xAAAAAAAA) >>  1) | ((n & 0x55555555) << 1);

  n = ((n & 0xCCCCCCCC) >>  2) | ((n & 0x33333333) << 2);

  n = ((n & 0xF0F0F0F0) >>  4) | ((n & 0x0F0F0F0F) << 4);

  n = ((n & 0xFF00FF00) >>  8) | ((n & 0x00FF00FF) << 8);

  return (n >> 16) | (n << 16);

}



static float square(float x)

{

   return x*x;

}



// this is a weird definition of log2() for which log2(1) = 1, log2(2) = 2, log2(4) = 3

// as required by the specification. fast(?) implementation from stb.h

// @OPTIMIZE: called multiple times per-packet with "constants"; move to setup

static int ilog(int32 n)

{

   static signed char log2_4[16] = { 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4 };



   // 2 compares if n < 16, 3 compares otherwise (4 if signed or n > 1<<29)

   if (n < (1U << 14))

        if (n < (1U <<  4))        return     0 + log2_4[n      ];

        else if (n < (1U <<  9))      return  5 + log2_4[n >>  5];

             else                     return 10 + log2_4[n >> 10];

   else if (n < (1U << 24))

             if (n < (1U << 19))      return 15 + log2_4[n >> 15];

             else                     return 20 + log2_4[n >> 20];

        else if (n < (1U << 29))      return 25 + log2_4[n >> 25];

             else if (n < (1U << 31)) return 30 + log2_4[n >> 30];

                  else                return 0; // signed n returns 0

}



#ifndef M_PI

  #define M_PI  3.14159265358979323846264f  // from CRC

#endif



// code length assigned to a value with no huffman encoding

#define NO_CODE   255



/////////////////////// LEAF SETUP FUNCTIONS //////////////////////////

//

// these functions are only called at setup, and only a few times

// per file



static float float32_unpack(uint32 x)

{

   // from the specification

   uint32 mantissa = x & 0x1fffff;

   uint32 sign = x & 0x80000000;

   uint32 exp = (x & 0x7fe00000) >> 21;

   double res = sign ? -(double)mantissa : (double)mantissa;

   return (float) ldexp((float)res, exp-788);

}





// zlib & jpeg huffman tables assume that the output symbols

// can either be arbitrarily arranged, or have monotonically

// increasing frequencies--they rely on the lengths being sorted;

// this makes for a very simple generation algorithm.

// vorbis allows a huffman table with non-sorted lengths. This

// requires a more sophisticated construction, since symbols in

// order do not map to huffman codes "in order".

static void add_entry(Codebook *c, uint32 huff_code, int symbol, int count, int len, uint32 *values)

{

   if (!c->sparse) {

      c->codewords      [symbol] = huff_code;

   } else {

      c->codewords       [count] = huff_code;

      c->codeword_lengths[count] = len;

      values             [count] = symbol;

   }

}



static int compute_codewords(Codebook *c, uint8 *len, int n, uint32 *values)

{

   int i,k,m=0;

   uint32 available[32];



   memset(available, 0, sizeof(available));

   // find the first entry

   for (k=0; k < n; ++k) if (len[k] < NO_CODE) break;

   if (k == n) { assert(c->sorted_entries == 0); return TRUE; }

   // add to the list

   add_entry(c, 0, k, m++, len[k], values);

   // add all available leaves

   for (i=1; i <= len[k]; ++i)

      available[i] = 1 << (32-i);

   // note that the above code treats the first case specially,

   // but it's really the same as the following code, so they

   // could probably be combined (except the initial code is 0,

   // and I use 0 in available[] to mean 'empty')

   for (i=k+1; i < n; ++i) {

      uint32 res;

      int z = len[i], y;

      if (z == NO_CODE) continue;

      // find lowest available leaf (should always be earliest,

      // which is what the specification calls for)

      // note that this property, and the fact we can never have

      // more than one free leaf at a given level, isn't totally

      // trivial to prove, but it seems true and the assert never

      // fires, so!

      while (z > 0 && !available[z]) --z;

      if (z == 0) { assert(0); return FALSE; }

      res = available[z];

      available[z] = 0;

      add_entry(c, bit_reverse(res), i, m++, len[i], values);

      // propogate availability up the tree

      if (z != len[i]) {

         for (y=len[i]; y > z; --y) {

            assert(available[y] == 0);

            available[y] = res + (1 << (32-y));

         }

      }

   }

   return TRUE;

}



// accelerated huffman table allows fast O(1) match of all symbols

// of length <= STB_VORBIS_FAST_HUFFMAN_LENGTH

static void compute_accelerated_huffman(Codebook *c)

{

   int i, len;

   for (i=0; i < FAST_HUFFMAN_TABLE_SIZE; ++i)

      c->fast_huffman[i] = -1;



   len = c->sparse ? c->sorted_entries : c->entries;

   #ifdef STB_VORBIS_FAST_HUFFMAN_SHORT

   if (len > 32767) len = 32767; // largest possible value we can encode!

   #endif

   for (i=0; i < len; ++i) {

      if (c->codeword_lengths[i] <= STB_VORBIS_FAST_HUFFMAN_LENGTH) {

         uint32 z = c->sparse ? bit_reverse(c->sorted_codewords[i]) : c->codewords[i];

         // set table entries for all bit combinations in the higher bits

         while (z < FAST_HUFFMAN_TABLE_SIZE) {

             c->fast_huffman[z] = i;

             z += 1 << c->codeword_lengths[i];

         }

      }

   }

}



static int uint32_compare(const void *p, const void *q)

{

   uint32 x = * (uint32 *) p;

   uint32 y = * (uint32 *) q;

   return x < y ? -1 : x > y;

}



static int include_in_sort(Codebook *c, uint8 len)

{

   if (c->sparse) { assert(len != NO_CODE); return TRUE; }

   if (len == NO_CODE) return FALSE;

   if (len > STB_VORBIS_FAST_HUFFMAN_LENGTH) return TRUE;

   return FALSE;

}



// if the fast table above doesn't work, we want to binary

// search them... need to reverse the bits

static void compute_sorted_huffman(Codebook *c, uint8 *lengths, uint32 *values)

{

   int i, len;

   // build a list of all the entries

   // OPTIMIZATION: don't include the short ones, since they'll be caught by FAST_HUFFMAN.

   // this is kind of a frivolous optimization--I don't see any performance improvement,

   // but it's like 4 extra lines of code, so.

   if (!c->sparse) {

      int k = 0;

      for (i=0; i < c->entries; ++i)

         if (include_in_sort(c, lengths[i])) 

            c->sorted_codewords[k++] = bit_reverse(c->codewords[i]);

      assert(k == c->sorted_entries);

   } else {

      for (i=0; i < c->sorted_entries; ++i)

         c->sorted_codewords[i] = bit_reverse(c->codewords[i]);

   }



   qsort(c->sorted_codewords, c->sorted_entries, sizeof(c->sorted_codewords[0]), uint32_compare);

   c->sorted_codewords[c->sorted_entries] = 0xffffffff;



   len = c->sparse ? c->sorted_entries : c->entries;

   // now we need to indicate how they correspond; we could either

   //   #1: sort a different data structure that says who they correspond to

   //   #2: for each sorted entry, search the original list to find who corresponds

   //   #3: for each original entry, find the sorted entry

   // #1 requires extra storage, #2 is slow, #3 can use binary search!

   for (i=0; i < len; ++i) {

      int huff_len = c->sparse ? lengths[values[i]] : lengths[i];

      if (include_in_sort(c,huff_len)) {

         uint32 code = bit_reverse(c->codewords[i]);

         int x=0, n=c->sorted_entries;

         while (n > 1) {

            // invariant: sc[x] <= code < sc[x+n]

            int m = x + (n >> 1);

            if (c->sorted_codewords[m] <= code) {

               x = m;

               n -= (n>>1);

            } else {

               n >>= 1;

            }

         }

         assert(c->sorted_codewords[x] == code);

         if (c->sparse) {

            c->sorted_values[x] = values[i];

            c->codeword_lengths[x] = huff_len;

         } else {

            c->sorted_values[x] = i;

         }

      }

   }

}



// only run while parsing the header (3 times)

static int vorbis_validate(uint8 *data)

{

   static uint8 vorbis[6] = { 'v', 'o', 'r', 'b', 'i', 's' };

   return memcmp(data, vorbis, 6) == 0;

}



// called from setup only, once per code book

// (formula implied by specification)

static int lookup1_values(int entries, int dim)

{

   int r = (int) floor(exp((float) log((float) entries) / dim));

   if ((int) floor(pow((float) r+1, dim)) <= entries)   // (int) cast for MinGW warning;

      ++r;                                              // floor() to avoid _ftol() when non-CRT

   assert(pow((float) r+1, dim) > entries);

   assert((int) floor(pow((float) r, dim)) <= entries); // (int),floor() as above

   return r;

}



// called twice per file

static void compute_twiddle_factors(int n, float *A, float *B, float *C)

{

   int n4 = n >> 2, n8 = n >> 3;

   int k,k2;



   for (k=k2=0; k < n4; ++k,k2+=2) {

      A[k2  ] = (float)  cos(4*k*M_PI/n);

      A[k2+1] = (float) -sin(4*k*M_PI/n);

      B[k2  ] = (float)  cos((k2+1)*M_PI/n/2) * 0.5f;

      B[k2+1] = (float)  sin((k2+1)*M_PI/n/2) * 0.5f;

   }

   for (k=k2=0; k < n8; ++k,k2+=2) {

      C[k2  ] = (float)  cos(2*(k2+1)*M_PI/n);

      C[k2+1] = (float) -sin(2*(k2+1)*M_PI/n);

   }

}



static void compute_window(int n, float *window)

{

   int n2 = n >> 1, i;

   for (i=0; i < n2; ++i)

      window[i] = (float) sin(0.5 * M_PI * square((float) sin((i - 0 + 0.5) / n2 * 0.5 * M_PI)));

}



static void compute_bitreverse(int n, uint16 *rev)

{

   int ld = ilog(n) - 1; // ilog is off-by-one from normal definitions

   int i, n8 = n >> 3;

   for (i=0; i < n8; ++i)

      rev[i] = (bit_reverse(i) >> (32-ld+3)) << 2;

}



static int init_blocksize(vorb *f, int b, int n)

{

   int n2 = n >> 1, n4 = n >> 2, n8 = n >> 3;

   f->A[b] = (float *) setup_malloc(f, sizeof(float) * n2);

   f->B[b] = (float *) setup_malloc(f, sizeof(float) * n2);

   f->C[b] = (float *) setup_malloc(f, sizeof(float) * n4);

   if (!f->A[b] || !f->B[b] || !f->C[b]) return error(f, VORBIS_outofmem);

   compute_twiddle_factors(n, f->A[b], f->B[b], f->C[b]);

   f->window[b] = (float *) setup_malloc(f, sizeof(float) * n2);

   if (!f->window[b]) return error(f, VORBIS_outofmem);

   compute_window(n, f->window[b]);

   f->bit_reverse[b] = (uint16 *) setup_malloc(f, sizeof(uint16) * n8);

   if (!f->bit_reverse[b]) return error(f, VORBIS_outofmem);

   compute_bitreverse(n, f->bit_reverse[b]);

   return TRUE;

}



static void neighbors(uint16 *x, int n, int *plow, int *phigh)

{

   int low = -1;

   int high = 65536;

   int i;

   for (i=0; i < n; ++i) {

      if (x[i] > low  && x[i] < x[n]) { *plow  = i; low = x[i]; }

      if (x[i] < high && x[i] > x[n]) { *phigh = i; high = x[i]; }

   }

}



// this has been repurposed so y is now the original index instead of y

typedef struct

{

   uint16 x,y;

} Point;



int point_compare(const void *p, const void *q)

{

   Point *a = (Point *) p;

   Point *b = (Point *) q;

   return a->x < b->x ? -1 : a->x > b->x;

}



//

/////////////////////// END LEAF SETUP FUNCTIONS //////////////////////////





#if defined(STB_VORBIS_NO_STDIO)

   #define USE_MEMORY(z)    TRUE

#else

   #define USE_MEMORY(z)    ((z)->stream)

#endif

#ifdef STB_VORBIS_USE_CALLBACKS



#define USE_CALLBACKS(z)  ((z)->data_callback)



int stb_read_from_callback(vorb* z, int size, uint8* ptr)

{

	int read = z->data_callback(size,ptr,z->user_data);

	if(read < 1 && size > 0)

		z->eof = 1;

	else

		z->cb_offset+=read;

	return read;

}	



int stb_reset_callback(vorb* z)

{

	int result = z->reset_callback(z->user_data);

	if(result == -1)

		z->eof = 1;

	else

	{	

		z->cb_offset = 0;

		z->eof = 0;

	}

	return result;

}



#endif 



static uint8 get8(vorb *z)

{

   if (USE_MEMORY(z)) {

      if (z->stream >= z->stream_end) { z->eof = TRUE; return 0; }

      return *z->stream++;

   }



#ifdef STB_VORBIS_USE_CALLBACKS

   if(USE_CALLBACKS(z))

   {

		uint8 data;

		int read = stb_read_from_callback(z,1,&data);

		if(z->eof)

			return 0;

		else

			return data;

   }

#endif

   

   #ifndef STB_VORBIS_NO_STDIO

   {

   int c = fgetc(z->f);

   if (c == EOF) { z->eof = TRUE; return 0; }

   return c;

   }

   #endif

}



static uint32 get32(vorb *f)

{

   uint32 x;

   x = get8(f);

   x += get8(f) << 8;

   x += get8(f) << 16;

   x += get8(f) << 24;

   return x;

}



static int getn(vorb *z, uint8 *data, int n)

{

   if (USE_MEMORY(z)) {

      if (z->stream+n > z->stream_end) { z->eof = 1; return 0; }

      memcpy(data, z->stream, n);

      z->stream += n;

      return 1;

   }



#ifdef STB_VORBIS_USE_CALLBACKS

   if(USE_CALLBACKS(z))

   {

		int read = stb_read_from_callback(z,n,data);

		if(read < n)

		{

			z->eof = 1;

			return 0;

		}

		else

			return 1;

   }

#endif



   #ifndef STB_VORBIS_NO_STDIO   

   if (fread(data, n, 1, z->f) == 1)

      return 1;

   else {

      z->eof = 1;

      return 0;

   }

   #endif

}



static void skip(vorb *z, int n)

{

   if (USE_MEMORY(z)) {

      z->stream += n;

      if (z->stream >= z->stream_end) z->eof = 1;

      return;

   }

#ifdef STB_VORBIS_USE_CALLBACKS

 if(USE_CALLBACKS(z))

   {

		int read = stb_read_from_callback(z,n,NULL);

		if(read < n)

			z->eof = 1;

		return;

   }

#endif

   



   #ifndef STB_VORBIS_NO_STDIO

   {

      long x = ftell(z->f);

      fseek(z->f, x+n, SEEK_SET);

   }

   #endif

}



static int set_file_offset(stb_vorbis *f, unsigned int loc)

{

   #ifndef STB_VORBIS_NO_PUSHDATA_API

   if (f->push_mode) return 0;

   #endif

   f->eof = 0;

   if (USE_MEMORY(f)) {

      if (f->stream_start + loc >= f->stream_end || f->stream_start + loc < f->stream_start) {

         f->stream = f->stream_end;

         f->eof = 1;

         return 0;

      } else {

         f->stream = f->stream_start + loc;

         return 1;

      }

   }



#ifdef STB_VORBIS_USE_CALLBACKS

	if(USE_CALLBACKS(f))

	{

		int read = stb_reset_callback(f);

		if(read < 0)

		{

			f->eof = 1;

			return 0;

		}

		read = stb_read_from_callback(f,loc,NULL);

		if(read < loc)

		{

			f->eof = 1;

			return 0;

		}

		return 1;

	}

#endif

   

   #ifndef STB_VORBIS_NO_STDIO

   if (loc + f->f_start < loc || loc >= 0x80000000) {

      loc = 0x7fffffff;

      f->eof = 1;

   } else {

      loc += f->f_start;

   }

   if (!fseek(f->f, loc, SEEK_SET))

      return 1;

   f->eof = 1;

   fseek(f->f, f->f_start, SEEK_END);

   return 0;

   #endif

}





static uint8 ogg_page_header[4] = { 0x4f, 0x67, 0x67, 0x53 };



static int capture_pattern(vorb *f)

{

   if (0x4f != get8(f)) return FALSE;

   if (0x67 != get8(f)) return FALSE;

   if (0x67 != get8(f)) return FALSE;

   if (0x53 != get8(f)) return FALSE;

   return TRUE;

}



#define PAGEFLAG_continued_packet   1

#define PAGEFLAG_first_page         2

#define PAGEFLAG_last_page          4



static int start_page_no_capturepattern(vorb *f)

{

   uint32 loc0,loc1,n,i;

   // stream structure version

   if (0 != get8(f)) return error(f, VORBIS_invalid_stream_structure_version);

   // header flag

   f->page_flag = get8(f);

   // absolute granule position

   loc0 = get32(f); 

   loc1 = get32(f);

   // @TODO: validate loc0,loc1 as valid positions?

   // stream serial number -- vorbis doesn't interleave, so discard

   get32(f);

   //if (f->serial != get32(f)) return error(f, VORBIS_incorrect_stream_serial_number);

   // page sequence number

   n = get32(f);

   f->last_page = n;

   // CRC32

   get32(f);

   // page_segments

   f->segment_count = get8(f);

   if (!getn(f, f->segments, f->segment_count))

      return error(f, VORBIS_unexpected_eof);

   // assume we _don't_ know any the sample position of any segments

   f->end_seg_with_known_loc = -2;

   if (loc0 != ~0 || loc1 != ~0) {

      // determine which packet is the last one that will complete

      for (i=f->segment_count-1; i >= 0; --i)

         if (f->segments[i] < 255)

            break;

      // 'i' is now the index of the _last_ segment of a packet that ends

      if (i >= 0) {

         f->end_seg_with_known_loc = i;

         f->known_loc_for_packet   = loc0;

      }

   }

   if (f->first_decode) {

      int i,len;

      ProbedPage p;

      len = 0;

      for (i=0; i < f->segment_count; ++i)

         len += f->segments[i];

      len += 27 + f->segment_count;

      p.page_start = f->first_audio_page_offset;

      p.page_end = p.page_start + len;

      p.after_previous_page_start = p.page_start;

      p.first_decoded_sample = 0;

      p.last_decoded_sample = loc0;

      f->p_first = p;

   }

   f->next_seg = 0;

   return TRUE;

}



static int start_page(vorb *f)

{

   if (!capture_pattern(f)) return error(f, VORBIS_missing_capture_pattern);

   return start_page_no_capturepattern(f);

}



static int start_packet(vorb *f)

{

   while (f->next_seg == -1) {

      if (!start_page(f)) return FALSE;

      if (f->page_flag & PAGEFLAG_continued_packet)

         return error(f, VORBIS_continued_packet_flag_invalid);

   }

   f->last_seg = FALSE;

   f->valid_bits = 0;

   f->packet_bytes = 0;

   f->bytes_in_seg = 0;

   // f->next_seg is now valid

   return TRUE;

}



static int maybe_start_packet(vorb *f)

{

   if (f->next_seg == -1) {

      int x = get8(f);

      if (f->eof) return FALSE; // EOF at page boundary is not an error!

      if (0x4f != x      ) return error(f, VORBIS_missing_capture_pattern);

      if (0x67 != get8(f)) return error(f, VORBIS_missing_capture_pattern);

      if (0x67 != get8(f)) return error(f, VORBIS_missing_capture_pattern);

      if (0x53 != get8(f)) return error(f, VORBIS_missing_capture_pattern);

      if (!start_page_no_capturepattern(f)) return FALSE;

      if (f->page_flag & PAGEFLAG_continued_packet) {

         // set up enough state that we can read this packet if we want,

         // e.g. during recovery

         f->last_seg = FALSE;

         f->bytes_in_seg = 0;

         return error(f, VORBIS_continued_packet_flag_invalid);

      }

   }

   return start_packet(f);

}



static int next_segment(vorb *f)

{

   int len;

   if (f->last_seg) return 0;

   if (f->next_seg == -1) {

      f->last_seg_which = f->segment_count-1; // in case start_page fails

      if (!start_page(f)) { f->last_seg = 1; return 0; }

      if (!(f->page_flag & PAGEFLAG_continued_packet)) return error(f, VORBIS_continued_packet_flag_invalid);

   }

   len = f->segments[f->next_seg++];

   if (len < 255) {

      f->last_seg = TRUE;

      f->last_seg_which = f->next_seg-1;

   }

   if (f->next_seg >= f->segment_count)

      f->next_seg = -1;

   assert(f->bytes_in_seg == 0);

   f->bytes_in_seg = len;

   return len;

}



#define EOP    (-1)

