/media/libjpeg/jcdctmgr.c
http://github.com/zpao/v8monkey · C · 642 lines · 413 code · 76 blank · 153 comment · 58 complexity · b6da7b64fea85e4819bff0947a3178ed MD5 · raw file
- /*
- * jcdctmgr.c
- *
- * Copyright (C) 1994-1996, Thomas G. Lane.
- * Copyright (C) 1999-2006, MIYASAKA Masaru.
- * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
- * Copyright (C) 2011 D. R. Commander
- * This file is part of the Independent JPEG Group's software.
- * For conditions of distribution and use, see the accompanying README file.
- *
- * This file contains the forward-DCT management logic.
- * This code selects a particular DCT implementation to be used,
- * and it performs related housekeeping chores including coefficient
- * quantization.
- */
- #define JPEG_INTERNALS
- #include "jinclude.h"
- #include "jpeglib.h"
- #include "jdct.h" /* Private declarations for DCT subsystem */
- #include "jsimddct.h"
- /* Private subobject for this module */
- typedef JMETHOD(void, forward_DCT_method_ptr, (DCTELEM * data));
- typedef JMETHOD(void, float_DCT_method_ptr, (FAST_FLOAT * data));
- typedef JMETHOD(void, convsamp_method_ptr,
- (JSAMPARRAY sample_data, JDIMENSION start_col,
- DCTELEM * workspace));
- typedef JMETHOD(void, float_convsamp_method_ptr,
- (JSAMPARRAY sample_data, JDIMENSION start_col,
- FAST_FLOAT *workspace));
- typedef JMETHOD(void, quantize_method_ptr,
- (JCOEFPTR coef_block, DCTELEM * divisors,
- DCTELEM * workspace));
- typedef JMETHOD(void, float_quantize_method_ptr,
- (JCOEFPTR coef_block, FAST_FLOAT * divisors,
- FAST_FLOAT * workspace));
- METHODDEF(void) quantize (JCOEFPTR, DCTELEM *, DCTELEM *);
- typedef struct {
- struct jpeg_forward_dct pub; /* public fields */
- /* Pointer to the DCT routine actually in use */
- forward_DCT_method_ptr dct;
- convsamp_method_ptr convsamp;
- quantize_method_ptr quantize;
- /* The actual post-DCT divisors --- not identical to the quant table
- * entries, because of scaling (especially for an unnormalized DCT).
- * Each table is given in normal array order.
- */
- DCTELEM * divisors[NUM_QUANT_TBLS];
- /* work area for FDCT subroutine */
- DCTELEM * workspace;
- #ifdef DCT_FLOAT_SUPPORTED
- /* Same as above for the floating-point case. */
- float_DCT_method_ptr float_dct;
- float_convsamp_method_ptr float_convsamp;
- float_quantize_method_ptr float_quantize;
- FAST_FLOAT * float_divisors[NUM_QUANT_TBLS];
- FAST_FLOAT * float_workspace;
- #endif
- } my_fdct_controller;
- typedef my_fdct_controller * my_fdct_ptr;
- /*
- * Find the highest bit in an integer through binary search.
- */
- LOCAL(int)
- flss (UINT16 val)
- {
- int bit;
- bit = 16;
- if (!val)
- return 0;
- if (!(val & 0xff00)) {
- bit -= 8;
- val <<= 8;
- }
- if (!(val & 0xf000)) {
- bit -= 4;
- val <<= 4;
- }
- if (!(val & 0xc000)) {
- bit -= 2;
- val <<= 2;
- }
- if (!(val & 0x8000)) {
- bit -= 1;
- val <<= 1;
- }
- return bit;
- }
- /*
- * Compute values to do a division using reciprocal.
- *
- * This implementation is based on an algorithm described in
- * "How to optimize for the Pentium family of microprocessors"
- * (http://www.agner.org/assem/).
- * More information about the basic algorithm can be found in
- * the paper "Integer Division Using Reciprocals" by Robert Alverson.
