source: trunk/libjpeg/jdmaster.c @ 283

Last change on this file since 283 was 283, checked in by rbri, 12 years ago

JPEG plugin: libjpeg updated to version 7

File size: 25.2 KB
Line 
1/*
2 * jdmaster.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * Modified 2002-2008 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{
91#ifdef IDCT_SCALING_SUPPORTED
92  int ci;
93  jpeg_component_info *compptr;
94#endif
95
96  /* Prevent application from calling me at wrong times */
97  if (cinfo->global_state != DSTATE_READY)
98    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
99
100#ifdef IDCT_SCALING_SUPPORTED
101
102  /* Compute actual output image dimensions and DCT scaling choices. */
103  if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
104    /* Provide 1/8 scaling */
105    cinfo->output_width = (JDIMENSION)
106      jdiv_round_up((long) cinfo->image_width, 8L);
107    cinfo->output_height = (JDIMENSION)
108      jdiv_round_up((long) cinfo->image_height, 8L);
109    cinfo->min_DCT_h_scaled_size = 1;
110    cinfo->min_DCT_v_scaled_size = 1;
111  } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
112    /* Provide 1/4 scaling */
113    cinfo->output_width = (JDIMENSION)
114      jdiv_round_up((long) cinfo->image_width, 4L);
115    cinfo->output_height = (JDIMENSION)
116      jdiv_round_up((long) cinfo->image_height, 4L);
117    cinfo->min_DCT_h_scaled_size = 2;
118    cinfo->min_DCT_v_scaled_size = 2;
119  } else if (cinfo->scale_num * 8 <= cinfo->scale_denom * 3) {
120    /* Provide 3/8 scaling */
121    cinfo->output_width = (JDIMENSION)
122      jdiv_round_up((long) cinfo->image_width * 3L, 8L);
123    cinfo->output_height = (JDIMENSION)
124      jdiv_round_up((long) cinfo->image_height * 3L, 8L);
125    cinfo->min_DCT_h_scaled_size = 3;
126    cinfo->min_DCT_v_scaled_size = 3;
127  } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
128    /* Provide 1/2 scaling */
129    cinfo->output_width = (JDIMENSION)
130      jdiv_round_up((long) cinfo->image_width, 2L);
131    cinfo->output_height = (JDIMENSION)
132      jdiv_round_up((long) cinfo->image_height, 2L);
133    cinfo->min_DCT_h_scaled_size = 4;
134    cinfo->min_DCT_v_scaled_size = 4;
135  } else if (cinfo->scale_num * 8 <= cinfo->scale_denom * 5) {
136    /* Provide 5/8 scaling */
137    cinfo->output_width = (JDIMENSION)
138      jdiv_round_up((long) cinfo->image_width * 5L, 8L);
139    cinfo->output_height = (JDIMENSION)
140      jdiv_round_up((long) cinfo->image_height * 5L, 8L);
141    cinfo->min_DCT_h_scaled_size = 5;
142    cinfo->min_DCT_v_scaled_size = 5;
143  } else if (cinfo->scale_num * 4 <= cinfo->scale_denom * 3) {
144    /* Provide 3/4 scaling */
145    cinfo->output_width = (JDIMENSION)
146      jdiv_round_up((long) cinfo->image_width * 3L, 4L);
147    cinfo->output_height = (JDIMENSION)
148      jdiv_round_up((long) cinfo->image_height * 3L, 4L);
149    cinfo->min_DCT_h_scaled_size = 6;
150    cinfo->min_DCT_v_scaled_size = 6;
151  } else if (cinfo->scale_num * 8 <= cinfo->scale_denom * 7) {
152    /* Provide 7/8 scaling */
153    cinfo->output_width = (JDIMENSION)
154      jdiv_round_up((long) cinfo->image_width * 7L, 8L);
155    cinfo->output_height = (JDIMENSION)
156      jdiv_round_up((long) cinfo->image_height * 7L, 8L);
157    cinfo->min_DCT_h_scaled_size = 7;
158    cinfo->min_DCT_v_scaled_size = 7;
159  } else if (cinfo->scale_num <= cinfo->scale_denom) {
160    /* Provide 1/1 scaling */
161    cinfo->output_width = cinfo->image_width;