#define INVALID_BITS  (-1)



static int get8_packet_raw(vorb *f)

{

   if (!f->bytes_in_seg)

      if (f->last_seg) return EOP;

      else if (!next_segment(f)) return EOP;

   assert(f->bytes_in_seg > 0);

   --f->bytes_in_seg;

   ++f->packet_bytes;

   return get8(f);

}



static int get8_packet(vorb *f)

{

   int x = get8_packet_raw(f);

   f->valid_bits = 0;

   return x;

}



static void flush_packet(vorb *f)

{

   while (get8_packet_raw(f) != EOP);

}



// @OPTIMIZE: this is the secondary bit decoder, so it's probably not as important

// as the huffman decoder?

static uint32 get_bits(vorb *f, int n)

{

   uint32 z;



   if (f->valid_bits < 0) return 0;

   if (f->valid_bits < n) {

      if (n > 24) {

         // the accumulator technique below would not work correctly in this case

         z = get_bits(f, 24);

         z += get_bits(f, n-24) << 24;

         return z;

      }

      if (f->valid_bits == 0) f->acc = 0;

      while (f->valid_bits < n) {

         int z = get8_packet_raw(f);

         if (z == EOP) {

            f->valid_bits = INVALID_BITS;

            return 0;

         }

         f->acc += z << f->valid_bits;

         f->valid_bits += 8;

      }

   }

   if (f->valid_bits < 0) return 0;

   z = f->acc & ((1 << n)-1);

   f->acc >>= n;

   f->valid_bits -= n;

   return z;

}



static int32 get_bits_signed(vorb *f, int n)

{

   uint32 z = get_bits(f, n);

   if (z & (1 << (n-1)))

      z += ~((1 << n) - 1);

   return (int32) z;

}



// @OPTIMIZE: primary accumulator for huffman

// expand the buffer to as many bits as possible without reading off end of packet

// it might be nice to allow f->valid_bits and f->acc to be stored in registers,

// e.g. cache them locally and decode locally

static __forceinline void prep_huffman(vorb *f)

{

   if (f->valid_bits <= 24) {

      if (f->valid_bits == 0) f->acc = 0;

      do {

         int z;

         if (f->last_seg && !f->bytes_in_seg) return;

         z = get8_packet_raw(f);

         if (z == EOP) return;

         f->acc += z << f->valid_bits;

         f->valid_bits += 8;

      } while (f->valid_bits <= 24);

   }

}



enum

{

   VORBIS_packet_id = 1,

   VORBIS_packet_comment = 3,

   VORBIS_packet_setup = 5,

};



static int codebook_decode_scalar_raw(vorb *f, Codebook *c)

{

   int i;

   prep_huffman(f);



   assert(c->sorted_codewords || c->codewords);

   // cases to use binary search: sorted_codewords && !c->codewords

   //                             sorted_codewords && c->entries > 8

   if (c->entries > 8 ? c->sorted_codewords!=NULL : !c->codewords) {

      // binary search

      uint32 code = bit_reverse(f->acc);

      int x=0, n=c->sorted_entries, len;



      while (n > 1) {

         // invariant: sc[x] <= code < sc[x+n]

         int m = x + (n >> 1);

         if (c->sorted_codewords[m] <= code) {

            x = m;

            n -= (n>>1);

         } else {

            n >>= 1;

         }

      }

      // x is now the sorted index

      if (!c->sparse) x = c->sorted_values[x];

      // x is now sorted index if sparse, or symbol otherwise

      len = c->codeword_lengths[x];

      if (f->valid_bits >= len) {

         f->acc >>= len;

         f->valid_bits -= len;

         return x;

      }



      f->valid_bits = 0;

      return -1;

   }



   // if small, linear search

   assert(!c->sparse);

   for (i=0; i < c->entries; ++i) {

      if (c->codeword_lengths[i] == NO_CODE) continue;

      if (c->codewords[i] == (f->acc & ((1 << c->codeword_lengths[i])-1))) {

         if (f->valid_bits >= c->codeword_lengths[i]) {

            f->acc >>= c->codeword_lengths[i];

            f->valid_bits -= c->codeword_lengths[i];

            return i;

         }

         f->valid_bits = 0;

         return -1;

      }

   }



   error(f, VORBIS_invalid_stream);

   f->valid_bits = 0;

   return -1;

}



static int codebook_decode_scalar(vorb *f, Codebook *c)

{

   int i;

   if (f->valid_bits < STB_VORBIS_FAST_HUFFMAN_LENGTH)

      prep_huffman(f);

   // fast huffman table lookup

   i = f->acc & FAST_HUFFMAN_TABLE_MASK;

   i = c->fast_huffman[i];

   if (i >= 0) {

      f->acc >>= c->codeword_lengths[i];

      f->valid_bits -= c->codeword_lengths[i];

      if (f->valid_bits < 0) { f->valid_bits = 0; return -1; }

      return i;

   }

   return codebook_decode_scalar_raw(f,c);

}



#ifndef STB_VORBIS_NO_INLINE_DECODE



#define DECODE_RAW(var, f,c)                                  \

   if (f->valid_bits < STB_VORBIS_FAST_HUFFMAN_LENGTH)        \

      prep_huffman(f);                                        \

   var = f->acc & FAST_HUFFMAN_TABLE_MASK;                    \

   var = c->fast_huffman[var];                                \

   if (var >= 0) {                                            \

      int n = c->codeword_lengths[var];                       \

      f->acc >>= n;                                           \

      f->valid_bits -= n;                                     \

      if (f->valid_bits < 0) { f->valid_bits = 0; var = -1; } \

   } else {                                                   \

      var = codebook_decode_scalar_raw(f,c);                  \

   }



#else



#define DECODE_RAW(var,f,c)    var = codebook_decode_scalar(f,c);



#endif



#define DECODE(var,f,c)                                       \

   DECODE_RAW(var,f,c)                                        \

   if (c->sparse) var = c->sorted_values[var];



#ifndef STB_VORBIS_DIVIDES_IN_CODEBOOK

  #define DECODE_VQ(var,f,c)   DECODE_RAW(var,f,c)

#else

  #define DECODE_VQ(var,f,c)   DECODE(var,f,c)

#endif













// CODEBOOK_ELEMENT_FAST is an optimization for the CODEBOOK_FLOATS case

// where we avoid one addition

#ifndef STB_VORBIS_CODEBOOK_FLOATS

   #define CODEBOOK_ELEMENT(c,off)          (c->multiplicands[off] * c->delta_value + c->minimum_value)

   #define CODEBOOK_ELEMENT_FAST(c,off)     (c->multiplicands[off] * c->delta_value)

   #define CODEBOOK_ELEMENT_BASE(c)         (c->minimum_value)

#else

   #define CODEBOOK_ELEMENT(c,off)          (c->multiplicands[off])

   #define CODEBOOK_ELEMENT_FAST(c,off)     (c->multiplicands[off])

   #define CODEBOOK_ELEMENT_BASE(c)         (0)

#endif



static int codebook_decode_start(vorb *f, Codebook *c, int len)

{

   int z = -1;



   // type 0 is only legal in a scalar context

   if (c->lookup_type == 0)

      error(f, VORBIS_invalid_stream);

   else {

      DECODE_VQ(z,f,c);

      if (c->sparse) assert(z < c->sorted_entries);

      if (z < 0) {  // check for EOP

         if (!f->bytes_in_seg)

            if (f->last_seg)

               return z;

         error(f, VORBIS_invalid_stream);

      }

   }

   return z;

}



static int codebook_decode(vorb *f, Codebook *c, float *output, int len)

{

   int i,z = codebook_decode_start(f,c,len);

   if (z < 0) return FALSE;

   if (len > c->dimensions) len = c->dimensions;



#ifdef STB_VORBIS_DIVIDES_IN_CODEBOOK

   if (c->lookup_type == 1) {

      float last = CODEBOOK_ELEMENT_BASE(c);

      int div = 1;

      for (i=0; i < len; ++i) {

         int off = (z / div) % c->lookup_values;

         float val = CODEBOOK_ELEMENT_FAST(c,off) + last;

         output[i] += val;

         if (c->sequence_p) last = val + c->minimum_value;

         div *= c->lookup_values;

      }

      return TRUE;

   }

#endif



   z *= c->dimensions;

   if (c->sequence_p) {

      float last = CODEBOOK_ELEMENT_BASE(c);

      for (i=0; i < len; ++i) {

         float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;

         output[i] += val;

         last = val + c->minimum_value;

      }

   } else {

      float last = CODEBOOK_ELEMENT_BASE(c);

      for (i=0; i < len; ++i) {

         output[i] += CODEBOOK_ELEMENT_FAST(c,z+i) + last;

      }

   }



   return TRUE;

}



static int codebook_decode_step(vorb *f, Codebook *c, float *output, int len, int step)

{

   int i,z = codebook_decode_start(f,c,len);

   float last = CODEBOOK_ELEMENT_BASE(c);

   if (z < 0) return FALSE;

   if (len > c->dimensions) len = c->dimensions;



#ifdef STB_VORBIS_DIVIDES_IN_CODEBOOK

   if (c->lookup_type == 1) {

      int div = 1;

      for (i=0; i < len; ++i) {

         int off = (z / div) % c->lookup_values;

         float val = CODEBOOK_ELEMENT_FAST(c,off) + last;

         output[i*step] += val;

         if (c->sequence_p) last = val;

         div *= c->lookup_values;

      }

      return TRUE;

   }

#endif



   z *= c->dimensions;

   for (i=0; i < len; ++i) {

      float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;

      output[i*step] += val;

      if (c->sequence_p) last = val;

   }



   return TRUE;

}



static int codebook_decode_deinterleave_repeat(vorb *f, Codebook *c, float **outputs, int ch, int *c_inter_p, int *p_inter_p, int len, int total_decode)

{

   int c_inter = *c_inter_p;

   int p_inter = *p_inter_p;

   int i,z, effective = c->dimensions;



   // type 0 is only legal in a scalar context

   if (c->lookup_type == 0)   return error(f, VORBIS_invalid_stream);



   while (total_decode > 0) {

      float last = CODEBOOK_ELEMENT_BASE(c);

      DECODE_VQ(z,f,c);

      #ifndef STB_VORBIS_DIVIDES_IN_CODEBOOK

      assert(!c->sparse || z < c->sorted_entries);

      #endif

      if (z < 0) {

         if (!f->bytes_in_seg)

            if (f->last_seg) return FALSE;

         return error(f, VORBIS_invalid_stream);

      }



      // if this will take us off the end of the buffers, stop short!

      // we check by computing the length of the virtual interleaved

      // buffer (len*ch), our current offset within it (p_inter*ch)+(c_inter),

      // and the length we'll be using (effective)

      if (c_inter + p_inter*ch + effective > len * ch) {

         effective = len*ch - (p_inter*ch - c_inter);

      }



   #ifdef STB_VORBIS_DIVIDES_IN_CODEBOOK

      if (c->lookup_type == 1) {

         int div = 1;

         for (i=0; i < effective; ++i) {

            int off = (z / div) % c->lookup_values;

            float val = CODEBOOK_ELEMENT_FAST(c,off) + last;

            outputs[c_inter][p_inter] += val;

            if (++c_inter == ch) { c_inter = 0; ++p_inter; }

            if (c->sequence_p) last = val;

            div *= c->lookup_values;

         }

      } else

   #endif

      {

         z *= c->dimensions;

         if (c->sequence_p) {

            for (i=0; i < effective; ++i) {

               float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;

               outputs[c_inter][p_inter] += val;

               if (++c_inter == ch) { c_inter = 0; ++p_inter; }

               last = val;

            }

         } else {

            for (i=0; i < effective; ++i) {

               float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;

               outputs[c_inter][p_inter] += val;

               if (++c_inter == ch) { c_inter = 0; ++p_inter; }

            }

         }

      }



      total_decode -= effective;

   }

   *c_inter_p = c_inter;

   *p_inter_p = p_inter;

   return TRUE;

}



#ifndef STB_VORBIS_DIVIDES_IN_CODEBOOK

static int codebook_decode_deinterleave_repeat_2(vorb *f, Codebook *c, float **outputs, int *c_inter_p, int *p_inter_p, int len, int total_decode)

{

   int c_inter = *c_inter_p;

   int p_inter = *p_inter_p;

   int i,z, effective = c->dimensions;



   // type 0 is only legal in a scalar context

   if (c->lookup_type == 0)   return error(f, VORBIS_invalid_stream);



   while (total_decode > 0) {

      float last = CODEBOOK_ELEMENT_BASE(c);

      DECODE_VQ(z,f,c);



      if (z < 0) {

         if (!f->bytes_in_seg)

            if (f->last_seg) return FALSE;

         return error(f, VORBIS_invalid_stream);

      }



      // if this will take us off the end of the buffers, stop short!

      // we check by computing the length of the virtual interleaved

      // buffer (len*ch), our current offset within it (p_inter*ch)+(c_inter),

      // and the length we'll be using (effective)

      if (c_inter + p_inter*2 + effective > len * 2) {

         effective = len*2 - (p_inter*2 - c_inter);

      }



      {

         z *= c->dimensions;

         stb_prof(11);

         if (c->sequence_p) {

            // haven't optimized this case because I don't have any examples

            for (i=0; i < effective; ++i) {

               float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;

               outputs[c_inter][p_inter] += val;

               if (++c_inter == 2) { c_inter = 0; ++p_inter; }

               last = val;

            }

         } else {

            i=0;

            if (c_inter == 1) {

               float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;

               outputs[c_inter][p_inter] += val;

               c_inter = 0; ++p_inter;

               ++i;

            }

            {

               float *z0 = outputs[0];

               float *z1 = outputs[1];

               for (; i+1 < effective;) {

                  z0[p_inter] += CODEBOOK_ELEMENT_FAST(c,z+i) + last;

                  z1[p_inter] += CODEBOOK_ELEMENT_FAST(c,z+i+1) + last;

                  ++p_inter;

                  i += 2;

               }

            }

            if (i < effective) {

               float val = CODEBOOK_ELEMENT_FAST(c,z+i) + last;

               outputs[c_inter][p_inter] += val;

               if (++c_inter == 2) { c_inter = 0; ++p_inter; }

            }

         }

      }



      total_decode -= effective;

   }

   *c_inter_p = c_inter;

   *p_inter_p = p_inter;

   return TRUE;

}

#endif



static int predict_point(int x, int x0, int x1, int y0, int y1)

{

   int dy = y1 - y0;

   int adx = x1 - x0;

   // @OPTIMIZE: force int division to round in the right direction... is this necessary on x86?

   int err = abs(dy) * (x - x0);

   int off = err / adx;

   return dy < 0 ? y0 - off : y0 + off;

}



// the following table is block-copied from the specification

static float inverse_db_table[256] =

{

  1.0649863e-07f, 1.1341951e-07f, 1.2079015e-07f, 1.2863978e-07f, 

  1.3699951e-07f, 1.4590251e-07f, 1.5538408e-07f, 1.6548181e-07f, 

  1.7623575e-07f, 1.8768855e-07f, 1.9988561e-07f, 2.1287530e-07f, 

  2.2670913e-07f, 2.4144197e-07f, 2.5713223e-07f, 2.7384213e-07f, 

  2.9163793e-07f, 3.1059021e-07f, 3.3077411e-07f, 3.5226968e-07f, 

  3.7516214e-07f, 3.9954229e-07f, 4.2550680e-07f, 4.5315863e-07f, 

  4.8260743e-07f, 5.1396998e-07f, 5.4737065e-07f, 5.8294187e-07f, 

  6.2082472e-07f, 6.6116941e-07f, 7.0413592e-07f, 7.4989464e-07f, 

  7.9862701e-07f, 8.5052630e-07f, 9.0579828e-07f, 9.6466216e-07f, 

  1.0273513e-06f, 1.0941144e-06f, 1.1652161e-06f, 1.2409384e-06f, 

  1.3215816e-06f, 1.4074654e-06f, 1.4989305e-06f, 1.5963394e-06f, 

  1.7000785e-06f, 1.8105592e-06f, 1.9282195e-06f, 2.0535261e-06f, 

  2.1869758e-06f, 2.3290978e-06f, 2.4804557e-06f, 2.6416497e-06f, 

  2.8133190e-06f, 2.9961443e-06f, 3.1908506e-06f, 3.3982101e-06f, 

  3.6190449e-06f, 3.8542308e-06f, 4.1047004e-06f, 4.3714470e-06f, 

  4.6555282e-06f, 4.9580707e-06f, 5.2802740e-06f, 5.6234160e-06f, 

  5.9888572e-06f, 6.3780469e-06f, 6.7925283e-06f, 7.2339451e-06f, 

  7.7040476e-06f, 8.2047000e-06f, 8.7378876e-06f, 9.3057248e-06f, 

  9.9104632e-06f, 1.0554501e-05f, 1.1240392e-05f, 1.1970856e-05f, 

  1.2748789e-05f, 1.3577278e-05f, 1.4459606e-05f, 1.5399272e-05f, 

  1.6400004e-05f, 1.7465768e-05f, 1.8600792e-05f, 1.9809576e-05f, 

  2.1096914e-05f, 2.2467911e-05f, 2.3928002e-05f, 2.5482978e-05f, 

  2.7139006e-05f, 2.8902651e-05f, 3.0780908e-05f, 3.2781225e-05f, 

  3.4911534e-05f, 3.7180282e-05f, 3.9596466e-05f, 4.2169667e-05f, 

  4.4910090e-05f, 4.7828601e-05f, 5.0936773e-05f, 5.4246931e-05f, 

  5.7772202e-05f, 6.1526565e-05f, 6.5524908e-05f, 6.9783085e-05f, 

  7.4317983e-05f, 7.9147585e-05f, 8.4291040e-05f, 8.9768747e-05f, 

  9.5602426e-05f, 0.00010181521f, 0.00010843174f, 0.00011547824f, 

  0.00012298267f, 0.00013097477f, 0.00013948625f, 0.00014855085f, 

  0.00015820453f, 0.00016848555f, 0.00017943469f, 0.00019109536f, 

  0.00020351382f, 0.00021673929f, 0.00023082423f, 0.00024582449f, 

  0.00026179955f, 0.00027881276f, 0.00029693158f, 0.00031622787f, 

  0.00033677814f, 0.00035866388f, 0.00038197188f, 0.00040679456f, 

  0.00043323036f, 0.00046138411f, 0.00049136745f, 0.00052329927f, 

  0.00055730621f, 0.00059352311f, 0.00063209358f, 0.00067317058f, 

  0.00071691700f, 0.00076350630f, 0.00081312324f, 0.00086596457f, 

  0.00092223983f, 0.00098217216f, 0.0010459992f,  0.0011139742f, 

  0.0011863665f,  0.0012634633f,  0.0013455702f,  0.0014330129f, 

  0.0015261382f,  0.0016253153f,  0.0017309374f,  0.0018434235f, 

  0.0019632195f,  0.0020908006f,  0.0022266726f,  0.0023713743f, 

  0.0025254795f,  0.0026895994f,  0.0028643847f,  0.0030505286f, 

  0.0032487691f,  0.0034598925f,  0.0036847358f,  0.0039241906f, 

  0.0041792066f,  0.0044507950f,  0.0047400328f,  0.0050480668f, 

  0.0053761186f,  0.0057254891f,  0.0060975636f,  0.0064938176f, 

  0.0069158225f,  0.0073652516f,  0.0078438871f,  0.0083536271f, 

  0.0088964928f,  0.009474637f,   0.010090352f,   0.010746080f, 

  0.011444421f,   0.012188144f,   0.012980198f,   0.013823725f, 

  0.014722068f,   0.015678791f,   0.016697687f,   0.017782797f, 

  0.018938423f,   0.020169149f,   0.021479854f,   0.022875735f, 

  0.024362330f,   0.025945531f,   0.027631618f,   0.029427276f, 

  0.031339626f,   0.033376252f,   0.035545228f,   0.037855157f, 

  0.040315199f,   0.042935108f,   0.045725273f,   0.048696758f, 

  0.051861348f,   0.055231591f,   0.058820850f,   0.062643361f, 

  0.066714279f,   0.071049749f,   0.075666962f,   0.080584227f, 

  0.085821044f,   0.091398179f,   0.097337747f,   0.10366330f, 

  0.11039993f,    0.11757434f,    0.12521498f,    0.13335215f, 

  0.14201813f,    0.15124727f,    0.16107617f,    0.17154380f, 

  0.18269168f,    0.19456402f,    0.20720788f,    0.22067342f, 

  0.23501402f,    0.25028656f,    0.26655159f,    0.28387361f, 

  0.30232132f,    0.32196786f,    0.34289114f,    0.36517414f, 

  0.38890521f,    0.41417847f,    0.44109412f,    0.46975890f, 

  0.50028648f,    0.53279791f,    0.56742212f,    0.60429640f, 

  0.64356699f,    0.68538959f,    0.72993007f,    0.77736504f, 

  0.82788260f,    0.88168307f,    0.9389798f,     1.0f

};





// @OPTIMIZE: if you want to replace this bresenham line-drawing routine,

// note that you must produce bit-identical output to decode correctly;

// this specific sequence of operations is specified in the spec (it's

// drawing integer-quantized frequency-space lines that the encoder

// expects to be exactly the same)

//     ... also, isn't the whole point of Bresenham's algorithm to NOT

// have to divide in the setup? sigh.

