jdk

1
/*
2
 * reserved comment block
3
 * DO NOT REMOVE OR ALTER!
4
 */
5
/*
6
 * jdmaster.c
7
 *
8
 * Copyright (C) 1991-1997, Thomas G. Lane.
9
 * This file is part of the Independent JPEG Group's software.
10
 * For conditions of distribution and use, see the accompanying README file.
11
 *
12
 * This file contains master control logic for the JPEG decompressor.
13
 * These routines are concerned with selecting the modules to be executed
14
 * and with determining the number of passes and the work to be done in each
15
 * pass.
16
 */
17

18
#define JPEG_INTERNALS
19
#include "jinclude.h"
20
#include "jpeglib.h"
21

22

23
/* Private state */
24

25
typedef struct {
26
  struct jpeg_decomp_master pub; /* public fields */
27

28
  int pass_number;              /* # of passes completed */
29

30
  boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
31

32
  /* Saved references to initialized quantizer modules,
33
   * in case we need to switch modes.
34
   */
35
  struct jpeg_color_quantizer * quantizer_1pass;
36
  struct jpeg_color_quantizer * quantizer_2pass;
37
} my_decomp_master;
38

39
typedef my_decomp_master * my_master_ptr;
40

41

42
/*
43
 * Determine whether merged upsample/color conversion should be used.
44
 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
45
 */
46

47
LOCAL(boolean)
48
use_merged_upsample (j_decompress_ptr cinfo)
49
{
50
#ifdef UPSAMPLE_MERGING_SUPPORTED
51
  /* Merging is the equivalent of plain box-filter upsampling */
52
  if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
53
    return FALSE;
54
  /* jdmerge.c only supports YCC=>RGB color conversion */
55
  if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
56
      cinfo->out_color_space != JCS_RGB ||
57
      cinfo->out_color_components != RGB_PIXELSIZE)
58
    return FALSE;
59
  /* and it only handles 2h1v or 2h2v sampling ratios */
60
  if (cinfo->comp_info[0].h_samp_factor != 2 ||
61
      cinfo->comp_info[1].h_samp_factor != 1 ||
62
      cinfo->comp_info[2].h_samp_factor != 1 ||
63
      cinfo->comp_info[0].v_samp_factor >  2 ||
64
      cinfo->comp_info[1].v_samp_factor != 1 ||
65
      cinfo->comp_info[2].v_samp_factor != 1)
66
    return FALSE;
67
  /* furthermore, it doesn't work if we've scaled the IDCTs differently */
68
  if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
69
      cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
70
      cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_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

87
GLOBAL(void)
88
jpeg_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_scaled_size = 1;
110
  } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
111
    /* Provide 1/4 scaling */
112
    cinfo->output_width = (JDIMENSION)
113
      jdiv_round_up((long) cinfo->image_width, 4L);
114
    cinfo->output_height = (JDIMENSION)
115
      jdiv_round_up((long) cinfo->image_height, 4L);
116
    cinfo->min_DCT_scaled_size = 2;
117
  } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
118
    /* Provide 1/2 scaling */
119
    cinfo->output_width = (JDIMENSION)
120
      jdiv_round_up((long) cinfo->image_width, 2L);
121
    cinfo->output_height = (JDIMENSION)
122
      jdiv_round_up((long) cinfo->image_height, 2L);
123
    cinfo->min_DCT_scaled_size = 4;
124
  } else {
125
    /* Provide 1/1 scaling */
126
    cinfo->output_width = cinfo->image_width;
127
    cinfo->output_height = cinfo->image_height;
128
    cinfo->min_DCT_scaled_size = DCTSIZE;
129
  }
130
  /* In selecting the actual DCT scaling for each component, we try to
131
   * scale up the chroma components via IDCT scaling rather than upsampling.
132
   * This saves time if the upsampler gets to use 1:1 scaling.
133
   * Note this code assumes that the supported DCT scalings are powers of 2.
134
   */
135
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
136
       ci++, compptr++) {
137
    int ssize = cinfo->min_DCT_scaled_size;
138
    while (ssize < DCTSIZE &&
139
           (compptr->h_samp_factor * ssize * 2 <=
140
            cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
141
           (compptr->v_samp_factor * ssize * 2 <=
142
            cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
143
      ssize = ssize * 2;
144
    }
145
    compptr->DCT_scaled_size = ssize;
146
  }
147

