1/*
2 * jdmaster.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1997, Thomas G. Lane.
6 * Modified 2002-2009 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2009-2011, 2016, D. R. Commander.
9 * Copyright (C) 2013, Linaro Limited.
10 * Copyright (C) 2015, Google, Inc.
11 * For conditions of distribution and use, see the accompanying README.ijg
12 * file.
13 *
14 * This file contains master control logic for the JPEG decompressor.
15 * These routines are concerned with selecting the modules to be executed
16 * and with determining the number of passes and the work to be done in each
17 * pass.
18 */
19
20#define JPEG_INTERNALS
21#include "jinclude.h"
22#include "jpeglib.h"
23#include "jpegcomp.h"
24#include "jdmaster.h"
25#include "jsimd.h"
26
27
28/*
29 * Determine whether merged upsample/color conversion should be used.
30 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
31 */
32
33LOCAL(boolean)
34use_merged_upsample(j_decompress_ptr cinfo)
35{
36#ifdef UPSAMPLE_MERGING_SUPPORTED
37 /* Merging is the equivalent of plain box-filter upsampling */
38 if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
39 return FALSE;
40 /* jdmerge.c only supports YCC=>RGB and YCC=>RGB565 color conversion */
41 if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
42 (cinfo->out_color_space != JCS_RGB &&
43 cinfo->out_color_space != JCS_RGB565 &&
44 cinfo->out_color_space != JCS_EXT_RGB &&
45 cinfo->out_color_space != JCS_EXT_RGBX &&
46 cinfo->out_color_space != JCS_EXT_BGR &&
47 cinfo->out_color_space != JCS_EXT_BGRX &&
48 cinfo->out_color_space != JCS_EXT_XBGR &&
49 cinfo->out_color_space != JCS_EXT_XRGB &&
50 cinfo->out_color_space != JCS_EXT_RGBA &&
51 cinfo->out_color_space != JCS_EXT_BGRA &&
52 cinfo->out_color_space != JCS_EXT_ABGR &&
53 cinfo->out_color_space != JCS_EXT_ARGB))
54 return FALSE;
55 if ((cinfo->out_color_space == JCS_RGB565 &&
56 cinfo->out_color_components != 3) ||
57 (cinfo->out_color_space != JCS_RGB565 &&
58 cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space]))
59 return FALSE;
60 /* and it only handles 2h1v or 2h2v sampling ratios */
61 if (cinfo->comp_info[0].h_samp_factor != 2 ||
62 cinfo->comp_info[1].h_samp_factor != 1 ||
63 cinfo->comp_info[2].h_samp_factor != 1 ||
64 cinfo->comp_info[0].v_samp_factor > 2 ||
65 cinfo->comp_info[1].v_samp_factor != 1 ||
66 cinfo->comp_info[2].v_samp_factor != 1)
67 return FALSE;
68 /* furthermore, it doesn't work if we've scaled the IDCTs differently */
69 if (cinfo->comp_info[0]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
70 cinfo->comp_info[1]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
71 cinfo->comp_info[2]._DCT_scaled_size != cinfo->_min_DCT_scaled_size)
72 return FALSE;
73#ifdef WITH_SIMD
74 /* If YCbCr-to-RGB color conversion is SIMD-accelerated but merged upsampling
75 isn't, then disabling merged upsampling is likely to be faster when
76 decompressing YCbCr JPEG images. */
77 if (!jsimd_can_h2v2_merged_upsample() && !jsimd_can_h2v1_merged_upsample() &&
78 jsimd_can_ycc_rgb() && cinfo->jpeg_color_space == JCS_YCbCr &&
79 (cinfo->out_color_space == JCS_RGB ||
80 (cinfo->out_color_space >= JCS_EXT_RGB &&
81 cinfo->out_color_space <= JCS_EXT_ARGB)))
82 return FALSE;
83#endif
84 /* ??? also need to test for upsample-time rescaling, when & if supported */
85 return TRUE; /* by golly, it'll work... */
86#else
87 return FALSE;
88#endif
89}
90
91
92/*
93 * Compute output image dimensions and related values.