#ifndef STB_VORBIS_NO_DEFER_FLOOR

#define LINE_OP(a,b)   a *= b

#else

#define LINE_OP(a,b)   a = b

#endif



#ifdef STB_VORBIS_DIVIDE_TABLE

#define DIVTAB_NUMER   32

#define DIVTAB_DENOM   64

int8 integer_divide_table[DIVTAB_NUMER][DIVTAB_DENOM]; // 2KB

#endif



static __forceinline void draw_line(float *output, int x0, int y0, int x1, int y1, int n)

{

   int dy = y1 - y0;

   int adx = x1 - x0;

   int ady = abs(dy);

   int base;

   int x=x0,y=y0;

   int err = 0;

   int sy;



#ifdef STB_VORBIS_DIVIDE_TABLE

   if (adx < DIVTAB_DENOM && ady < DIVTAB_NUMER) {

      if (dy < 0) {

         base = -integer_divide_table[ady][adx];

         sy = base-1;

      } else {

         base =  integer_divide_table[ady][adx];

         sy = base+1;

      }

   } else {

      base = dy / adx;

      if (dy < 0)

         sy = base - 1;

      else

         sy = base+1;

   }

#else

   base = dy / adx;

   if (dy < 0)

      sy = base - 1;

   else

      sy = base+1;

#endif

   ady -= abs(base) * adx;

   if (x1 > n) x1 = n;

   LINE_OP(output[x], inverse_db_table[y]);

   for (++x; x < x1; ++x) {

      err += ady;

      if (err >= adx) {

         err -= adx;

         y += sy;

      } else

         y += base;

      LINE_OP(output[x], inverse_db_table[y]);

   }

}



static int residue_decode(vorb *f, Codebook *book, float *target, int offset, int n, int rtype)

{

   int k;

   if (rtype == 0) {

      int step = n / book->dimensions;

      for (k=0; k < step; ++k)

         if (!codebook_decode_step(f, book, target+offset+k, n-offset-k, step))

            return FALSE;

   } else {

      for (k=0; k < n; ) {

         if (!codebook_decode(f, book, target+offset, n-k))

            return FALSE;

         k += book->dimensions;

         offset += book->dimensions;

      }

   }

   return TRUE;

}



static void decode_residue(vorb *f, float *residue_buffers[], int ch, int n, int rn, uint8 *do_not_decode)

{

   int i,j,pass;

   Residue *r = f->residue_config + rn;

   int rtype = f->residue_types[rn];

   int c = r->classbook;

   int classwords = f->codebooks[c].dimensions;

   int n_read = r->end - r->begin;

   int part_read = n_read / r->part_size;

   int temp_alloc_point = temp_alloc_save(f);

   #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

   uint8 ***part_classdata = (uint8 ***) temp_block_array(f,f->channels, part_read * sizeof(**part_classdata));

   #else

   int **classifications = (int **) temp_block_array(f,f->channels, part_read * sizeof(**classifications));

   #endif



   stb_prof(2);

   for (i=0; i < ch; ++i)

      if (!do_not_decode[i])

         memset(residue_buffers[i], 0, sizeof(float) * n);



   if (rtype == 2 && ch != 1) {

      int len = ch * n;

      for (j=0; j < ch; ++j)

         if (!do_not_decode[j])

            break;

      if (j == ch)

         goto done;



      stb_prof(3);

      for (pass=0; pass < 8; ++pass) {

         int pcount = 0, class_set = 0;

         if (ch == 2) {

            stb_prof(13);

            while (pcount < part_read) {

               int z = r->begin + pcount*r->part_size;

               int c_inter = (z & 1), p_inter = z>>1;

               if (pass == 0) {

                  Codebook *c = f->codebooks+r->classbook;

                  int q;

                  DECODE(q,f,c);

                  if (q == EOP) goto done;

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  part_classdata[0][class_set] = r->classdata[q];

                  #else

                  for (i=classwords-1; i >= 0; --i) {

                     classifications[0][i+pcount] = q % r->classifications;

                     q /= r->classifications;

                  }

                  #endif

               }

               stb_prof(5);

               for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {

                  int z = r->begin + pcount*r->part_size;

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  int c = part_classdata[0][class_set][i];

                  #else

                  int c = classifications[0][pcount];

                  #endif

                  int b = r->residue_books[c][pass];

                  if (b >= 0) {

                     Codebook *book = f->codebooks + b;

                     stb_prof(20);  // accounts for X time

                     #ifdef STB_VORBIS_DIVIDES_IN_CODEBOOK

                     if (!codebook_decode_deinterleave_repeat(f, book, residue_buffers, ch, &c_inter, &p_inter, n, r->part_size))

                        goto done;

                     #else

                     // saves 1%

                     if (!codebook_decode_deinterleave_repeat_2(f, book, residue_buffers, &c_inter, &p_inter, n, r->part_size))

                        goto done;

                     #endif

                     stb_prof(7);

                  } else {

                     z += r->part_size;

                     c_inter = z & 1;

                     p_inter = z >> 1;

                  }

               }

               stb_prof(8);

               #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

               ++class_set;

               #endif

            }

         } else if (ch == 1) {

            while (pcount < part_read) {

               int z = r->begin + pcount*r->part_size;

               int c_inter = 0, p_inter = z;

               if (pass == 0) {

                  Codebook *c = f->codebooks+r->classbook;

                  int q;

                  DECODE(q,f,c);

                  if (q == EOP) goto done;

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  part_classdata[0][class_set] = r->classdata[q];

                  #else

                  for (i=classwords-1; i >= 0; --i) {

                     classifications[0][i+pcount] = q % r->classifications;

                     q /= r->classifications;

                  }

                  #endif

               }

               for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {

                  int z = r->begin + pcount*r->part_size;

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  int c = part_classdata[0][class_set][i];

                  #else

                  int c = classifications[0][pcount];

                  #endif

                  int b = r->residue_books[c][pass];

                  if (b >= 0) {

                     Codebook *book = f->codebooks + b;

                     stb_prof(22);

                     if (!codebook_decode_deinterleave_repeat(f, book, residue_buffers, ch, &c_inter, &p_inter, n, r->part_size))

                        goto done;

                     stb_prof(3);

                  } else {

                     z += r->part_size;

                     c_inter = 0;

                     p_inter = z;

                  }

               }

               #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

               ++class_set;

               #endif

            }

         } else {

            while (pcount < part_read) {

               int z = r->begin + pcount*r->part_size;

               int c_inter = z % ch, p_inter = z/ch;

               if (pass == 0) {

                  Codebook *c = f->codebooks+r->classbook;

                  int q;

                  DECODE(q,f,c);

                  if (q == EOP) goto done;

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  part_classdata[0][class_set] = r->classdata[q];

                  #else

                  for (i=classwords-1; i >= 0; --i) {

                     classifications[0][i+pcount] = q % r->classifications;

                     q /= r->classifications;

                  }

                  #endif

               }

               for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {

                  int z = r->begin + pcount*r->part_size;

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  int c = part_classdata[0][class_set][i];

                  #else

                  int c = classifications[0][pcount];

                  #endif

                  int b = r->residue_books[c][pass];

                  if (b >= 0) {

                     Codebook *book = f->codebooks + b;

                     stb_prof(22);

                     if (!codebook_decode_deinterleave_repeat(f, book, residue_buffers, ch, &c_inter, &p_inter, n, r->part_size))

                        goto done;

                     stb_prof(3);

                  } else {

                     z += r->part_size;

                     c_inter = z % ch;

                     p_inter = z / ch;

                  }

               }

               #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

               ++class_set;

               #endif

            }

         }

      }

      goto done;

   }

   stb_prof(9);



   for (pass=0; pass < 8; ++pass) {

      int pcount = 0, class_set=0;

      while (pcount < part_read) {

         if (pass == 0) {

            for (j=0; j < ch; ++j) {

               if (!do_not_decode[j]) {

                  Codebook *c = f->codebooks+r->classbook;

                  int temp;

                  DECODE(temp,f,c);

                  if (temp == EOP) goto done;

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  part_classdata[j][class_set] = r->classdata[temp];

                  #else

                  for (i=classwords-1; i >= 0; --i) {

                     classifications[j][i+pcount] = temp % r->classifications;

                     temp /= r->classifications;

                  }

                  #endif

               }

            }

         }

         for (i=0; i < classwords && pcount < part_read; ++i, ++pcount) {

            for (j=0; j < ch; ++j) {

               if (!do_not_decode[j]) {

                  #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

                  int c = part_classdata[j][class_set][i];

                  #else

                  int c = classifications[j][pcount];

                  #endif

                  int b = r->residue_books[c][pass];

                  if (b >= 0) {

                     float *target = residue_buffers[j];

                     int offset = r->begin + pcount * r->part_size;

                     int n = r->part_size;

                     Codebook *book = f->codebooks + b;

                     if (!residue_decode(f, book, target, offset, n, rtype))

                        goto done;

                  }

               }

            }

         }

         #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

         ++class_set;

         #endif

      }

   }

  done:

   stb_prof(0);

   temp_alloc_restore(f,temp_alloc_point);

}





#if 0

// slow way for debugging

void inverse_mdct_slow(float *buffer, int n)

{

   int i,j;

   int n2 = n >> 1;

   float *x = (float *) malloc(sizeof(*x) * n2);

   memcpy(x, buffer, sizeof(*x) * n2);

   for (i=0; i < n; ++i) {

      float acc = 0;

      for (j=0; j < n2; ++j)

         // formula from paper:

         //acc += n/4.0f * x[j] * (float) cos(M_PI / 2 / n * (2 * i + 1 + n/2.0)*(2*j+1));

         // formula from wikipedia

         //acc += 2.0f / n2 * x[j] * (float) cos(M_PI/n2 * (i + 0.5 + n2/2)*(j + 0.5));

         // these are equivalent, except the formula from the paper inverts the multiplier!

         // however, what actually works is NO MULTIPLIER!?!

         //acc += 64 * 2.0f / n2 * x[j] * (float) cos(M_PI/n2 * (i + 0.5 + n2/2)*(j + 0.5));

         acc += x[j] * (float) cos(M_PI / 2 / n * (2 * i + 1 + n/2.0)*(2*j+1));

      buffer[i] = acc;

   }

   free(x);

}

#elif 0

// same as above, but just barely able to run in real time on modern machines

void inverse_mdct_slow(float *buffer, int n, vorb *f, int blocktype)

{

   float mcos[16384];

   int i,j;

   int n2 = n >> 1, nmask = (n << 2) -1;

   float *x = (float *) malloc(sizeof(*x) * n2);

   memcpy(x, buffer, sizeof(*x) * n2);

   for (i=0; i < 4*n; ++i)

      mcos[i] = (float) cos(M_PI / 2 * i / n);



   for (i=0; i < n; ++i) {

      float acc = 0;

      for (j=0; j < n2; ++j)

         acc += x[j] * mcos[(2 * i + 1 + n2)*(2*j+1) & nmask];

      buffer[i] = acc;

   }

   free(x);

}

#else

// transform to use a slow dct-iv; this is STILL basically trivial,

// but only requires half as many ops

void dct_iv_slow(float *buffer, int n)

{

   float mcos[16384];

   float x[2048];

   int i,j;

   int n2 = n >> 1, nmask = (n << 3) - 1;

   memcpy(x, buffer, sizeof(*x) * n);

   for (i=0; i < 8*n; ++i)

      mcos[i] = (float) cos(M_PI / 4 * i / n);

   for (i=0; i < n; ++i) {

      float acc = 0;

      for (j=0; j < n; ++j)

         acc += x[j] * mcos[((2 * i + 1)*(2*j+1)) & nmask];

         //acc += x[j] * cos(M_PI / n * (i + 0.5) * (j + 0.5));

      buffer[i] = acc;

   }

   free(x);

}



void inverse_mdct_slow(float *buffer, int n, vorb *f, int blocktype)

{

   int i, n4 = n >> 2, n2 = n >> 1, n3_4 = n - n4;

   float temp[4096];



   memcpy(temp, buffer, n2 * sizeof(float));

   dct_iv_slow(temp, n2);  // returns -c'-d, a-b'



   for (i=0; i < n4  ; ++i) buffer[i] = temp[i+n4];            // a-b'

   for (   ; i < n3_4; ++i) buffer[i] = -temp[n3_4 - i - 1];   // b-a', c+d'

   for (   ; i < n   ; ++i) buffer[i] = -temp[i - n3_4];       // c'+d

}

#endif



#ifndef LIBVORBIS_MDCT

#define LIBVORBIS_MDCT 0

#endif



#if LIBVORBIS_MDCT

// directly call the vorbis MDCT using an interface documented

// by Jeff Roberts... useful for performance comparison

typedef struct 

{

  int n;

  int log2n;

  

  float *trig;

  int   *bitrev;



  float scale;

} mdct_lookup;



extern void mdct_init(mdct_lookup *lookup, int n);

extern void mdct_clear(mdct_lookup *l);

extern void mdct_backward(mdct_lookup *init, float *in, float *out);



mdct_lookup M1,M2;



void inverse_mdct(float *buffer, int n, vorb *f, int blocktype)

{

   mdct_lookup *M;

   if (M1.n == n) M = &M1;

   else if (M2.n == n) M = &M2;

   else if (M1.n == 0) { mdct_init(&M1, n); M = &M1; }

   else { 

      if (M2.n) __asm int 3;

      mdct_init(&M2, n);

      M = &M2;

   }



   mdct_backward(M, buffer, buffer);

}

#endif





// the following were split out into separate functions while optimizing;

// they could be pushed back up but eh. __forceinline showed no change;

// they're probably already being inlined.

static void imdct_step3_iter0_loop(int n, float *e, int i_off, int k_off, float *A)

{

   float *ee0 = e + i_off;

   float *ee2 = ee0 + k_off;

   int i;



   assert((n & 3) == 0);

   for (i=(n>>2); i > 0; --i) {

      float k00_20, k01_21;

      k00_20  = ee0[ 0] - ee2[ 0];

      k01_21  = ee0[-1] - ee2[-1];

      ee0[ 0] += ee2[ 0];//ee0[ 0] = ee0[ 0] + ee2[ 0];

      ee0[-1] += ee2[-1];//ee0[-1] = ee0[-1] + ee2[-1];

      ee2[ 0] = k00_20 * A[0] - k01_21 * A[1];

      ee2[-1] = k01_21 * A[0] + k00_20 * A[1];

      A += 8;



      k00_20  = ee0[-2] - ee2[-2];

      k01_21  = ee0[-3] - ee2[-3];

      ee0[-2] += ee2[-2];//ee0[-2] = ee0[-2] + ee2[-2];

      ee0[-3] += ee2[-3];//ee0[-3] = ee0[-3] + ee2[-3];

      ee2[-2] = k00_20 * A[0] - k01_21 * A[1];

      ee2[-3] = k01_21 * A[0] + k00_20 * A[1];

      A += 8;



      k00_20  = ee0[-4] - ee2[-4];

      k01_21  = ee0[-5] - ee2[-5];

      ee0[-4] += ee2[-4];//ee0[-4] = ee0[-4] + ee2[-4];

      ee0[-5] += ee2[-5];//ee0[-5] = ee0[-5] + ee2[-5];

      ee2[-4] = k00_20 * A[0] - k01_21 * A[1];

      ee2[-5] = k01_21 * A[0] + k00_20 * A[1];

      A += 8;



      k00_20  = ee0[-6] - ee2[-6];

      k01_21  = ee0[-7] - ee2[-7];

      ee0[-6] += ee2[-6];//ee0[-6] = ee0[-6] + ee2[-6];

      ee0[-7] += ee2[-7];//ee0[-7] = ee0[-7] + ee2[-7];

      ee2[-6] = k00_20 * A[0] - k01_21 * A[1];

      ee2[-7] = k01_21 * A[0] + k00_20 * A[1];

      A += 8;

      ee0 -= 8;

      ee2 -= 8;

   }

}



static void imdct_step3_inner_r_loop(int lim, float *e, int d0, int k_off, float *A, int k1)

{

   int i;

   float k00_20, k01_21;



   float *e0 = e + d0;

   float *e2 = e0 + k_off;



   for (i=lim >> 2; i > 0; --i) {

      k00_20 = e0[-0] - e2[-0];

      k01_21 = e0[-1] - e2[-1];

      e0[-0] += e2[-0];//e0[-0] = e0[-0] + e2[-0];

      e0[-1] += e2[-1];//e0[-1] = e0[-1] + e2[-1];

      e2[-0] = (k00_20)*A[0] - (k01_21) * A[1];

      e2[-1] = (k01_21)*A[0] + (k00_20) * A[1];



      A += k1;



      k00_20 = e0[-2] - e2[-2];

      k01_21 = e0[-3] - e2[-3];

      e0[-2] += e2[-2];//e0[-2] = e0[-2] + e2[-2];

      e0[-3] += e2[-3];//e0[-3] = e0[-3] + e2[-3];

      e2[-2] = (k00_20)*A[0] - (k01_21) * A[1];

      e2[-3] = (k01_21)*A[0] + (k00_20) * A[1];



      A += k1;



      k00_20 = e0[-4] - e2[-4];

      k01_21 = e0[-5] - e2[-5];

      e0[-4] += e2[-4];//e0[-4] = e0[-4] + e2[-4];

      e0[-5] += e2[-5];//e0[-5] = e0[-5] + e2[-5];

      e2[-4] = (k00_20)*A[0] - (k01_21) * A[1];

      e2[-5] = (k01_21)*A[0] + (k00_20) * A[1];



      A += k1;



      k00_20 = e0[-6] - e2[-6];

      k01_21 = e0[-7] - e2[-7];

      e0[-6] += e2[-6];//e0[-6] = e0[-6] + e2[-6];

      e0[-7] += e2[-7];//e0[-7] = e0[-7] + e2[-7];

      e2[-6] = (k00_20)*A[0] - (k01_21) * A[1];

      e2[-7] = (k01_21)*A[0] + (k00_20) * A[1];



      e0 -= 8;

      e2 -= 8;



      A += k1;

   }

}



static void imdct_step3_inner_s_loop(int n, float *e, int i_off, int k_off, float *A, int a_off, int k0)

{

   int i;

   float A0 = A[0];

   float A1 = A[0+1];

   float A2 = A[0+a_off];

   float A3 = A[0+a_off+1];

   float A4 = A[0+a_off*2+0];

   float A5 = A[0+a_off*2+1];

   float A6 = A[0+a_off*3+0];

   float A7 = A[0+a_off*3+1];



   float k00,k11;



   float *ee0 = e  +i_off;

   float *ee2 = ee0+k_off;



   for (i=n; i > 0; --i) {

      k00     = ee0[ 0] - ee2[ 0];

      k11     = ee0[-1] - ee2[-1];

      ee0[ 0] =  ee0[ 0] + ee2[ 0];

      ee0[-1] =  ee0[-1] + ee2[-1];

      ee2[ 0] = (k00) * A0 - (k11) * A1;

      ee2[-1] = (k11) * A0 + (k00) * A1;



      k00     = ee0[-2] - ee2[-2];

      k11     = ee0[-3] - ee2[-3];

      ee0[-2] =  ee0[-2] + ee2[-2];

      ee0[-3] =  ee0[-3] + ee2[-3];

      ee2[-2] = (k00) * A2 - (k11) * A3;

      ee2[-3] = (k11) * A2 + (k00) * A3;



      k00     = ee0[-4] - ee2[-4];

      k11     = ee0[-5] - ee2[-5];

      ee0[-4] =  ee0[-4] + ee2[-4];

      ee0[-5] =  ee0[-5] + ee2[-5];

      ee2[-4] = (k00) * A4 - (k11) * A5;

      ee2[-5] = (k11) * A4 + (k00) * A5;



      k00     = ee0[-6] - ee2[-6];

      k11     = ee0[-7] - ee2[-7];

      ee0[-6] =  ee0[-6] + ee2[-6];

      ee0[-7] =  ee0[-7] + ee2[-7];

      ee2[-6] = (k00) * A6 - (k11) * A7;

      ee2[-7] = (k11) * A6 + (k00) * A7;



      ee0 -= k0;

      ee2 -= k0;

   }

}



static __forceinline void iter_54(float *z)

