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/thirdparty/jpeg/jdmaster.c

http://crashrpt.googlecode.com/
C | 533 lines | 311 code | 64 blank | 158 comment | 89 complexity | 70943ee65370cb9b19d9b67b67887f47 MD5 | raw file
  1/*
  2 * jdmaster.c
  3 *
  4 * Copyright (C) 1991-1997, Thomas G. Lane.
  5 * Modified 2002-2009 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 master control logic for the JPEG decompressor.
 10 * These routines are concerned with selecting the modules to be executed
 11 * and with determining the number of passes and the work to be done in each
 12 * pass.
 13 */
 14
 15#define JPEG_INTERNALS
 16#include "jinclude.h"
 17#include "jpeglib.h"
 18
 19
 20/* Private state */
 21
 22typedef struct {
 23  struct jpeg_decomp_master pub; /* public fields */
 24
 25  int pass_number;		/* # of passes completed */
 26
 27  boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
 28
 29  /* Saved references to initialized quantizer modules,
 30   * in case we need to switch modes.
 31   */
 32  struct jpeg_color_quantizer * quantizer_1pass;
 33  struct jpeg_color_quantizer * quantizer_2pass;
 34} my_decomp_master;
 35
 36typedef my_decomp_master * my_master_ptr;
 37
 38
 39/*
 40 * Determine whether merged upsample/color conversion should be used.
 41 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
 42 */
 43
 44LOCAL(boolean)
 45use_merged_upsample (j_decompress_ptr cinfo)
 46{
 47#ifdef UPSAMPLE_MERGING_SUPPORTED
 48  /* Merging is the equivalent of plain box-filter upsampling */
 49  if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
 50    return FALSE;
 51  /* jdmerge.c only supports YCC=>RGB color conversion */
 52  if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
 53      cinfo->out_color_space != JCS_RGB ||
 54      cinfo->out_color_components != RGB_PIXELSIZE)
 55    return FALSE;
 56  /* and it only handles 2h1v or 2h2v sampling ratios */
 57  if (cinfo->comp_info[0].h_samp_factor != 2 ||
 58      cinfo->comp_info[1].h_samp_factor != 1 ||
 59      cinfo->comp_info[2].h_samp_factor != 1 ||
 60      cinfo->comp_info[0].v_samp_factor >  2 ||
 61      cinfo->comp_info[1].v_samp_factor != 1 ||
 62      cinfo->comp_info[2].v_samp_factor != 1)
 63    return FALSE;
 64  /* furthermore, it doesn't work if we've scaled the IDCTs differently */
 65  if (cinfo->comp_info[0].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
 66      cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
 67      cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
 68      cinfo->comp_info[0].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
 69      cinfo->comp_info[1].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
 70      cinfo->comp_info[2].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size)
 71    return FALSE;
 72  /* ??? also need to test for upsample-time rescaling, when & if supported */
 73  return TRUE;			/* by golly, it'll work... */
 74#else
 75  return FALSE;
 76#endif
 77}
 78
 79
 80/*
 81 * Compute output image dimensions and related values.
 82 * NOTE: this is exported for possible use by application.
 83 * Hence it mustn't do anything that can't be done twice.
 84 * Also note that it may be called before the master module is initialized!
 85 */
 86
 87GLOBAL(void)
 88jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
 89/* Do computations that are needed before master selection phase.
 90 * This function is used for full decompression.
 91 */
 92{
 93#ifdef IDCT_SCALING_SUPPORTED
 94  int ci;
 95  jpeg_component_info *compptr;
 96#endif
 97
 98  /* Prevent application from calling me at wrong times */
 99  if (cinfo->global_state != DSTATE_READY)
100    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
101
102  /* Compute core output image dimensions and DCT scaling choices. */
103  jpeg_core_output_dimensions(cinfo);
104
105#ifdef IDCT_SCALING_SUPPORTED
106
107  /* In selecting the actual DCT scaling for each component, we try to
108   * scale up the chroma components via IDCT scaling rather than upsampling.