94 * NOTE: this is exported for possible use by application.
95 * Hence it mustn't do anything that can't be done twice.
96 */
97
98#if JPEG_LIB_VERSION >= 80
99GLOBAL(void)
100#else
101LOCAL(void)
102#endif
103jpeg_core_output_dimensions(j_decompress_ptr cinfo)
104/* Do computations that are needed before master selection phase.
105 * This function is used for transcoding and full decompression.
106 */
107{
108#ifdef IDCT_SCALING_SUPPORTED
109 int ci;
110 jpeg_component_info *compptr;
111
112 /* Compute actual output image dimensions and DCT scaling choices. */
113 if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom) {
114 /* Provide 1/block_size scaling */
115 cinfo->output_width = (JDIMENSION)
116 jdiv_round_up((long)cinfo->image_width, (long)DCTSIZE);
117 cinfo->output_height = (JDIMENSION)
118 jdiv_round_up((long)cinfo->image_height, (long)DCTSIZE);
119 cinfo->_min_DCT_h_scaled_size = 1;
120 cinfo->_min_DCT_v_scaled_size = 1;
121 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 2) {
122 /* Provide 2/block_size scaling */
123 cinfo->output_width = (JDIMENSION)
124 jdiv_round_up((long)cinfo->image_width * 2L, (long)DCTSIZE);
125 cinfo->output_height = (JDIMENSION)
126 jdiv_round_up((long)cinfo->image_height * 2L, (long)DCTSIZE);
127 cinfo->_min_DCT_h_scaled_size = 2;
128 cinfo->_min_DCT_v_scaled_size = 2;
129 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 3) {
130 /* Provide 3/block_size scaling */
131 cinfo->output_width = (JDIMENSION)
132 jdiv_round_up((long)cinfo->image_width * 3L, (long)DCTSIZE);
133 cinfo->output_height = (JDIMENSION)
134 jdiv_round_up((long)cinfo->image_height * 3L, (long)DCTSIZE);
135 cinfo->_min_DCT_h_scaled_size = 3;
136 cinfo->_min_DCT_v_scaled_size = 3;
137 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 4) {
138 /* Provide 4/block_size scaling */
139 cinfo->output_width = (JDIMENSION)
140 jdiv_round_up((long)cinfo->image_width * 4L, (long)DCTSIZE);
141 cinfo->output_height = (JDIMENSION)
142 jdiv_round_up((long)cinfo->image_height * 4L, (long)DCTSIZE);
143 cinfo->_min_DCT_h_scaled_size = 4;
144 cinfo->_min_DCT_v_scaled_size = 4;
145 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 5) {
146 /* Provide 5/block_size scaling */
147 cinfo->output_width = (JDIMENSION)
148 jdiv_round_up((long)cinfo->image_width * 5L, (long)DCTSIZE);
149 cinfo->output_height = (JDIMENSION)
150 jdiv_round_up((long)cinfo->image_height * 5L, (long)DCTSIZE);
151 cinfo->_min_DCT_h_scaled_size = 5;
152 cinfo->_min_DCT_v_scaled_size = 5;
153 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 6) {
154 /* Provide 6/block_size scaling */
155 cinfo->output_width = (JDIMENSION)
156 jdiv_round_up((long)cinfo->image_width * 6L, (long)DCTSIZE);
157 cinfo->output_height = (JDIMENSION)
158 jdiv_round_up((long)cinfo->image_height * 6L, (long)DCTSIZE);
159 cinfo->_min_DCT_h_scaled_size = 6;
160 cinfo->_min_DCT_v_scaled_size = 6;
161 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 7) {
162 /* Provide 7/block_size scaling */
163 cinfo->output_width = (JDIMENSION)
164 jdiv_round_up((long)cinfo->image_width * 7L, (long)DCTSIZE);
165 cinfo->output_height = (JDIMENSION)
166 jdiv_round_up((long)cinfo->image_height * 7L, (long)DCTSIZE);
167 cinfo->_min_DCT_h_scaled_size = 7;
168 cinfo->_min_DCT_v_scaled_size = 7;
169 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 8) {
170 /* Provide 8/block_size scaling */
