1/*
2 * jdmaster.c
3 *
4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * Modified 2002-2011 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains master control logic for the JPEG decompressor.
10 * These routines are concerned with selecting the modules to be executed
11 * and with determining the number of passes and the work to be done in each
12 * pass.
13 */
14
15#define JPEG_INTERNALS
16#include "jinclude.h"
17#include "jpeglib.h"
18
19
20/* Private state */
21
22typedef struct {
23 struct jpeg_decomp_master pub; /* public fields */
24
25 int pass_number; /* # of passes completed */
26
27 boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
28
29 /* Saved references to initialized quantizer modules,
30 * in case we need to switch modes.
31 */
32 struct jpeg_color_quantizer * quantizer_1pass;
33 struct jpeg_color_quantizer * quantizer_2pass;
34} my_decomp_master;
35
36typedef my_decomp_master * my_master_ptr;
37
38
39/*
40 * Determine whether merged upsample/color conversion should be used.
41 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
42 */
43
44LOCAL(boolean)
45use_merged_upsample (j_decompress_ptr cinfo)
46{
47#ifdef UPSAMPLE_MERGING_SUPPORTED
48 /* Merging is the equivalent of plain box-filter upsampling */
49 if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
50 return FALSE;
51 /* jdmerge.c only supports YCC=>RGB color conversion */
52 if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
53 cinfo->out_color_space != JCS_RGB ||
54 cinfo->out_color_components != RGB_PIXELSIZE)
55 return FALSE;
56 /* and it only handles 2h1v or 2h2v sampling ratios */
57 if (cinfo->comp_info[0].h_samp_factor != 2 ||
58 cinfo->comp_info[1].h_samp_factor != 1 ||
59 cinfo->comp_info[2].h_samp_factor != 1 ||
60 cinfo->comp_info[0].v_samp_factor > 2 ||
61 cinfo->comp_info[1].v_samp_factor != 1 ||
62 cinfo->comp_info[2].v_samp_factor != 1)
63 return FALSE;
64 /* furthermore, it doesn't work if we've scaled the IDCTs differently */
65 if (cinfo->comp_info[0].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
66 cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
67 cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
68 cinfo->comp_info[0].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
69 cinfo->comp_info[1].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
70 cinfo->comp_info[2].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size)
71 return FALSE;
72 /* ??? also need to test for upsample-time rescaling, when & if supported */
73 return TRUE; /* by golly, it'll work... */
74#else
75 return FALSE;
76#endif
77}
78
79
80/*
81 * Compute output image dimensions and related values.
82 * NOTE: this is exported for possible use by application.
83 * Hence it mustn't do anything that can't be done twice.
84 * Also note that it may be called before the master module is initialized!
85 */
86
87GLOBAL(void)
88jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
89/* Do computations that are needed before master selection phase.
90 * This function is used for full decompression.
91 */
92{
93#ifdef IDCT_SCALING_SUPPORTED
94 int ci;
95 jpeg_component_info *compptr;
96#endif
97
98 /* Prevent application from calling me at wrong times */
99 if (cinfo->global_state != DSTATE_READY)
100 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
101
102 /* Compute core output image dimensions and DCT scaling choices. */
103 jpeg_core_output_dimensions(cinfo);
104
105#ifdef IDCT_SCALING_SUPPORTED
106
107 /* In selecting the actual DCT scaling for each component, we try to
108 * scale up the chroma components via IDCT scaling rather than upsampling.
109 * This saves time if the upsampler gets to use 1:1 scaling.
110 * Note this code adapts subsampling ratios which are powers of 2.
111 */
112 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
113 ci++, compptr++) {
114 int ssize = 1;
115 while (cinfo->min_DCT_h_scaled_size * ssize <=
116 (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
117 (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
118 ssize = ssize * 2;
119 }
120 compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
121 ssize = 1;
122 while (cinfo->min_DCT_v_scaled_size * ssize <=
123 (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
124 (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
125 ssize = ssize * 2;
126 }
127 compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
128
129 /* We don't support IDCT ratios larger than 2. */
130 if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
131 compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
132 else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
133 compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
134 }
135
136 /* Recompute downsampled dimensions of components;
137 * application needs to know these if using raw downsampled data.