{

   float k00,k11,k22,k33;

   float y0,y1,y2,y3;



   k00  = z[ 0] - z[-4];

   y0   = z[ 0] + z[-4];

   y2   = z[-2] + z[-6];

   k22  = z[-2] - z[-6];



   z[-0] = y0 + y2;      // z0 + z4 + z2 + z6

   z[-2] = y0 - y2;      // z0 + z4 - z2 - z6



   // done with y0,y2



   k33  = z[-3] - z[-7];



   z[-4] = k00 + k33;    // z0 - z4 + z3 - z7

   z[-6] = k00 - k33;    // z0 - z4 - z3 + z7



   // done with k33



   k11  = z[-1] - z[-5];

   y1   = z[-1] + z[-5];

   y3   = z[-3] + z[-7];



   z[-1] = y1 + y3;      // z1 + z5 + z3 + z7

   z[-3] = y1 - y3;      // z1 + z5 - z3 - z7

   z[-5] = k11 - k22;    // z1 - z5 + z2 - z6

   z[-7] = k11 + k22;    // z1 - z5 - z2 + z6

}



static void imdct_step3_inner_s_loop_ld654(int n, float *e, int i_off, float *A, int base_n)

{

   int k_off = -8;

   int a_off = base_n >> 3;

   float A2 = A[0+a_off];

   float *z = e + i_off;

   float *base = z - 16 * n;



   while (z > base) {

      float k00,k11;



      k00   = z[-0] - z[-8];

      k11   = z[-1] - z[-9];

      z[-0] = z[-0] + z[-8];

      z[-1] = z[-1] + z[-9];

      z[-8] =  k00;

      z[-9] =  k11 ;



      k00    = z[ -2] - z[-10];

      k11    = z[ -3] - z[-11];

      z[ -2] = z[ -2] + z[-10];

      z[ -3] = z[ -3] + z[-11];

      z[-10] = (k00+k11) * A2;

      z[-11] = (k11-k00) * A2;



      k00    = z[-12] - z[ -4];  // reverse to avoid a unary negation

      k11    = z[ -5] - z[-13];

      z[ -4] = z[ -4] + z[-12];

      z[ -5] = z[ -5] + z[-13];

      z[-12] = k11;

      z[-13] = k00;



      k00    = z[-14] - z[ -6];  // reverse to avoid a unary negation

      k11    = z[ -7] - z[-15];

      z[ -6] = z[ -6] + z[-14];

      z[ -7] = z[ -7] + z[-15];

      z[-14] = (k00+k11) * A2;

      z[-15] = (k00-k11) * A2;



      iter_54(z);

      iter_54(z-8);

      z -= 16;

   }

}



static void inverse_mdct(float *buffer, int n, vorb *f, int blocktype)

{

   int n2 = n >> 1, n4 = n >> 2, n8 = n >> 3, l;

   int n3_4 = n - n4, ld;

   // @OPTIMIZE: reduce register pressure by using fewer variables?

   int save_point = temp_alloc_save(f);

   float *buf2 = (float *) temp_alloc(f, n2 * sizeof(*buf2));

   float *u=NULL,*v=NULL;

   // twiddle factors

   float *A = f->A[blocktype];



   // IMDCT algorithm from "The use of multirate filter banks for coding of high quality digital audio"

   // See notes about bugs in that paper in less-optimal implementation 'inverse_mdct_old' after this function.



   // kernel from paper





   // merged:

   //   copy and reflect spectral data

   //   step 0



   // note that it turns out that the items added together during

   // this step are, in fact, being added to themselves (as reflected

   // by step 0). inexplicable inefficiency! this became obvious

   // once I combined the passes.



   // so there's a missing 'times 2' here (for adding X to itself).

   // this propogates through linearly to the end, where the numbers

   // are 1/2 too small, and need to be compensated for.



   {

      float *d,*e, *AA, *e_stop;

      d = &buf2[n2-2];

      AA = A;

      e = &buffer[0];

      e_stop = &buffer[n2];

      while (e != e_stop) {

         d[1] = (e[0] * AA[0] - e[2]*AA[1]);

         d[0] = (e[0] * AA[1] + e[2]*AA[0]);

         d -= 2;

         AA += 2;

         e += 4;

      }



      e = &buffer[n2-3];

      while (d >= buf2) {

         d[1] = (-e[2] * AA[0] - -e[0]*AA[1]);

         d[0] = (-e[2] * AA[1] + -e[0]*AA[0]);

         d -= 2;

         AA += 2;

         e -= 4;

      }

   }



   // now we use symbolic names for these, so that we can

   // possibly swap their meaning as we change which operations

   // are in place



   u = buffer;

   v = buf2;



   // step 2    (paper output is w, now u)

   // this could be in place, but the data ends up in the wrong

   // place... _somebody_'s got to swap it, so this is nominated

   {

      float *AA = &A[n2-8];

      float *d0,*d1, *e0, *e1;



      e0 = &v[n4];

      e1 = &v[0];



      d0 = &u[n4];

      d1 = &u[0];



      while (AA >= A) {

         float v40_20, v41_21;



         v41_21 = e0[1] - e1[1];

         v40_20 = e0[0] - e1[0];

         d0[1]  = e0[1] + e1[1];

         d0[0]  = e0[0] + e1[0];

         d1[1]  = v41_21*AA[4] - v40_20*AA[5];

         d1[0]  = v40_20*AA[4] + v41_21*AA[5];



         v41_21 = e0[3] - e1[3];

         v40_20 = e0[2] - e1[2];

         d0[3]  = e0[3] + e1[3];

         d0[2]  = e0[2] + e1[2];

         d1[3]  = v41_21*AA[0] - v40_20*AA[1];

         d1[2]  = v40_20*AA[0] + v41_21*AA[1];



         AA -= 8;



         d0 += 4;

         d1 += 4;

         e0 += 4;

         e1 += 4;

      }

   }



   // step 3

   ld = ilog(n) - 1; // ilog is off-by-one from normal definitions



   // optimized step 3:



   // the original step3 loop can be nested r inside s or s inside r;

   // it's written originally as s inside r, but this is dumb when r

   // iterates many times, and s few. So I have two copies of it and

   // switch between them halfway.



   // this is iteration 0 of step 3

   imdct_step3_iter0_loop(n >> 4, u, n2-1-n4*0, -(n >> 3), A);

   imdct_step3_iter0_loop(n >> 4, u, n2-1-n4*1, -(n >> 3), A);



   // this is iteration 1 of step 3

   imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*0, -(n >> 4), A, 16);

   imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*1, -(n >> 4), A, 16);

   imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*2, -(n >> 4), A, 16);

   imdct_step3_inner_r_loop(n >> 5, u, n2-1 - n8*3, -(n >> 4), A, 16);



   l=2;

   for (; l < (ld-3)>>1; ++l) {

      int k0 = n >> (l+2), k0_2 = k0>>1;

      int lim = 1 << (l+1);

      int i;

      for (i=0; i < lim; ++i)

         imdct_step3_inner_r_loop(n >> (l+4), u, n2-1 - k0*i, -k0_2, A, 1 << (l+3));

   }



   for (; l < ld-6; ++l) {

      int k0 = n >> (l+2), k1 = 1 << (l+3), k0_2 = k0>>1;

      int rlim = n >> (l+6), r;

      int lim = 1 << (l+1);

      int i_off;

      float *A0 = A;

      i_off = n2-1;

      for (r=rlim; r > 0; --r) {

         imdct_step3_inner_s_loop(lim, u, i_off, -k0_2, A0, k1, k0);

         A0 += k1*4;

         i_off -= 8;

      }

   }



   // iterations with count:

   //   ld-6,-5,-4 all interleaved together

   //       the big win comes from getting rid of needless flops

   //         due to the constants on pass 5 & 4 being all 1 and 0;

   //       combining them to be simultaneous to improve cache made little difference

   imdct_step3_inner_s_loop_ld654(n >> 5, u, n2-1, A, n);



   // output is u



   // step 4, 5, and 6

   // cannot be in-place because of step 5

   {

      uint16 *bitrev = f->bit_reverse[blocktype];

      // weirdly, I'd have thought reading sequentially and writing

      // erratically would have been better than vice-versa, but in

      // fact that's not what my testing showed. (That is, with

      // j = bitreverse(i), do you read i and write j, or read j and write i.)



      float *d0 = &v[n4-4];

      float *d1 = &v[n2-4];

      while (d0 >= v) {

         int k4;



         k4 = bitrev[0];

         d1[3] = u[k4+0];

         d1[2] = u[k4+1];

         d0[3] = u[k4+2];

         d0[2] = u[k4+3];



         k4 = bitrev[1];

         d1[1] = u[k4+0];

         d1[0] = u[k4+1];

         d0[1] = u[k4+2];

         d0[0] = u[k4+3];

         

         d0 -= 4;

         d1 -= 4;

         bitrev += 2;

      }

   }

   // (paper output is u, now v)





   // data must be in buf2

   assert(v == buf2);



   // step 7   (paper output is v, now v)

   // this is now in place

   {

      float *C = f->C[blocktype];

      float *d, *e;



      d = v;

      e = v + n2 - 4;



      while (d < e) {

         float a02,a11,b0,b1,b2,b3;



         a02 = d[0] - e[2];

         a11 = d[1] + e[3];



         b0 = C[1]*a02 + C[0]*a11;

         b1 = C[1]*a11 - C[0]*a02;



         b2 = d[0] + e[ 2];

         b3 = d[1] - e[ 3];



         d[0] = b2 + b0;

         d[1] = b3 + b1;

         e[2] = b2 - b0;

         e[3] = b1 - b3;



         a02 = d[2] - e[0];

         a11 = d[3] + e[1];



         b0 = C[3]*a02 + C[2]*a11;

         b1 = C[3]*a11 - C[2]*a02;



         b2 = d[2] + e[ 0];

         b3 = d[3] - e[ 1];



         d[2] = b2 + b0;

         d[3] = b3 + b1;

         e[0] = b2 - b0;

         e[1] = b1 - b3;



         C += 4;

         d += 4;

         e -= 4;

      }

   }



   // data must be in buf2





   // step 8+decode   (paper output is X, now buffer)

   // this generates pairs of data a la 8 and pushes them directly through

   // the decode kernel (pushing rather than pulling) to avoid having

   // to make another pass later



   // this cannot POSSIBLY be in place, so we refer to the buffers directly



   {

      float *d0,*d1,*d2,*d3;



      float *B = f->B[blocktype] + n2 - 8;

      float *e = buf2 + n2 - 8;

      d0 = &buffer[0];

      d1 = &buffer[n2-4];

      d2 = &buffer[n2];

      d3 = &buffer[n-4];

      while (e >= v) {

         float p0,p1,p2,p3;



         p3 =  e[6]*B[7] - e[7]*B[6];

         p2 = -e[6]*B[6] - e[7]*B[7]; 



         d0[0] =   p3;

         d1[3] = - p3;

         d2[0] =   p2;

         d3[3] =   p2;



         p1 =  e[4]*B[5] - e[5]*B[4];

         p0 = -e[4]*B[4] - e[5]*B[5]; 



         d0[1] =   p1;

         d1[2] = - p1;

         d2[1] =   p0;

         d3[2] =   p0;



         p3 =  e[2]*B[3] - e[3]*B[2];

         p2 = -e[2]*B[2] - e[3]*B[3]; 



         d0[2] =   p3;

         d1[1] = - p3;

         d2[2] =   p2;

         d3[1] =   p2;



         p1 =  e[0]*B[1] - e[1]*B[0];

         p0 = -e[0]*B[0] - e[1]*B[1]; 



         d0[3] =   p1;

         d1[0] = - p1;

         d2[3] =   p0;

         d3[0] =   p0;



         B -= 8;

         e -= 8;

         d0 += 4;

         d2 += 4;

         d1 -= 4;

         d3 -= 4;

      }

   }



   temp_alloc_restore(f,save_point);

}



#if 0

// this is the original version of the above code, if you want to optimize it from scratch

void inverse_mdct_naive(float *buffer, int n)

{

   float s;

   float A[1 << 12], B[1 << 12], C[1 << 11];

   int i,k,k2,k4, n2 = n >> 1, n4 = n >> 2, n8 = n >> 3, l;

   int n3_4 = n - n4, ld;

   // how can they claim this only uses N words?!

   // oh, because they're only used sparsely, whoops

   float u[1 << 13], X[1 << 13], v[1 << 13], w[1 << 13];

   // set up twiddle factors



   for (k=k2=0; k < n4; ++k,k2+=2) {

      A[k2  ] = (float)  cos(4*k*M_PI/n);

      A[k2+1] = (float) -sin(4*k*M_PI/n);

      B[k2  ] = (float)  cos((k2+1)*M_PI/n/2);

      B[k2+1] = (float)  sin((k2+1)*M_PI/n/2);

   }

   for (k=k2=0; k < n8; ++k,k2+=2) {

      C[k2  ] = (float)  cos(2*(k2+1)*M_PI/n);

      C[k2+1] = (float) -sin(2*(k2+1)*M_PI/n);

   }



   // IMDCT algorithm from "The use of multirate filter banks for coding of high quality digital audio"

   // Note there are bugs in that pseudocode, presumably due to them attempting

   // to rename the arrays nicely rather than representing the way their actual

   // implementation bounces buffers back and forth. As a result, even in the

   // "some formulars corrected" version, a direct implementation fails. These

   // are noted below as "paper bug".



   // copy and reflect spectral data

   for (k=0; k < n2; ++k) u[k] = buffer[k];

   for (   ; k < n ; ++k) u[k] = -buffer[n - k - 1];

   // kernel from paper

   // step 1

   for (k=k2=k4=0; k < n4; k+=1, k2+=2, k4+=4) {

      v[n-k4-1] = (u[k4] - u[n-k4-1]) * A[k2]   - (u[k4+2] - u[n-k4-3])*A[k2+1];

      v[n-k4-3] = (u[k4] - u[n-k4-1]) * A[k2+1] + (u[k4+2] - u[n-k4-3])*A[k2];

   }

   // step 2

   for (k=k4=0; k < n8; k+=1, k4+=4) {

      w[n2+3+k4] = v[n2+3+k4] + v[k4+3];

      w[n2+1+k4] = v[n2+1+k4] + v[k4+1];

      w[k4+3]    = (v[n2+3+k4] - v[k4+3])*A[n2-4-k4] - (v[n2+1+k4]-v[k4+1])*A[n2-3-k4];

      w[k4+1]    = (v[n2+1+k4] - v[k4+1])*A[n2-4-k4] + (v[n2+3+k4]-v[k4+3])*A[n2-3-k4];

   }

   // step 3

   ld = ilog(n) - 1; // ilog is off-by-one from normal definitions

   for (l=0; l < ld-3; ++l) {

      int k0 = n >> (l+2), k1 = 1 << (l+3);

      int rlim = n >> (l+4), r4, r;

      int s2lim = 1 << (l+2), s2;

      for (r=r4=0; r < rlim; r4+=4,++r) {

         for (s2=0; s2 < s2lim; s2+=2) {

            u[n-1-k0*s2-r4] = w[n-1-k0*s2-r4] + w[n-1-k0*(s2+1)-r4];

            u[n-3-k0*s2-r4] = w[n-3-k0*s2-r4] + w[n-3-k0*(s2+1)-r4];

            u[n-1-k0*(s2+1)-r4] = (w[n-1-k0*s2-r4] - w[n-1-k0*(s2+1)-r4]) * A[r*k1]

                                - (w[n-3-k0*s2-r4] - w[n-3-k0*(s2+1)-r4]) * A[r*k1+1];

            u[n-3-k0*(s2+1)-r4] = (w[n-3-k0*s2-r4] - w[n-3-k0*(s2+1)-r4]) * A[r*k1]

                                + (w[n-1-k0*s2-r4] - w[n-1-k0*(s2+1)-r4]) * A[r*k1+1];

         }

      }

      if (l+1 < ld-3) {

         // paper bug: ping-ponging of u&w here is omitted

         memcpy(w, u, sizeof(u));

      }

   }



   // step 4

   for (i=0; i < n8; ++i) {

      int j = bit_reverse(i) >> (32-ld+3);

      assert(j < n8);

      if (i == j) {

         // paper bug: original code probably swapped in place; if copying,

         //            need to directly copy in this case

         int i8 = i << 3;

         v[i8+1] = u[i8+1];

         v[i8+3] = u[i8+3];

         v[i8+5] = u[i8+5];

         v[i8+7] = u[i8+7];

      } else if (i < j) {

         int i8 = i << 3, j8 = j << 3;

         v[j8+1] = u[i8+1], v[i8+1] = u[j8 + 1];

         v[j8+3] = u[i8+3], v[i8+3] = u[j8 + 3];

         v[j8+5] = u[i8+5], v[i8+5] = u[j8 + 5];

         v[j8+7] = u[i8+7], v[i8+7] = u[j8 + 7];

      }

   }

   // step 5

   for (k=0; k < n2; ++k) {

      w[k] = v[k*2+1];

   }

   // step 6

   for (k=k2=k4=0; k < n8; ++k, k2 += 2, k4 += 4) {

      u[n-1-k2] = w[k4];

      u[n-2-k2] = w[k4+1];

      u[n3_4 - 1 - k2] = w[k4+2];

      u[n3_4 - 2 - k2] = w[k4+3];

   }

   // step 7

   for (k=k2=0; k < n8; ++k, k2 += 2) {

      v[n2 + k2 ] = ( u[n2 + k2] + u[n-2-k2] + C[k2+1]*(u[n2+k2]-u[n-2-k2]) + C[k2]*(u[n2+k2+1]+u[n-2-k2+1]))/2;

      v[n-2 - k2] = ( u[n2 + k2] + u[n-2-k2] - C[k2+1]*(u[n2+k2]-u[n-2-k2]) - C[k2]*(u[n2+k2+1]+u[n-2-k2+1]))/2;

      v[n2+1+ k2] = ( u[n2+1+k2] - u[n-1-k2] + C[k2+1]*(u[n2+1+k2]+u[n-1-k2]) - C[k2]*(u[n2+k2]-u[n-2-k2]))/2;

      v[n-1 - k2] = (-u[n2+1+k2] + u[n-1-k2] + C[k2+1]*(u[n2+1+k2]+u[n-1-k2]) - C[k2]*(u[n2+k2]-u[n-2-k2]))/2;

   }

   // step 8

   for (k=k2=0; k < n4; ++k,k2 += 2) {

      X[k]      = v[k2+n2]*B[k2  ] + v[k2+1+n2]*B[k2+1];

      X[n2-1-k] = v[k2+n2]*B[k2+1] - v[k2+1+n2]*B[k2  ];

   }



   // decode kernel to output

   // determined the following value experimentally

   // (by first figuring out what made inverse_mdct_slow work); then matching that here

   // (probably vorbis encoder premultiplies by n or n/2, to save it on the decoder?)

   s = 0.5; // theoretically would be n4



   // [[[ note! the s value of 0.5 is compensated for by the B[] in the current code,

   //     so it needs to use the "old" B values to behave correctly, or else

   //     set s to 1.0 ]]]

   for (i=0; i < n4  ; ++i) buffer[i] = s * X[i+n4];

   for (   ; i < n3_4; ++i) buffer[i] = -s * X[n3_4 - i - 1];

   for (   ; i < n   ; ++i) buffer[i] = -s * X[i - n3_4];

}

#endif



static float *get_window(vorb *f, int len)

{

   len <<= 1;

   if (len == f->blocksize_0) return f->window[0];

   if (len == f->blocksize_1) return f->window[1];

   assert(0);

   return NULL;

}



#ifndef STB_VORBIS_NO_DEFER_FLOOR

typedef int16 YTYPE;

#else

typedef int YTYPE;

#endif

static int do_floor(vorb *f, Mapping *map, int i, int n, float *target, YTYPE *finalY, uint8 *step2_flag)

{

   int n2 = n >> 1;

   int s = map->chan[i].mux, floor;

   floor = map->submap_floor[s];

   if (f->floor_types[floor] == 0) {

      return error(f, VORBIS_invalid_stream);

   } else {

      Floor1 *g = &f->floor_config[floor].floor1;

      int j,q;

      int lx = 0, ly = finalY[0] * g->floor1_multiplier;

      for (q=1; q < g->values; ++q) {

         j = g->sorted_order[q];

         #ifndef STB_VORBIS_NO_DEFER_FLOOR

         if (finalY[j] >= 0)

         #else

         if (step2_flag[j])

         #endif

         {

            int hy = finalY[j] * g->floor1_multiplier;

            int hx = g->Xlist[j];

            draw_line(target, lx,ly, hx,hy, n2);

            lx = hx, ly = hy;

         }

      }

      if (lx < n2)

         // optimization of: draw_line(target, lx,ly, n,ly, n2);

         for (j=lx; j < n2; ++j)

            LINE_OP(target[j], inverse_db_table[ly]);

   }

   return TRUE;