148
  /* Recompute downsampled dimensions of components;
149
   * application needs to know these if using raw downsampled data.
150
   */
151
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
152
       ci++, compptr++) {
153
    /* Size in samples, after IDCT scaling */
154
    compptr->downsampled_width = (JDIMENSION)
155
      jdiv_round_up((long) cinfo->image_width *
156
                    (long) (compptr->h_samp_factor * compptr->DCT_scaled_size),
157
                    (long) (cinfo->max_h_samp_factor * DCTSIZE));
158
    compptr->downsampled_height = (JDIMENSION)
159
      jdiv_round_up((long) cinfo->image_height *
160
                    (long) (compptr->v_samp_factor * compptr->DCT_scaled_size),
161
                    (long) (cinfo->max_v_samp_factor * DCTSIZE));
162
  }
163

164
#else /* !IDCT_SCALING_SUPPORTED */
165

166
  /* Hardwire it to "no scaling" */
167
  cinfo->output_width = cinfo->image_width;
168
  cinfo->output_height = cinfo->image_height;
169
  /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
170
   * and has computed unscaled downsampled_width and downsampled_height.
171
   */
172

173
#endif /* IDCT_SCALING_SUPPORTED */
174

175
  /* Report number of components in selected colorspace. */
176
  /* Probably this should be in the color conversion module... */
177
  switch (cinfo->out_color_space) {
178
  case JCS_GRAYSCALE:
179
    cinfo->out_color_components = 1;
180
    break;
181
  case JCS_RGB:
182
#if RGB_PIXELSIZE != 3
183
    cinfo->out_color_components = RGB_PIXELSIZE;
184
    break;
185
#endif /* else share code with YCbCr */
186
  case JCS_YCbCr:
187
    cinfo->out_color_components = 3;
188
    break;
189
  case JCS_CMYK:
190
  case JCS_YCCK:
191
    cinfo->out_color_components = 4;
192
    break;
193
  default:                      /* else must be same colorspace as in file */
194
    cinfo->out_color_components = cinfo->num_components;
195
    break;
196
  }
197
  cinfo->output_components = (cinfo->quantize_colors ? 1 :
198
                              cinfo->out_color_components);
199

200
  /* See if upsampler will want to emit more than one row at a time */
201
  if (use_merged_upsample(cinfo))
202
    cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
203
  else
204
    cinfo->rec_outbuf_height = 1;
205
}
206

207

208
/*
209
 * Several decompression processes need to range-limit values to the range
210
 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
211
 * due to noise introduced by quantization, roundoff error, etc.  These
212
 * processes are inner loops and need to be as fast as possible.  On most
213
 * machines, particularly CPUs with pipelines or instruction prefetch,
214
 * a (subscript-check-less) C table lookup
215
 *              x = sample_range_limit[x];
216
 * is faster than explicit tests
217
 *              if (x < 0)  x = 0;
218
 *              else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
219
 * These processes all use a common table prepared by the routine below.
220
 *
221
 * For most steps we can mathematically guarantee that the initial value
222
 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
223
 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
224
 * limiting step (just after the IDCT), a wildly out-of-range value is
225
 * possible if the input data is corrupt.  To avoid any chance of indexing
226
 * off the end of memory and getting a bad-pointer trap, we perform the
227
 * post-IDCT limiting thus:
228
 *              x = range_limit[x & MASK];
229
 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
230
 * samples.  Under normal circumstances this is more than enough range and
231
 * a correct output will be generated; with bogus input data the mask will
232
 * cause wraparound, and we will safely generate a bogus-but-in-range output.
233
 * For the post-IDCT step, we want to convert the data from signed to unsigned
234
 * representation by adding CENTERJSAMPLE at the same time that we limit it.
235
 * So the post-IDCT limiting table ends up looking like this:
236
 *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
237
 *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
238
 *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
239
 *   0,1,...,CENTERJSAMPLE-1
240
 * Negative inputs select values from the upper half of the table after
241
 * masking.
242
 *
243
 * We can save some space by overlapping the start of the post-IDCT table
244
 * with the simpler range limiting table.  The post-IDCT table begins at
245
 * sample_range_limit + CENTERJSAMPLE.
246
 *
247
 * Note that the table is allocated in near data space on PCs; it's small
248
 * enough and used often enough to justify this.
249
 */
250