109   * This saves time if the upsampler gets to use 1:1 scaling.
110   * Note this code adapts subsampling ratios which are powers of 2.
111   */
112  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
113       ci++, compptr++) {
114    int ssize = 1;
115    while (cinfo->min_DCT_h_scaled_size * ssize <=
116	   (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
117	   (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
118      ssize = ssize * 2;
119    }
120    compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
121    ssize = 1;
122    while (cinfo->min_DCT_v_scaled_size * ssize <=
123	   (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
124	   (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
125      ssize = ssize * 2;
126    }
127    compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
128
129    /* We don't support IDCT ratios larger than 2. */
130    if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
131	compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
132    else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
133	compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
134  }
135
136  /* Recompute downsampled dimensions of components;
137   * application needs to know these if using raw downsampled data.
138   */
139  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
140       ci++, compptr++) {
141    /* Size in samples, after IDCT scaling */
142    compptr->downsampled_width = (JDIMENSION)
143      jdiv_round_up((long) cinfo->image_width *
144		    (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
145		    (long) (cinfo->max_h_samp_factor * cinfo->block_size));
146    compptr->downsampled_height = (JDIMENSION)
147      jdiv_round_up((long) cinfo->image_height *
148		    (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
149		    (long) (cinfo->max_v_samp_factor * cinfo->block_size));
150  }
151
152#endif /* IDCT_SCALING_SUPPORTED */
153
154  /* Report number of components in selected colorspace. */
155  /* Probably this should be in the color conversion module... */
156  switch (cinfo->out_color_space) {
157  case JCS_GRAYSCALE:
158    cinfo->out_color_components = 1;
159    break;
160  case JCS_RGB:
161#if RGB_PIXELSIZE != 3
162    cinfo->out_color_components = RGB_PIXELSIZE;
163    break;
164#endif /* else share code with YCbCr */
165  case JCS_YCbCr:
166    cinfo->out_color_components = 3;
167    break;
168  case JCS_CMYK:
169  case JCS_YCCK:
170    cinfo->out_color_components = 4;
171    break;
172  default:			/* else must be same colorspace as in file */
173    cinfo->out_color_components = cinfo->num_components;
174    break;
175  }
176  cinfo->output_components = (cinfo->quantize_colors ? 1 :
177			      cinfo->out_color_components);
178
179  /* See if upsampler will want to emit more than one row at a time */
180  if (use_merged_upsample(cinfo))
181    cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
182  else
183    cinfo->rec_outbuf_height = 1;
184}
185
186
187/*
188 * Several decompression processes need to range-limit values to the range
189 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
190 * due to noise introduced by quantization, roundoff error, etc.  These
191 * processes are inner loops and need to be as fast as possible.  On most
192 * machines, particularly CPUs with pipelines or instruction prefetch,
193 * a (subscript-check-less) C table lookup
194 *		x = sample_range_limit[x];
195 * is faster than explicit tests
196 *		if (x < 0)  x = 0;
197 *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
198 * These processes all use a common table prepared by the routine below.
199 *
200 * For most steps we can mathematically guarantee that the initial value
201 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
202 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
203 * limiting step (just after the IDCT), a wildly out-of-range value is 
204 * possible if the input data is corrupt.  To avoid any chance of indexing
205 * off the end of memory and getting a bad-pointer trap, we perform the
206 * post-IDCT limiting thus:
207 *		x = range_limit[x & MASK];
208 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
209 * samples.  Under normal circumstances this is more than enough range and
210 * a correct output will be generated; with bogus input data the mask will
211 * cause wraparound, and we will safely generate a bogus-but-in-range output.
212 * For the post-IDCT step, we want to convert the data from signed to unsigned
213 * representation by adding CENTERJSAMPLE at the same time that we limit it.
