1 /*
2 * jdmaster.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains master control logic for the JPEG decompressor.
9 * These routines are concerned with selecting the modules to be executed
10 * and with determining the number of passes and the work to be done in each
11 * pass.
12 */
13
14 #define JPEG_INTERNALS
15 #include "jinclude.h"
16 #include "jpeglib.h"
17
18
19 /* Private state */
20
21 typedef struct {
22 struct jpeg_decomp_master pub; /* public fields */
23
24 int pass_number; /* # of passes completed */
25
26 boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
27
28 /* Saved references to initialized quantizer modules,
29 * in case we need to switch modes.
30 */
31 struct jpeg_color_quantizer * quantizer_1pass;
32 struct jpeg_color_quantizer * quantizer_2pass;
33 } my_decomp_master;
34
35 typedef my_decomp_master * my_master_ptr;
36
37
38 /*
39 * Determine whether merged upsample/color conversion should be used.
40 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
41 */
42
43 LOCAL(boolean)
use_merged_upsample(j_decompress_ptr cinfo)44 use_merged_upsample (j_decompress_ptr cinfo)
45 {
46 #ifdef UPSAMPLE_MERGING_SUPPORTED
47 /* Merging is the equivalent of plain box-filter upsampling */
48 if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
49 return FALSE;
50
51 #ifdef ANDROID_RGB
52 /* jdmerge.c only supports YCC=>RGB565 and YCC=>RGB color conversion */
53 if (cinfo->jpeg_color_space != JCS_YCbCr ||
54 cinfo->num_components != 3 ||
55 cinfo->out_color_components != 3 ||
56 (cinfo->out_color_space != JCS_RGB_565 &&
57 cinfo->out_color_space != JCS_RGB)) {
58 return FALSE;
59 }
60 #else
61 /* jdmerge.c only supports YCC=>RGB color conversion */
62 if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
63 cinfo->out_color_space != JCS_RGB ||
64 cinfo->out_color_components != RGB_PIXELSIZE)
65 return FALSE;
66 #endif
67
68 /* and it only handles 2h1v or 2h2v sampling ratios */
69 if (cinfo->comp_info[0].h_samp_factor != 2 ||
70 cinfo->comp_info[1].h_samp_factor != 1 ||
71 cinfo->comp_info[2].h_samp_factor != 1 ||
72 cinfo->comp_info[0].v_samp_factor > 2 ||
73 cinfo->comp_info[1].v_samp_factor != 1 ||
74 cinfo->comp_info[2].v_samp_factor != 1)
75 return FALSE;
76 /* furthermore, it doesn't work if we've scaled the IDCTs differently */
77 if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
78 cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
79 cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
80 return FALSE;
81 /* ??? also need to test for upsample-time rescaling, when & if supported */
82 return TRUE; /* by golly, it'll work... */
83 #else
84 return FALSE;
85 #endif
86 }
87
88
89 /*
90 * Compute output image dimensions and related values.
91 * NOTE: this is exported for possible use by application.
92 * Hence it mustn't do anything that can't be done twice.
93 * Also note that it may be called before the master module is initialized!
94 */
95
96 GLOBAL(void)
jpeg_calc_output_dimensions(j_decompress_ptr cinfo)97 jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
98 /* Do computations that are needed before master selection phase */
99 {
100 #ifdef IDCT_SCALING_SUPPORTED
101 int ci;
102 jpeg_component_info *compptr;
103 #endif
104
105 /* Prevent application from calling me at wrong times */
106 #if ANDROID_TILE_BASED_DECODE
107 // Tile based decoding may call this function several times.