138 */
139 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
140 ci++, compptr++) {
141 /* Size in samples, after IDCT scaling */
142 compptr->downsampled_width = (JDIMENSION)
143 jdiv_round_up((long) cinfo->image_width *
144 (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
145 (long) (cinfo->max_h_samp_factor * cinfo->block_size));
146 compptr->downsampled_height = (JDIMENSION)
147 jdiv_round_up((long) cinfo->image_height *
148 (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
149 (long) (cinfo->max_v_samp_factor * cinfo->block_size));
150 }
151
152#endif /* IDCT_SCALING_SUPPORTED */
153
154 /* Report number of components in selected colorspace. */
155 /* Probably this should be in the color conversion module... */
156 switch (cinfo->out_color_space) {
157 case JCS_GRAYSCALE:
158 cinfo->out_color_components = 1;
159 break;
160 case JCS_RGB:
161 cinfo->out_color_components = RGB_PIXELSIZE;
162 break;
163 case JCS_YCbCr:
164 cinfo->out_color_components = 3;
165 break;
166 case JCS_CMYK:
167 case JCS_YCCK:
168 cinfo->out_color_components = 4;
169 break;
170 default: /* else must be same colorspace as in file */
171 cinfo->out_color_components = cinfo->num_components;
172 break;
173 }
174 cinfo->output_components = (cinfo->quantize_colors ? 1 :
175 cinfo->out_color_components);
176
177 /* See if upsampler will want to emit more than one row at a time */
178 if (use_merged_upsample(cinfo))
179 cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
180 else
181 cinfo->rec_outbuf_height = 1;
182}
183
184
185/*
186 * Several decompression processes need to range-limit values to the range
187 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
188 * due to noise introduced by quantization, roundoff error, etc. These
189 * processes are inner loops and need to be as fast as possible. On most
190 * machines, particularly CPUs with pipelines or instruction prefetch,
191 * a (subscript-check-less) C table lookup
192 * x = sample_range_limit[x];
193 * is faster than explicit tests
194 * if (x < 0) x = 0;
195 * else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
196 * These processes all use a common table prepared by the routine below.
197 *
198 * For most steps we can mathematically guarantee that the initial value
199 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
200 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
201 * limiting step (just after the IDCT), a wildly out-of-range value is
202 * possible if the input data is corrupt. To avoid any chance of indexing
203 * off the end of memory and getting a bad-pointer trap, we perform the
204 * post-IDCT limiting thus:
205 * x = range_limit[x & MASK];
206 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
207 * samples. Under normal circumstances this is more than enough range and
208 * a correct output will be generated; with bogus input data the mask will
209 * cause wraparound, and we will safely generate a bogus-but-in-range output.
210 * For the post-IDCT step, we want to convert the data from signed to unsigned
211 * representation by adding CENTERJSAMPLE at the same time that we limit it.
212 * So the post-IDCT limiting table ends up looking like this:
213 * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
214 * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
215 * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
216 * 0,1,...,CENTERJSAMPLE-1
217 * Negative inputs select values from the upper half of the table after
218 * masking.
219 *
220 * We can save some space by overlapping the start of the post-IDCT table
221 * with the simpler range limiting table. The post-IDCT table begins at
222 * sample_range_limit + CENTERJSAMPLE.
223 *
224 * Note that the table is allocated in near data space on PCs; it's small
225 * enough and used often enough to justify this.
226 */
227
228LOCAL(void)
229prepare_range_limit_table (j_decompress_ptr cinfo)
230/* Allocate and fill in the sample_range_limit table */
231{
232 JSAMPLE * table;
233 int i;
234
235 table = (JSAMPLE *)
236 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
237 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
238 table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */
239 cinfo->sample_range_limit = table;
240 /* First segment of "simple" table: limit[x] = 0 for x < 0 */
241 MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
242 /* Main part of "simple" table: limit[x] = x */
243 for (i = 0; i <= MAXJSAMPLE; i++)
244 table[i] = (JSAMPLE) i;
245 table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */
246 /* End of simple table, rest of first half of post-IDCT table */
247 for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
248 table[i] = MAXJSAMPLE;
249 /* Second half of post-IDCT table */
250 MEMZERO(table + (2 * (MAXJSAMPLE+1)),
251 (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
252 MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
253 cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
254}
255
256
257/*
258 * Master selection of decompression modules.
259 * This is done once at jpeg_start_decompress time. We determine
260 * which modules will be used and give them appropriate initialization calls.
261 * We also initialize the decompressor input side to begin consuming data.
262 *
263 * Since jpeg_read_header has finished, we know what is in the SOF
264 * and (first) SOS markers. We also have all the application parameter
265 * settings.