- *
- * The basic idea is to replace x/d by x * d^-1. In order to store
- * d^-1 with enough precision we shift it left a few places. It turns
- * out that this algoright gives just enough precision, and also fits
- * into DCTELEM:
- *
- * b = (the number of significant bits in divisor) - 1
- * r = (word size) + b
- * f = 2^r / divisor
- *
- * f will not be an integer for most cases, so we need to compensate
- * for the rounding error introduced:
- *
- * no fractional part:
- *
- * result = input >> r
- *
- * fractional part of f < 0.5:
- *
- * round f down to nearest integer
- * result = ((input + 1) * f) >> r
- *
- * fractional part of f > 0.5:
- *
- * round f up to nearest integer
- * result = (input * f) >> r
- *
- * This is the original algorithm that gives truncated results. But we
- * want properly rounded results, so we replace "input" with
- * "input + divisor/2".
- *
- * In order to allow SIMD implementations we also tweak the values to
- * allow the same calculation to be made at all times:
- *
- * dctbl[0] = f rounded to nearest integer
- * dctbl[1] = divisor / 2 (+ 1 if fractional part of f < 0.5)
- * dctbl[2] = 1 << ((word size) * 2 - r)
- * dctbl[3] = r - (word size)
- *
- * dctbl[2] is for stupid instruction sets where the shift operation
- * isn't member wise (e.g. MMX).
- *
- * The reason dctbl[2] and dctbl[3] reduce the shift with (word size)
- * is that most SIMD implementations have a "multiply and store top
- * half" operation.
- *
- * Lastly, we store each of the values in their own table instead
- * of in a consecutive manner, yet again in order to allow SIMD
- * routines.
- */
- LOCAL(int)
- compute_reciprocal (UINT16 divisor, DCTELEM * dtbl)
- {
- UDCTELEM2 fq, fr;
- UDCTELEM c;
- int b, r;
- b = flss(divisor) - 1;
- r = sizeof(DCTELEM) * 8 + b;
- fq = ((UDCTELEM2)1 << r) / divisor;
- fr = ((UDCTELEM2)1 << r) % divisor;
- c = divisor / 2; /* for rounding */
- if (fr == 0) { /* divisor is power of two */
- /* fq will be one bit too large to fit in DCTELEM, so adjust */
- fq >>= 1;
- r--;
- } else if (fr <= (divisor / 2)) { /* fractional part is < 0.5 */
- c++;
- } else { /* fractional part is > 0.5 */
- fq++;
- }
- dtbl[DCTSIZE2 * 0] = (DCTELEM) fq; /* reciprocal */
- dtbl[DCTSIZE2 * 1] = (DCTELEM) c; /* correction + roundfactor */
- dtbl[DCTSIZE2 * 2] = (DCTELEM) (1 << (sizeof(DCTELEM)*8*2 - r)); /* scale */
- dtbl[DCTSIZE2 * 3] = (DCTELEM) r - sizeof(DCTELEM)*8; /* shift */
- if(r <= 16) return 0;
- else return 1;
- }
- /*
- * Initialize for a processing pass.
- * Verify that all referenced Q-tables are present, and set up
- * the divisor table for each one.
- * In the current implementation, DCT of all components is done during
- * the first pass, even if only some components will be output in the
- * first scan. Hence all components should be examined here.
- */
- METHODDEF(void)
- start_pass_fdctmgr (j_compress_ptr cinfo)
- {
- my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
- int ci, qtblno, i;
- jpeg_component_info *compptr;
- JQUANT_TBL * qtbl;
- DCTELEM * dtbl;
- for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
- ci++, compptr++) {
- qtblno = compptr->quant_tbl_no;
- /* Make sure specified quantization table is present */
- if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
- cinfo->quant_tbl_ptrs[qtblno] == NULL)
- ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
- qtbl = cinfo->quant_tbl_ptrs[qtblno];
- /* Compute divisors for this quant table */
- /* We may do this more than once for same table, but it's not a big deal */
- switch (cinfo->dct_method) {
- #ifdef DCT_ISLOW_SUPPORTED
- case JDCT_ISLOW:
- /* For LL&M IDCT method, divisors are equal to raw quantization
- * coefficients multiplied by 8 (to counteract scaling).
