1/*
2 * jdapistd.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1996, Thomas G. Lane.
6 * libjpeg-turbo Modifications:
7 * Copyright (C) 2010, 2015-2016, D. R. Commander.
8 * Copyright (C) 2015, Google, Inc.
9 * For conditions of distribution and use, see the accompanying README.ijg
10 * file.
11 *
12 * This file contains application interface code for the decompression half
13 * of the JPEG library. These are the "standard" API routines that are
14 * used in the normal full-decompression case. They are not used by a
15 * transcoding-only application. Note that if an application links in
16 * jpeg_start_decompress, it will end up linking in the entire decompressor.
17 * We thus must separate this file from jdapimin.c to avoid linking the
18 * whole decompression library into a transcoder.
19 */
20
21#include "jinclude.h"
22#include "jdmainct.h"
23#include "jdcoefct.h"
24#include "jdsample.h"
25#include "jmemsys.h"
26
27/* Forward declarations */
28LOCAL(boolean) output_pass_setup (j_decompress_ptr cinfo);
29
30
31/*
32 * Decompression initialization.
33 * jpeg_read_header must be completed before calling this.
34 *
35 * If a multipass operating mode was selected, this will do all but the
36 * last pass, and thus may take a great deal of time.
37 *
38 * Returns FALSE if suspended. The return value need be inspected only if
39 * a suspending data source is used.
40 */
41
42GLOBAL(boolean)
43jpeg_start_decompress (j_decompress_ptr cinfo)
44{
45 if (cinfo->global_state == DSTATE_READY) {
46 /* First call: initialize master control, select active modules */
47 jinit_master_decompress(cinfo);
48 if (cinfo->buffered_image) {
49 /* No more work here; expecting jpeg_start_output next */
50 cinfo->global_state = DSTATE_BUFIMAGE;
51 return TRUE;
52 }
53 cinfo->global_state = DSTATE_PRELOAD;
54 }
55 if (cinfo->global_state == DSTATE_PRELOAD) {
56 /* If file has multiple scans, absorb them all into the coef buffer */
57 if (cinfo->inputctl->has_multiple_scans) {
58#ifdef D_MULTISCAN_FILES_SUPPORTED
59 for (;;) {
60 int retcode;
61 /* Call progress monitor hook if present */
62 if (cinfo->progress != NULL)
63 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
64 /* Absorb some more input */
65 retcode = (*cinfo->inputctl->consume_input) (cinfo);
66 if (retcode == JPEG_SUSPENDED)
67 return FALSE;
68 if (retcode == JPEG_REACHED_EOI)
69 break;
70 /* Advance progress counter if appropriate */
71 if (cinfo->progress != NULL &&
72 (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
73 if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
74 /* jdmaster underestimated number of scans; ratchet up one scan */
75 cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
76 }
77 }
78 }
79#else
80 ERREXIT(cinfo, JERR_NOT_COMPILED);
81#endif /* D_MULTISCAN_FILES_SUPPORTED */
82 }
83 cinfo->output_scan_number = cinfo->input_scan_number;
84 } else if (cinfo->global_state != DSTATE_PRESCAN)
85 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
86 /* Perform any dummy output passes, and set up for the final pass */
87 return output_pass_setup(cinfo);
88}
89
90
91/*
92 * Set up for an output pass, and perform any dummy pass(es) needed.
93 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
94 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
95 * Exit: If done, returns TRUE and sets global_state for proper output mode.
96 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
97 */
98
99LOCAL(boolean)
100output_pass_setup (j_decompress_ptr cinfo)
101{
102 if (cinfo->global_state != DSTATE_PRESCAN) {
103 /* First call: do pass setup */
104 (*cinfo->master->prepare_for_output_pass) (cinfo);
105 cinfo->output_scanline = 0;
106 cinfo->global_state = DSTATE_PRESCAN;
107 }
108 /* Loop over any required dummy passes */
109 while (cinfo->master->is_dummy_pass) {
110#ifdef QUANT_2PASS_SUPPORTED
111 /* Crank through the dummy pass */
112 while (cinfo->output_scanline < cinfo->output_height) {
113 JDIMENSION last_scanline;
114 /* Call progress monitor hook if present */
115 if (cinfo->progress != NULL) {
116 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
117 cinfo->progress->pass_limit = (long) cinfo->output_height;
118 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
119 }
120 /* Process some data */
121 last_scanline = cinfo->output_scanline;
122 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
123 &cinfo->output_scanline, (JDIMENSION) 0);
124 if (cinfo->output_scanline == last_scanline)
125 return FALSE; /* No progress made, must suspend */
126 }
127 /* Finish up dummy pass, and set up for another one */
128 (*cinfo->master->finish_output_pass) (cinfo);
129 (*cinfo->master->prepare_for_output_pass) (cinfo);
130 cinfo->output_scanline = 0;
131#else
132 ERREXIT(cinfo, JERR_NOT_COMPILED);
133#endif /* QUANT_2PASS_SUPPORTED */
134 }
135 /* Ready for application to drive output pass through
136 * jpeg_read_scanlines or jpeg_read_raw_data.