251
LOCAL(void)
252
prepare_range_limit_table (j_decompress_ptr cinfo)
253
/* Allocate and fill in the sample_range_limit table */
254
{
255
  JSAMPLE * table;
256
  int i;
257

258
  table = (JSAMPLE *)
259
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
260
                (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
261
  table += (MAXJSAMPLE+1);      /* allow negative subscripts of simple table */
262
  cinfo->sample_range_limit = table;
263
  /* First segment of "simple" table: limit[x] = 0 for x < 0 */
264
  MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
265
  /* Main part of "simple" table: limit[x] = x */
266
  for (i = 0; i <= MAXJSAMPLE; i++)
267
    table[i] = (JSAMPLE) i;
268
  table += CENTERJSAMPLE;       /* Point to where post-IDCT table starts */
269
  /* End of simple table, rest of first half of post-IDCT table */
270
  for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
271
    table[i] = MAXJSAMPLE;
272
  /* Second half of post-IDCT table */
273
  MEMZERO(table + (2 * (MAXJSAMPLE+1)),
274
          (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
275
  MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
276
          cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
277
}
278

279

280
/*
281
 * Master selection of decompression modules.
282
 * This is done once at jpeg_start_decompress time.  We determine
283
 * which modules will be used and give them appropriate initialization calls.
284
 * We also initialize the decompressor input side to begin consuming data.
285
 *
286
 * Since jpeg_read_header has finished, we know what is in the SOF
287
 * and (first) SOS markers.  We also have all the application parameter
288
 * settings.
289
 */
290

291
LOCAL(void)
292
master_selection (j_decompress_ptr cinfo)
293
{
294
  my_master_ptr master = (my_master_ptr) cinfo->master;
295
  boolean use_c_buffer;
296
  long samplesperrow;
297
  JDIMENSION jd_samplesperrow;
298

299
  /* Initialize dimensions and other stuff */
300
  jpeg_calc_output_dimensions(cinfo);
301
  prepare_range_limit_table(cinfo);
302

303
  /* Width of an output scanline must be representable as JDIMENSION. */
304
  samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
305
  jd_samplesperrow = (JDIMENSION) samplesperrow;
306
  if ((long) jd_samplesperrow != samplesperrow)
307
    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
308

309
  /* Initialize my private state */
310
  master->pass_number = 0;
311
  master->using_merged_upsample = use_merged_upsample(cinfo);
312

313
  /* Color quantizer selection */
314
  master->quantizer_1pass = NULL;
315
  master->quantizer_2pass = NULL;
316
  /* No mode changes if not using buffered-image mode. */
317
  if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
318
    cinfo->enable_1pass_quant = FALSE;
319
    cinfo->enable_external_quant = FALSE;
320
    cinfo->enable_2pass_quant = FALSE;
321
  }
322
  if (cinfo->quantize_colors) {
323
    if (cinfo->raw_data_out)
324
      ERREXIT(cinfo, JERR_NOTIMPL);
325
    /* 2-pass quantizer only works in 3-component color space. */
326
    if (cinfo->out_color_components != 3) {
327
      cinfo->enable_1pass_quant = TRUE;
328
      cinfo->enable_external_quant = FALSE;
329
      cinfo->enable_2pass_quant = FALSE;
330
      cinfo->colormap = NULL;
331
    } else if (cinfo->colormap != NULL) {
332
      cinfo->enable_external_quant = TRUE;
333
    } else if (cinfo->two_pass_quantize) {
334
      cinfo->enable_2pass_quant = TRUE;
335
    } else {
336
      cinfo->enable_1pass_quant = TRUE;
337
    }
338