- */
- if (fdct->divisors[qtblno] == NULL) {
- fdct->divisors[qtblno] = (DCTELEM *)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- (DCTSIZE2 * 4) * SIZEOF(DCTELEM));
- }
- dtbl = fdct->divisors[qtblno];
- for (i = 0; i < DCTSIZE2; i++) {
- if(!compute_reciprocal(qtbl->quantval[i] << 3, &dtbl[i])
- && fdct->quantize == jsimd_quantize)
- fdct->quantize = quantize;
- }
- break;
- #endif
- #ifdef DCT_IFAST_SUPPORTED
- case JDCT_IFAST:
- {
- /* For AA&N IDCT method, divisors are equal to quantization
- * coefficients scaled by scalefactor[row]*scalefactor[col], where
- * scalefactor[0] = 1
- * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
- * We apply a further scale factor of 8.
- */
- #define CONST_BITS 14
- static const INT16 aanscales[DCTSIZE2] = {
- /* precomputed values scaled up by 14 bits */
- 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
- 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270,
- 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906,
- 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315,
- 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
- 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552,
- 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446,
- 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247
- };
- SHIFT_TEMPS
- if (fdct->divisors[qtblno] == NULL) {
- fdct->divisors[qtblno] = (DCTELEM *)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- (DCTSIZE2 * 4) * SIZEOF(DCTELEM));
- }
- dtbl = fdct->divisors[qtblno];
- for (i = 0; i < DCTSIZE2; i++) {
- if(!compute_reciprocal(
- DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
- (INT32) aanscales[i]),
- CONST_BITS-3), &dtbl[i])
- && fdct->quantize == jsimd_quantize)
- fdct->quantize = quantize;
- }
- }
- break;
- #endif
- #ifdef DCT_FLOAT_SUPPORTED
- case JDCT_FLOAT:
- {
- /* For float AA&N IDCT method, divisors are equal to quantization
- * coefficients scaled by scalefactor[row]*scalefactor[col], where
- * scalefactor[0] = 1
- * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
- * We apply a further scale factor of 8.
- * What's actually stored is 1/divisor so that the inner loop can
- * use a multiplication rather than a division.
- */
- FAST_FLOAT * fdtbl;
- int row, col;
- static const double aanscalefactor[DCTSIZE] = {
- 1.0, 1.387039845, 1.306562965, 1.175875602,
- 1.0, 0.785694958, 0.541196100, 0.275899379
- };
- if (fdct->float_divisors[qtblno] == NULL) {
- fdct->float_divisors[qtblno] = (FAST_FLOAT *)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- DCTSIZE2 * SIZEOF(FAST_FLOAT));
- }
- fdtbl = fdct->float_divisors[qtblno];
- i = 0;
- for (row = 0; row < DCTSIZE; row++) {
- for (col = 0; col < DCTSIZE; col++) {
- fdtbl[i] = (FAST_FLOAT)
- (1.0 / (((double) qtbl->quantval[i] *
- aanscalefactor[row] * aanscalefactor[col] * 8.0)));
- i++;
- }
- }
- }
- break;
- #endif
- default:
- ERREXIT(cinfo, JERR_NOT_COMPILED);
- break;
- }
- }
- }
- /*
- * Load data into workspace, applying unsigned->signed conversion.
- */
- METHODDEF(void)
- convsamp (JSAMPARRAY sample_data, JDIMENSION start_col, DCTELEM * workspace)
- {
- register DCTELEM *workspaceptr;
- register JSAMPROW elemptr;
- register int elemr;
- workspaceptr = workspace;
- for (elemr = 0; elemr < DCTSIZE; elemr++) {
- elemptr = sample_data[elemr] + start_col;
- #if DCTSIZE == 8 /* unroll the inner loop */
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- #else
- {
- register int elemc;
- for (elemc = DCTSIZE; elemc > 0; elemc--)
- *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
- }
- #endif
- }
- }
- /*
- * Quantize/descale the coefficients, and store into coef_blocks[].
- */
- METHODDEF(void)
- quantize (JCOEFPTR coef_block, DCTELEM * divisors, DCTELEM * workspace)
- {
- int i;
- DCTELEM temp;
- UDCTELEM recip, corr, shift;
- UDCTELEM2 product;
- JCOEFPTR output_ptr = coef_block;
- for (i = 0; i < DCTSIZE2; i++) {
- temp = workspace[i];
- recip = divisors[i + DCTSIZE2 * 0];
- corr = divisors[i + DCTSIZE2 * 1];
- shift = divisors[i + DCTSIZE2 * 3];
- if (temp < 0) {
- temp = -temp;
- product = (UDCTELEM2)(temp + corr) * recip;
- product >>= shift + sizeof(DCTELEM)*8;
- temp = product;
- temp = -temp;
- } else {
- product = (UDCTELEM2)(temp + corr) * recip;
- product >>= shift + sizeof(DCTELEM)*8;
- temp = product;
- }
- output_ptr[i] = (JCOEF) temp;
- }
- }
- /*
- * Perform forward DCT on one or more blocks of a component.