162    cinfo->output_height = cinfo->image_height;
163    cinfo->min_DCT_h_scaled_size = DCTSIZE;
164    cinfo->min_DCT_v_scaled_size = DCTSIZE;
165  } else if (cinfo->scale_num * 8 <= cinfo->scale_denom * 9) {
166    /* Provide 9/8 scaling */
167    cinfo->output_width = cinfo->image_width + (JDIMENSION)
168      jdiv_round_up((long) cinfo->image_width, 8L);
169    cinfo->output_height = cinfo->image_height + (JDIMENSION)
170      jdiv_round_up((long) cinfo->image_height, 8L);
171    cinfo->min_DCT_h_scaled_size = 9;
172    cinfo->min_DCT_v_scaled_size = 9;
173  } else if (cinfo->scale_num * 4 <= cinfo->scale_denom * 5) {
174    /* Provide 5/4 scaling */
175    cinfo->output_width = cinfo->image_width + (JDIMENSION)
176      jdiv_round_up((long) cinfo->image_width, 4L);
177    cinfo->output_height = cinfo->image_height + (JDIMENSION)
178      jdiv_round_up((long) cinfo->image_height, 4L);
179    cinfo->min_DCT_h_scaled_size = 10;
180    cinfo->min_DCT_v_scaled_size = 10;
181  } else if (cinfo->scale_num * 8 <= cinfo->scale_denom * 11) {
182    /* Provide 11/8 scaling */
183    cinfo->output_width = cinfo->image_width + (JDIMENSION)
184      jdiv_round_up((long) cinfo->image_width * 3L, 8L);
185    cinfo->output_height = cinfo->image_height + (JDIMENSION)
186      jdiv_round_up((long) cinfo->image_height * 3L, 8L);
187    cinfo->min_DCT_h_scaled_size = 11;
188    cinfo->min_DCT_v_scaled_size = 11;
189  } else if (cinfo->scale_num * 2 <= cinfo->scale_denom * 3) {
190    /* Provide 3/2 scaling */
191    cinfo->output_width = cinfo->image_width + (JDIMENSION)
192      jdiv_round_up((long) cinfo->image_width, 2L);
193    cinfo->output_height = cinfo->image_height + (JDIMENSION)
194      jdiv_round_up((long) cinfo->image_height, 2L);
195    cinfo->min_DCT_h_scaled_size = 12;
196    cinfo->min_DCT_v_scaled_size = 12;
197  } else if (cinfo->scale_num * 8 <= cinfo->scale_denom * 13) {
198    /* Provide 13/8 scaling */
199    cinfo->output_width = cinfo->image_width + (JDIMENSION)
200      jdiv_round_up((long) cinfo->image_width * 5L, 8L);
201    cinfo->output_height = cinfo->image_height + (JDIMENSION)
202      jdiv_round_up((long) cinfo->image_height * 5L, 8L);
203    cinfo->min_DCT_h_scaled_size = 13;
204    cinfo->min_DCT_v_scaled_size = 13;
205  } else if (cinfo->scale_num * 4 <= cinfo->scale_denom * 7) {
206    /* Provide 7/4 scaling */
207    cinfo->output_width = cinfo->image_width + (JDIMENSION)
208      jdiv_round_up((long) cinfo->image_width * 3L, 4L);
209    cinfo->output_height = cinfo->image_height + (JDIMENSION)
210      jdiv_round_up((long) cinfo->image_height * 3L, 4L);
211    cinfo->min_DCT_h_scaled_size = 14;
212    cinfo->min_DCT_v_scaled_size = 14;
213  } else if (cinfo->scale_num * 8 <= cinfo->scale_denom * 15) {
214    /* Provide 15/8 scaling */
215    cinfo->output_width = cinfo->image_width + (JDIMENSION)
216      jdiv_round_up((long) cinfo->image_width * 7L, 8L);
217    cinfo->output_height = cinfo->image_height + (JDIMENSION)
218      jdiv_round_up((long) cinfo->image_height * 7L, 8L);
219    cinfo->min_DCT_h_scaled_size = 15;
220    cinfo->min_DCT_v_scaled_size = 15;
221  } else {
222    /* Provide 2/1 scaling */
223    cinfo->output_width = cinfo->image_width << 1;
224    cinfo->output_height = cinfo->image_height << 1;
225    cinfo->min_DCT_h_scaled_size = 16;
226    cinfo->min_DCT_v_scaled_size = 16;
227  }
228  /* In selecting the actual DCT scaling for each component, we try to
229   * scale up the chroma components via IDCT scaling rather than upsampling.