108 if (!cinfo->tile_decode)
109 #endif
110 if (cinfo->global_state != DSTATE_READY)
111 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
112
113 #ifdef IDCT_SCALING_SUPPORTED
114
115 /* Compute actual output image dimensions and DCT scaling choices. */
116 if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
117 /* Provide 1/8 scaling */
118 cinfo->output_width = (JDIMENSION)
119 jdiv_round_up((long) cinfo->image_width, 8L);
120 cinfo->output_height = (JDIMENSION)
121 jdiv_round_up((long) cinfo->image_height, 8L);
122 cinfo->min_DCT_scaled_size = 1;
123 } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
124 /* Provide 1/4 scaling */
125 cinfo->output_width = (JDIMENSION)
126 jdiv_round_up((long) cinfo->image_width, 4L);
127 cinfo->output_height = (JDIMENSION)
128 jdiv_round_up((long) cinfo->image_height, 4L);
129 cinfo->min_DCT_scaled_size = 2;
130 } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
131 /* Provide 1/2 scaling */
132 cinfo->output_width = (JDIMENSION)
133 jdiv_round_up((long) cinfo->image_width, 2L);
134 cinfo->output_height = (JDIMENSION)
135 jdiv_round_up((long) cinfo->image_height, 2L);
136 cinfo->min_DCT_scaled_size = 4;
137 } else {
138 /* Provide 1/1 scaling */
139 cinfo->output_width = cinfo->image_width;
140 cinfo->output_height = cinfo->image_height;
141 cinfo->min_DCT_scaled_size = DCTSIZE;
142 }
143 /* In selecting the actual DCT scaling for each component, we try to
144 * scale up the chroma components via IDCT scaling rather than upsampling.
145 * This saves time if the upsampler gets to use 1:1 scaling.
146 * Note this code assumes that the supported DCT scalings are powers of 2.
147 */
148 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
149 ci++, compptr++) {
150 int ssize = cinfo->min_DCT_scaled_size;
151 while (ssize < DCTSIZE &&
152 (compptr->h_samp_factor * ssize * 2 <=
153 cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
154 (compptr->v_samp_factor * ssize * 2 <=
155 cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
156 ssize = ssize * 2;
157 }
158 compptr->DCT_scaled_size = ssize;
159 }
160
161 /* Recompute downsampled dimensions of components;
162 * application needs to know these if using raw downsampled data.
163 */
164 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
165 ci++, compptr++) {
166 /* Size in samples, after IDCT scaling */
167 compptr->downsampled_width = (JDIMENSION)
168 jdiv_round_up((long) cinfo->image_width *
169 (long) (compptr->h_samp_factor * compptr->DCT_scaled_size),
170 (long) (cinfo->max_h_samp_factor * DCTSIZE));
171 compptr->downsampled_height = (JDIMENSION)
172 jdiv_round_up((long) cinfo->image_height *
173 (long) (compptr->v_samp_factor * compptr->DCT_scaled_size),
174 (long) (cinfo->max_v_samp_factor * DCTSIZE));
175 }
176
177 #else /* !IDCT_SCALING_SUPPORTED */
178
179 /* Hardwire it to "no scaling" */
180 cinfo->output_width = cinfo->image_width;
181 cinfo->output_height = cinfo->image_height;
182 /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
183 * and has computed unscaled downsampled_width and downsampled_height.
184 */
185
186 #endif /* IDCT_SCALING_SUPPORTED */
187
188 /* Report number of components in selected colorspace. */
189 /* Probably this should be in the color conversion module... */
190 switch (cinfo->out_color_space) {
191 case JCS_GRAYSCALE:
192 cinfo->out_color_components = 1;
193 break;
194 case JCS_RGB:
195 #if RGB_PIXELSIZE != 3
196 cinfo->out_color_components = RGB_PIXELSIZE;
197 break;
198 #endif /* else share code with YCbCr */
199 #ifdef ANDROID_RGB
200 case JCS_RGB_565:
201 #endif
202 case JCS_YCbCr:
203 cinfo->out_color_components = 3;
204 break;
205 case JCS_CMYK:
206 case JCS_YCCK:
207 #ifdef ANDROID_RGB
208 case JCS_RGBA_8888:
209 #endif
210 cinfo->out_color_components = 4;
211 break;
212 default: /* else must be same colorspace as in file */
213 cinfo->out_color_components = cinfo->num_components;
214 break;
215 }
216 cinfo->output_components = (cinfo->quantize_colors ? 1 :
217 cinfo->out_color_components);
218
219 /* See if upsampler will want to emit more than one row at a time */
220 if (use_merged_upsample(cinfo))
221 cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
222 else
223 cinfo->rec_outbuf_height = 1;
224 }
225
226
227 /*
228 * Several decompression processes need to range-limit values to the range
229 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
230 * due to noise introduced by quantization, roundoff error, etc. These
231 * processes are inner loops and need to be as fast as possible. On most
232 * machines, particularly CPUs with pipelines or instruction prefetch,
233 * a (subscript-check-less) C table lookup
234 * x = sample_range_limit[x];
235 * is faster than explicit tests
236 * if (x < 0) x = 0;
237 * else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
238 * These processes all use a common table prepared by the routine below.