}



static int vorbis_decode_initial(vorb *f, int *p_left_start, int *p_left_end, int *p_right_start, int *p_right_end, int *mode)

{

   Mode *m;

   int i, n, prev, next, window_center;

   f->channel_buffer_start = f->channel_buffer_end = 0;



  retry:

   if (f->eof) return FALSE;

   if (!maybe_start_packet(f))

      return FALSE;

   // check packet type

   if (get_bits(f,1) != 0) {

      if (IS_PUSH_MODE(f))

         return error(f,VORBIS_bad_packet_type);

      while (EOP != get8_packet(f));

      goto retry;

   }



   if (f->alloc.alloc_buffer)

      assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);



   i = get_bits(f, ilog(f->mode_count-1));

   if (i == EOP) return FALSE;

   if (i >= f->mode_count) return FALSE;

   *mode = i;

   m = f->mode_config + i;

   if (m->blockflag) {

      n = f->blocksize_1;

      prev = get_bits(f,1);

      next = get_bits(f,1);

   } else {

      prev = next = 0;

      n = f->blocksize_0;

   }



// WINDOWING



   window_center = n >> 1;

   if (m->blockflag && !prev) {

      *p_left_start = (n - f->blocksize_0) >> 2;

      *p_left_end   = (n + f->blocksize_0) >> 2;

   } else {

      *p_left_start = 0;

      *p_left_end   = window_center;

   }

   if (m->blockflag && !next) {

      *p_right_start = (n*3 - f->blocksize_0) >> 2;

      *p_right_end   = (n*3 + f->blocksize_0) >> 2;

   } else {

      *p_right_start = window_center;

      *p_right_end   = n;

   }

   return TRUE;

}



static int vorbis_decode_packet_rest(vorb *f, int *len, Mode *m, int left_start, int left_end, int right_start, int right_end, int *p_left)

{

   Mapping *map;

   int i,j,k,n,n2;

   int zero_channel[256];

   int really_zero_channel[256];

   int window_center;



// WINDOWING



   n = f->blocksize[m->blockflag];

   window_center = n >> 1;



   map = &f->mapping[m->mapping];



// FLOORS

   n2 = n >> 1;



   stb_prof(1);

   for (i=0; i < f->channels; ++i) {

      int s = map->chan[i].mux, floor;

      zero_channel[i] = FALSE;

      floor = map->submap_floor[s];

      if (f->floor_types[floor] == 0) {

         return error(f, VORBIS_invalid_stream);

      } else {

         Floor1 *g = &f->floor_config[floor].floor1;

         if (get_bits(f, 1)) {

            short *finalY;

            uint8 step2_flag[256];

            static int range_list[4] = { 256, 128, 86, 64 };

            int range = range_list[g->floor1_multiplier-1];

            int offset = 2;

            finalY = f->finalY[i];

            finalY[0] = get_bits(f, ilog(range)-1);

            finalY[1] = get_bits(f, ilog(range)-1);

            for (j=0; j < g->partitions; ++j) {

               int pclass = g->partition_class_list[j];

               int cdim = g->class_dimensions[pclass];

               int cbits = g->class_subclasses[pclass];

               int csub = (1 << cbits)-1;

               int cval = 0;

               if (cbits) {

                  Codebook *c = f->codebooks + g->class_masterbooks[pclass];

                  DECODE(cval,f,c);

               }

               for (k=0; k < cdim; ++k) {

                  int book = g->subclass_books[pclass][cval & csub];

                  cval = cval >> cbits;

                  if (book >= 0) {

                     int temp;

                     Codebook *c = f->codebooks + book;

                     DECODE(temp,f,c);

                     finalY[offset++] = temp;

                  } else

                     finalY[offset++] = 0;

               }

            }

            if (f->valid_bits == INVALID_BITS) goto error; // behavior according to spec

            step2_flag[0] = step2_flag[1] = 1;

            for (j=2; j < g->values; ++j) {

               int low, high, pred, highroom, lowroom, room, val;

               low = g->neighbors[j][0];

               high = g->neighbors[j][1];

               //neighbors(g->Xlist, j, &low, &high);

               pred = predict_point(g->Xlist[j], g->Xlist[low], g->Xlist[high], finalY[low], finalY[high]);

               val = finalY[j];

               highroom = range - pred;

               lowroom = pred;

               if (highroom < lowroom)

                  room = highroom * 2;

               else

                  room = lowroom * 2;

               if (val) {

                  step2_flag[low] = step2_flag[high] = 1;

                  step2_flag[j] = 1;

                  if (val >= room)

                     if (highroom > lowroom)

                        finalY[j] = val - lowroom + pred;

                     else

                        finalY[j] = pred - val + highroom - 1;

                  else

                     if (val & 1)

                        finalY[j] = pred - ((val+1)>>1);

                     else

                        finalY[j] = pred + (val>>1);

               } else {

                  step2_flag[j] = 0;

                  finalY[j] = pred;

               }

            }



#ifdef STB_VORBIS_NO_DEFER_FLOOR

            do_floor(f, map, i, n, f->floor_buffers[i], finalY, step2_flag);

#else

            // defer final floor computation until _after_ residue

            for (j=0; j < g->values; ++j) {

               if (!step2_flag[j])

                  finalY[j] = -1;

            }

#endif

         } else {

           error:

            zero_channel[i] = TRUE;

         }

         // So we just defer everything else to later



         // at this point we've decoded the floor into buffer

      }

   }

   stb_prof(0);

   // at this point we've decoded all floors



   if (f->alloc.alloc_buffer)

      assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);



   // re-enable coupled channels if necessary

   memcpy(really_zero_channel, zero_channel, sizeof(really_zero_channel[0]) * f->channels);

   for (i=0; i < map->coupling_steps; ++i)

      if (!zero_channel[map->chan[i].magnitude] || !zero_channel[map->chan[i].angle]) {

         zero_channel[map->chan[i].magnitude] = zero_channel[map->chan[i].angle] = FALSE;

      }



// RESIDUE DECODE

   for (i=0; i < map->submaps; ++i) {

      float *residue_buffers[STB_VORBIS_MAX_CHANNELS];

      int r,t;

      uint8 do_not_decode[256];

      int ch = 0;

      for (j=0; j < f->channels; ++j) {

         if (map->chan[j].mux == i) {

            if (zero_channel[j]) {

               do_not_decode[ch] = TRUE;

               residue_buffers[ch] = NULL;

            } else {

               do_not_decode[ch] = FALSE;

               residue_buffers[ch] = f->channel_buffers[j];

            }

            ++ch;

         }

      }

      r = map->submap_residue[i];

      t = f->residue_types[r];

      decode_residue(f, residue_buffers, ch, n2, r, do_not_decode);

   }



   if (f->alloc.alloc_buffer)

      assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);



// INVERSE COUPLING

   stb_prof(14);

   for (i = map->coupling_steps-1; i >= 0; --i) {

      int n2 = n >> 1;

      float *m = f->channel_buffers[map->chan[i].magnitude];

      float *a = f->channel_buffers[map->chan[i].angle    ];

      for (j=0; j < n2; ++j) {

         float a2,m2;

         if (m[j] > 0)

            if (a[j] > 0)

               m2 = m[j], a2 = m[j] - a[j];

            else

               a2 = m[j], m2 = m[j] + a[j];

         else

            if (a[j] > 0)

               m2 = m[j], a2 = m[j] + a[j];

            else

               a2 = m[j], m2 = m[j] - a[j];

         m[j] = m2;

         a[j] = a2;

      }

   }



   // finish decoding the floors

#ifndef STB_VORBIS_NO_DEFER_FLOOR

   stb_prof(15);

   for (i=0; i < f->channels; ++i) {

      if (really_zero_channel[i]) {

         memset(f->channel_buffers[i], 0, sizeof(*f->channel_buffers[i]) * n2);

      } else {

         do_floor(f, map, i, n, f->channel_buffers[i], f->finalY[i], NULL);

      }

   }

#else

   for (i=0; i < f->channels; ++i) {

      if (really_zero_channel[i]) {

         memset(f->channel_buffers[i], 0, sizeof(*f->channel_buffers[i]) * n2);

      } else {

         for (j=0; j < n2; ++j)

            f->channel_buffers[i][j] *= f->floor_buffers[i][j];

      }

   }

#endif



// INVERSE MDCT

   stb_prof(16);

   for (i=0; i < f->channels; ++i)

      inverse_mdct(f->channel_buffers[i], n, f, m->blockflag);

   stb_prof(0);



   // this shouldn't be necessary, unless we exited on an error

   // and want to flush to get to the next packet

   flush_packet(f);



   if (f->first_decode) {

      // assume we start so first non-discarded sample is sample 0

      // this isn't to spec, but spec would require us to read ahead

      // and decode the size of all current frames--could be done,

      // but presumably it's not a commonly used feature

      f->current_loc = -n2; // start of first frame is positioned for discard

      // we might have to discard samples "from" the next frame too,

      // if we're lapping a large block then a small at the start?

      f->discard_samples_deferred = n - right_end;

      f->current_loc_valid = TRUE;

      f->first_decode = FALSE;

   } else if (f->discard_samples_deferred) {

      left_start += f->discard_samples_deferred;

      *p_left = left_start;

      f->discard_samples_deferred = 0;

   } else if (f->previous_length == 0 && f->current_loc_valid) {

      // we're recovering from a seek... that means we're going to discard

      // the samples from this packet even though we know our position from

      // the last page header, so we need to update the position based on

      // the discarded samples here

      // but wait, the code below is going to add this in itself even

      // on a discard, so we don't need to do it here...

   }



   // check if we have ogg information about the sample # for this packet

   if (f->last_seg_which == f->end_seg_with_known_loc) {

      // if we have a valid current loc, and this is final:

      if (f->current_loc_valid && (f->page_flag & PAGEFLAG_last_page)) {

         uint32 current_end = f->known_loc_for_packet - (n-right_end);

         // then let's infer the size of the (probably) short final frame

         if (current_end < f->current_loc + right_end) {

            if (current_end < f->current_loc) {

               // negative truncation, that's impossible!

               *len = 0;

            } else {

               *len = current_end - f->current_loc;

            }

            *len += left_start;

            f->current_loc += *len;

            return TRUE;

         }

      }

      // otherwise, just set our sample loc

      // guess that the ogg granule pos refers to the _middle_ of the

      // last frame?

      // set f->current_loc to the position of left_start

      f->current_loc = f->known_loc_for_packet - (n2-left_start);

      f->current_loc_valid = TRUE;

   }

   if (f->current_loc_valid)

      f->current_loc += (right_start - left_start);



   if (f->alloc.alloc_buffer)

      assert(f->alloc.alloc_buffer_length_in_bytes == f->temp_offset);

   *len = right_end;  // ignore samples after the window goes to 0

   return TRUE;

}



static int vorbis_decode_packet(vorb *f, int *len, int *p_left, int *p_right)

{

   int mode, left_end, right_end;

   if (!vorbis_decode_initial(f, p_left, &left_end, p_right, &right_end, &mode)) return 0;

   return vorbis_decode_packet_rest(f, len, f->mode_config + mode, *p_left, left_end, *p_right, right_end, p_left);

}



static int vorbis_finish_frame(stb_vorbis *f, int len, int left, int right)

{

   int prev,i,j;

   // we use right&left (the start of the right- and left-window sin()-regions)

   // to determine how much to return, rather than inferring from the rules

   // (same result, clearer code); 'left' indicates where our sin() window

   // starts, therefore where the previous window's right edge starts, and

   // therefore where to start mixing from the previous buffer. 'right'

   // indicates where our sin() ending-window starts, therefore that's where

   // we start saving, and where our returned-data ends.



   // mixin from previous window

   if (f->previous_length) {

      int i,j, n = f->previous_length;

      float *w = get_window(f, n);

      for (i=0; i < f->channels; ++i) {

         for (j=0; j < n; ++j)

            f->channel_buffers[i][left+j] =

               f->channel_buffers[i][left+j]*w[    j] +

               f->previous_window[i][     j]*w[n-1-j];

      }

   }



   prev = f->previous_length;



   // last half of this data becomes previous window

   f->previous_length = len - right;



   // @OPTIMIZE: could avoid this copy by double-buffering the

   // output (flipping previous_window with channel_buffers), but

   // then previous_window would have to be 2x as large, and

   // channel_buffers couldn't be temp mem (although they're NOT

   // currently temp mem, they could be (unless we want to level

   // performance by spreading out the computation))

   for (i=0; i < f->channels; ++i)

      for (j=0; right+j < len; ++j)

         f->previous_window[i][j] = f->channel_buffers[i][right+j];



   if (!prev)

      // there was no previous packet, so this data isn't valid...

      // this isn't entirely true, only the would-have-overlapped data

      // isn't valid, but this seems to be what the spec requires

      return 0;



   // truncate a short frame

   if (len < right) right = len;



   f->samples_output += right-left;



   return right - left;

}



static void vorbis_pump_first_frame(stb_vorbis *f)

{

   int len, right, left;

   if (vorbis_decode_packet(f, &len, &left, &right))

      vorbis_finish_frame(f, len, left, right);

}



#ifndef STB_VORBIS_NO_PUSHDATA_API

static int is_whole_packet_present(stb_vorbis *f, int end_page)

{

   // make sure that we have the packet available before continuing...

   // this requires a full ogg parse, but we know we can fetch from f->stream



   // instead of coding this out explicitly, we could save the current read state,

   // read the next packet with get8() until end-of-packet, check f->eof, then

   // reset the state? but that would be slower, esp. since we'd have over 256 bytes

   // of state to restore (primarily the page segment table)



   int s = f->next_seg, first = TRUE;

   uint8 *p = f->stream;



   if (s != -1) { // if we're not starting the packet with a 'continue on next page' flag

      for (; s < f->segment_count; ++s) {

         p += f->segments[s];

         if (f->segments[s] < 255)               // stop at first short segment

            break;

      }

      // either this continues, or it ends it...

      if (end_page)

         if (s < f->segment_count-1)             return error(f, VORBIS_invalid_stream);

      if (s == f->segment_count)

         s = -1; // set 'crosses page' flag

      if (p > f->stream_end)                     return error(f, VORBIS_need_more_data);

      first = FALSE;

   }

   for (; s == -1;) {

      uint8 *q; 

      int n;



      // check that we have the page header ready

      if (p + 26 >= f->stream_end)               return error(f, VORBIS_need_more_data);

      // validate the page

      if (memcmp(p, ogg_page_header, 4))         return error(f, VORBIS_invalid_stream);

      if (p[4] != 0)                             return error(f, VORBIS_invalid_stream);

      if (first) { // the first segment must NOT have 'continued_packet', later ones MUST

         if (f->previous_length)

            if ((p[5] & PAGEFLAG_continued_packet))  return error(f, VORBIS_invalid_stream);

         // if no previous length, we're resynching, so we can come in on a continued-packet,

         // which we'll just drop

      } else {

         if (!(p[5] & PAGEFLAG_continued_packet)) return error(f, VORBIS_invalid_stream);

      }

      n = p[26]; // segment counts

      q = p+27;  // q points to segment table

      p = q + n; // advance past header

      // make sure we've read the segment table

      if (p > f->stream_end)                     return error(f, VORBIS_need_more_data);

      for (s=0; s < n; ++s) {

         p += q[s];

         if (q[s] < 255)

            break;

      }

      if (end_page)

         if (s < n-1)                            return error(f, VORBIS_invalid_stream);

      if (s == f->segment_count)

         s = -1; // set 'crosses page' flag

      if (p > f->stream_end)                     return error(f, VORBIS_need_more_data);

      first = FALSE;

   }

   return TRUE;

}

#endif // !STB_VORBIS_NO_PUSHDATA_API



static int start_decoder(vorb *f)

{

   uint8 header[6], x,y;

   int len,i,j,k, max_submaps = 0;

   int longest_floorlist=0;



   // first page, first packet



   if (!start_page(f))                              return FALSE;

   // validate page flag

   if (!(f->page_flag & PAGEFLAG_first_page))       return error(f, VORBIS_invalid_first_page);

   if (f->page_flag & PAGEFLAG_last_page)           return error(f, VORBIS_invalid_first_page);

   if (f->page_flag & PAGEFLAG_continued_packet)    return error(f, VORBIS_invalid_first_page);

   // check for expected packet length

   if (f->segment_count != 1)                       return error(f, VORBIS_invalid_first_page);

   if (f->segments[0] != 30)                        return error(f, VORBIS_invalid_first_page);

   // read packet

   // check packet header

   if (get8(f) != VORBIS_packet_id)                 return error(f, VORBIS_invalid_first_page);

   if (!getn(f, header, 6))                         return error(f, VORBIS_unexpected_eof);

   if (!vorbis_validate(header))                    return error(f, VORBIS_invalid_first_page);

   // vorbis_version

   if (get32(f) != 0)                               return error(f, VORBIS_invalid_first_page);

   f->channels = get8(f); if (!f->channels)         return error(f, VORBIS_invalid_first_page);

   if (f->channels > STB_VORBIS_MAX_CHANNELS)       return error(f, VORBIS_too_many_channels);

   f->sample_rate = get32(f); if (!f->sample_rate)  return error(f, VORBIS_invalid_first_page);

   get32(f); // bitrate_maximum

   get32(f); // bitrate_nominal

   get32(f); // bitrate_minimum

   x = get8(f);

   { int log0,log1;

   log0 = x & 15;

   log1 = x >> 4;

   f->blocksize_0 = 1 << log0;

   f->blocksize_1 = 1 << log1;

   if (log0 < 6 || log0 > 13)                       return error(f, VORBIS_invalid_setup);

   if (log1 < 6 || log1 > 13)                       return error(f, VORBIS_invalid_setup);

   if (log0 > log1)                                 return error(f, VORBIS_invalid_setup);

   }



   // framing_flag

   x = get8(f);

   if (!(x & 1))                                    return error(f, VORBIS_invalid_first_page);



   // second packet!

   if (!start_page(f))                              return FALSE;



   if (!start_packet(f))                            return FALSE;

   do {

      len = next_segment(f);

      skip(f, len);

      f->bytes_in_seg = 0;

   } while (len);



   // third packet!

   if (!start_packet(f))                            return FALSE;



   #ifndef STB_VORBIS_NO_PUSHDATA_API

   if (IS_PUSH_MODE(f)) {

      if (!is_whole_packet_present(f, TRUE)) {

         // convert error in ogg header to write type

         if (f->error == VORBIS_invalid_stream)

            f->error = VORBIS_invalid_setup;

         return FALSE;

      }

   }

   #endif



   crc32_init(); // always init it, to avoid multithread race conditions



   if (get8_packet(f) != VORBIS_packet_setup)       return error(f, VORBIS_invalid_setup);

   for (i=0; i < 6; ++i) header[i] = get8_packet(f);

   if (!vorbis_validate(header))                    return error(f, VORBIS_invalid_setup);



   // codebooks



   f->codebook_count = get_bits(f,8) + 1;

   f->codebooks = (Codebook *) setup_malloc(f, sizeof(*f->codebooks) * f->codebook_count);

   if (f->codebooks == NULL)                        return error(f, VORBIS_outofmem);

   memset(f->codebooks, 0, sizeof(*f->codebooks) * f->codebook_count);

   for (i=0; i < f->codebook_count; ++i) {

      uint32 *values;

      int ordered, sorted_count;

      int total=0;

      uint8 *lengths;

      Codebook *c = f->codebooks+i;

      x = get_bits(f, 8); if (x != 0x42)            return error(f, VORBIS_invalid_setup);

      x = get_bits(f, 8); if (x != 0x43)            return error(f, VORBIS_invalid_setup);

      x = get_bits(f, 8); if (x != 0x56)            return error(f, VORBIS_invalid_setup);

      x = get_bits(f, 8);

      c->dimensions = (get_bits(f, 8)<<8) + x;

      x = get_bits(f, 8);

      y = get_bits(f, 8);

      c->entries = (get_bits(f, 8)<<16) + (y<<8) + x;

      ordered = get_bits(f,1);

      c->sparse = ordered ? 0 : get_bits(f,1);



      if (c->sparse)

         lengths = (uint8 *) setup_temp_malloc(f, c->entries);

      else

         lengths = c->codeword_lengths = (uint8 *) setup_malloc(f, c->entries);



      if (!lengths) return error(f, VORBIS_outofmem);



      if (ordered) {

         int current_entry = 0;

         int current_length = get_bits(f,5) + 1;

         while (current_entry < c->entries) {

            int limit = c->entries - current_entry;

            int n = get_bits(f, ilog(limit));

            if (current_entry + n > (int) c->entries) { return error(f, VORBIS_invalid_setup); }

            memset(lengths + current_entry, current_length, n);

            current_entry += n;

            ++current_length;

         }

      } else {

         for (j=0; j < c->entries; ++j) {

            int present = c->sparse ? get_bits(f,1) : 1;

            if (present) {

               lengths[j] = get_bits(f, 5) + 1;