230   * This saves time if the upsampler gets to use 1:1 scaling.
231   * Note this code adapts subsampling ratios which are powers of 2.
232   */
233  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
234       ci++, compptr++) {
235    int ssize = 1;
236    while (cinfo->min_DCT_h_scaled_size * ssize <=
237           (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
238           (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
239      ssize = ssize * 2;
240    }
241    compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
242    ssize = 1;
243    while (cinfo->min_DCT_v_scaled_size * ssize <=
244           (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
245           (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
246      ssize = ssize * 2;
247    }
248    compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
249
250    /* We don't support IDCT ratios larger than 2. */
251    if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
252        compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
253    else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
254        compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
255  }
256
257  /* Recompute downsampled dimensions of components;
258   * application needs to know these if using raw downsampled data.
259   */
260  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
261       ci++, compptr++) {
262    /* Size in samples, after IDCT scaling */
263    compptr->downsampled_width = (JDIMENSION)
264      jdiv_round_up((long) cinfo->image_width *
265                    (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
266                    (long) (cinfo->max_h_samp_factor * DCTSIZE));
267    compptr->downsampled_height = (JDIMENSION)
268      jdiv_round_up((long) cinfo->image_height *
269                    (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
270                    (long) (cinfo->max_v_samp_factor * DCTSIZE));
271  }
272
273#else /* !IDCT_SCALING_SUPPORTED */
274
275  /* Hardwire it to "no scaling" */
276  cinfo->output_width = cinfo->image_width;
277  cinfo->output_height = cinfo->image_height;
278  /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
279   * and has computed unscaled downsampled_width and downsampled_height.
280   */
281
282#endif /* IDCT_SCALING_SUPPORTED */
283
284  /* Report number of components in selected colorspace. */
285  /* Probably this should be in the color conversion module... */
286  switch (cinfo->out_color_space) {
287  case JCS_GRAYSCALE:
288    cinfo->out_color_components = 1;
289    break;
290  case JCS_RGB:
291#if RGB_PIXELSIZE != 3
292    cinfo->out_color_components = RGB_PIXELSIZE;
293    break;
294#endif /* else share code with YCbCr */
295  case JCS_YCbCr:
296    cinfo->out_color_components = 3;
297    break;
298  case JCS_CMYK:
299  case JCS_YCCK:
300    cinfo->out_color_components = 4;
301    break;
302  default:                      /* else must be same colorspace as in file */
303    cinfo->out_color_components = cinfo->num_components;
304    break;
305  }
306  cinfo->output_components = (cinfo->quantize_colors ? 1 :
307                              cinfo->out_color_components);
308
309  /* See if upsampler will want to emit more than one row at a time */
310  if (use_merged_upsample(cinfo))
311    cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
312  else
313    cinfo->rec_outbuf_height = 1;
314}
315
316
317/*
318 * Several decompression processes need to range-limit values to the range
319 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
320 * due to noise introduced by quantization, roundoff error, etc.  These
321 * processes are inner loops and need to be as fast as possible.  On most
322 * machines, particularly CPUs with pipelines or instruction prefetch,
323 * a (subscript-check-less) C table lookup
324 *              x = sample_range_limit[x];
325 * is faster than explicit tests
326 *              if (x < 0)  x = 0;
327 *              else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
328 * These processes all use a common table prepared by the routine below.