239 *
240 * For most steps we can mathematically guarantee that the initial value
241 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
242 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
243 * limiting step (just after the IDCT), a wildly out-of-range value is
244 * possible if the input data is corrupt. To avoid any chance of indexing
245 * off the end of memory and getting a bad-pointer trap, we perform the
246 * post-IDCT limiting thus:
247 * x = range_limit[x & MASK];
248 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
249 * samples. Under normal circumstances this is more than enough range and
250 * a correct output will be generated; with bogus input data the mask will
251 * cause wraparound, and we will safely generate a bogus-but-in-range output.
252 * For the post-IDCT step, we want to convert the data from signed to unsigned
253 * representation by adding CENTERJSAMPLE at the same time that we limit it.
254 * So the post-IDCT limiting table ends up looking like this:
255 * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
256 * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
257 * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
258 * 0,1,...,CENTERJSAMPLE-1
259 * Negative inputs select values from the upper half of the table after
260 * masking.
261 *
262 * We can save some space by overlapping the start of the post-IDCT table
263 * with the simpler range limiting table. The post-IDCT table begins at
264 * sample_range_limit + CENTERJSAMPLE.
265 *
266 * Note that the table is allocated in near data space on PCs; it's small
267 * enough and used often enough to justify this.
268 */
269
270 LOCAL(void)
prepare_range_limit_table(j_decompress_ptr cinfo)271 prepare_range_limit_table (j_decompress_ptr cinfo)
272 /* Allocate and fill in the sample_range_limit table */
273 {
274 JSAMPLE * table;
275 int i;
276
277 table = (JSAMPLE *)
278 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
279 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
280 table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */
281 cinfo->sample_range_limit = table;
282 /* First segment of "simple" table: limit[x] = 0 for x < 0 */
283 MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
284 /* Main part of "simple" table: limit[x] = x */
285 for (i = 0; i <= MAXJSAMPLE; i++)
286 table[i] = (JSAMPLE) i;
287 table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */
288 /* End of simple table, rest of first half of post-IDCT table */
289 for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
290 table[i] = MAXJSAMPLE;
291 /* Second half of post-IDCT table */
292 MEMZERO(table + (2 * (MAXJSAMPLE+1)),
293 (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
294 MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
295 cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
296 }
297
298
299 /*
300 * Master selection of decompression modules.
301 * This is done once at jpeg_start_decompress time. We determine
302 * which modules will be used and give them appropriate initialization calls.
303 * We also initialize the decompressor input side to begin consuming data.
304 *
305 * Since jpeg_read_header has finished, we know what is in the SOF
306 * and (first) SOS markers. We also have all the application parameter
307 * settings.
308 */
309
310 LOCAL(void)
master_selection(j_decompress_ptr cinfo)311 master_selection (j_decompress_ptr cinfo)
312 {
313 my_master_ptr master = (my_master_ptr) cinfo->master;
314 boolean use_c_buffer;
315 long samplesperrow;
316 JDIMENSION jd_samplesperrow;
317
318 /* Initialize dimensions and other stuff */
319 jpeg_calc_output_dimensions(cinfo);
320 prepare_range_limit_table(cinfo);
321
322 /* Width of an output scanline must be representable as JDIMENSION. */
323 samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
324 jd_samplesperrow = (JDIMENSION) samplesperrow;
325 if ((long) jd_samplesperrow != samplesperrow)
326 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
327
328 /* Initialize my private state */
329 master->pass_number = 0;
330 master->using_merged_upsample = use_merged_upsample(cinfo);
331
332 /* Color quantizer selection */
333 master->quantizer_1pass = NULL;
334 master->quantizer_2pass = NULL;
335 /* No mode changes if not using buffered-image mode. */
336 if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
337 cinfo->enable_1pass_quant = FALSE;
338 cinfo->enable_external_quant = FALSE;
339 cinfo->enable_2pass_quant = FALSE;
340 }
341 if (cinfo->quantize_colors) {
342 if (cinfo->raw_data_out)
343 ERREXIT(cinfo, JERR_NOTIMPL);
344 /* 2-pass quantizer only works in 3-component color space. */
345 if (cinfo->out_color_components != 3) {
346 cinfo->enable_1pass_quant = TRUE;
347 cinfo->enable_external_quant = FALSE;
348 cinfo->enable_2pass_quant = FALSE;
349 cinfo->colormap = NULL;
350 } else if (cinfo->colormap != NULL) {
351 cinfo->enable_external_quant = TRUE;
352 } else if (cinfo->two_pass_quantize) {
353 cinfo->enable_2pass_quant = TRUE;
354 } else {
355 cinfo->enable_1pass_quant = TRUE;
356 }
357
358 if (cinfo->enable_1pass_quant) {
359 #ifdef QUANT_1PASS_SUPPORTED
360 jinit_1pass_quantizer(cinfo);
361 master->quantizer_1pass = cinfo->cquantize;
362 #else
363 ERREXIT(cinfo, JERR_NOT_COMPILED);
364 #endif
365 }
366
367 /* We use the 2-pass code to map to external colormaps. */
368 if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
369 #ifdef QUANT_2PASS_SUPPORTED
370 jinit_2pass_quantizer(cinfo);
371 master->quantizer_2pass = cinfo->cquantize;
372 #else
373 ERREXIT(cinfo, JERR_NOT_COMPILED);
374 #endif
375 }
376 /* If both quantizers are initialized, the 2-pass one is left active;
377 * this is necessary for starting with quantization to an external map.