171 cinfo->output_width = (JDIMENSION)
172 jdiv_round_up((long)cinfo->image_width * 8L, (long)DCTSIZE);
173 cinfo->output_height = (JDIMENSION)
174 jdiv_round_up((long)cinfo->image_height * 8L, (long)DCTSIZE);
175 cinfo->_min_DCT_h_scaled_size = 8;
176 cinfo->_min_DCT_v_scaled_size = 8;
177 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 9) {
178 /* Provide 9/block_size scaling */
179 cinfo->output_width = (JDIMENSION)
180 jdiv_round_up((long)cinfo->image_width * 9L, (long)DCTSIZE);
181 cinfo->output_height = (JDIMENSION)
182 jdiv_round_up((long)cinfo->image_height * 9L, (long)DCTSIZE);
183 cinfo->_min_DCT_h_scaled_size = 9;
184 cinfo->_min_DCT_v_scaled_size = 9;
185 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 10) {
186 /* Provide 10/block_size scaling */
187 cinfo->output_width = (JDIMENSION)
188 jdiv_round_up((long)cinfo->image_width * 10L, (long)DCTSIZE);
189 cinfo->output_height = (JDIMENSION)
190 jdiv_round_up((long)cinfo->image_height * 10L, (long)DCTSIZE);
191 cinfo->_min_DCT_h_scaled_size = 10;
192 cinfo->_min_DCT_v_scaled_size = 10;
193 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 11) {
194 /* Provide 11/block_size scaling */
195 cinfo->output_width = (JDIMENSION)
196 jdiv_round_up((long)cinfo->image_width * 11L, (long)DCTSIZE);
197 cinfo->output_height = (JDIMENSION)
198 jdiv_round_up((long)cinfo->image_height * 11L, (long)DCTSIZE);
199 cinfo->_min_DCT_h_scaled_size = 11;
200 cinfo->_min_DCT_v_scaled_size = 11;
201 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 12) {
202 /* Provide 12/block_size scaling */
203 cinfo->output_width = (JDIMENSION)
204 jdiv_round_up((long)cinfo->image_width * 12L, (long)DCTSIZE);
205 cinfo->output_height = (JDIMENSION)
206 jdiv_round_up((long)cinfo->image_height * 12L, (long)DCTSIZE);
207 cinfo->_min_DCT_h_scaled_size = 12;
208 cinfo->_min_DCT_v_scaled_size = 12;
209 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 13) {
210 /* Provide 13/block_size scaling */
211 cinfo->output_width = (JDIMENSION)
212 jdiv_round_up((long)cinfo->image_width * 13L, (long)DCTSIZE);
213 cinfo->output_height = (JDIMENSION)
214 jdiv_round_up((long)cinfo->image_height * 13L, (long)DCTSIZE);
215 cinfo->_min_DCT_h_scaled_size = 13;
216 cinfo->_min_DCT_v_scaled_size = 13;
217 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 14) {
218 /* Provide 14/block_size scaling */
219 cinfo->output_width = (JDIMENSION)
220 jdiv_round_up((long)cinfo->image_width * 14L, (long)DCTSIZE);
221 cinfo->output_height = (JDIMENSION)
222 jdiv_round_up((long)cinfo->image_height * 14L, (long)DCTSIZE);
223 cinfo->_min_DCT_h_scaled_size = 14;
224 cinfo->_min_DCT_v_scaled_size = 14;
225 } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 15) {
226 /* Provide 15/block_size scaling */
227 cinfo->output_width = (JDIMENSION)
228 jdiv_round_up((long)cinfo->image_width * 15L, (long)DCTSIZE);
229 cinfo->output_height = (JDIMENSION)
230 jdiv_round_up((long)cinfo->image_height * 15L, (long)DCTSIZE);
231 cinfo->_min_DCT_h_scaled_size = 15;
232 cinfo->_min_DCT_v_scaled_size = 15;
233 } else {
234 /* Provide 16/block_size scaling */
235 cinfo->output_width = (JDIMENSION)
236 jdiv_round_up((long)cinfo->image_width * 16L, (long)DCTSIZE);
237 cinfo->output_height = (JDIMENSION)
238 jdiv_round_up((long)cinfo->image_height * 16L, (long)DCTSIZE);
239 cinfo->_min_DCT_h_scaled_size = 16;