329 *
330 * For most steps we can mathematically guarantee that the initial value
331 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
332 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
333 * limiting step (just after the IDCT), a wildly out-of-range value is
334 * possible if the input data is corrupt.  To avoid any chance of indexing
335 * off the end of memory and getting a bad-pointer trap, we perform the
336 * post-IDCT limiting thus:
337 *              x = range_limit[x & MASK];
338 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
339 * samples.  Under normal circumstances this is more than enough range and
340 * a correct output will be generated; with bogus input data the mask will
341 * cause wraparound, and we will safely generate a bogus-but-in-range output.
342 * For the post-IDCT step, we want to convert the data from signed to unsigned
343 * representation by adding CENTERJSAMPLE at the same time that we limit it.
344 * So the post-IDCT limiting table ends up looking like this:
345 *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
346 *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
347 *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
348 *   0,1,...,CENTERJSAMPLE-1
349 * Negative inputs select values from the upper half of the table after
350 * masking.
351 *
352 * We can save some space by overlapping the start of the post-IDCT table
353 * with the simpler range limiting table.  The post-IDCT table begins at
354 * sample_range_limit + CENTERJSAMPLE.
355 *
356 * Note that the table is allocated in near data space on PCs; it's small
357 * enough and used often enough to justify this.
358 */
359
360LOCAL(void)
361prepare_range_limit_table (j_decompress_ptr cinfo)
362/* Allocate and fill in the sample_range_limit table */
363{
364  JSAMPLE * table;
365  int i;
366
367  table = (JSAMPLE *)
368    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
369                (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
370  table += (MAXJSAMPLE+1);      /* allow negative subscripts of simple table */
371  cinfo->sample_range_limit = table;
372  /* First segment of "simple" table: limit[x] = 0 for x < 0 */
373  MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
374  /* Main part of "simple" table: limit[x] = x */
375  for (i = 0; i <= MAXJSAMPLE; i++)
376    table[i] = (JSAMPLE) i;
377  table += CENTERJSAMPLE;       /* Point to where post-IDCT table starts */
378  /* End of simple table, rest of first half of post-IDCT table */
379  for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
380    table[i] = MAXJSAMPLE;
381  /* Second half of post-IDCT table */
382  MEMZERO(table + (2 * (MAXJSAMPLE+1)),
383          (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
384  MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
385          cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
386}
387
388
389/*
390 * Master selection of decompression modules.
391 * This is done once at jpeg_start_decompress time.  We determine
392 * which modules will be used and give them appropriate initialization calls.
393 * We also initialize the decompressor input side to begin consuming data.
394 *
395 * Since jpeg_read_header has finished, we know what is in the SOF
396 * and (first) SOS markers.  We also have all the application parameter
397 * settings.
398 */
399
400LOCAL(void)
401master_selection (j_decompress_ptr cinfo)
402{
403  my_master_ptr master = (my_master_ptr) cinfo->master;
404  boolean use_c_buffer;
405  long samplesperrow;
406  JDIMENSION jd_samplesperrow;
407
408  /* Initialize dimensions and other stuff */
409  jpeg_calc_output_dimensions(cinfo);
410  prepare_range_limit_table(cinfo);
411
412  /* Width of an output scanline must be representable as JDIMENSION. */
413  samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
414  jd_samplesperrow = (JDIMENSION) samplesperrow;
415  if ((long) jd_samplesperrow != samplesperrow)
416    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
417
418  /* Initialize my private state */
419  master->pass_number = 0;
420  master->using_merged_upsample = use_merged_upsample(cinfo);
421
422  /* Color quantizer selection */
423  master->quantizer_1pass = NULL;
424  master->quantizer_2pass = NULL;
425  /* No mode changes if not using buffered-image mode. */