137 */
138 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
139 return TRUE;
140}
141
142
143/*
144 * Enable partial scanline decompression
145 *
146 * Must be called after jpeg_start_decompress() and before any calls to
147 * jpeg_read_scanlines() or jpeg_skip_scanlines().
148 *
149 * Refer to libjpeg.txt for more information.
150 */
151
152GLOBAL(void)
153jpeg_crop_scanline (j_decompress_ptr cinfo, JDIMENSION *xoffset,
154 JDIMENSION *width)
155{
156 int ci, align, orig_downsampled_width;
157 JDIMENSION input_xoffset;
158 boolean reinit_upsampler = FALSE;
159 jpeg_component_info *compptr;
160
161 if (cinfo->global_state != DSTATE_SCANNING || cinfo->output_scanline != 0)
162 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
163
164 if (!xoffset || !width)
165 ERREXIT(cinfo, JERR_BAD_CROP_SPEC);
166
167 /* xoffset and width must fall within the output image dimensions. */
168 if (*width == 0 || *xoffset + *width > cinfo->output_width)
169 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
170
171 /* No need to do anything if the caller wants the entire width. */
172 if (*width == cinfo->output_width)
173 return;
174
175 /* Ensuring the proper alignment of xoffset is tricky. At minimum, it
176 * must align with an MCU boundary, because:
177 *
178 * (1) The IDCT is performed in blocks, and it is not feasible to modify
179 * the algorithm so that it can transform partial blocks.
180 * (2) Because of the SIMD extensions, any input buffer passed to the
181 * upsampling and color conversion routines must be aligned to the
182 * SIMD word size (for instance, 128-bit in the case of SSE2.) The
183 * easiest way to accomplish this without copying data is to ensure
184 * that upsampling and color conversion begin at the start of the
185 * first MCU column that will be inverse transformed.
186 *
187 * In practice, we actually impose a stricter alignment requirement. We
188 * require that xoffset be a multiple of the maximum MCU column width of all
189 * of the components (the "iMCU column width.") This is to simplify the
190 * single-pass decompression case, allowing us to use the same MCU column
191 * width for all of the components.
192 */
193 align = cinfo->_min_DCT_scaled_size * cinfo->max_h_samp_factor;
194
195 /* Adjust xoffset to the nearest iMCU boundary <= the requested value */
196 input_xoffset = *xoffset;
197 *xoffset = (input_xoffset / align) * align;
198
199 /* Adjust the width so that the right edge of the output image is as
200 * requested (only the left edge is altered.) It is important that calling
201 * programs check this value after this function returns, so that they can
202 * allocate an output buffer with the appropriate size.
203 */
204 *width = *width + input_xoffset - *xoffset;
205 cinfo->output_width = *width;
206
207 /* Set the first and last iMCU columns that we must decompress. These values
208 * will be used in single-scan decompressions.
209 */
210 cinfo->master->first_iMCU_col =
211 (JDIMENSION) (long) (*xoffset) / (long) align;
212 cinfo->master->last_iMCU_col =
213 (JDIMENSION) jdiv_round_up((long) (*xoffset + cinfo->output_width),
214 (long) align) - 1;
215
216 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
217 ci++, compptr++) {
218 /* Set downsampled_width to the new output width. */
219 orig_downsampled_width = compptr->downsampled_width;
220 compptr->downsampled_width =
221 (JDIMENSION) jdiv_round_up((long) (cinfo->output_width *
222 compptr->h_samp_factor),
223 (long) cinfo->max_h_samp_factor);
224 if (compptr->downsampled_width < 2 && orig_downsampled_width >= 2)
225 reinit_upsampler = TRUE;
226
227 /* Set the first and last iMCU columns that we must decompress. These
228 * values will be used in multi-scan decompressions.