266 */
267
268LOCAL(void)
269master_selection (j_decompress_ptr cinfo)
270{
271 my_master_ptr master = (my_master_ptr) cinfo->master;
272 boolean use_c_buffer;
273 long samplesperrow;
274 JDIMENSION jd_samplesperrow;
275
276 /* Initialize dimensions and other stuff */
277 jpeg_calc_output_dimensions(cinfo);
278 prepare_range_limit_table(cinfo);
279
280 /* Width of an output scanline must be representable as JDIMENSION. */
281 samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
282 jd_samplesperrow = (JDIMENSION) samplesperrow;
283 if ((long) jd_samplesperrow != samplesperrow)
284 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
285
286 /* Initialize my private state */
287 master->pass_number = 0;
288 master->using_merged_upsample = use_merged_upsample(cinfo);
289
290 /* Color quantizer selection */
291 master->quantizer_1pass = NULL;
292 master->quantizer_2pass = NULL;
293 /* No mode changes if not using buffered-image mode. */
294 if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
295 cinfo->enable_1pass_quant = FALSE;
296 cinfo->enable_external_quant = FALSE;
297 cinfo->enable_2pass_quant = FALSE;
298 }
299 if (cinfo->quantize_colors) {
300 if (cinfo->raw_data_out)
301 ERREXIT(cinfo, JERR_NOTIMPL);
302 /* 2-pass quantizer only works in 3-component color space. */
303 if (cinfo->out_color_components != 3) {
304 cinfo->enable_1pass_quant = TRUE;
305 cinfo->enable_external_quant = FALSE;
306 cinfo->enable_2pass_quant = FALSE;
307 cinfo->colormap = NULL;
308 } else if (cinfo->colormap != NULL) {
309 cinfo->enable_external_quant = TRUE;
310 } else if (cinfo->two_pass_quantize) {
311 cinfo->enable_2pass_quant = TRUE;
312 } else {
313 cinfo->enable_1pass_quant = TRUE;
314 }
315
316 if (cinfo->enable_1pass_quant) {
317#ifdef QUANT_1PASS_SUPPORTED
318 jinit_1pass_quantizer(cinfo);
319 master->quantizer_1pass = cinfo->cquantize;
320#else
321 ERREXIT(cinfo, JERR_NOT_COMPILED);
322#endif
323 }
324
325 /* We use the 2-pass code to map to external colormaps. */
326 if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
327#ifdef QUANT_2PASS_SUPPORTED
328 jinit_2pass_quantizer(cinfo);
329 master->quantizer_2pass = cinfo->cquantize;
330#else
331 ERREXIT(cinfo, JERR_NOT_COMPILED);
332#endif
333 }
334 /* If both quantizers are initialized, the 2-pass one is left active;
335 * this is necessary for starting with quantization to an external map.
336 */
337 }
338
339 /* Post-processing: in particular, color conversion first */
340 if (! cinfo->raw_data_out) {
341 if (master->using_merged_upsample) {
342#ifdef UPSAMPLE_MERGING_SUPPORTED
343 jinit_merged_upsampler(cinfo); /* does color conversion too */
344#else
345 ERREXIT(cinfo, JERR_NOT_COMPILED);
346#endif
347 } else {
348 jinit_color_deconverter(cinfo);
349 jinit_upsampler(cinfo);
350 }
351 jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
352 }
353 /* Inverse DCT */
354 jinit_inverse_dct(cinfo);
355 /* Entropy decoding: either Huffman or arithmetic coding. */
356 if (cinfo->arith_code)
357 jinit_arith_decoder(cinfo);
358 else {
359 jinit_huff_decoder(cinfo);
360 }
361
362 /* Initialize principal buffer controllers. */
363 use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
364 jinit_d_coef_controller(cinfo, use_c_buffer);
365
366 if (! cinfo->raw_data_out)
367 jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
368
369 /* We can now tell the memory manager to allocate virtual arrays. */
370 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
371
372 /* Initialize input side of decompressor to consume first scan. */
373 (*cinfo->inputctl->start_input_pass) (cinfo);
374
375#ifdef D_MULTISCAN_FILES_SUPPORTED
376 /* If jpeg_start_decompress will read the whole file, initialize
377 * progress monitoring appropriately. The input step is counted
378 * as one pass.
379 */
380 if (cinfo->progress != NULL && ! cinfo->buffered_image &&
381 cinfo->inputctl->has_multiple_scans) {
382 int nscans;
383 /* Estimate number of scans to set pass_limit. */
384 if (cinfo->progressive_mode) {
385 /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
386 nscans = 2 + 3 * cinfo->num_components;
387 } else {
388 /* For a nonprogressive multiscan file, estimate 1 scan per component. */
389 nscans = cinfo->num_components;
390 }
391 cinfo->progress->pass_counter = 0L;
392 cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
393 cinfo->progress->completed_passes = 0;
394 cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
395 /* Count the input pass as done */
396 master->pass_number++;
397 }
398#endif /* D_MULTISCAN_FILES_SUPPORTED */
399}
400
401
402/*
403 * Per-pass setup.