339
    if (cinfo->enable_1pass_quant) {
340
#ifdef QUANT_1PASS_SUPPORTED
341
      jinit_1pass_quantizer(cinfo);
342
      master->quantizer_1pass = cinfo->cquantize;
343
#else
344
      ERREXIT(cinfo, JERR_NOT_COMPILED);
345
#endif
346
    }
347

348
    /* We use the 2-pass code to map to external colormaps. */
349
    if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
350
#ifdef QUANT_2PASS_SUPPORTED
351
      jinit_2pass_quantizer(cinfo);
352
      master->quantizer_2pass = cinfo->cquantize;
353
#else
354
      ERREXIT(cinfo, JERR_NOT_COMPILED);
355
#endif
356
    }
357
    /* If both quantizers are initialized, the 2-pass one is left active;
358
     * this is necessary for starting with quantization to an external map.
359
     */
360
  }
361

362
  /* Post-processing: in particular, color conversion first */
363
  if (! cinfo->raw_data_out) {
364
    if (master->using_merged_upsample) {
365
#ifdef UPSAMPLE_MERGING_SUPPORTED
366
      jinit_merged_upsampler(cinfo); /* does color conversion too */
367
#else
368
      ERREXIT(cinfo, JERR_NOT_COMPILED);
369
#endif
370
    } else {
371
      jinit_color_deconverter(cinfo);
372
      jinit_upsampler(cinfo);
373
    }
374
    jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
375
  }
376
  /* Inverse DCT */
377
  jinit_inverse_dct(cinfo);
378
  /* Entropy decoding: either Huffman or arithmetic coding. */
379
  if (cinfo->arith_code) {
380
    ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
381
  } else {
382
    if (cinfo->progressive_mode) {
383
#ifdef D_PROGRESSIVE_SUPPORTED
384
      jinit_phuff_decoder(cinfo);
385
#else
386
      ERREXIT(cinfo, JERR_NOT_COMPILED);
387
#endif
388
    } else
389
      jinit_huff_decoder(cinfo);
390
  }
391

392
  /* Initialize principal buffer controllers. */
393
  use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
394
  jinit_d_coef_controller(cinfo, use_c_buffer);
395

396
  if (! cinfo->raw_data_out)
397
    jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
398

399
  /* We can now tell the memory manager to allocate virtual arrays. */
400
  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
401

402
  /* Initialize input side of decompressor to consume first scan. */
403
  (*cinfo->inputctl->start_input_pass) (cinfo);
404

405
#ifdef D_MULTISCAN_FILES_SUPPORTED
406
  /* If jpeg_start_decompress will read the whole file, initialize
407
   * progress monitoring appropriately.  The input step is counted
408
   * as one pass.
409
   */
410
  if (cinfo->progress != NULL && ! cinfo->buffered_image &&
411
      cinfo->inputctl->has_multiple_scans) {
412
    int nscans;
413
    /* Estimate number of scans to set pass_limit. */
414
    if (cinfo->progressive_mode) {
415
      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
416
      nscans = 2 + 3 * cinfo->num_components;
417
    } else {
418
      /* For a nonprogressive multiscan file, estimate 1 scan per component. */
419
      nscans = cinfo->num_components;
420
    }
421
    cinfo->progress->pass_counter = 0L;
422
    cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
423
    cinfo->progress->completed_passes = 0;
424
    cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
425
    /* Count the input pass as done */
426
    master->pass_number++;
427
  }
428
#endif /* D_MULTISCAN_FILES_SUPPORTED */
429
}
430

431

432
/*
433
 * Per-pass setup.
434
 * This is called at the beginning of each output pass.  We determine which
435
 * modules will be active during this pass and give them appropriate
436
 * start_pass calls.  We also set is_dummy_pass to indicate whether this
437
 * is a "real" output pass or a dummy pass for color quantization.
438
 * (In the latter case, jdapistd.c will crank the pass to completion.)
439
 */
440

441
METHODDEF(void)
442
prepare_for_output_pass (j_decompress_ptr cinfo)
443
{
444
  my_master_ptr master = (my_master_ptr) cinfo->master;
445

