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