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