446
  if (master->pub.is_dummy_pass) {
447
#ifdef QUANT_2PASS_SUPPORTED
448
    /* Final pass of 2-pass quantization */
449
    master->pub.is_dummy_pass = FALSE;
450
    (*cinfo->cquantize->start_pass) (cinfo, FALSE);
451
    (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
452
    (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
453
#else
454
    ERREXIT(cinfo, JERR_NOT_COMPILED);
455
#endif /* QUANT_2PASS_SUPPORTED */
456
  } else {
457
    if (cinfo->quantize_colors && cinfo->colormap == NULL) {
458
      /* Select new quantization method */
459
      if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
460
        cinfo->cquantize = master->quantizer_2pass;
461
        master->pub.is_dummy_pass = TRUE;
462
      } else if (cinfo->enable_1pass_quant) {
463
        cinfo->cquantize = master->quantizer_1pass;
464
      } else {
465
        ERREXIT(cinfo, JERR_MODE_CHANGE);
466
      }
467
    }
468
    (*cinfo->idct->start_pass) (cinfo);
469
    (*cinfo->coef->start_output_pass) (cinfo);
470
    if (! cinfo->raw_data_out) {
471
      if (! master->using_merged_upsample)
472
        (*cinfo->cconvert->start_pass) (cinfo);
473
      (*cinfo->upsample->start_pass) (cinfo);
474
      if (cinfo->quantize_colors)
475
        (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
476
      (*cinfo->post->start_pass) (cinfo,
477
            (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
478
      (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
479
    }
480
  }
481

482
  /* Set up progress monitor's pass info if present */
483
  if (cinfo->progress != NULL) {
484
    cinfo->progress->completed_passes = master->pass_number;
485
    cinfo->progress->total_passes = master->pass_number +
486
                                    (master->pub.is_dummy_pass ? 2 : 1);
487
    /* In buffered-image mode, we assume one more output pass if EOI not
488
     * yet reached, but no more passes if EOI has been reached.
489
     */
490
    if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
491
      cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
492
    }
493
  }
494
}
495

496

497
/*
498
 * Finish up at end of an output pass.
499
 */
500

501
METHODDEF(void)
502
finish_output_pass (j_decompress_ptr cinfo)
503
{
504
  my_master_ptr master = (my_master_ptr) cinfo->master;
505

506
  if (cinfo->quantize_colors)
507
    (*cinfo->cquantize->finish_pass) (cinfo);
508
  master->pass_number++;
509
}
510

511

512
#ifdef D_MULTISCAN_FILES_SUPPORTED
513

514
/*
515
 * Switch to a new external colormap between output passes.
516
 */
517

518
GLOBAL(void)
519
jpeg_new_colormap (j_decompress_ptr cinfo)
520
{
521
  my_master_ptr master = (my_master_ptr) cinfo->master;
522

523
  /* Prevent application from calling me at wrong times */
524
  if (cinfo->global_state != DSTATE_BUFIMAGE)
525
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
526

527
  if (cinfo->quantize_colors && cinfo->enable_external_quant &&
528
      cinfo->colormap != NULL) {
529
    /* Select 2-pass quantizer for external colormap use */
530
    cinfo->cquantize = master->quantizer_2pass;
531
    /* Notify quantizer of colormap change */
532
    (*cinfo->cquantize->new_color_map) (cinfo);
533
    master->pub.is_dummy_pass = FALSE; /* just in case */
534
  } else
535
    ERREXIT(cinfo, JERR_MODE_CHANGE);
536
}
537

538
#endif /* D_MULTISCAN_FILES_SUPPORTED */
539

540

541
/*
542
 * Initialize master decompression control and select active modules.
543
 * This is performed at the start of jpeg_start_decompress.
544
 */
545

546
GLOBAL(void)
547
jinit_master_decompress (j_decompress_ptr cinfo)
548
{
549
  my_master_ptr master;
550

551
  master = (my_master_ptr)
552
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
553
                                  SIZEOF(my_decomp_master));
554
  cinfo->master = (struct jpeg_decomp_master *) master;
555
  master->pub.prepare_for_output_pass = prepare_for_output_pass;
556
  master->pub.finish_output_pass = finish_output_pass;
557

558
  master->pub.is_dummy_pass = FALSE;
559

560
  master_selection(cinfo);
561
}
562