               ++total;

            } else {

               lengths[j] = NO_CODE;

            }

         }

      }



      if (c->sparse && total >= c->entries >> 2) {

         // convert sparse items to non-sparse!

         if (c->entries > (int) f->setup_temp_memory_required)

            f->setup_temp_memory_required = c->entries;



         c->codeword_lengths = (uint8 *) setup_malloc(f, c->entries);

         memcpy(c->codeword_lengths, lengths, c->entries);

         setup_temp_free(f, lengths, c->entries); // note this is only safe if there have been no intervening temp mallocs!

         lengths = c->codeword_lengths;

         c->sparse = 0;

      }



      // compute the size of the sorted tables

      if (c->sparse) {

         sorted_count = total;

         //assert(total != 0);

      } else {

         sorted_count = 0;

         #ifndef STB_VORBIS_NO_HUFFMAN_BINARY_SEARCH

         for (j=0; j < c->entries; ++j)

            if (lengths[j] > STB_VORBIS_FAST_HUFFMAN_LENGTH && lengths[j] != NO_CODE)

               ++sorted_count;

         #endif

      }



      c->sorted_entries = sorted_count;

      values = NULL;



      if (!c->sparse) {

         c->codewords = (uint32 *) setup_malloc(f, sizeof(c->codewords[0]) * c->entries);

         if (!c->codewords)                  return error(f, VORBIS_outofmem);

      } else {

         unsigned int size;

         if (c->sorted_entries) {

            c->codeword_lengths = (uint8 *) setup_malloc(f, c->sorted_entries);

            if (!c->codeword_lengths)           return error(f, VORBIS_outofmem);

            c->codewords = (uint32 *) setup_temp_malloc(f, sizeof(*c->codewords) * c->sorted_entries);

            if (!c->codewords)                  return error(f, VORBIS_outofmem);

            values = (uint32 *) setup_temp_malloc(f, sizeof(*values) * c->sorted_entries);

            if (!values)                        return error(f, VORBIS_outofmem);

         }

         size = c->entries + (sizeof(*c->codewords) + sizeof(*values)) * c->sorted_entries;

         if (size > f->setup_temp_memory_required)

            f->setup_temp_memory_required = size;

      }



      if (!compute_codewords(c, lengths, c->entries, values)) {

         if (c->sparse) setup_temp_free(f, values, 0);

         return error(f, VORBIS_invalid_setup);

      }



      if (c->sorted_entries) {

         // allocate an extra slot for sentinels

         c->sorted_codewords = (uint32 *) setup_malloc(f, sizeof(*c->sorted_codewords) * (c->sorted_entries+1));

         // allocate an extra slot at the front so that c->sorted_values[-1] is defined

         // so that we can catch that case without an extra if

         c->sorted_values    = ( int   *) setup_malloc(f, sizeof(*c->sorted_values   ) * (c->sorted_entries+1));

         if (c->sorted_values) { ++c->sorted_values; c->sorted_values[-1] = -1; }

         compute_sorted_huffman(c, lengths, values);

      }



      if (c->sparse) {

         setup_temp_free(f, values, sizeof(*values)*c->sorted_entries);

         setup_temp_free(f, c->codewords, sizeof(*c->codewords)*c->sorted_entries);

         setup_temp_free(f, lengths, c->entries);

         c->codewords = NULL;

      }



      compute_accelerated_huffman(c);



      c->lookup_type = get_bits(f, 4);

      if (c->lookup_type > 2) return error(f, VORBIS_invalid_setup);

      if (c->lookup_type > 0) {

         uint16 *mults;

         c->minimum_value = float32_unpack(get_bits(f, 32));

         c->delta_value = float32_unpack(get_bits(f, 32));

         c->value_bits = get_bits(f, 4)+1;

         c->sequence_p = get_bits(f,1);

         if (c->lookup_type == 1) {

            c->lookup_values = lookup1_values(c->entries, c->dimensions);

         } else {

            c->lookup_values = c->entries * c->dimensions;

         }

         mults = (uint16 *) setup_temp_malloc(f, sizeof(mults[0]) * c->lookup_values);

         if (mults == NULL) return error(f, VORBIS_outofmem);

         for (j=0; j < (int) c->lookup_values; ++j) {

            int q = get_bits(f, c->value_bits);

            if (q == EOP) { setup_temp_free(f,mults,sizeof(mults[0])*c->lookup_values); return error(f, VORBIS_invalid_setup); }

            mults[j] = q;

         }



#ifndef STB_VORBIS_DIVIDES_IN_CODEBOOK

         if (c->lookup_type == 1) {

            int len, sparse = c->sparse;

            // pre-expand the lookup1-style multiplicands, to avoid a divide in the inner loop

            if (sparse) {

               if (c->sorted_entries == 0) goto skip;

               c->multiplicands = (codetype *) setup_malloc(f, sizeof(c->multiplicands[0]) * c->sorted_entries * c->dimensions);

            } else

               c->multiplicands = (codetype *) setup_malloc(f, sizeof(c->multiplicands[0]) * c->entries        * c->dimensions);

            if (c->multiplicands == NULL) { setup_temp_free(f,mults,sizeof(mults[0])*c->lookup_values); return error(f, VORBIS_outofmem); }

            len = sparse ? c->sorted_entries : c->entries;

            for (j=0; j < len; ++j) {

               int z = sparse ? c->sorted_values[j] : j, div=1;

               for (k=0; k < c->dimensions; ++k) {

                  int off = (z / div) % c->lookup_values;

                  c->multiplicands[j*c->dimensions + k] =

                         #ifndef STB_VORBIS_CODEBOOK_FLOATS

                            mults[off];

                         #else

                            mults[off]*c->delta_value + c->minimum_value;

                            // in this case (and this case only) we could pre-expand c->sequence_p,

                            // and throw away the decode logic for it; have to ALSO do

                            // it in the case below, but it can only be done if

                            //    STB_VORBIS_CODEBOOK_FLOATS

                            //   !STB_VORBIS_DIVIDES_IN_CODEBOOK

                         #endif

                  div *= c->lookup_values;

               }

            }

            setup_temp_free(f, mults,sizeof(mults[0])*c->lookup_values);

            c->lookup_type = 2;

         }

         else

#endif

         {

            c->multiplicands = (codetype *) setup_malloc(f, sizeof(c->multiplicands[0]) * c->lookup_values);

            #ifndef STB_VORBIS_CODEBOOK_FLOATS

            memcpy(c->multiplicands, mults, sizeof(c->multiplicands[0]) * c->lookup_values);

            #else

            for (j=0; j < (int) c->lookup_values; ++j)

               c->multiplicands[j] = mults[j] * c->delta_value + c->minimum_value;

            setup_temp_free(f, mults,sizeof(mults[0])*c->lookup_values);

            #endif

         }

        skip:;



         #ifdef STB_VORBIS_CODEBOOK_FLOATS

         if (c->lookup_type == 2 && c->sequence_p) {

            for (j=1; j < (int) c->lookup_values; ++j)

               c->multiplicands[j] = c->multiplicands[j-1];

            c->sequence_p = 0;

         }

         #endif

      }

   }



   // time domain transfers (notused)



   x = get_bits(f, 6) + 1;

   for (i=0; i < x; ++i) {

      uint32 z = get_bits(f, 16);

      if (z != 0) return error(f, VORBIS_invalid_setup);

   }



   // Floors

   f->floor_count = get_bits(f, 6)+1;

   f->floor_config = (Floor *)  setup_malloc(f, f->floor_count * sizeof(*f->floor_config));

   for (i=0; i < f->floor_count; ++i) {

      f->floor_types[i] = get_bits(f, 16);

      if (f->floor_types[i] > 1) return error(f, VORBIS_invalid_setup);

      if (f->floor_types[i] == 0) {

         Floor0 *g = &f->floor_config[i].floor0;

         g->order = get_bits(f,8);

         g->rate = get_bits(f,16);

         g->bark_map_size = get_bits(f,16);

         g->amplitude_bits = get_bits(f,6);

         g->amplitude_offset = get_bits(f,8);

         g->number_of_books = get_bits(f,4) + 1;

         for (j=0; j < g->number_of_books; ++j)

            g->book_list[j] = get_bits(f,8);

         return error(f, VORBIS_feature_not_supported);

      } else {

         Point p[31*8+2];

         Floor1 *g = &f->floor_config[i].floor1;

         int max_class = -1; 

         g->partitions = get_bits(f, 5);

         for (j=0; j < g->partitions; ++j) {

            g->partition_class_list[j] = get_bits(f, 4);

            if (g->partition_class_list[j] > max_class)

               max_class = g->partition_class_list[j];

         }

         for (j=0; j <= max_class; ++j) {

            g->class_dimensions[j] = get_bits(f, 3)+1;

            g->class_subclasses[j] = get_bits(f, 2);

            if (g->class_subclasses[j]) {

               g->class_masterbooks[j] = get_bits(f, 8);

               if (g->class_masterbooks[j] >= f->codebook_count) return error(f, VORBIS_invalid_setup);

            }

            for (k=0; k < 1 << g->class_subclasses[j]; ++k) {

               g->subclass_books[j][k] = get_bits(f,8)-1;

               if (g->subclass_books[j][k] >= f->codebook_count) return error(f, VORBIS_invalid_setup);

            }

         }

         g->floor1_multiplier = get_bits(f,2)+1;

         g->rangebits = get_bits(f,4);

         g->Xlist[0] = 0;

         g->Xlist[1] = 1 << g->rangebits;

         g->values = 2;

         for (j=0; j < g->partitions; ++j) {

            int c = g->partition_class_list[j];

            for (k=0; k < g->class_dimensions[c]; ++k) {

               g->Xlist[g->values] = get_bits(f, g->rangebits);

               ++g->values;

            }

         }

         // precompute the sorting

         for (j=0; j < g->values; ++j) {

            p[j].x = g->Xlist[j];

            p[j].y = j;

         }

         qsort(p, g->values, sizeof(p[0]), point_compare);

         for (j=0; j < g->values; ++j)

            g->sorted_order[j] = (uint8) p[j].y;

         // precompute the neighbors

         for (j=2; j < g->values; ++j) {

            int low,hi;

            neighbors(g->Xlist, j, &low,&hi);

            g->neighbors[j][0] = low;

            g->neighbors[j][1] = hi;

         }



         if (g->values > longest_floorlist)

            longest_floorlist = g->values;

      }

   }



   // Residue

   f->residue_count = get_bits(f, 6)+1;

   f->residue_config = (Residue *) setup_malloc(f, f->residue_count * sizeof(*f->residue_config));

   for (i=0; i < f->residue_count; ++i) {

      uint8 residue_cascade[64];

      Residue *r = f->residue_config+i;

      f->residue_types[i] = get_bits(f, 16);

      if (f->residue_types[i] > 2) return error(f, VORBIS_invalid_setup);

      r->begin = get_bits(f, 24);

      r->end = get_bits(f, 24);

      r->part_size = get_bits(f,24)+1;

      r->classifications = get_bits(f,6)+1;

      r->classbook = get_bits(f,8);

      for (j=0; j < r->classifications; ++j) {

         uint8 high_bits=0;

         uint8 low_bits=get_bits(f,3);

         if (get_bits(f,1))

            high_bits = get_bits(f,5);

         residue_cascade[j] = high_bits*8 + low_bits;

      }

      r->residue_books = (short (*)[8]) setup_malloc(f, sizeof(r->residue_books[0]) * r->classifications);

      for (j=0; j < r->classifications; ++j) {

         for (k=0; k < 8; ++k) {

            if (residue_cascade[j] & (1 << k)) {

               r->residue_books[j][k] = get_bits(f, 8);

               if (r->residue_books[j][k] >= f->codebook_count) return error(f, VORBIS_invalid_setup);

            } else {

               r->residue_books[j][k] = -1;

            }

         }

      }

      // precompute the classifications[] array to avoid inner-loop mod/divide

      // call it 'classdata' since we already have r->classifications

      r->classdata = (uint8 **) setup_malloc(f, sizeof(*r->classdata) * f->codebooks[r->classbook].entries);

      if (!r->classdata) return error(f, VORBIS_outofmem);

      memset(r->classdata, 0, sizeof(*r->classdata) * f->codebooks[r->classbook].entries);

      for (j=0; j < f->codebooks[r->classbook].entries; ++j) {

         int classwords = f->codebooks[r->classbook].dimensions;

         int temp = j;

         r->classdata[j] = (uint8 *) setup_malloc(f, sizeof(r->classdata[j][0]) * classwords);

         for (k=classwords-1; k >= 0; --k) {

            r->classdata[j][k] = temp % r->classifications;

            temp /= r->classifications;

         }

      }

   }



   f->mapping_count = get_bits(f,6)+1;

   f->mapping = (Mapping *) setup_malloc(f, f->mapping_count * sizeof(*f->mapping));

   for (i=0; i < f->mapping_count; ++i) {

      Mapping *m = f->mapping + i;      

      int mapping_type = get_bits(f,16);

      if (mapping_type != 0) return error(f, VORBIS_invalid_setup);

      m->chan = (MappingChannel *) setup_malloc(f, f->channels * sizeof(*m->chan));

      if (get_bits(f,1))

         m->submaps = get_bits(f,4);

      else

         m->submaps = 1;

      if (m->submaps > max_submaps)

         max_submaps = m->submaps;

      if (get_bits(f,1)) {

         m->coupling_steps = get_bits(f,8)+1;

         for (k=0; k < m->coupling_steps; ++k) {

            m->chan[k].magnitude = get_bits(f, ilog(f->channels)-1);

            m->chan[k].angle = get_bits(f, ilog(f->channels)-1);

            if (m->chan[k].magnitude >= f->channels)        return error(f, VORBIS_invalid_setup);

            if (m->chan[k].angle     >= f->channels)        return error(f, VORBIS_invalid_setup);

            if (m->chan[k].magnitude == m->chan[k].angle)   return error(f, VORBIS_invalid_setup);

         }

      } else

         m->coupling_steps = 0;



      // reserved field

      if (get_bits(f,2)) return error(f, VORBIS_invalid_setup);

      if (m->submaps > 1) {

         for (j=0; j < f->channels; ++j) {

            m->chan[j].mux = get_bits(f, 4);

            if (m->chan[j].mux >= m->submaps)                return error(f, VORBIS_invalid_setup);

         }

      } else

         // @SPECIFICATION: this case is missing from the spec

         for (j=0; j < f->channels; ++j)

            m->chan[j].mux = 0;



      for (j=0; j < m->submaps; ++j) {

         get_bits(f,8); // discard

         m->submap_floor[j] = get_bits(f,8);

         m->submap_residue[j] = get_bits(f,8);

         if (m->submap_floor[j] >= f->floor_count)      return error(f, VORBIS_invalid_setup);

         if (m->submap_residue[j] >= f->residue_count)  return error(f, VORBIS_invalid_setup);

      }

   }



   // Modes

   f->mode_count = get_bits(f, 6)+1;

   for (i=0; i < f->mode_count; ++i) {

      Mode *m = f->mode_config+i;

      m->blockflag = get_bits(f,1);

      m->windowtype = get_bits(f,16);

      m->transformtype = get_bits(f,16);

      m->mapping = get_bits(f,8);

      if (m->windowtype != 0)                 return error(f, VORBIS_invalid_setup);

      if (m->transformtype != 0)              return error(f, VORBIS_invalid_setup);

      if (m->mapping >= f->mapping_count)     return error(f, VORBIS_invalid_setup);

   }



   flush_packet(f);



   f->previous_length = 0;



   for (i=0; i < f->channels; ++i) {

      f->channel_buffers[i] = (float *) setup_malloc(f, sizeof(float) * f->blocksize_1);

      f->previous_window[i] = (float *) setup_malloc(f, sizeof(float) * f->blocksize_1/2);

      f->finalY[i]          = (int16 *) setup_malloc(f, sizeof(int16) * longest_floorlist);

      #ifdef STB_VORBIS_NO_DEFER_FLOOR

      f->floor_buffers[i]   = (float *) setup_malloc(f, sizeof(float) * f->blocksize_1/2);

      #endif

   }



   if (!init_blocksize(f, 0, f->blocksize_0)) return FALSE;

   if (!init_blocksize(f, 1, f->blocksize_1)) return FALSE;

   f->blocksize[0] = f->blocksize_0;

   f->blocksize[1] = f->blocksize_1;



#ifdef STB_VORBIS_DIVIDE_TABLE

   if (integer_divide_table[1][1]==0)

      for (i=0; i < DIVTAB_NUMER; ++i)

         for (j=1; j < DIVTAB_DENOM; ++j)

            integer_divide_table[i][j] = i / j;

#endif



   // compute how much temporary memory is needed



   // 1.

   {

      uint32 imdct_mem = (f->blocksize_1 * sizeof(float) >> 1);

      uint32 classify_mem;

      int i,max_part_read=0;

      for (i=0; i < f->residue_count; ++i) {

         Residue *r = f->residue_config + i;

         int n_read = r->end - r->begin;

         int part_read = n_read / r->part_size;

         if (part_read > max_part_read)

            max_part_read = part_read;

      }

      #ifndef STB_VORBIS_DIVIDES_IN_RESIDUE

      classify_mem = f->channels * (sizeof(void*) + max_part_read * sizeof(uint8 *));

      #else

      classify_mem = f->channels * (sizeof(void*) + max_part_read * sizeof(int *));

      #endif



      f->temp_memory_required = classify_mem;

      if (imdct_mem > f->temp_memory_required)

         f->temp_memory_required = imdct_mem;

   }



   f->first_decode = TRUE;



   if (f->alloc.alloc_buffer) {

      assert(f->temp_offset == f->alloc.alloc_buffer_length_in_bytes);

      // check if there's enough temp memory so we don't error later

      if (f->setup_offset + sizeof(*f) + f->temp_memory_required > (unsigned) f->temp_offset)

         return error(f, VORBIS_outofmem);

   }



   f->first_audio_page_offset = stb_vorbis_get_file_offset(f);



   return TRUE;

}



static void vorbis_deinit(stb_vorbis *p)

{

   int i,j;

   for (i=0; i < p->residue_count; ++i) {

      Residue *r = p->residue_config+i;

      if (r->classdata) {

         for (j=0; j < p->codebooks[r->classbook].entries; ++j)

            setup_free(p, r->classdata[j]);

         setup_free(p, r->classdata);

      }

      setup_free(p, r->residue_books);

   }



   if (p->codebooks) {

      for (i=0; i < p->codebook_count; ++i) {

         Codebook *c = p->codebooks + i;

         setup_free(p, c->codeword_lengths);

         setup_free(p, c->multiplicands);

         setup_free(p, c->codewords);

         setup_free(p, c->sorted_codewords);

         // c->sorted_values[-1] is the first entry in the array

         setup_free(p, c->sorted_values ? c->sorted_values-1 : NULL);

      }

      setup_free(p, p->codebooks);

   }

   setup_free(p, p->floor_config);

   setup_free(p, p->residue_config);

   for (i=0; i < p->mapping_count; ++i)

      setup_free(p, p->mapping[i].chan);

   setup_free(p, p->mapping);

   for (i=0; i < p->channels; ++i) {

      setup_free(p, p->channel_buffers[i]);

      setup_free(p, p->previous_window[i]);

      #ifdef STB_VORBIS_NO_DEFER_FLOOR

      setup_free(p, p->floor_buffers[i]);

      #endif

      setup_free(p, p->finalY[i]);

   }

   for (i=0; i < 2; ++i) {

      setup_free(p, p->A[i]);

      setup_free(p, p->B[i]);

      setup_free(p, p->C[i]);

      setup_free(p, p->window[i]);

   }

   #ifndef STB_VORBIS_NO_STDIO

   if (p->close_on_free) fclose(p->f);

   #endif

}



void stb_vorbis_close(stb_vorbis *p)

{

   if (p == NULL) return;

   vorbis_deinit(p);

   setup_free(p,p);

}



static void vorbis_init(stb_vorbis *p, stb_vorbis_alloc *z)

{

   memset(p, 0, sizeof(*p)); // NULL out all malloc'd pointers to start

   if (z) {

      p->alloc = *z;

      p->alloc.alloc_buffer_length_in_bytes = (p->alloc.alloc_buffer_length_in_bytes+3) & ~3;

      p->temp_offset = p->alloc.alloc_buffer_length_in_bytes;

   }

   p->eof = 0;

   p->error = VORBIS__no_error;

   p->stream = NULL;

   p->codebooks = NULL;

   p->page_crc_tests = -1;

   #ifndef STB_VORBIS_NO_STDIO

   p->close_on_free = FALSE;

   p->f = NULL;

   #endif

}



int stb_vorbis_get_sample_offset(stb_vorbis *f)

{

   if (f->current_loc_valid)

      return f->current_loc;

   else

      return -1;