426  if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
427    cinfo->enable_1pass_quant = FALSE;
428    cinfo->enable_external_quant = FALSE;
429    cinfo->enable_2pass_quant = FALSE;
430  }
431  if (cinfo->quantize_colors) {
432    if (cinfo->raw_data_out)
433      ERREXIT(cinfo, JERR_NOTIMPL);
434    /* 2-pass quantizer only works in 3-component color space. */
435    if (cinfo->out_color_components != 3) {
436      cinfo->enable_1pass_quant = TRUE;
437      cinfo->enable_external_quant = FALSE;
438      cinfo->enable_2pass_quant = FALSE;
439      cinfo->colormap = NULL;
440    } else if (cinfo->colormap != NULL) {
441      cinfo->enable_external_quant = TRUE;
442    } else if (cinfo->two_pass_quantize) {
443      cinfo->enable_2pass_quant = TRUE;
444    } else {
445      cinfo->enable_1pass_quant = TRUE;
446    }
447
448    if (cinfo->enable_1pass_quant) {
449#ifdef QUANT_1PASS_SUPPORTED
450      jinit_1pass_quantizer(cinfo);
451      master->quantizer_1pass = cinfo->cquantize;
452#else
453      ERREXIT(cinfo, JERR_NOT_COMPILED);
454#endif
455    }
456
457    /* We use the 2-pass code to map to external colormaps. */
458    if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
459#ifdef QUANT_2PASS_SUPPORTED
460      jinit_2pass_quantizer(cinfo);
461      master->quantizer_2pass = cinfo->cquantize;
462#else
463      ERREXIT(cinfo, JERR_NOT_COMPILED);
464#endif
465    }
466    /* If both quantizers are initialized, the 2-pass one is left active;
467     * this is necessary for starting with quantization to an external map.
468     */
469  }
470
471  /* Post-processing: in particular, color conversion first */
472  if (! cinfo->raw_data_out) {
473    if (master->using_merged_upsample) {
474#ifdef UPSAMPLE_MERGING_SUPPORTED
475      jinit_merged_upsampler(cinfo); /* does color conversion too */
476#else
477      ERREXIT(cinfo, JERR_NOT_COMPILED);
478#endif
479    } else {
480      jinit_color_deconverter(cinfo);
481      jinit_upsampler(cinfo);
482    }
483    jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
484  }
485  /* Inverse DCT */
486  jinit_inverse_dct(cinfo);
487  /* Entropy decoding: either Huffman or arithmetic coding. */
488  if (cinfo->arith_code) {
489    jinit_arith_decoder(cinfo);
490  } else {
491    jinit_huff_decoder(cinfo);
492  }
493
494  /* Initialize principal buffer controllers. */
495  use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
496  jinit_d_coef_controller(cinfo, use_c_buffer);
497
498  if (! cinfo->raw_data_out)
499    jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
500
501  /* We can now tell the memory manager to allocate virtual arrays. */
502  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
503
504  /* Initialize input side of decompressor to consume first scan. */
505  (*cinfo->inputctl->start_input_pass) (cinfo);
506
507#ifdef D_MULTISCAN_FILES_SUPPORTED
508  /* If jpeg_start_decompress will read the whole file, initialize
509   * progress monitoring appropriately.  The input step is counted
510   * as one pass.
511   */
512  if (cinfo->progress != NULL && ! cinfo->buffered_image &&
513      cinfo->inputctl->has_multiple_scans) {
514    int nscans;
515    /* Estimate number of scans to set pass_limit. */
516    if (cinfo->progressive_mode) {
517      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
518      nscans = 2 + 3 * cinfo->num_components;
519    } else {
520      /* For a nonprogressive multiscan file, estimate 1 scan per component. */
521      nscans = cinfo->num_components;
522    }
523    cinfo->progress->pass_counter = 0L;
524    cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
525    cinfo->progress->completed_passes = 0;
526    cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
527    /* Count the input pass as done */
528    master->pass_number++;
529  }
530#endif /* D_MULTISCAN_FILES_SUPPORTED */
531}
532
533
534/*
535 * Per-pass setup.
536 * This is called at the beginning of each output pass.  We determine which
537 * modules will be active during this pass and give them appropriate
538 * start_pass calls.  We also set is_dummy_pass to indicate whether this
539 * is a "real" output pass or a dummy pass for color quantization.
540 * (In the latter case, jdapistd.c will crank the pass to completion.)