378 */
379 }
380
381 /* Post-processing: in particular, color conversion first */
382 if (! cinfo->raw_data_out) {
383 if (master->using_merged_upsample) {
384 #ifdef UPSAMPLE_MERGING_SUPPORTED
385 jinit_merged_upsampler(cinfo); /* does color conversion too */
386 #else
387 ERREXIT(cinfo, JERR_NOT_COMPILED);
388 #endif
389 } else {
390 jinit_color_deconverter(cinfo);
391 jinit_upsampler(cinfo);
392 }
393 jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
394 }
395 /* Inverse DCT */
396 jinit_inverse_dct(cinfo);
397 /* Entropy decoding: either Huffman or arithmetic coding. */
398 if (cinfo->arith_code) {
399 ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
400 } else {
401 if (cinfo->progressive_mode) {
402 #ifdef D_PROGRESSIVE_SUPPORTED
403 jinit_phuff_decoder(cinfo);
404 #else
405 ERREXIT(cinfo, JERR_NOT_COMPILED);
406 #endif
407 } else
408 jinit_huff_decoder(cinfo);
409 }
410
411 /* Initialize principal buffer controllers. */
412 use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
413 jinit_d_coef_controller(cinfo, use_c_buffer);
414
415 if (! cinfo->raw_data_out)
416 jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
417
418 /* We can now tell the memory manager to allocate virtual arrays. */
419 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
420
421 /* Initialize input side of decompressor to consume first scan. */
422 (*cinfo->inputctl->start_input_pass) (cinfo);
423
424 #ifdef D_MULTISCAN_FILES_SUPPORTED
425 /* If jpeg_start_decompress will read the whole file, initialize
426 * progress monitoring appropriately. The input step is counted
427 * as one pass.
428 */
429 if (cinfo->progress != NULL && ! cinfo->buffered_image &&
430 cinfo->inputctl->has_multiple_scans) {
431 int nscans;
432 /* Estimate number of scans to set pass_limit. */
433 if (cinfo->progressive_mode) {
434 /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
435 nscans = 2 + 3 * cinfo->num_components;
436 } else {
437 /* For a nonprogressive multiscan file, estimate 1 scan per component. */
438 nscans = cinfo->num_components;
439 }
440 cinfo->progress->pass_counter = 0L;
441 cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
442 cinfo->progress->completed_passes = 0;
443 cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
444 /* Count the input pass as done */
445 master->pass_number++;
446 }
447 #endif /* D_MULTISCAN_FILES_SUPPORTED */
448 }
449
450
451 /*
452 * Per-pass setup.
453 * This is called at the beginning of each output pass. We determine which
454 * modules will be active during this pass and give them appropriate
455 * start_pass calls. We also set is_dummy_pass to indicate whether this
456 * is a "real" output pass or a dummy pass for color quantization.
457 * (In the latter case, jdapistd.c will crank the pass to completion.)