}



stb_vorbis_info stb_vorbis_get_info(stb_vorbis *f)

{

   stb_vorbis_info d;

   d.channels = f->channels;

   d.sample_rate = f->sample_rate;

   d.setup_memory_required = f->setup_memory_required;

   d.setup_temp_memory_required = f->setup_temp_memory_required;

   d.temp_memory_required = f->temp_memory_required;

   d.max_frame_size = f->blocksize_1 >> 1;

   return d;

}



int stb_vorbis_get_error(stb_vorbis *f)

{

   int e = f->error;

   f->error = VORBIS__no_error;

   return e;

}



static stb_vorbis * vorbis_alloc(stb_vorbis *f)

{

   stb_vorbis *p = (stb_vorbis *) setup_malloc(f, sizeof(*p));

   return p;

}



#ifndef STB_VORBIS_NO_PUSHDATA_API



void stb_vorbis_flush_pushdata(stb_vorbis *f)

{

   f->previous_length = 0;

   f->page_crc_tests  = 0;

   f->discard_samples_deferred = 0;

   f->current_loc_valid = FALSE;

   f->first_decode = FALSE;

   f->samples_output = 0;

   f->channel_buffer_start = 0;

   f->channel_buffer_end = 0;

}



static int vorbis_search_for_page_pushdata(vorb *f, uint8 *data, int data_len)

{

   int i,n;

   for (i=0; i < f->page_crc_tests; ++i)

      f->scan[i].bytes_done = 0;



   // if we have room for more scans, search for them first, because

   // they may cause us to stop early if their header is incomplete

   if (f->page_crc_tests < STB_VORBIS_PUSHDATA_CRC_COUNT) {

      if (data_len < 4) return 0;

      data_len -= 3; // need to look for 4-byte sequence, so don't miss

                     // one that straddles a boundary

      for (i=0; i < data_len; ++i) {

         if (data[i] == 0x4f) {

            if (0==memcmp(data+i, ogg_page_header, 4)) {

               int j,len;

               uint32 crc;

               // make sure we have the whole page header

               if (i+26 >= data_len || i+27+data[i+26] >= data_len) {

                  // only read up to this page start, so hopefully we'll

                  // have the whole page header start next time

                  data_len = i;

                  break;

               }

               // ok, we have it all; compute the length of the page

               len = 27 + data[i+26];

               for (j=0; j < data[i+26]; ++j)

                  len += data[i+27+j];

               // scan everything up to the embedded crc (which we must 0)

               crc = 0;

               for (j=0; j < 22; ++j)

                  crc = crc32_update(crc, data[i+j]);

               // now process 4 0-bytes

               for (   ; j < 26; ++j)

                  crc = crc32_update(crc, 0);

               // len is the total number of bytes we need to scan

               n = f->page_crc_tests++;

               f->scan[n].bytes_left = len-j;

               f->scan[n].crc_so_far = crc;

               f->scan[n].goal_crc = data[i+22] + (data[i+23] << 8) + (data[i+24]<<16) + (data[i+25]<<24);

               // if the last frame on a page is continued to the next, then

               // we can't recover the sample_loc immediately

               if (data[i+27+data[i+26]-1] == 255)

                  f->scan[n].sample_loc = ~0;

               else

                  f->scan[n].sample_loc = data[i+6] + (data[i+7] << 8) + (data[i+ 8]<<16) + (data[i+ 9]<<24);

               f->scan[n].bytes_done = i+j;

               if (f->page_crc_tests == STB_VORBIS_PUSHDATA_CRC_COUNT)

                  break;

               // keep going if we still have room for more

            }

         }

      }

   }



   for (i=0; i < f->page_crc_tests;) {

      uint32 crc;

      int j;

      int n = f->scan[i].bytes_done;

      int m = f->scan[i].bytes_left;

      if (m > data_len - n) m = data_len - n;

      // m is the bytes to scan in the current chunk

      crc = f->scan[i].crc_so_far;

      for (j=0; j < m; ++j)

         crc = crc32_update(crc, data[n+j]);

      f->scan[i].bytes_left -= m;

      f->scan[i].crc_so_far = crc;

      if (f->scan[i].bytes_left == 0) {

         // does it match?

         if (f->scan[i].crc_so_far == f->scan[i].goal_crc) {

            // Houston, we have page

            data_len = n+m; // consumption amount is wherever that scan ended

            f->page_crc_tests = -1; // drop out of page scan mode

            f->previous_length = 0; // decode-but-don't-output one frame

            f->next_seg = -1;       // start a new page

            f->current_loc = f->scan[i].sample_loc; // set the current sample location

                                    // to the amount we'd have decoded had we decoded this page

            f->current_loc_valid = f->current_loc != ~0;

            return data_len;

         }

         // delete entry

         f->scan[i] = f->scan[--f->page_crc_tests];

      } else {

         ++i;

      }

   }



   return data_len;

}



// return value: number of bytes we used

int stb_vorbis_decode_frame_pushdata(

         stb_vorbis *f,                 // the file we're decoding

         uint8 *data, int data_len,     // the memory available for decoding

         int *channels,                 // place to write number of float * buffers

         float ***output,               // place to write float ** array of float * buffers

         int *samples                   // place to write number of output samples

     )

{

   int i;

   int len,right,left;



   if (!IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing);



   if (f->page_crc_tests >= 0) {

      *samples = 0;

      return vorbis_search_for_page_pushdata(f, data, data_len);

   }



   f->stream     = data;

   f->stream_end = data + data_len;

   f->error      = VORBIS__no_error;



   // check that we have the entire packet in memory

   if (!is_whole_packet_present(f, FALSE)) {

      *samples = 0;

      return 0;

   }



   if (!vorbis_decode_packet(f, &len, &left, &right)) {

      // save the actual error we encountered

      enum STBVorbisError error = f->error;

      if (error == VORBIS_bad_packet_type) {

         // flush and resynch

         f->error = VORBIS__no_error;

         while (get8_packet(f) != EOP)

            if (f->eof) break;

         *samples = 0;

         return f->stream - data;

      }

      if (error == VORBIS_continued_packet_flag_invalid) {

         if (f->previous_length == 0) {

            // we may be resynching, in which case it's ok to hit one

            // of these; just discard the packet

            f->error = VORBIS__no_error;

            while (get8_packet(f) != EOP)

               if (f->eof) break;

            *samples = 0;

            return f->stream - data;

         }

      }

      // if we get an error while parsing, what to do?

      // well, it DEFINITELY won't work to continue from where we are!

      stb_vorbis_flush_pushdata(f);

      // restore the error that actually made us bail

      f->error = error;

      *samples = 0;

      return 1;

   }



   // success!

   len = vorbis_finish_frame(f, len, left, right);

   for (i=0; i < f->channels; ++i)

      f->outputs[i] = f->channel_buffers[i] + left;



   if (channels) *channels = f->channels;

   *samples = len;

   *output = f->outputs;

   return f->stream - data;

}



stb_vorbis *stb_vorbis_open_pushdata(

         unsigned char *data, int data_len, // the memory available for decoding

         int *data_used,              // only defined if result is not NULL

         int *error, stb_vorbis_alloc *alloc)

{

   stb_vorbis *f, p;

   vorbis_init(&p, alloc);

   p.stream     = data;

   p.stream_end = data + data_len;

   p.push_mode  = TRUE;

   if (!start_decoder(&p)) {

      if (p.eof)

         *error = VORBIS_need_more_data;

      else

         *error = p.error;

      return NULL;

   }

   f = vorbis_alloc(&p);

   if (f) {

      *f = p;

      *data_used = f->stream - data;

      *error = 0;

      return f;

   } else {

      vorbis_deinit(&p);

      return NULL;

   }

}

#endif // STB_VORBIS_NO_PUSHDATA_API



unsigned int stb_vorbis_get_file_offset(stb_vorbis *f)

{

   #ifndef STB_VORBIS_NO_PUSHDATA_API

   if (f->push_mode) return 0;

   #endif

   if (USE_MEMORY(f)) return f->stream - f->stream_start;



#ifdef STB_VORBIS_USE_CALLBACKS

	if(USE_CALLBACKS(f))

		return f->cb_offset;

#endif



   #ifndef STB_VORBIS_NO_STDIO

   return ftell(f->f) - f->f_start;

   #endif

}



#ifndef STB_VORBIS_NO_PULLDATA_API

//

// DATA-PULLING API

//



static uint32 vorbis_find_page(stb_vorbis *f, uint32 *end, uint32 *last)

{

   for(;;) {

      int n;

      if (f->eof) return 0;

      n = get8(f);

      if (n == 0x4f) { // page header

         unsigned int retry_loc = stb_vorbis_get_file_offset(f);

         int i;

         // check if we're off the end of a file_section stream

         if (retry_loc - 25 > f->stream_len)

            return 0;

         // check the rest of the header

         for (i=1; i < 4; ++i)

            if (get8(f) != ogg_page_header[i])

               break;

         if (f->eof) return 0;

         if (i == 4) {

            uint8 header[27];

            uint32 i, crc, goal, len;

            for (i=0; i < 4; ++i)

               header[i] = ogg_page_header[i];

            for (; i < 27; ++i)

               header[i] = get8(f);

            if (f->eof) return 0;

            if (header[4] != 0) goto invalid;

            goal = header[22] + (header[23] << 8) + (header[24]<<16) + (header[25]<<24);

            for (i=22; i < 26; ++i)

               header[i] = 0;

            crc = 0;

            for (i=0; i < 27; ++i)

               crc = crc32_update(crc, header[i]);

            len = 0;

            for (i=0; i < header[26]; ++i) {

               int s = get8(f);

               crc = crc32_update(crc, s);

               len += s;

            }

            if (len && f->eof) return 0;

            for (i=0; i < len; ++i)

               crc = crc32_update(crc, get8(f));

            // finished parsing probable page

            if (crc == goal) {

               // we could now check that it's either got the last

               // page flag set, OR it's followed by the capture

               // pattern, but I guess TECHNICALLY you could have

               // a file with garbage between each ogg page and recover

               // from it automatically? So even though that paranoia

               // might decrease the chance of an invalid decode by

               // another 2^32, not worth it since it would hose those

               // invalid-but-useful files?

               if (end)

                  *end = stb_vorbis_get_file_offset(f);

               if (last)

                  if (header[5] & 0x04)

                     *last = 1;

                  else

                     *last = 0;

               set_file_offset(f, retry_loc-1);

               return 1;

            }

         }

        invalid:

         // not a valid page, so rewind and look for next one

         set_file_offset(f, retry_loc);

      }

   }

}



// seek is implemented with 'interpolation search'--this is like

// binary search, but we use the data values to estimate the likely

// location of the data item (plus a bit of a bias so when the

// estimation is wrong we don't waste overly much time)



#define SAMPLE_unknown  0xffffffff





// ogg vorbis, in its insane infinite wisdom, only provides

// information about the sample at the END of the page.

// therefore we COULD have the data we need in the current

// page, and not know it. we could just use the end location

// as our only knowledge for bounds, seek back, and eventually

// the binary search finds it. or we can try to be smart and

// not waste time trying to locate more pages. we try to be

// smart, since this data is already in memory anyway, so

// doing needless I/O would be crazy!

static int vorbis_analyze_page(stb_vorbis *f, ProbedPage *z)

{

   uint8 header[27], lacing[255];

   uint8 packet_type[255];

   int num_packet, packet_start, previous =0;

   int i,len;

   uint32 samples;



   // record where the page starts

   z->page_start = stb_vorbis_get_file_offset(f);



   // parse the header

   getn(f, header, 27);

   assert(header[0] == 'O' && header[1] == 'g' && header[2] == 'g' && header[3] == 'S');

   getn(f, lacing, header[26]);



   // determine the length of the payload

   len = 0;

   for (i=0; i < header[26]; ++i)

      len += lacing[i];



   // this implies where the page ends

   z->page_end = z->page_start + 27 + header[26] + len;



   // read the last-decoded sample out of the data

   z->last_decoded_sample = header[6] + (header[7] << 8) + (header[8] << 16) + (header[9] << 16);



   if (header[5] & 4) {

      // if this is the last page, it's not possible to work

      // backwards to figure out the first sample! whoops! fuck.

      z->first_decoded_sample = SAMPLE_unknown;

      set_file_offset(f, z->page_start);

      return 1;

   }



   // scan through the frames to determine the sample-count of each one...

   // our goal is the sample # of the first fully-decoded sample on the

   // page, which is the first decoded sample of the 2nd page



   num_packet=0;



   packet_start = ((header[5] & 1) == 0);



   for (i=0; i < header[26]; ++i) {

      if (packet_start) {

         uint8 n,b,m;

         if (lacing[i] == 0) goto bail; // trying to read from zero-length packet

         n = get8(f);

         // if bottom bit is non-zero, we've got corruption

         if (n & 1) goto bail;

         n >>= 1;

         b = ilog(f->mode_count-1);

         m = n >> b;

         n &= (1 << b)-1;

         if (n >= f->mode_count) goto bail;

         if (num_packet == 0 && f->mode_config[n].blockflag)

            previous = (m & 1);

         packet_type[num_packet++] = f->mode_config[n].blockflag;

         skip(f, lacing[i]-1);

      } else

         skip(f, lacing[i]);

      packet_start = (lacing[i] < 255);

   }



   // now that we know the sizes of all the pages, we can start determining

   // how much sample data there is.



   samples = 0;



   // for the last packet, we step by its whole length, because the definition

   // is that we encoded the end sample loc of the 'last packet completed',

   // where 'completed' refers to packets being split, and we are left to guess

   // what 'end sample loc' means. we assume it means ignoring the fact that

   // the last half of the data is useless without windowing against the next

   // packet... (so it's not REALLY complete in that sense)

   if (num_packet > 1)

      samples += f->blocksize[packet_type[num_packet-1]];



   for (i=num_packet-2; i >= 1; --i) {

      // now, for this packet, how many samples do we have that

      // do not overlap the following packet?

      if (packet_type[i] == 1)

         if (packet_type[i+1] == 1)

            samples += f->blocksize_1 >> 1;

         else

            samples += ((f->blocksize_1 - f->blocksize_0) >> 2) + (f->blocksize_0 >> 1);

      else

         samples += f->blocksize_0 >> 1;

   }

   // now, at this point, we've rewound to the very beginning of the

   // _second_ packet. if we entirely discard the first packet after

   // a seek, this will be exactly the right sample number. HOWEVER!

   // we can't as easily compute this number for the LAST page. The

   // only way to get the sample offset of the LAST page is to use

   // the end loc from the previous page. But what that returns us

   // is _exactly_ the place where we get our first non-overlapped

   // sample. (I think. Stupid spec for being ambiguous.) So for

   // consistency it's better to do that here, too. However, that

   // will then require us to NOT discard all of the first frame we

   // decode, in some cases, which means an even weirder frame size

   // and extra code. what a fucking pain.

   

   // we're going to discard the first packet if we

   // start the seek here, so we don't care about it. (we could actually

   // do better; if the first packet is long, and the previous packet

   // is short, there's actually data in the first half of the first

   // packet that doesn't need discarding... but not worth paying the

   // effort of tracking that of that here and in the seeking logic)

   // except crap, if we infer it from the _previous_ packet's end

   // location, we DO need to use that definition... and we HAVE to

   // infer the start loc of the LAST packet from the previous packet's

   // end location. fuck you, ogg vorbis.



   z->first_decoded_sample = z->last_decoded_sample - samples;



   // restore file state to where we were

   set_file_offset(f, z->page_start);

   return 1;



   // restore file state to where we were

  bail:

   set_file_offset(f, z->page_start);

   return 0;

}



static int vorbis_seek_frame_from_page(stb_vorbis *f, uint32 page_start, uint32 first_sample, uint32 target_sample, int fine)

{

   int left_start, left_end, right_start, right_end, mode,i;

   int frame=0;

   uint32 frame_start;

   int frames_to_skip, data_to_skip;



   // first_sample is the sample # of the first sample that doesn't

   // overlap the previous page... note that this requires us to

   // _partially_ discard the first packet! bleh.

   set_file_offset(f, page_start);



   f->next_seg = -1;  // force page resync



   frame_start = first_sample;

   // frame start is where the previous packet's last decoded sample

   // was, which corresponds to left_end... EXCEPT if the previous

   // packet was long and this packet is short? Probably a bug here.





   // now, we can start decoding frames... we'll only FAKE decode them,

   // until we find the frame that contains our sample; then we'll rewind,

   // and try again

   for (;;) {

      int start;



      if (!vorbis_decode_initial(f, &left_start, &left_end, &right_start, &right_end, &mode))

         return error(f, VORBIS_seek_failed);



      if (frame == 0)

         start = left_end;

      else

         start = left_start;



      // the window starts at left_start; the last valid sample we generate

      // before the next frame's window start is right_start-1

      if (target_sample < frame_start + right_start-start)

         break;



      flush_packet(f);

      if (f->eof)

         return error(f, VORBIS_seek_failed);



      frame_start += right_start - start;



      ++frame;

   }



   // ok, at this point, the sample we want is contained in frame #'frame'



   // to decode frame #'frame' normally, we have to decode the

   // previous frame first... but if it's the FIRST frame of the page

   // we can't. if it's the first frame, it means it falls in the part

   // of the first frame that doesn't overlap either of the other frames.

   // so, if we have to handle that case for the first frame, we might

   // as well handle it for all of them, so:

   if (target_sample > frame_start + (left_end - left_start)) {

      // so what we want to do is go ahead and just immediately decode

      // this frame, but then make it so the next get_frame_float() uses

      // this already-decoded data? or do we want to go ahead and rewind,

      // and leave a flag saying to skip the first N data? let's do that

      frames_to_skip = frame;  // if this is frame #1, skip 1 frame (#0)

      data_to_skip = left_end - left_start;

   } else {

      // otherwise, we want to skip frames 0, 1, 2, ... frame-2

      // (which means frame-2+1 total frames) then decode frame-1,

      // then leave frame pending

      frames_to_skip = frame - 1;

      assert(frames_to_skip >= 0);

      data_to_skip = -1;      

   }



   set_file_offset(f, page_start);

   f->next_seg = - 1; // force page resync



   for (i=0; i < frames_to_skip; ++i) {

      maybe_start_packet(f);

      flush_packet(f);

   }



   if (data_to_skip >= 0) {

      int i,j,n = f->blocksize_0 >> 1;

      f->discard_samples_deferred = data_to_skip;

      for (i=0; i < f->channels; ++i)

         for (j=0; j < n; ++j)

            f->previous_window[i][j] = 0;

      f->previous_length = n;

      frame_start += data_to_skip;

   } else {

      f->previous_length = 0;

      vorbis_pump_first_frame(f);

   }



   // at this point, the NEXT decoded frame will generate the desired sample

   if (fine) {

      // so if we're doing sample accurate streaming, we want to go ahead and decode it!

      if (target_sample != frame_start) {

         int n;

         stb_vorbis_get_frame_float(f, &n, NULL);

         assert(target_sample > frame_start);

         assert(f->channel_buffer_start + (int) (target_sample-frame_start) < f->channel_buffer_end);

         f->channel_buffer_start += (target_sample - frame_start);

      }

   }



   return 0;

}



static int vorbis_seek_base(stb_vorbis *f, unsigned int sample_number, int fine)

{

   ProbedPage p[2],q;

   if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing);



   // do we know the location of the last page?

   if (f->p_last.page_start == 0) {

      uint32 z = stb_vorbis_stream_length_in_samples(f);

      if (z == 0) return error(f, VORBIS_cant_find_last_page);

   }



   p[0] = f->p_first;

   p[1] = f->p_last;



   if (sample_number >= f->p_last.last_decoded_sample)

      sample_number = f->p_last.last_decoded_sample-1;



   if (sample_number < f->p_first.last_decoded_sample) {

      vorbis_seek_frame_from_page(f, p[0].page_start, 0, sample_number, fine);

      return 0;

   } else {

      int attempts=0;

      while (p[0].page_end < p[1].page_start) {

         uint32 probe;

         uint32 start_offset, end_offset;

         uint32 start_sample, end_sample;



         // copy these into local variables so we can tweak them

         // if any are unknown

         start_offset = p[0].page_end;

         end_offset   = p[1].after_previous_page_start; // an address known to seek to page p[1]

         start_sample = p[0].last_decoded_sample;

         end_sample   = p[1].last_decoded_sample;



         // currently there is no such tweaking logic needed/possible?

         if (start_sample == SAMPLE_unknown || end_sample == SAMPLE_unknown)

            return error(f, VORBIS_seek_failed);



         // now we want to lerp between these for the target samples...

      

         // step 1: we need to bias towards the page start...

         if (start_offset + 4000 < end_offset)

            end_offset -= 4000;



         // now compute an interpolated search loc

         probe = start_offset + (int) floor((float) (end_offset - start_offset) / (end_sample - start_sample) * (sample_number - start_sample));



         // next we need to bias towards binary search...