541 */
542
543METHODDEF(void)
544prepare_for_output_pass (j_decompress_ptr cinfo)
545{
546  my_master_ptr master = (my_master_ptr) cinfo->master;
547
548  if (master->pub.is_dummy_pass) {
549#ifdef QUANT_2PASS_SUPPORTED
550    /* Final pass of 2-pass quantization */
551    master->pub.is_dummy_pass = FALSE;
552    (*cinfo->cquantize->start_pass) (cinfo, FALSE);
553    (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
554    (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
555#else
556    ERREXIT(cinfo, JERR_NOT_COMPILED);
557#endif /* QUANT_2PASS_SUPPORTED */
558  } else {
559    if (cinfo->quantize_colors && cinfo->colormap == NULL) {
560      /* Select new quantization method */
561      if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
562        cinfo->cquantize = master->quantizer_2pass;
563        master->pub.is_dummy_pass = TRUE;
564      } else if (cinfo->enable_1pass_quant) {
565        cinfo->cquantize = master->quantizer_1pass;
566      } else {
567        ERREXIT(cinfo, JERR_MODE_CHANGE);
568      }
569    }
570    (*cinfo->idct->start_pass) (cinfo);
571    (*cinfo->coef->start_output_pass) (cinfo);
572    if (! cinfo->raw_data_out) {
573      if (! master->using_merged_upsample)
574        (*cinfo->cconvert->start_pass) (cinfo);
575      (*cinfo->upsample->start_pass) (cinfo);
576      if (cinfo->quantize_colors)
577        (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
578      (*cinfo->post->start_pass) (cinfo,
579            (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
580      (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
581    }
582  }
583
584  /* Set up progress monitor's pass info if present */
585  if (cinfo->progress != NULL) {
586    cinfo->progress->completed_passes = master->pass_number;
587    cinfo->progress->total_passes = master->pass_number +
588                                    (master->pub.is_dummy_pass ? 2 : 1);
589    /* In buffered-image mode, we assume one more output pass if EOI not
590     * yet reached, but no more passes if EOI has been reached.
591     */
592    if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
593      cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
594    }
595  }
596}
597
598
599/*
600 * Finish up at end of an output pass.
601 */
602
603METHODDEF(void)
604finish_output_pass (j_decompress_ptr cinfo)
605{
606  my_master_ptr master = (my_master_ptr) cinfo->master;
607
608  if (cinfo->quantize_colors)
609    (*cinfo->cquantize->finish_pass) (cinfo);
610  master->pass_number++;
611}
612
613
614#ifdef D_MULTISCAN_FILES_SUPPORTED
615
616/*
617 * Switch to a new external colormap between output passes.
618 */
619
620GLOBAL(void)
621jpeg_new_colormap (j_decompress_ptr cinfo)
622{
623  my_master_ptr master = (my_master_ptr) cinfo->master;
624
625  /* Prevent application from calling me at wrong times */
626  if (cinfo->global_state != DSTATE_BUFIMAGE)
627    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
628
629  if (cinfo->quantize_colors && cinfo->enable_external_quant &&
630      cinfo->colormap != NULL) {
631    /* Select 2-pass quantizer for external colormap use */
632    cinfo->cquantize = master->quantizer_2pass;
633    /* Notify quantizer of colormap change */
634    (*cinfo->cquantize->new_color_map) (cinfo);
635    master->pub.is_dummy_pass = FALSE; /* just in case */
636  } else
637    ERREXIT(cinfo, JERR_MODE_CHANGE);
638}
639
640#endif /* D_MULTISCAN_FILES_SUPPORTED */
641
642
643/*
644 * Initialize master decompression control and select active modules.
645 * This is performed at the start of jpeg_start_decompress.
646 */
647
648GLOBAL(void)
649jinit_master_decompress (j_decompress_ptr cinfo)
650{
651  my_master_ptr master;
652
653  master = (my_master_ptr)
654      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
655                                  SIZEOF(my_decomp_master));
656  cinfo->master = (struct jpeg_decomp_master *) master;
657  master->pub.prepare_for_output_pass = prepare_for_output_pass;
658  master->pub.finish_output_pass = finish_output_pass;
659
660  master->pub.is_dummy_pass = FALSE;
661
662  master_selection(cinfo);
663}
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