458 */
459
460 METHODDEF(void)
prepare_for_output_pass(j_decompress_ptr cinfo)461 prepare_for_output_pass (j_decompress_ptr cinfo)
462 {
463 my_master_ptr master = (my_master_ptr) cinfo->master;
464
465 if (master->pub.is_dummy_pass) {
466 #ifdef QUANT_2PASS_SUPPORTED
467 /* Final pass of 2-pass quantization */
468 master->pub.is_dummy_pass = FALSE;
469 (*cinfo->cquantize->start_pass) (cinfo, FALSE);
470 (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
471 (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
472 #else
473 ERREXIT(cinfo, JERR_NOT_COMPILED);
474 #endif /* QUANT_2PASS_SUPPORTED */
475 } else {
476 if (cinfo->quantize_colors && cinfo->colormap == NULL) {
477 /* Select new quantization method */
478 if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
479 cinfo->cquantize = master->quantizer_2pass;
480 master->pub.is_dummy_pass = TRUE;
481 } else if (cinfo->enable_1pass_quant) {
482 cinfo->cquantize = master->quantizer_1pass;
483 } else {
484 ERREXIT(cinfo, JERR_MODE_CHANGE);
485 }
486 }
487 (*cinfo->idct->start_pass) (cinfo);
488 (*cinfo->coef->start_output_pass) (cinfo);
489 if (! cinfo->raw_data_out) {
490 if (! master->using_merged_upsample)
491 (*cinfo->cconvert->start_pass) (cinfo);
492 (*cinfo->upsample->start_pass) (cinfo);
493 if (cinfo->quantize_colors)
494 (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
495 (*cinfo->post->start_pass) (cinfo,
496 (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
497 (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
498 }
499 }
500
501 /* Set up progress monitor's pass info if present */
502 if (cinfo->progress != NULL) {
503 cinfo->progress->completed_passes = master->pass_number;
504 cinfo->progress->total_passes = master->pass_number +
505 (master->pub.is_dummy_pass ? 2 : 1);
506 /* In buffered-image mode, we assume one more output pass if EOI not
507 * yet reached, but no more passes if EOI has been reached.
508 */
509 if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
510 cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
511 }
512 }
513 }
514
515
516 /*
517 * Finish up at end of an output pass.
518 */
519
520 METHODDEF(void)
finish_output_pass(j_decompress_ptr cinfo)521 finish_output_pass (j_decompress_ptr cinfo)
522 {
523 my_master_ptr master = (my_master_ptr) cinfo->master;
524
525 if (cinfo->quantize_colors)
526 (*cinfo->cquantize->finish_pass) (cinfo);
527 master->pass_number++;
528 }
529
530
531 #ifdef D_MULTISCAN_FILES_SUPPORTED
532
533 /*
534 * Switch to a new external colormap between output passes.
535 */
536
537 GLOBAL(void)
jpeg_new_colormap(j_decompress_ptr cinfo)538 jpeg_new_colormap (j_decompress_ptr cinfo)
539 {
540 my_master_ptr master = (my_master_ptr) cinfo->master;
541
542 /* Prevent application from calling me at wrong times */
543 if (cinfo->global_state != DSTATE_BUFIMAGE)
544 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
545
546 if (cinfo->quantize_colors && cinfo->enable_external_quant &&
547 cinfo->colormap != NULL) {
548 /* Select 2-pass quantizer for external colormap use */
549 cinfo->cquantize = master->quantizer_2pass;
550 /* Notify quantizer of colormap change */
551 (*cinfo->cquantize->new_color_map) (cinfo);
552 master->pub.is_dummy_pass = FALSE; /* just in case */
553 } else
554 ERREXIT(cinfo, JERR_MODE_CHANGE);
555 }
556
557 #endif /* D_MULTISCAN_FILES_SUPPORTED */
558
559
560 /*
561 * Initialize master decompression control and select active modules.
562 * This is performed at the start of jpeg_start_decompress.
563 */
564
565 GLOBAL(void)
jinit_master_decompress(j_decompress_ptr cinfo)566 jinit_master_decompress (j_decompress_ptr cinfo)
567 {
568 my_master_ptr master;
569
570 master = (my_master_ptr)
571 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
572 SIZEOF(my_decomp_master));
573 cinfo->master = (struct jpeg_decomp_master *) master;
574 master->pub.prepare_for_output_pass = prepare_for_output_pass;
575 master->pub.finish_output_pass = finish_output_pass;
576
577 master->pub.is_dummy_pass = FALSE;
578
579 master_selection(cinfo);
580 }
581