         // code is a little wonky to allow for full 32-bit unsigned values

         if (attempts >= 4) {

            uint32 probe2 = start_offset + ((end_offset - start_offset) >> 1);

            if (attempts >= 8)

               probe = probe2;

            else if (probe < probe2)

               probe = probe + ((probe2 - probe) >> 1);

            else

               probe = probe2 + ((probe - probe2) >> 1);

         }

         ++attempts;



         set_file_offset(f, probe);

         if (!vorbis_find_page(f, NULL, NULL))   return error(f, VORBIS_seek_failed);

         if (!vorbis_analyze_page(f, &q))        return error(f, VORBIS_seek_failed);

         q.after_previous_page_start = probe;



         // it's possible we've just found the last page again

         if (q.page_start == p[1].page_start) {

            p[1] = q;

            continue;

         }



         if (sample_number < q.last_decoded_sample)

            p[1] = q;

         else

            p[0] = q;

      }



      if (p[0].last_decoded_sample <= sample_number && sample_number < p[1].last_decoded_sample) {

         vorbis_seek_frame_from_page(f, p[1].page_start, p[0].last_decoded_sample, sample_number, fine);

         return 0;

      }

      return error(f, VORBIS_seek_failed);

   }

}



int stb_vorbis_seek_frame(stb_vorbis *f, unsigned int sample_number)

{

   return vorbis_seek_base(f, sample_number, FALSE);

}



int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number)

{

   return vorbis_seek_base(f, sample_number, TRUE);

}



void stb_vorbis_seek_start(stb_vorbis *f)

{

   if (IS_PUSH_MODE(f)) { error(f, VORBIS_invalid_api_mixing); return; }

   set_file_offset(f, f->first_audio_page_offset);

   f->previous_length = 0;

   f->first_decode = TRUE;

   f->next_seg = -1;

   vorbis_pump_first_frame(f);

}



unsigned int stb_vorbis_stream_length_in_samples(stb_vorbis *f)

{

   unsigned int restore_offset, previous_safe;

   unsigned int end, last_page_loc;



   if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing);

   if (!f->total_samples) {

      int last;

      uint32 lo,hi;

      char header[6];



      // first, store the current decode position so we can restore it

      restore_offset = stb_vorbis_get_file_offset(f);



      // now we want to seek back 64K from the end (the last page must

      // be at most a little less than 64K, but let's allow a little slop)

      if (f->stream_len >= 65536 && f->stream_len-65536 >= f->first_audio_page_offset)

         previous_safe = f->stream_len - 65536;

      else

         previous_safe = f->first_audio_page_offset;



      set_file_offset(f, previous_safe);

      // previous_safe is now our candidate 'earliest known place that seeking

      // to will lead to the final page'



      if (!vorbis_find_page(f, &end, (int unsigned *)&last)) {

         // if we can't find a page, we're hosed!

         f->error = VORBIS_cant_find_last_page;

         f->total_samples = 0xffffffff;

         goto done;

      }



      // check if there are more pages

      last_page_loc = stb_vorbis_get_file_offset(f);



      // stop when the last_page flag is set, not when we reach eof;

      // this allows us to stop short of a 'file_section' end without

      // explicitly checking the length of the section

      while (!last) {

         set_file_offset(f, end);

         if (!vorbis_find_page(f, &end, (int unsigned *)&last)) {

            // the last page we found didn't have the 'last page' flag

            // set. whoops!

            break;

         }

         previous_safe = last_page_loc+1;

         last_page_loc = stb_vorbis_get_file_offset(f);

      }



      set_file_offset(f, last_page_loc);



      // parse the header

      getn(f, (unsigned char *)header, 6);

      // extract the absolute granule position

      lo = get32(f);

      hi = get32(f);

      if (lo == 0xffffffff && hi == 0xffffffff) {

         f->error = VORBIS_cant_find_last_page;

         f->total_samples = SAMPLE_unknown;

         goto done;

      }

      if (hi)

         lo = 0xfffffffe; // saturate

      f->total_samples = lo;



      f->p_last.page_start = last_page_loc;

      f->p_last.page_end   = end;

      f->p_last.last_decoded_sample = lo;

      f->p_last.first_decoded_sample = SAMPLE_unknown;

      f->p_last.after_previous_page_start = previous_safe;



     done:

      set_file_offset(f, restore_offset);

   }

   return f->total_samples == SAMPLE_unknown ? 0 : f->total_samples;

}



float stb_vorbis_stream_length_in_seconds(stb_vorbis *f)

{

   return stb_vorbis_stream_length_in_samples(f) / (float) f->sample_rate;

}







int stb_vorbis_get_frame_float(stb_vorbis *f, int *channels, float ***output)

{

   int len, right,left,i;

   if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing);



   if (!vorbis_decode_packet(f, &len, &left, &right)) {

      f->channel_buffer_start = f->channel_buffer_end = 0;

      return 0;

   }



   len = vorbis_finish_frame(f, len, left, right);

   for (i=0; i < f->channels; ++i)

      f->outputs[i] = f->channel_buffers[i] + left;



   f->channel_buffer_start = left;

   f->channel_buffer_end   = left+len;



   if (channels) *channels = f->channels;

   if (output)   *output = f->outputs;

   return len;

}



#ifndef STB_VORBIS_NO_STDIO



stb_vorbis * stb_vorbis_open_file_section(FILE *file, int close_on_free, int *error, stb_vorbis_alloc *alloc, unsigned int length)

{

   stb_vorbis *f, p;

   vorbis_init(&p, alloc);

   p.f = file;

   p.f_start = ftell(file);

   p.stream_len   = length;

   p.close_on_free = close_on_free;

   if (start_decoder(&p)) {

      f = vorbis_alloc(&p);

      if (f) {

         *f = p;

         vorbis_pump_first_frame(f);

         return f;

      }

   }

   if (error) *error = p.error;

   vorbis_deinit(&p);

   return NULL;

}



stb_vorbis * stb_vorbis_open_file(FILE *file, int close_on_free, int *error, stb_vorbis_alloc *alloc)

{

   unsigned int len, start;

   start = ftell(file);

   fseek(file, 0, SEEK_END);

   len = ftell(file) - start;

   fseek(file, start, SEEK_SET);

   return stb_vorbis_open_file_section(file, close_on_free, error, alloc, len);

}



stb_vorbis * stb_vorbis_open_filename(char *filename, int *error, stb_vorbis_alloc *alloc)

{

   FILE *f = fopen(filename, "rb");

   if (f) 

      return stb_vorbis_open_file(f, TRUE, error, alloc);

   if (error) *error = VORBIS_file_open_failure;

   return NULL;

}

#endif // STB_VORBIS_NO_STDIO



stb_vorbis * stb_vorbis_open_memory(unsigned char *data, int len, int *error, stb_vorbis_alloc *alloc)

{

   stb_vorbis *f, p;

   if (data == NULL) return NULL;

   vorbis_init(&p, alloc);

   p.stream = data;

   p.stream_end = data + len;

   p.stream_start = p.stream;

   p.stream_len = len;

   p.push_mode = FALSE;

   if (start_decoder(&p)) {

      f = vorbis_alloc(&p);

      if (f) {

         *f = p;

         vorbis_pump_first_frame(f);

         return f;

      }

   }

   if (error) *error = p.error;

   vorbis_deinit(&p);

   return NULL;

}



#ifndef STB_VORBIS_NO_INTEGER_CONVERSION

#define PLAYBACK_MONO     1

#define PLAYBACK_LEFT     2

#define PLAYBACK_RIGHT    4



#define L  (PLAYBACK_LEFT  | PLAYBACK_MONO)

#define C  (PLAYBACK_LEFT  | PLAYBACK_RIGHT | PLAYBACK_MONO)

#define R  (PLAYBACK_RIGHT | PLAYBACK_MONO)



static int8 channel_position[7][6] =

{

   { 0 },

   { C },

   { L, R },

   { L, C, R },

   { L, R, L, R },

   { L, C, R, L, R },

   { L, C, R, L, R, C },

};





#ifndef STB_VORBIS_NO_FAST_SCALED_FLOAT

   typedef union {

      float f;

      int i;

   } float_conv;

   typedef char stb_vorbis_float_size_test[sizeof(float)==4 && sizeof(int) == 4];

   #define FASTDEF(x) float_conv x

   // add (1<<23) to convert to int, then divide by 2^SHIFT, then add 0.5/2^SHIFT to round

   #define MAGIC(SHIFT) (1.5f * (1 << (23-SHIFT)) + 0.5f/(1 << SHIFT))

   #define ADDEND(SHIFT) (((150-SHIFT) << 23) + (1 << 22))

   #define FAST_SCALED_FLOAT_TO_INT(temp,x,s) (temp.f = (x) + MAGIC(s), temp.i - ADDEND(s))

   #define check_endianness()  

#else

   #define FAST_SCALED_FLOAT_TO_INT(temp,x,s) ((int) ((x) * (1 << (s))))

   #define check_endianness()

   #define FASTDEF(x)

#endif



static void copy_samples(short *dest, float *src, int len)

{

   int i;

   check_endianness();

   for (i=0; i < len; ++i) {

      FASTDEF(temp);

      int v = FAST_SCALED_FLOAT_TO_INT(temp, src[i],15);

      if ((unsigned int) (v + 32768) > 65535)

         v = v < 0 ? -32768 : 32767;

      dest[i] = v;

   }

}



static void compute_samples(int mask, short *output, int num_c, float **data, int d_offset, int len)

{

   #define BUFFER_SIZE  32

   float buffer[BUFFER_SIZE];

   int i,j,o,n = BUFFER_SIZE;

   check_endianness();

   for (o = 0; o < len; o += BUFFER_SIZE) {

      memset(buffer, 0, sizeof(buffer));

      if (o + n > len) n = len - o;

      for (j=0; j < num_c; ++j) {

         if (channel_position[num_c][j] & mask) {

            for (i=0; i < n; ++i)

               buffer[i] += data[j][d_offset+o+i];

         }

      }

      for (i=0; i < n; ++i) {

         FASTDEF(temp);

         int v = FAST_SCALED_FLOAT_TO_INT(temp,buffer[i],15);

         if ((unsigned int) (v + 32768) > 65535)

            v = v < 0 ? -32768 : 32767;

         output[o+i] = v;

      }

   }

}



static int channel_selector[3][2] = { {0}, {PLAYBACK_MONO}, {PLAYBACK_LEFT, PLAYBACK_RIGHT} };

static void compute_stereo_samples(short *output, int num_c, float **data, int d_offset, int len)

{

   #define BUFFER_SIZE  32

   float buffer[BUFFER_SIZE];

   int i,j,o,n = BUFFER_SIZE >> 1;

   // o is the offset in the source data

   check_endianness();

   for (o = 0; o < len; o += BUFFER_SIZE >> 1) {

      // o2 is the offset in the output data

      int o2 = o << 1;

      memset(buffer, 0, sizeof(buffer));

      if (o + n > len) n = len - o;

      for (j=0; j < num_c; ++j) {

         int m = channel_position[num_c][j] & (PLAYBACK_LEFT | PLAYBACK_RIGHT);

         if (m == (PLAYBACK_LEFT | PLAYBACK_RIGHT)) {

            for (i=0; i < n; ++i) {

               buffer[i*2+0] += data[j][d_offset+o+i];

               buffer[i*2+1] += data[j][d_offset+o+i];

            }

         } else if (m == PLAYBACK_LEFT) {

            for (i=0; i < n; ++i) {

               buffer[i*2+0] += data[j][d_offset+o+i];

            }

         } else if (m == PLAYBACK_RIGHT) {

            for (i=0; i < n; ++i) {

               buffer[i*2+1] += data[j][d_offset+o+i];

            }

         }

      }

      for (i=0; i < (n<<1); ++i) {

         FASTDEF(temp);

         int v = FAST_SCALED_FLOAT_TO_INT(temp,buffer[i],15);

         if ((unsigned int) (v + 32768) > 65535)

            v = v < 0 ? -32768 : 32767;

         output[o2+i] = v;

      }

   }

}



static void convert_samples_short(int buf_c, short **buffer, int b_offset, int data_c, float **data, int d_offset, int samples)

{

   int i;

   if (buf_c != data_c && buf_c <= 2 && data_c <= 6) {

      static int channel_selector[3][2] = { {0}, {PLAYBACK_MONO}, {PLAYBACK_LEFT, PLAYBACK_RIGHT} };

      for (i=0; i < buf_c; ++i)

         compute_samples(channel_selector[buf_c][i], buffer[i]+b_offset, data_c, data, d_offset, samples);

   } else {

      int limit = buf_c < data_c ? buf_c : data_c;

      for (i=0; i < limit; ++i)

         copy_samples(buffer[i]+b_offset, data[i], samples);

      for (   ; i < buf_c; ++i)

         memset(buffer[i]+b_offset, 0, sizeof(short) * samples);

   }

}



int stb_vorbis_get_frame_short(stb_vorbis *f, int num_c, short **buffer, int num_samples)

{

   float **output;

   int len = stb_vorbis_get_frame_float(f, NULL, &output);

   if (len > num_samples) len = num_samples;

   if (len)

      convert_samples_short(num_c, buffer, 0, f->channels, output, 0, len);

   return len;

}



static void convert_channels_short_interleaved(int buf_c, short *buffer, int data_c, float **data, int d_offset, int len)

{

   int i;

   check_endianness();

   if (buf_c != data_c && buf_c <= 2 && data_c <= 6) {

      assert(buf_c == 2);

      for (i=0; i < buf_c; ++i)

         compute_stereo_samples(buffer, data_c, data, d_offset, len);

   } else {

      int limit = buf_c < data_c ? buf_c : data_c;

      int j;

      for (j=0; j < len; ++j) {

         for (i=0; i < limit; ++i) {

            FASTDEF(temp);

            float f = data[i][d_offset+j];

            int v = FAST_SCALED_FLOAT_TO_INT(temp, f,15);//data[i][d_offset+j],15);

            if ((unsigned int) (v + 32768) > 65535)

               v = v < 0 ? -32768 : 32767;

            *buffer++ = v;

         }

         for (   ; i < buf_c; ++i)

            *buffer++ = 0;

      }

   }

}



int stb_vorbis_get_frame_short_interleaved(stb_vorbis *f, int num_c, short *buffer, int num_shorts)

{

   float **output;

   int len;

   if (num_c == 1) return stb_vorbis_get_frame_short(f,num_c,&buffer, num_shorts);

   len = stb_vorbis_get_frame_float(f, NULL, &output);

   if (len) {

      if (len*num_c > num_shorts) len = num_shorts / num_c;

      convert_channels_short_interleaved(num_c, buffer, f->channels, output, 0, len);

   }

   return len;

}



int stb_vorbis_get_samples_short_interleaved(stb_vorbis *f, int channels, short *buffer, int num_shorts)

{

   float **outputs;

   int len = num_shorts / channels;

   int n=0;

   int z = f->channels;

   if (z > channels) z = channels;

   while (n < len) {

      int k = f->channel_buffer_end - f->channel_buffer_start;

      if (n+k >= len) k = len - n;

      if (k)

         convert_channels_short_interleaved(channels, buffer, f->channels, f->channel_buffers, f->channel_buffer_start, k);

      buffer += k*channels;

      n += k;

      f->channel_buffer_start += k;

      if (n == len) break;

      if (!stb_vorbis_get_frame_float(f, NULL, &outputs)) break;

   }

   return n;

}



int stb_vorbis_get_samples_short(stb_vorbis *f, int channels, short **buffer, int len)

{

   float **outputs;

   int n=0;

   int z = f->channels;

   if (z > channels) z = channels;

   while (n < len) {

      int k = f->channel_buffer_end - f->channel_buffer_start;

      if (n+k >= len) k = len - n;

      if (k)

         convert_samples_short(channels, buffer, n, f->channels, f->channel_buffers, f->channel_buffer_start, k);

      n += k;

      f->channel_buffer_start += k;

      if (n == len) break;

      if (!stb_vorbis_get_frame_float(f, NULL, &outputs)) break;

   }

   return n;

}



#ifndef STB_VORBIS_NO_STDIO

int stb_vorbis_decode_filename(char *filename, int *channels, short **output)

{

   int data_len, offset, total, limit, error;

   short *data;

   stb_vorbis *v = stb_vorbis_open_filename(filename, &error, NULL);

   if (v == NULL) return -1;

   limit = v->channels * 4096;

   *channels = v->channels;

   offset = data_len = 0;

   total = limit;

   data = (short *) malloc(total * sizeof(*data));

   if (data == NULL) {

      stb_vorbis_close(v);

      return -2;

   }

   for (;;) {

      int n = stb_vorbis_get_frame_short_interleaved(v, v->channels, data+offset, total-offset);

      if (n == 0) break;

      data_len += n;

      offset += n * v->channels;

      if (offset + limit > total) {

         short *data2;

         total *= 2;

         data2 = (short *) realloc(data, total * sizeof(*data));

         if (data2 == NULL) {

            free(data);

            stb_vorbis_close(v);

            return -2;

         }

         data = data2;

      }

   }

   *output = data;

   return data_len;

}

#endif // NO_STDIO



int stb_vorbis_decode_memory(uint8 *mem, int len, int *channels, short **output)

{

   int data_len, offset, total, limit, error;

   short *data;

   stb_vorbis *v = stb_vorbis_open_memory(mem, len, &error, NULL);

   if (v == NULL) return -1;

   limit = v->channels * 4096;

   *channels = v->channels;

   offset = data_len = 0;

   total = limit;

   data = (short *) malloc(total * sizeof(*data));

   if (data == NULL) {

      stb_vorbis_close(v);

      return -2;

   }

   for (;;) {

      int n = stb_vorbis_get_frame_short_interleaved(v, v->channels, data+offset, total-offset);

      if (n == 0) break;

      data_len += n;

      offset += n * v->channels;

      if (offset + limit > total) {

         short *data2;

         total *= 2;

         data2 = (short *) realloc(data, total * sizeof(*data));

         if (data2 == NULL) {

            free(data);

            stb_vorbis_close(v);

            return -2;

         }

         data = data2;

      }

   }

   *output = data;

   return data_len;

}

#endif



int stb_vorbis_get_samples_float_interleaved(stb_vorbis *f, int channels, float *buffer, int num_floats)

{

   float **outputs;

   int len = num_floats / channels;

   int n=0;

   int z = f->channels;

   if (z > channels) z = channels;

   while (n < len) {

      int i,j;

      int k = f->channel_buffer_end - f->channel_buffer_start;

      if (n+k >= len) k = len - n;

      for (j=0; j < k; ++j) {

         for (i=0; i < z; ++i)

            *buffer++ = f->channel_buffers[i][f->channel_buffer_start+j];

         for (   ; i < channels; ++i)

            *buffer++ = 0;

      }

      n += k;

      f->channel_buffer_start += k;

      if (n == len) break;

      if (!stb_vorbis_get_frame_float(f, NULL, &outputs)) break;

   }

   return n;

}



int stb_vorbis_get_samples_float(stb_vorbis *f, int channels, float **buffer, int num_samples)

{

   float **outputs;

   int n=0;

   int z = f->channels;

   if (z > channels) z = channels;

   while (n < num_samples) {

      int i;

      int k = f->channel_buffer_end - f->channel_buffer_start;

      if (n+k >= num_samples) k = num_samples - n;

      if (k) {

         for (i=0; i < z; ++i)

            memcpy(buffer[i]+n, f->channel_buffers+f->channel_buffer_start, sizeof(float)*k);

         for (   ; i < channels; ++i)

            memset(buffer[i]+n, 0, sizeof(float) * k);

      }

      n += k;

      f->channel_buffer_start += k;

      if (n == num_samples) break;

      if (!stb_vorbis_get_frame_float(f, NULL, &outputs)) break;

   }

   return n;

}



#ifdef STB_VORBIS_USE_CALLBACKS



stb_vorbis * stb_vorbis_open_callback(STREAM_DATA_CLLBACK data, STREAM_RESET_CLLBACK reset, void* user, int *error, stb_vorbis_alloc *alloc)

{

	stb_vorbis *f, p;

	unsigned int len;

	vorbis_init(&p, alloc);



	p.data_callback = data;

	p.reset_callback = reset;

	p.user_data = user;



	len = stb_read_from_callback(&p,0xFFFFFFFF,NULL);

	stb_reset_callback(&p);



	p.stream_len = len;

	p.push_mode = FALSE;

	if (start_decoder(&p))

	{

		f = vorbis_alloc(&p);

		if (f) {

			*f = p;

			vorbis_pump_first_frame(f);

			return f;

		}

	}

	if (error) *error = p.error;

	vorbis_deinit(&p);

	return NULL;

}



#endif



#endif // STB_VORBIS_NO_PULLDATA_API



#endif // STB_VORBIS_HEADER_ONLY