229 */
230 cinfo->master->first_MCU_col[ci] =
231 (JDIMENSION) (long) (*xoffset * compptr->h_samp_factor) /
232 (long) align;
233 cinfo->master->last_MCU_col[ci] =
234 (JDIMENSION) jdiv_round_up((long) ((*xoffset + cinfo->output_width) *
235 compptr->h_samp_factor),
236 (long) align) - 1;
237 }
238
239 if (reinit_upsampler) {
240 cinfo->master->jinit_upsampler_no_alloc = TRUE;
241 jinit_upsampler(cinfo);
242 cinfo->master->jinit_upsampler_no_alloc = FALSE;
243 }
244}
245
246
247/*
248 * Read some scanlines of data from the JPEG decompressor.
249 *
250 * The return value will be the number of lines actually read.
251 * This may be less than the number requested in several cases,
252 * including bottom of image, data source suspension, and operating
253 * modes that emit multiple scanlines at a time.
254 *
255 * Note: we warn about excess calls to jpeg_read_scanlines() since
256 * this likely signals an application programmer error. However,
257 * an oversize buffer (max_lines > scanlines remaining) is not an error.
258 */
259
260GLOBAL(JDIMENSION)
261jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
262 JDIMENSION max_lines)
263{
264 JDIMENSION row_ctr;
265
266 if (cinfo->global_state != DSTATE_SCANNING)
267 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
268 if (cinfo->output_scanline >= cinfo->output_height) {
269 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
270 return 0;
271 }
272
273 /* Call progress monitor hook if present */
274 if (cinfo->progress != NULL) {
275 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
276 cinfo->progress->pass_limit = (long) cinfo->output_height;
277 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
278 }
279
280 /* Process some data */
281 row_ctr = 0;
282 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
283 cinfo->output_scanline += row_ctr;
284 return row_ctr;
285}
286
287
288/* Dummy color convert function used by jpeg_skip_scanlines() */
289LOCAL(void)
290noop_convert (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
291 JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
292{
293}
294
295
296/*
297 * In some cases, it is best to call jpeg_read_scanlines() and discard the
298 * output, rather than skipping the scanlines, because this allows us to
299 * maintain the internal state of the context-based upsampler. In these cases,
300 * we set up and tear down a dummy color converter in order to avoid valgrind
301 * errors and to achieve the best possible performance.
302 */
303
304LOCAL(void)
305read_and_discard_scanlines (j_decompress_ptr cinfo, JDIMENSION num_lines)
306{
307 JDIMENSION n;
308 void (*color_convert) (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
309 JDIMENSION input_row, JSAMPARRAY output_buf,
310 int num_rows);
311
312 color_convert = cinfo->cconvert->color_convert;
313 cinfo->cconvert->color_convert = noop_convert;
314
315 for (n = 0; n < num_lines; n++)
316 jpeg_read_scanlines(cinfo, NULL, 1);
317
318 cinfo->cconvert->color_convert = color_convert;
319}
320
321
322/*
323 * Called by jpeg_skip_scanlines(). This partially skips a decompress block by
324 * incrementing the rowgroup counter.
325 */
326
327LOCAL(void)
328increment_simple_rowgroup_ctr (j_decompress_ptr cinfo, JDIMENSION rows)
329{
330 JDIMENSION rows_left;
331 my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
332
333 /* Increment the counter to the next row group after the skipped rows. */
334 main_ptr->rowgroup_ctr += rows / cinfo->max_v_samp_factor;
335
336 /* Partially skipping a row group would involve modifying the internal state
337 * of the upsampler, so read the remaining rows into a dummy buffer instead.
338 */
339 rows_left = rows % cinfo->max_v_samp_factor;
340 cinfo->output_scanline += rows - rows_left;
341
342 read_and_discard_scanlines(cinfo, rows_left);
343}
344
345/*
346 * Skips some scanlines of data from the JPEG decompressor.
347 *
348 * The return value will be the number of lines actually skipped. If skipping
349 * num_lines would move beyond the end of the image, then the actual number of
350 * lines remaining in the image is returned. Otherwise, the return value will
351 * be equal to num_lines.
352 *
353 * Refer to libjpeg.txt for more information.