240 cinfo->_min_DCT_v_scaled_size = 16;
241 }
242
243 /* Recompute dimensions of components */
244 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
245 ci++, compptr++) {
246 compptr->_DCT_h_scaled_size = cinfo->_min_DCT_h_scaled_size;
247 compptr->_DCT_v_scaled_size = cinfo->_min_DCT_v_scaled_size;
248 }
249
250#else /* !IDCT_SCALING_SUPPORTED */
251
252 /* Hardwire it to "no scaling" */
253 cinfo->output_width = cinfo->image_width;
254 cinfo->output_height = cinfo->image_height;
255 /* jdinput.c has already initialized DCT_scaled_size,
256 * and has computed unscaled downsampled_width and downsampled_height.
257 */
258
259#endif /* IDCT_SCALING_SUPPORTED */
260}
261
262
263/*
264 * Compute output image dimensions and related values.
265 * NOTE: this is exported for possible use by application.
266 * Hence it mustn't do anything that can't be done twice.
267 * Also note that it may be called before the master module is initialized!
268 */
269
270GLOBAL(void)
271jpeg_calc_output_dimensions(j_decompress_ptr cinfo)
272/* Do computations that are needed before master selection phase */
273{
274#ifdef IDCT_SCALING_SUPPORTED
275 int ci;
276 jpeg_component_info *compptr;
277#endif
278
279 /* Prevent application from calling me at wrong times */
280 if (cinfo->global_state != DSTATE_READY)
281 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
282
283 /* Compute core output image dimensions and DCT scaling choices. */
284 jpeg_core_output_dimensions(cinfo);
285
286#ifdef IDCT_SCALING_SUPPORTED
287
288 /* In selecting the actual DCT scaling for each component, we try to
289 * scale up the chroma components via IDCT scaling rather than upsampling.
290 * This saves time if the upsampler gets to use 1:1 scaling.
291 * Note this code adapts subsampling ratios which are powers of 2.
292 */
293 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
294 ci++, compptr++) {
295 int ssize = cinfo->_min_DCT_scaled_size;
296 while (ssize < DCTSIZE &&
297 ((cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) %
298 (compptr->h_samp_factor * ssize * 2) == 0) &&
299 ((cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size) %
300 (compptr->v_samp_factor * ssize * 2) == 0)) {
301 ssize = ssize * 2;
302 }
303#if JPEG_LIB_VERSION >= 70
304 compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = ssize;
305#else
306 compptr->DCT_scaled_size = ssize;
307#endif
308 }
309
310 /* Recompute downsampled dimensions of components;
311 * application needs to know these if using raw downsampled data.
312 */
313 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
314 ci++, compptr++) {
315 /* Size in samples, after IDCT scaling */
316 compptr->downsampled_width = (JDIMENSION)
317 jdiv_round_up((long)cinfo->image_width *
318 (long)(compptr->h_samp_factor * compptr->_DCT_scaled_size),
319 (long)(cinfo->max_h_samp_factor * DCTSIZE));
320 compptr->downsampled_height = (JDIMENSION)
321 jdiv_round_up((long)cinfo->image_height *
322 (long)(compptr->v_samp_factor * compptr->_DCT_scaled_size),
323 (long)(cinfo->max_v_samp_factor * DCTSIZE));
324 }
325
326#else /* !IDCT_SCALING_SUPPORTED */
327
328 /* Hardwire it to "no scaling" */
329 cinfo->output_width = cinfo->image_width;
330 cinfo->output_height = cinfo->image_height;
331 /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
332 * and has computed unscaled downsampled_width and downsampled_height.