214 * So the post-IDCT limiting table ends up looking like this:
215 *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
216 *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
217 *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
218 *   0,1,...,CENTERJSAMPLE-1
219 * Negative inputs select values from the upper half of the table after
220 * masking.
221 *
222 * We can save some space by overlapping the start of the post-IDCT table
223 * with the simpler range limiting table.  The post-IDCT table begins at
224 * sample_range_limit + CENTERJSAMPLE.
225 *
226 * Note that the table is allocated in near data space on PCs; it's small
227 * enough and used often enough to justify this.
228 */
229
230LOCAL(void)
231prepare_range_limit_table (j_decompress_ptr cinfo)
232/* Allocate and fill in the sample_range_limit table */
233{
234  JSAMPLE * table;
235  int i;
236
237  table = (JSAMPLE *)
238    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
239		(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
240  table += (MAXJSAMPLE+1);	/* allow negative subscripts of simple table */
241  cinfo->sample_range_limit = table;
242  /* First segment of "simple" table: limit[x] = 0 for x < 0 */
243  MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
244  /* Main part of "simple" table: limit[x] = x */
245  for (i = 0; i <= MAXJSAMPLE; i++)
246    table[i] = (JSAMPLE) i;
247  table += CENTERJSAMPLE;	/* Point to where post-IDCT table starts */
248  /* End of simple table, rest of first half of post-IDCT table */
249  for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
250    table[i] = MAXJSAMPLE;
251  /* Second half of post-IDCT table */
252  MEMZERO(table + (2 * (MAXJSAMPLE+1)),
253	  (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
254  MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
255	  cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
256}
257
258
259/*
260 * Master selection of decompression modules.
261 * This is done once at jpeg_start_decompress time.  We determine
262 * which modules will be used and give them appropriate initialization calls.
263 * We also initialize the decompressor input side to begin consuming data.
264 *
265 * Since jpeg_read_header has finished, we know what is in the SOF
266 * and (first) SOS markers.  We also have all the application parameter
267 * settings.
268 */
269
270LOCAL(void)
271master_selection (j_decompress_ptr cinfo)
272{
273  my_master_ptr master = (my_master_ptr) cinfo->master;
274  boolean use_c_buffer;
275  long samplesperrow;
276  JDIMENSION jd_samplesperrow;
277
278  /* Initialize dimensions and other stuff */
279  jpeg_calc_output_dimensions(cinfo);
280  prepare_range_limit_table(cinfo);
281
282  /* Width of an output scanline must be representable as JDIMENSION. */
283  samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
284  jd_samplesperrow = (JDIMENSION) samplesperrow;
285  if ((long) jd_samplesperrow != samplesperrow)
286    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
287
288  /* Initialize my private state */
289  master->pass_number = 0;
290  master->using_merged_upsample = use_merged_upsample(cinfo);
291
292  /* Color quantizer selection */
293  master->quantizer_1pass = NULL;
294  master->quantizer_2pass = NULL;
295  /* No mode changes if not using buffered-image mode. */
296  if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
297    cinfo->enable_1pass_quant = FALSE;
298    cinfo->enable_external_quant = FALSE;
299    cinfo->enable_2pass_quant = FALSE;
300  }
301  if (cinfo->quantize_colors) {
302    if (cinfo->raw_data_out)
303      ERREXIT(cinfo, JERR_NOTIMPL);
304    /* 2-pass quantizer only works in 3-component color space. */
305    if (cinfo->out_color_components != 3) {
306      cinfo->enable_1pass_quant = TRUE;
307      cinfo->enable_external_quant = FALSE;
308      cinfo->enable_2pass_quant = FALSE;
309      cinfo->colormap = NULL;
310    } else if (cinfo->colormap != NULL) {
311      cinfo->enable_external_quant = TRUE;
312    } else if (cinfo->two_pass_quantize) {
313      cinfo->enable_2pass_quant = TRUE;
314    } else {
315      cinfo->enable_1pass_quant = TRUE;
316    }
317
318    if (cinfo->enable_1pass_quant) {
319#ifdef QUANT_1PASS_SUPPORTED
320      jinit_1pass_quantizer(cinfo);
321      master->quantizer_1pass = cinfo->cquantize;
322#else
323      ERREXIT(cinfo, JERR_NOT_COMPILED);
324#endif
325    }
326
327    /* We use the 2-pass code to map to external colormaps. */
328    if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
329#ifdef QUANT_2PASS_SUPPORTED
330      jinit_2pass_quantizer(cinfo);
331      master->quantizer_2pass = cinfo->cquantize;
332#else
333      ERREXIT(cinfo, JERR_NOT_COMPILED);
334#endif
335    }
336    /* If both quantizers are initialized, the 2-pass one is left active;
337     * this is necessary for starting with quantization to an external map.