- *
- * The input samples are taken from the sample_data[] array starting at
- * position start_row/start_col, and moving to the right for any additional
- * blocks. The quantized coefficients are returned in coef_blocks[].
- */
- METHODDEF(void)
- forward_DCT (j_compress_ptr cinfo, jpeg_component_info * compptr,
- JSAMPARRAY sample_data, JBLOCKROW coef_blocks,
- JDIMENSION start_row, JDIMENSION start_col,
- JDIMENSION num_blocks)
- /* This version is used for integer DCT implementations. */
- {
- /* This routine is heavily used, so it's worth coding it tightly. */
- my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
- DCTELEM * divisors = fdct->divisors[compptr->quant_tbl_no];
- DCTELEM * workspace;
- JDIMENSION bi;
- /* Make sure the compiler doesn't look up these every pass */
- forward_DCT_method_ptr do_dct = fdct->dct;
- convsamp_method_ptr do_convsamp = fdct->convsamp;
- quantize_method_ptr do_quantize = fdct->quantize;
- workspace = fdct->workspace;
- sample_data += start_row; /* fold in the vertical offset once */
- for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) {
- /* Load data into workspace, applying unsigned->signed conversion */
- (*do_convsamp) (sample_data, start_col, workspace);
- /* Perform the DCT */
- (*do_dct) (workspace);
- /* Quantize/descale the coefficients, and store into coef_blocks[] */
- (*do_quantize) (coef_blocks[bi], divisors, workspace);
- }
- }
- #ifdef DCT_FLOAT_SUPPORTED
- METHODDEF(void)
- convsamp_float (JSAMPARRAY sample_data, JDIMENSION start_col, FAST_FLOAT * workspace)
- {
- register FAST_FLOAT *workspaceptr;
- register JSAMPROW elemptr;
- register int elemr;
- workspaceptr = workspace;
- for (elemr = 0; elemr < DCTSIZE; elemr++) {
- elemptr = sample_data[elemr] + start_col;
- #if DCTSIZE == 8 /* unroll the inner loop */
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- #else
- {
- register int elemc;
- for (elemc = DCTSIZE; elemc > 0; elemc--)
- *workspaceptr++ = (FAST_FLOAT)
- (GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
- }
- #endif
- }
- }
- METHODDEF(void)
- quantize_float (JCOEFPTR coef_block, FAST_FLOAT * divisors, FAST_FLOAT * workspace)
- {
- register FAST_FLOAT temp;
- register int i;
- register JCOEFPTR output_ptr = coef_block;
- for (i = 0; i < DCTSIZE2; i++) {
- /* Apply the quantization and scaling factor */
- temp = workspace[i] * divisors[i];
- /* Round to nearest integer.
- * Since C does not specify the direction of rounding for negative
- * quotients, we have to force the dividend positive for portability.
- * The maximum coefficient size is +-16K (for 12-bit data), so this
- * code should work for either 16-bit or 32-bit ints.
- */
- output_ptr[i] = (JCOEF) ((int) (temp + (FAST_FLOAT) 16384.5) - 16384);
- }
- }
- METHODDEF(void)
- forward_DCT_float (j_compress_ptr cinfo, jpeg_component_info * compptr,
- JSAMPARRAY sample_data, JBLOCKROW coef_blocks,
- JDIMENSION start_row, JDIMENSION start_col,
- JDIMENSION num_blocks)
- /* This version is used for floating-point DCT implementations. */
- {
- /* This routine is heavily used, so it's worth coding it tightly. */
- my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
- FAST_FLOAT * divisors = fdct->float_divisors[compptr->quant_tbl_no];
- FAST_FLOAT * workspace;
- JDIMENSION bi;
- /* Make sure the compiler doesn't look up these every pass */
- float_DCT_method_ptr do_dct = fdct->float_dct;
- float_convsamp_method_ptr do_convsamp = fdct->float_convsamp;
- float_quantize_method_ptr do_quantize = fdct->float_quantize;
- workspace = fdct->float_workspace;
- sample_data += start_row; /* fold in the vertical offset once */
- for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) {
- /* Load data into workspace, applying unsigned->signed conversion */
- (*do_convsamp) (sample_data, start_col, workspace);
- /* Perform the DCT */
- (*do_dct) (workspace);
- /* Quantize/descale the coefficients, and store into coef_blocks[] */
- (*do_quantize) (coef_blocks[bi], divisors, workspace);
- }
- }
- #endif /* DCT_FLOAT_SUPPORTED */
- /*
- * Initialize FDCT manager.
