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/thirdparty/jpeg/jddctmgr.c

http://crashrpt.googlecode.com/
C | 384 lines | 283 code | 24 blank | 77 comment | 14 complexity | 8ce95753db5c0bc524a5dc98f977621b MD5 | raw file
  1/*
  2 * jddctmgr.c
  3 *
  4 * Copyright (C) 1994-1996, Thomas G. Lane.
  5 * Modified 2002-2010 by Guido Vollbeding.
  6 * This file is part of the Independent JPEG Group's software.
  7 * For conditions of distribution and use, see the accompanying README file.
  8 *
  9 * This file contains the inverse-DCT management logic.
 10 * This code selects a particular IDCT implementation to be used,
 11 * and it performs related housekeeping chores.  No code in this file
 12 * is executed per IDCT step, only during output pass setup.
 13 *
 14 * Note that the IDCT routines are responsible for performing coefficient
 15 * dequantization as well as the IDCT proper.  This module sets up the
 16 * dequantization multiplier table needed by the IDCT routine.
 17 */
 18
 19#define JPEG_INTERNALS
 20#include "jinclude.h"
 21#include "jpeglib.h"
 22#include "jdct.h"		/* Private declarations for DCT subsystem */
 23
 24
 25/*
 26 * The decompressor input side (jdinput.c) saves away the appropriate
 27 * quantization table for each component at the start of the first scan
 28 * involving that component.  (This is necessary in order to correctly
 29 * decode files that reuse Q-table slots.)
 30 * When we are ready to make an output pass, the saved Q-table is converted
 31 * to a multiplier table that will actually be used by the IDCT routine.
 32 * The multiplier table contents are IDCT-method-dependent.  To support
 33 * application changes in IDCT method between scans, we can remake the
 34 * multiplier tables if necessary.
 35 * In buffered-image mode, the first output pass may occur before any data
 36 * has been seen for some components, and thus before their Q-tables have
 37 * been saved away.  To handle this case, multiplier tables are preset
 38 * to zeroes; the result of the IDCT will be a neutral gray level.
 39 */
 40
 41
 42/* Private subobject for this module */
 43
 44typedef struct {
 45  struct jpeg_inverse_dct pub;	/* public fields */
 46
 47  /* This array contains the IDCT method code that each multiplier table
 48   * is currently set up for, or -1 if it's not yet set up.
 49   * The actual multiplier tables are pointed to by dct_table in the
 50   * per-component comp_info structures.
 51   */
 52  int cur_method[MAX_COMPONENTS];
 53} my_idct_controller;
 54
 55typedef my_idct_controller * my_idct_ptr;
 56
 57
 58/* Allocated multiplier tables: big enough for any supported variant */
 59
 60typedef union {
 61  ISLOW_MULT_TYPE islow_array[DCTSIZE2];
 62#ifdef DCT_IFAST_SUPPORTED
 63  IFAST_MULT_TYPE ifast_array[DCTSIZE2];
 64#endif
 65#ifdef DCT_FLOAT_SUPPORTED
 66  FLOAT_MULT_TYPE float_array[DCTSIZE2];
 67#endif
 68} multiplier_table;
 69
 70
 71/* The current scaled-IDCT routines require ISLOW-style multiplier tables,
 72 * so be sure to compile that code if either ISLOW or SCALING is requested.
 73 */
 74#ifdef DCT_ISLOW_SUPPORTED
 75#define PROVIDE_ISLOW_TABLES
 76#else
 77#ifdef IDCT_SCALING_SUPPORTED
 78#define PROVIDE_ISLOW_TABLES
 79#endif
 80#endif
 81
 82
 83/*
 84 * Prepare for an output pass.
 85 * Here we select the proper IDCT routine for each component and build
 86 * a matching multiplier table.