338     */
339  }
340
341  /* Post-processing: in particular, color conversion first */
342  if (! cinfo->raw_data_out) {
343    if (master->using_merged_upsample) {
344#ifdef UPSAMPLE_MERGING_SUPPORTED
345      jinit_merged_upsampler(cinfo); /* does color conversion too */
346#else
347      ERREXIT(cinfo, JERR_NOT_COMPILED);
348#endif
349    } else {
350      jinit_color_deconverter(cinfo);
351      jinit_upsampler(cinfo);
352    }
353    jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
354  }
355  /* Inverse DCT */
356  jinit_inverse_dct(cinfo);
357  /* Entropy decoding: either Huffman or arithmetic coding. */
358  if (cinfo->arith_code)
359    jinit_arith_decoder(cinfo);
360  else {
361    jinit_huff_decoder(cinfo);
362  }
363
364  /* Initialize principal buffer controllers. */
365  use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
366  jinit_d_coef_controller(cinfo, use_c_buffer);
367
368  if (! cinfo->raw_data_out)
369    jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
370
371  /* We can now tell the memory manager to allocate virtual arrays. */
372  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
373
374  /* Initialize input side of decompressor to consume first scan. */
375  (*cinfo->inputctl->start_input_pass) (cinfo);
376
377#ifdef D_MULTISCAN_FILES_SUPPORTED
378  /* If jpeg_start_decompress will read the whole file, initialize
379   * progress monitoring appropriately.  The input step is counted
380   * as one pass.
381   */
382  if (cinfo->progress != NULL && ! cinfo->buffered_image &&
383      cinfo->inputctl->has_multiple_scans) {
384    int nscans;
385    /* Estimate number of scans to set pass_limit. */
386    if (cinfo->progressive_mode) {
387      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
388      nscans = 2 + 3 * cinfo->num_components;
389    } else {
390      /* For a nonprogressive multiscan file, estimate 1 scan per component. */
391      nscans = cinfo->num_components;
392    }
393    cinfo->progress->pass_counter = 0L;
394    cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
395    cinfo->progress->completed_passes = 0;
396    cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
397    /* Count the input pass as done */
398    master->pass_number++;
399  }
400#endif /* D_MULTISCAN_FILES_SUPPORTED */
401}
402
403
404/*
405 * Per-pass setup.
406 * This is called at the beginning of each output pass.  We determine which
407 * modules will be active during this pass and give them appropriate
408 * start_pass calls.  We also set is_dummy_pass to indicate whether this
409 * is a "real" output pass or a dummy pass for color quantization.
410 * (In the latter case, jdapistd.c will crank the pass to completion.)