333 */
334
335#endif /* IDCT_SCALING_SUPPORTED */
336
337 /* Report number of components in selected colorspace. */
338 /* Probably this should be in the color conversion module... */
339 switch (cinfo->out_color_space) {
340 case JCS_GRAYSCALE:
341 cinfo->out_color_components = 1;
342 break;
343 case JCS_RGB:
344 case JCS_EXT_RGB:
345 case JCS_EXT_RGBX:
346 case JCS_EXT_BGR:
347 case JCS_EXT_BGRX:
348 case JCS_EXT_XBGR:
349 case JCS_EXT_XRGB:
350 case JCS_EXT_RGBA:
351 case JCS_EXT_BGRA:
352 case JCS_EXT_ABGR:
353 case JCS_EXT_ARGB:
354 cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
355 break;
356 case JCS_YCbCr:
357 case JCS_RGB565:
358 cinfo->out_color_components = 3;
359 break;
360 case JCS_CMYK:
361 case JCS_YCCK:
362 cinfo->out_color_components = 4;
363 break;
364 default: /* else must be same colorspace as in file */
365 cinfo->out_color_components = cinfo->num_components;
366 break;
367 }
368 cinfo->output_components = (cinfo->quantize_colors ? 1 :
369 cinfo->out_color_components);
370
371 /* See if upsampler will want to emit more than one row at a time */
372 if (use_merged_upsample(cinfo))
373 cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
374 else
375 cinfo->rec_outbuf_height = 1;
376}
377
378
379/*
380 * Several decompression processes need to range-limit values to the range
381 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
382 * due to noise introduced by quantization, roundoff error, etc. These
383 * processes are inner loops and need to be as fast as possible. On most
384 * machines, particularly CPUs with pipelines or instruction prefetch,
385 * a (subscript-check-less) C table lookup
386 * x = sample_range_limit[x];
387 * is faster than explicit tests
388 * if (x < 0) x = 0;
389 * else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
390 * These processes all use a common table prepared by the routine below.
391 *
392 * For most steps we can mathematically guarantee that the initial value
393 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
394 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
395 * limiting step (just after the IDCT), a wildly out-of-range value is
396 * possible if the input data is corrupt. To avoid any chance of indexing
397 * off the end of memory and getting a bad-pointer trap, we perform the
398 * post-IDCT limiting thus:
399 * x = range_limit[x & MASK];
400 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
401 * samples. Under normal circumstances this is more than enough range and
402 * a correct output will be generated; with bogus input data the mask will
403 * cause wraparound, and we will safely generate a bogus-but-in-range output.
404 * For the post-IDCT step, we want to convert the data from signed to unsigned
405 * representation by adding CENTERJSAMPLE at the same time that we limit it.
406 * So the post-IDCT limiting table ends up looking like this:
407 * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
408 * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
409 * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
410 * 0,1,...,CENTERJSAMPLE-1
411 * Negative inputs select values from the upper half of the table after
412 * masking.
413 *
414 * We can save some space by overlapping the start of the post-IDCT table
415 * with the simpler range limiting table. The post-IDCT table begins at
416 * sample_range_limit + CENTERJSAMPLE.