 87 */
 88
 89METHODDEF(void)
 90start_pass (j_decompress_ptr cinfo)
 91{
 92  my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
 93  int ci, i;
 94  jpeg_component_info *compptr;
 95  int method = 0;
 96  inverse_DCT_method_ptr method_ptr = NULL;
 97  JQUANT_TBL * qtbl;
 98
 99  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
100       ci++, compptr++) {
101    /* Select the proper IDCT routine for this component's scaling */
102    switch ((compptr->DCT_h_scaled_size << 8) + compptr->DCT_v_scaled_size) {
103#ifdef IDCT_SCALING_SUPPORTED
104    case ((1 << 8) + 1):
105      method_ptr = jpeg_idct_1x1;
106      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
107      break;
108    case ((2 << 8) + 2):
109      method_ptr = jpeg_idct_2x2;
110      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
111      break;
112    case ((3 << 8) + 3):
113      method_ptr = jpeg_idct_3x3;
114      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
115      break;
116    case ((4 << 8) + 4):
117      method_ptr = jpeg_idct_4x4;
118      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
119      break;
120    case ((5 << 8) + 5):
121      method_ptr = jpeg_idct_5x5;
122      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
123      break;
124    case ((6 << 8) + 6):
125      method_ptr = jpeg_idct_6x6;
126      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
127      break;
128    case ((7 << 8) + 7):
129      method_ptr = jpeg_idct_7x7;
130      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
131      break;
132    case ((9 << 8) + 9):
133      method_ptr = jpeg_idct_9x9;
134      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
135      break;
136    case ((10 << 8) + 10):
137      method_ptr = jpeg_idct_10x10;
138      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
139      break;
140    case ((11 << 8) + 11):
141      method_ptr = jpeg_idct_11x11;
142      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
143      break;
144    case ((12 << 8) + 12):
145      method_ptr = jpeg_idct_12x12;
146      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
147      break;
148    case ((13 << 8) + 13):
149      method_ptr = jpeg_idct_13x13;
150      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
151      break;
152    case ((14 << 8) + 14):
153      method_ptr = jpeg_idct_14x14;
154      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
155      break;
156    case ((15 << 8) + 15):
157      method_ptr = jpeg_idct_15x15;
158      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
159      break;
160    case ((16 << 8) + 16):
161      method_ptr = jpeg_idct_16x16;
162      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
163      break;
164    case ((16 << 8) + 8):
165      method_ptr = jpeg_idct_16x8;
166      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
167      break;
168    case ((14 << 8) + 7):
169      method_ptr = jpeg_idct_14x7;
170      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
171      break;
172    case ((12 << 8) + 6):
173      method_ptr = jpeg_idct_12x6;
174      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
175      break;
176    case ((10 << 8) + 5):
177      method_ptr = jpeg_idct_10x5;
178      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
179      break;
180    case ((8 << 8) + 4):
181      method_ptr = jpeg_idct_8x4;
182      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
183      break;
184    case ((6 << 8) + 3):
185      method_ptr = jpeg_idct_6x3;
186      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
187      break;
188    case ((4 << 8) + 2):
189      method_ptr = jpeg_idct_4x2;
190      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
191      break;
192    case ((2 << 8) + 1):
193      method_ptr = jpeg_idct_2x1;
194      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
195      break;
196    case ((8 << 8) + 16):
197      method_ptr = jpeg_idct_8x16;
198      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
199      break;
200    case ((7 << 8) + 14):
201      method_ptr = jpeg_idct_7x14;
202      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
203      break;
204    case ((6 << 8) + 12):
205      method_ptr = jpeg_idct_6x12;
206      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
207      break;
208    case ((5 << 8) + 10):
209      method_ptr = jpeg_idct_5x10;
210      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
211      break;
212    case ((4 << 8) + 8):
213      method_ptr = jpeg_idct_4x8;
214      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
215      break;
216    case ((3 << 8) + 6):
217      method_ptr = jpeg_idct_3x6;
218      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
219      break;
220    case ((2 << 8) + 4):
221      method_ptr = jpeg_idct_2x4;
222      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
223      break;
224    case ((1 << 8) + 2):
225      method_ptr = jpeg_idct_1x2;
226      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
227      break;
228#endif
229    case ((DCTSIZE << 8) + DCTSIZE):
230      switch (cinfo->dct_method) {
231#ifdef DCT_ISLOW_SUPPORTED
232      case JDCT_ISLOW:
233	method_ptr = jpeg_idct_islow;
234	method = JDCT_ISLOW;
235	break;
236#endif
237#ifdef DCT_IFAST_SUPPORTED
238      case JDCT_IFAST:
239	method_ptr = jpeg_idct_ifast;
240	method = JDCT_IFAST;
241	break;
242#endif
243#ifdef DCT_FLOAT_SUPPORTED
244      case JDCT_FLOAT:
245	method_ptr = jpeg_idct_float;
246	method = JDCT_FLOAT;
247	break;
248#endif
249      default:
250	ERREXIT(cinfo, JERR_NOT_COMPILED);
251	break;
252      }
253      break;
254    default:
255      ERREXIT2(cinfo, JERR_BAD_DCTSIZE,
256	       compptr->DCT_h_scaled_size, compptr->DCT_v_scaled_size);
257      break;
258    }
259    idct->pub.inverse_DCT[ci] = method_ptr;
260    /* Create multiplier table from quant table.