411 */
412
413METHODDEF(void)
414prepare_for_output_pass (j_decompress_ptr cinfo)
415{
416  my_master_ptr master = (my_master_ptr) cinfo->master;
417
418  if (master->pub.is_dummy_pass) {
419#ifdef QUANT_2PASS_SUPPORTED
420    /* Final pass of 2-pass quantization */
421    master->pub.is_dummy_pass = FALSE;
422    (*cinfo->cquantize->start_pass) (cinfo, FALSE);
423    (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
424    (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
425#else
426    ERREXIT(cinfo, JERR_NOT_COMPILED);
427#endif /* QUANT_2PASS_SUPPORTED */
428  } else {
429    if (cinfo->quantize_colors && cinfo->colormap == NULL) {
430      /* Select new quantization method */
431      if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
432	cinfo->cquantize = master->quantizer_2pass;
433	master->pub.is_dummy_pass = TRUE;
434      } else if (cinfo->enable_1pass_quant) {
435	cinfo->cquantize = master->quantizer_1pass;
436      } else {
437	ERREXIT(cinfo, JERR_MODE_CHANGE);
438      }
439    }
440    (*cinfo->idct->start_pass) (cinfo);
441    (*cinfo->coef->start_output_pass) (cinfo);
442    if (! cinfo->raw_data_out) {
443      if (! master->using_merged_upsample)
444	(*cinfo->cconvert->start_pass) (cinfo);
445      (*cinfo->upsample->start_pass) (cinfo);
446      if (cinfo->quantize_colors)
447	(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
448      (*cinfo->post->start_pass) (cinfo,
449	    (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
450      (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
451    }
452  }
453
454  /* Set up progress monitor's pass info if present */
455  if (cinfo->progress != NULL) {
456    cinfo->progress->completed_passes = master->pass_number;
457    cinfo->progress->total_passes = master->pass_number +
458				    (master->pub.is_dummy_pass ? 2 : 1);
459    /* In buffered-image mode, we assume one more output pass if EOI not
460     * yet reached, but no more passes if EOI has been reached.
461     */
462    if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
463      cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
464    }
465  }
466}
467
468
469/*
470 * Finish up at end of an output pass.
471 */
472
473METHODDEF(void)
474finish_output_pass (j_decompress_ptr cinfo)
475{
476  my_master_ptr master = (my_master_ptr) cinfo->master;
477
478  if (cinfo->quantize_colors)
479    (*cinfo->cquantize->finish_pass) (cinfo);
480  master->pass_number++;
481}
482
483
484#ifdef D_MULTISCAN_FILES_SUPPORTED
485
486/*
487 * Switch to a new external colormap between output passes.
488 */
489
490GLOBAL(void)
491jpeg_new_colormap (j_decompress_ptr cinfo)
492{
493  my_master_ptr master = (my_master_ptr) cinfo->master;
494
495  /* Prevent application from calling me at wrong times */
496  if (cinfo->global_state != DSTATE_BUFIMAGE)
497    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
498
499  if (cinfo->quantize_colors && cinfo->enable_external_quant &&
500      cinfo->colormap != NULL) {
501    /* Select 2-pass quantizer for external colormap use */
502    cinfo->cquantize = master->quantizer_2pass;
503    /* Notify quantizer of colormap change */
504    (*cinfo->cquantize->new_color_map) (cinfo);
505    master->pub.is_dummy_pass = FALSE; /* just in case */
506  } else
507    ERREXIT(cinfo, JERR_MODE_CHANGE);
508}
509
510#endif /* D_MULTISCAN_FILES_SUPPORTED */
511
512
513/*
514 * Initialize master decompression control and select active modules.
515 * This is performed at the start of jpeg_start_decompress.
516 */
517
518GLOBAL(void)
519jinit_master_decompress (j_decompress_ptr cinfo)
520{
521  my_master_ptr master;
522
523  master = (my_master_ptr)
524      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
525				  SIZEOF(my_decomp_master));
526  cinfo->master = (struct jpeg_decomp_master *) master;
527  master->pub.prepare_for_output_pass = prepare_for_output_pass;
528  master->pub.finish_output_pass = finish_output_pass;
529
530  master->pub.is_dummy_pass = FALSE;
531
532  master_selection(cinfo);
533}