417 */
418
419LOCAL(void)
420prepare_range_limit_table(j_decompress_ptr cinfo)
421/* Allocate and fill in the sample_range_limit table */
422{
423 JSAMPLE *table;
424 int i;
425
426 table = (JSAMPLE *)
427 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
428 (5 * (MAXJSAMPLE + 1) + CENTERJSAMPLE) * sizeof(JSAMPLE));
429 table += (MAXJSAMPLE + 1); /* allow negative subscripts of simple table */
430 cinfo->sample_range_limit = table;
431 /* First segment of "simple" table: limit[x] = 0 for x < 0 */
432 MEMZERO(table - (MAXJSAMPLE + 1), (MAXJSAMPLE + 1) * sizeof(JSAMPLE));
433 /* Main part of "simple" table: limit[x] = x */
434 for (i = 0; i <= MAXJSAMPLE; i++)
435 table[i] = (JSAMPLE)i;
436 table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */
437 /* End of simple table, rest of first half of post-IDCT table */
438 for (i = CENTERJSAMPLE; i < 2 * (MAXJSAMPLE + 1); i++)
439 table[i] = MAXJSAMPLE;
440 /* Second half of post-IDCT table */
441 MEMZERO(table + (2 * (MAXJSAMPLE + 1)),
442 (2 * (MAXJSAMPLE + 1) - CENTERJSAMPLE) * sizeof(JSAMPLE));
443 MEMCOPY(table + (4 * (MAXJSAMPLE + 1) - CENTERJSAMPLE),
444 cinfo->sample_range_limit, CENTERJSAMPLE * sizeof(JSAMPLE));
445}
446
447
448/*
449 * Master selection of decompression modules.
450 * This is done once at jpeg_start_decompress time. We determine
451 * which modules will be used and give them appropriate initialization calls.
452 * We also initialize the decompressor input side to begin consuming data.
453 *
454 * Since jpeg_read_header has finished, we know what is in the SOF
455 * and (first) SOS markers. We also have all the application parameter
456 * settings.
457 */
458
459LOCAL(void)
460master_selection(j_decompress_ptr cinfo)
461{
462 my_master_ptr master = (my_master_ptr)cinfo->master;
463 boolean use_c_buffer;
464 long samplesperrow;
465 JDIMENSION jd_samplesperrow;
466
467 /* Initialize dimensions and other stuff */
468 jpeg_calc_output_dimensions(cinfo);
469 prepare_range_limit_table(cinfo);
470
471 /* Width of an output scanline must be representable as JDIMENSION. */
472 samplesperrow = (long)cinfo->output_width *
473 (long)cinfo->out_color_components;
474 jd_samplesperrow = (JDIMENSION)samplesperrow;
475 if ((long)jd_samplesperrow != samplesperrow)
476 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
477
478 /* Initialize my private state */
479 master->pass_number = 0;
480 master->using_merged_upsample = use_merged_upsample(cinfo);
481
482 /* Color quantizer selection */
483 master->quantizer_1pass = NULL;
484 master->quantizer_2pass = NULL;
485 /* No mode changes if not using buffered-image mode. */
486 if (!cinfo->quantize_colors || !cinfo->buffered_image) {
487 cinfo->enable_1pass_quant = FALSE;
488 cinfo->enable_external_quant = FALSE;
489 cinfo->enable_2pass_quant = FALSE;
490 }
491 if (cinfo->quantize_colors) {
492 if (cinfo->raw_data_out)
493 ERREXIT(cinfo, JERR_NOTIMPL);
494 /* 2-pass quantizer only works in 3-component color space. */
495 if (cinfo->out_color_components != 3) {
496 cinfo->enable_1pass_quant = TRUE;
497 cinfo->enable_external_quant = FALSE;
498 cinfo->enable_2pass_quant = FALSE;
499 cinfo->colormap = NULL;
500 } else if (cinfo->colormap != NULL) {
501 cinfo->enable_external_quant = TRUE;
502 } else if (cinfo->two_pass_quantize) {
503 cinfo->enable_2pass_quant = TRUE;
504 } else {
505 cinfo->enable_1pass_quant = TRUE;
506 }
507
508 if (cinfo->enable_1pass_quant) {
509#ifdef QUANT_1PASS_SUPPORTED
510 jinit_1pass_quantizer(cinfo);
511 master->quantizer_1pass = cinfo->cquantize;
512#else
513 ERREXIT(cinfo, JERR_NOT_COMPILED);
514#endif
515 }
516
517 /* We use the 2-pass code to map to external colormaps. */
518 if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
519#ifdef QUANT_2PASS_SUPPORTED
520 jinit_2pass_quantizer(cinfo);
521 master->quantizer_2pass = cinfo->cquantize;
522#else
523 ERREXIT(cinfo, JERR_NOT_COMPILED);
524#endif
525 }
526 /* If both quantizers are initialized, the 2-pass one is left active;
527 * this is necessary for starting with quantization to an external map.