261     * However, we can skip this if the component is uninteresting
262     * or if we already built the table.  Also, if no quant table
263     * has yet been saved for the component, we leave the
264     * multiplier table all-zero; we'll be reading zeroes from the
265     * coefficient controller's buffer anyway.
266     */
267    if (! compptr->component_needed || idct->cur_method[ci] == method)
268      continue;
269    qtbl = compptr->quant_table;
270    if (qtbl == NULL)		/* happens if no data yet for component */
271      continue;
272    idct->cur_method[ci] = method;
273    switch (method) {
274#ifdef PROVIDE_ISLOW_TABLES
275    case JDCT_ISLOW:
276      {
277	/* For LL&M IDCT method, multipliers are equal to raw quantization
278	 * coefficients, but are stored as ints to ensure access efficiency.
279	 */
280	ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
281	for (i = 0; i < DCTSIZE2; i++) {
282	  ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
283	}
284      }
285      break;
286#endif
287#ifdef DCT_IFAST_SUPPORTED
288    case JDCT_IFAST:
289      {
290	/* For AA&N IDCT method, multipliers are equal to quantization
291	 * coefficients scaled by scalefactor[row]*scalefactor[col], where
292	 *   scalefactor[0] = 1
293	 *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
294	 * For integer operation, the multiplier table is to be scaled by
295	 * IFAST_SCALE_BITS.
296	 */
297	IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
298#define CONST_BITS 14
299	static const INT16 aanscales[DCTSIZE2] = {
300	  /* precomputed values scaled up by 14 bits */
301	  16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
302	  22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
303	  21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
304	  19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
305	  16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
306	  12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
307	   8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
308	   4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
309	};
310	SHIFT_TEMPS
311
312	for (i = 0; i < DCTSIZE2; i++) {
313	  ifmtbl[i] = (IFAST_MULT_TYPE)
314	    DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
315				  (INT32) aanscales[i]),
316		    CONST_BITS-IFAST_SCALE_BITS);
317	}
318      }
319      break;
320#endif
321#ifdef DCT_FLOAT_SUPPORTED
322    case JDCT_FLOAT:
323      {
324	/* For float AA&N IDCT method, multipliers are equal to quantization
325	 * coefficients scaled by scalefactor[row]*scalefactor[col], where
326	 *   scalefactor[0] = 1
327	 *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
328	 * We apply a further scale factor of 1/8.
329	 */
330	FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
331	int row, col;
332	static const double aanscalefactor[DCTSIZE] = {
333	  1.0, 1.387039845, 1.306562965, 1.175875602,
334	  1.0, 0.785694958, 0.541196100, 0.275899379
335	};
336
337	i = 0;
338	for (row = 0; row < DCTSIZE; row++) {
339	  for (col = 0; col < DCTSIZE; col++) {
340	    fmtbl[i] = (FLOAT_MULT_TYPE)
341	      ((double) qtbl->quantval[i] *
342	       aanscalefactor[row] * aanscalefactor[col] * 0.125);
343	    i++;
344	  }
345	}
346      }
347      break;
348#endif
349    default:
350      ERREXIT(cinfo, JERR_NOT_COMPILED);
351      break;
352    }
353  }
354}
355
356
357/*
358 * Initialize IDCT manager.
359 */
360
361GLOBAL(void)
362jinit_inverse_dct (j_decompress_ptr cinfo)
363{
364  my_idct_ptr idct;
365  int ci;
366  jpeg_component_info *compptr;
367
368  idct = (my_idct_ptr)
369    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
370				SIZEOF(my_idct_controller));
371  cinfo->idct = (struct jpeg_inverse_dct *) idct;
372  idct->pub.start_pass = start_pass;
373
374  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
375       ci++, compptr++) {
376    /* Allocate and pre-zero a multiplier table for each component */
377    compptr->dct_table =
378      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
379				  SIZEOF(multiplier_table));
380    MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
381    /* Mark multiplier table not yet set up for any method */
382    idct->cur_method[ci] = -1;
383  }
384}