404 * This is called at the beginning of each output pass. We determine which
405 * modules will be active during this pass and give them appropriate
406 * start_pass calls. We also set is_dummy_pass to indicate whether this
407 * is a "real" output pass or a dummy pass for color quantization.
408 * (In the latter case, jdapistd.c will crank the pass to completion.)
409 */
410
411METHODDEF(void)
412prepare_for_output_pass (j_decompress_ptr cinfo)
413{
414 my_master_ptr master = (my_master_ptr) cinfo->master;
415
416 if (master->pub.is_dummy_pass) {
417#ifdef QUANT_2PASS_SUPPORTED
418 /* Final pass of 2-pass quantization */
419 master->pub.is_dummy_pass = FALSE;
420 (*cinfo->cquantize->start_pass) (cinfo, FALSE);
421 (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
422 (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
423#else
424 ERREXIT(cinfo, JERR_NOT_COMPILED);
425#endif /* QUANT_2PASS_SUPPORTED */
426 } else {
427 if (cinfo->quantize_colors && cinfo->colormap == NULL) {
428 /* Select new quantization method */
429 if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
430 cinfo->cquantize = master->quantizer_2pass;
431 master->pub.is_dummy_pass = TRUE;
432 } else if (cinfo->enable_1pass_quant) {
433 cinfo->cquantize = master->quantizer_1pass;
434 } else {
435 ERREXIT(cinfo, JERR_MODE_CHANGE);
436 }
437 }
438 (*cinfo->idct->start_pass) (cinfo);
439 (*cinfo->coef->start_output_pass) (cinfo);
440 if (! cinfo->raw_data_out) {
441 if (! master->using_merged_upsample)
442 (*cinfo->cconvert->start_pass) (cinfo);
443 (*cinfo->upsample->start_pass) (cinfo);
444 if (cinfo->quantize_colors)
445 (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
446 (*cinfo->post->start_pass) (cinfo,
447 (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
448 (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
449 }
450 }
451
452 /* Set up progress monitor's pass info if present */
453 if (cinfo->progress != NULL) {
454 cinfo->progress->completed_passes = master->pass_number;
455 cinfo->progress->total_passes = master->pass_number +
456 (master->pub.is_dummy_pass ? 2 : 1);
457 /* In buffered-image mode, we assume one more output pass if EOI not
458 * yet reached, but no more passes if EOI has been reached.
459 */
460 if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
461 cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
462 }
463 }
464}
465
466
467/*
468 * Finish up at end of an output pass.
469 */
470
471METHODDEF(void)
472finish_output_pass (j_decompress_ptr cinfo)
473{
474 my_master_ptr master = (my_master_ptr) cinfo->master;
475
476 if (cinfo->quantize_colors)
477 (*cinfo->cquantize->finish_pass) (cinfo);
478 master->pass_number++;
479}
480
481
482#ifdef D_MULTISCAN_FILES_SUPPORTED
483
484/*
485 * Switch to a new external colormap between output passes.
486 */
487
488GLOBAL(void)
489jpeg_new_colormap (j_decompress_ptr cinfo)
490{
491 my_master_ptr master = (my_master_ptr) cinfo->master;
492
493 /* Prevent application from calling me at wrong times */
494 if (cinfo->global_state != DSTATE_BUFIMAGE)
495 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
496
497 if (cinfo->quantize_colors && cinfo->enable_external_quant &&
498 cinfo->colormap != NULL) {
499 /* Select 2-pass quantizer for external colormap use */
500 cinfo->cquantize = master->quantizer_2pass;
501 /* Notify quantizer of colormap change */
502 (*cinfo->cquantize->new_color_map) (cinfo);
503 master->pub.is_dummy_pass = FALSE; /* just in case */
504 } else
505 ERREXIT(cinfo, JERR_MODE_CHANGE);
506}
507
508#endif /* D_MULTISCAN_FILES_SUPPORTED */
509
510
511/*
512 * Initialize master decompression control and select active modules.
513 * This is performed at the start of jpeg_start_decompress.
514 */
515
516GLOBAL(void)
517jinit_master_decompress (j_decompress_ptr cinfo)
518{
519 my_master_ptr master;
520
521 master = (my_master_ptr)
522 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
523 SIZEOF(my_decomp_master));
524 cinfo->master = (struct jpeg_decomp_master *) master;
525 master->pub.prepare_for_output_pass = prepare_for_output_pass;
526 master->pub.finish_output_pass = finish_output_pass;
527
528 master->pub.is_dummy_pass = FALSE;
529
530 master_selection(cinfo);
531}
532