528 */
529 }
530
531 /* Post-processing: in particular, color conversion first */
532 if (!cinfo->raw_data_out) {
533 if (master->using_merged_upsample) {
534#ifdef UPSAMPLE_MERGING_SUPPORTED
535 jinit_merged_upsampler(cinfo); /* does color conversion too */
536#else
537 ERREXIT(cinfo, JERR_NOT_COMPILED);
538#endif
539 } else {
540 jinit_color_deconverter(cinfo);
541 jinit_upsampler(cinfo);
542 }
543 jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
544 }
545 /* Inverse DCT */
546 jinit_inverse_dct(cinfo);
547 /* Entropy decoding: either Huffman or arithmetic coding. */
548 if (cinfo->arith_code) {
549#ifdef D_ARITH_CODING_SUPPORTED
550 jinit_arith_decoder(cinfo);
551#else
552 ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
553#endif
554 } else {
555 if (cinfo->progressive_mode) {
556#ifdef D_PROGRESSIVE_SUPPORTED
557 jinit_phuff_decoder(cinfo);
558#else
559 ERREXIT(cinfo, JERR_NOT_COMPILED);
560#endif
561 } else
562 jinit_huff_decoder(cinfo);
563 }
564
565 /* Initialize principal buffer controllers. */
566 use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
567 jinit_d_coef_controller(cinfo, use_c_buffer);
568
569 if (!cinfo->raw_data_out)
570 jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
571
572 /* We can now tell the memory manager to allocate virtual arrays. */
573 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);
574
575 /* Initialize input side of decompressor to consume first scan. */
576 (*cinfo->inputctl->start_input_pass) (cinfo);
577
578 /* Set the first and last iMCU columns to decompress from single-scan images.
579 * By default, decompress all of the iMCU columns.
580 */
581 cinfo->master->first_iMCU_col = 0;
582 cinfo->master->last_iMCU_col = cinfo->MCUs_per_row - 1;
583
584#ifdef D_MULTISCAN_FILES_SUPPORTED
585 /* If jpeg_start_decompress will read the whole file, initialize
586 * progress monitoring appropriately. The input step is counted
587 * as one pass.
588 */
589 if (cinfo->progress != NULL && !cinfo->buffered_image &&
590 cinfo->inputctl->has_multiple_scans) {
591 int nscans;
592 /* Estimate number of scans to set pass_limit. */
593 if (cinfo->progressive_mode) {
594 /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
595 nscans = 2 + 3 * cinfo->num_components;
596 } else {
597 /* For a nonprogressive multiscan file, estimate 1 scan per component. */
598 nscans = cinfo->num_components;
599 }
600 cinfo->progress->pass_counter = 0L;
601 cinfo->progress->pass_limit = (long)cinfo->total_iMCU_rows * nscans;
602 cinfo->progress->completed_passes = 0;
603 cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
604 /* Count the input pass as done */
605 master->pass_number++;
606 }
607#endif /* D_MULTISCAN_FILES_SUPPORTED */
608}
609
610
611/*
612 * Per-pass setup.
613 * This is called at the beginning of each output pass. We determine which
614 * modules will be active during this pass and give them appropriate
615 * start_pass calls. We also set is_dummy_pass to indicate whether this
616 * is a "real" output pass or a dummy pass for color quantization.
617 * (In the latter case, jdapistd.c will crank the pass to completion.)