- */
- GLOBAL(void)
- jinit_forward_dct (j_compress_ptr cinfo)
- {
- my_fdct_ptr fdct;
- int i;
- fdct = (my_fdct_ptr)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- SIZEOF(my_fdct_controller));
- cinfo->fdct = (struct jpeg_forward_dct *) fdct;
- fdct->pub.start_pass = start_pass_fdctmgr;
- /* First determine the DCT... */
- switch (cinfo->dct_method) {
- #ifdef DCT_ISLOW_SUPPORTED
- case JDCT_ISLOW:
- fdct->pub.forward_DCT = forward_DCT;
- if (jsimd_can_fdct_islow())
- fdct->dct = jsimd_fdct_islow;
- else
- fdct->dct = jpeg_fdct_islow;
- break;
- #endif
- #ifdef DCT_IFAST_SUPPORTED
- case JDCT_IFAST:
- fdct->pub.forward_DCT = forward_DCT;
- if (jsimd_can_fdct_ifast())
- fdct->dct = jsimd_fdct_ifast;
- else
- fdct->dct = jpeg_fdct_ifast;
- break;
- #endif
- #ifdef DCT_FLOAT_SUPPORTED
- case JDCT_FLOAT:
- fdct->pub.forward_DCT = forward_DCT_float;
- if (jsimd_can_fdct_float())
- fdct->float_dct = jsimd_fdct_float;
- else
- fdct->float_dct = jpeg_fdct_float;
- break;
- #endif
- default:
- ERREXIT(cinfo, JERR_NOT_COMPILED);
- break;
- }
- /* ...then the supporting stages. */
- switch (cinfo->dct_method) {
- #ifdef DCT_ISLOW_SUPPORTED
- case JDCT_ISLOW:
- #endif
- #ifdef DCT_IFAST_SUPPORTED
- case JDCT_IFAST:
- #endif
- #if defined(DCT_ISLOW_SUPPORTED) || defined(DCT_IFAST_SUPPORTED)
- if (jsimd_can_convsamp())
- fdct->convsamp = jsimd_convsamp;
- else
- fdct->convsamp = convsamp;
- if (jsimd_can_quantize())
- fdct->quantize = jsimd_quantize;
- else
- fdct->quantize = quantize;
- break;
- #endif
- #ifdef DCT_FLOAT_SUPPORTED
- case JDCT_FLOAT:
- if (jsimd_can_convsamp_float())
- fdct->float_convsamp = jsimd_convsamp_float;
- else
- fdct->float_convsamp = convsamp_float;
- if (jsimd_can_quantize_float())
- fdct->float_quantize = jsimd_quantize_float;
- else
- fdct->float_quantize = quantize_float;
- break;
- #endif
- default:
- ERREXIT(cinfo, JERR_NOT_COMPILED);
- break;
- }
- /* Allocate workspace memory */
- #ifdef DCT_FLOAT_SUPPORTED
- if (cinfo->dct_method == JDCT_FLOAT)
- fdct->float_workspace = (FAST_FLOAT *)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- SIZEOF(FAST_FLOAT) * DCTSIZE2);
- else
- #endif
- fdct->workspace = (DCTELEM *)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- SIZEOF(DCTELEM) * DCTSIZE2);
- /* Mark divisor tables unallocated */
- for (i = 0; i < NUM_QUANT_TBLS; i++) {
- fdct->divisors[i] = NULL;
- #ifdef DCT_FLOAT_SUPPORTED
- fdct->float_divisors[i] = NULL;
- #endif
- }
- }