618 */
619
620METHODDEF(void)
621prepare_for_output_pass(j_decompress_ptr cinfo)
622{
623 my_master_ptr master = (my_master_ptr)cinfo->master;
624
625 if (master->pub.is_dummy_pass) {
626#ifdef QUANT_2PASS_SUPPORTED
627 /* Final pass of 2-pass quantization */
628 master->pub.is_dummy_pass = FALSE;
629 (*cinfo->cquantize->start_pass) (cinfo, FALSE);
630 (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
631 (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
632#else
633 ERREXIT(cinfo, JERR_NOT_COMPILED);
634#endif /* QUANT_2PASS_SUPPORTED */
635 } else {
636 if (cinfo->quantize_colors && cinfo->colormap == NULL) {
637 /* Select new quantization method */
638 if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
639 cinfo->cquantize = master->quantizer_2pass;
640 master->pub.is_dummy_pass = TRUE;
641 } else if (cinfo->enable_1pass_quant) {
642 cinfo->cquantize = master->quantizer_1pass;
643 } else {
644 ERREXIT(cinfo, JERR_MODE_CHANGE);
645 }
646 }
647 (*cinfo->idct->start_pass) (cinfo);
648 (*cinfo->coef->start_output_pass) (cinfo);
649 if (!cinfo->raw_data_out) {
650 if (!master->using_merged_upsample)
651 (*cinfo->cconvert->start_pass) (cinfo);
652 (*cinfo->upsample->start_pass) (cinfo);
653 if (cinfo->quantize_colors)
654 (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
655 (*cinfo->post->start_pass) (cinfo,
656 (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
657 (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
658 }
659 }
660
661 /* Set up progress monitor's pass info if present */
662 if (cinfo->progress != NULL) {
663 cinfo->progress->completed_passes = master->pass_number;
664 cinfo->progress->total_passes = master->pass_number +
665 (master->pub.is_dummy_pass ? 2 : 1);
666 /* In buffered-image mode, we assume one more output pass if EOI not
667 * yet reached, but no more passes if EOI has been reached.
668 */
669 if (cinfo->buffered_image && !cinfo->inputctl->eoi_reached) {
670 cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
671 }
672 }
673}
674
675
676/*
677 * Finish up at end of an output pass.
678 */
679
680METHODDEF(void)
681finish_output_pass(j_decompress_ptr cinfo)
682{
683 my_master_ptr master = (my_master_ptr)cinfo->master;
684
685 if (cinfo->quantize_colors)
686 (*cinfo->cquantize->finish_pass) (cinfo);
687 master->pass_number++;
688}
689
690
691#ifdef D_MULTISCAN_FILES_SUPPORTED
692
693/*
694 * Switch to a new external colormap between output passes.
695 */
696
697GLOBAL(void)
698jpeg_new_colormap(j_decompress_ptr cinfo)
699{
700 my_master_ptr master = (my_master_ptr)cinfo->master;
701
702 /* Prevent application from calling me at wrong times */
703 if (cinfo->global_state != DSTATE_BUFIMAGE)
704 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
705
706 if (cinfo->quantize_colors && cinfo->enable_external_quant &&
707 cinfo->colormap != NULL) {
708 /* Select 2-pass quantizer for external colormap use */
709 cinfo->cquantize = master->quantizer_2pass;
710 /* Notify quantizer of colormap change */
711 (*cinfo->cquantize->new_color_map) (cinfo);
712 master->pub.is_dummy_pass = FALSE; /* just in case */
713 } else
714 ERREXIT(cinfo, JERR_MODE_CHANGE);
715}
716
717#endif /* D_MULTISCAN_FILES_SUPPORTED */
718
719
720/*
721 * Initialize master decompression control and select active modules.
722 * This is performed at the start of jpeg_start_decompress.
723 */
724
725GLOBAL(void)
726jinit_master_decompress(j_decompress_ptr cinfo)
727{
728 my_master_ptr master = (my_master_ptr)cinfo->master;
729
730 master->pub.prepare_for_output_pass = prepare_for_output_pass;
731 master->pub.finish_output_pass = finish_output_pass;
732
733 master->pub.is_dummy_pass = FALSE;
734 master->pub.jinit_upsampler_no_alloc = FALSE;
735
736 master_selection(cinfo);
737}
738