354 */
355
356GLOBAL(JDIMENSION)
357jpeg_skip_scanlines (j_decompress_ptr cinfo, JDIMENSION num_lines)
358{
359 my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
360 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
361 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
362 JDIMENSION i, x;
363 int y;
364 JDIMENSION lines_per_iMCU_row, lines_left_in_iMCU_row, lines_after_iMCU_row;
365 JDIMENSION lines_to_skip, lines_to_read;
366
367 if (cinfo->global_state != DSTATE_SCANNING)
368 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
369
370 /* Do not skip past the bottom of the image. */
371 if (cinfo->output_scanline + num_lines >= cinfo->output_height) {
372 cinfo->output_scanline = cinfo->output_height;
373 return cinfo->output_height - cinfo->output_scanline;
374 }
375
376 if (num_lines == 0)
377 return 0;
378
379 lines_per_iMCU_row = cinfo->_min_DCT_scaled_size * cinfo->max_v_samp_factor;
380 lines_left_in_iMCU_row =
381 (lines_per_iMCU_row - (cinfo->output_scanline % lines_per_iMCU_row)) %
382 lines_per_iMCU_row;
383 lines_after_iMCU_row = num_lines - lines_left_in_iMCU_row;
384
385 /* Skip the lines remaining in the current iMCU row. When upsampling
386 * requires context rows, we need the previous and next rows in order to read
387 * the current row. This adds some complexity.
388 */
389 if (cinfo->upsample->need_context_rows) {
390 /* If the skipped lines would not move us past the current iMCU row, we
391 * read the lines and ignore them. There might be a faster way of doing
392 * this, but we are facing increasing complexity for diminishing returns.
393 * The increasing complexity would be a by-product of meddling with the
394 * state machine used to skip context rows. Near the end of an iMCU row,
395 * the next iMCU row may have already been entropy-decoded. In this unique
396 * case, we will read the next iMCU row if we cannot skip past it as well.
397 */
398 if ((num_lines < lines_left_in_iMCU_row + 1) ||
399 (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full &&
400 lines_after_iMCU_row < lines_per_iMCU_row + 1)) {
401 read_and_discard_scanlines(cinfo, num_lines);
402 return num_lines;
403 }
404
405 /* If the next iMCU row has already been entropy-decoded, make sure that
406 * we do not skip too far.
407 */
408 if (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full) {
409 cinfo->output_scanline += lines_left_in_iMCU_row + lines_per_iMCU_row;
410 lines_after_iMCU_row -= lines_per_iMCU_row;
411 } else {
412 cinfo->output_scanline += lines_left_in_iMCU_row;
413 }
414
415 /* If we have just completed the first block, adjust the buffer pointers */
416 if (main_ptr->iMCU_row_ctr == 0 ||
417 (main_ptr->iMCU_row_ctr == 1 && lines_left_in_iMCU_row > 2))
418 set_wraparound_pointers(cinfo);
419 main_ptr->buffer_full = FALSE;
420 main_ptr->rowgroup_ctr = 0;
421 main_ptr->context_state = CTX_PREPARE_FOR_IMCU;
422 upsample->next_row_out = cinfo->max_v_samp_factor;
423 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
424 }
425
426 /* Skipping is much simpler when context rows are not required. */
427 else {
428 if (num_lines < lines_left_in_iMCU_row) {
429 increment_simple_rowgroup_ctr(cinfo, num_lines);
430 return num_lines;
431 } else {
432 cinfo->output_scanline += lines_left_in_iMCU_row;
433 main_ptr->buffer_full = FALSE;
434 main_ptr->rowgroup_ctr = 0;
435 upsample->next_row_out = cinfo->max_v_samp_factor;
436 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
437 }
438 }
439
440 /* Calculate how many full iMCU rows we can skip. */
441 if (cinfo->upsample->need_context_rows)
442 lines_to_skip = ((lines_after_iMCU_row - 1) / lines_per_iMCU_row) *
443 lines_per_iMCU_row;
444 else
445 lines_to_skip = (lines_after_iMCU_row / lines_per_iMCU_row) *
446 lines_per_iMCU_row;
447 /* Calculate the number of lines that remain to be skipped after skipping all
448 * of the full iMCU rows that we can. We will not read these lines unless we
449 * have to.
450 */
451 lines_to_read = lines_after_iMCU_row - lines_to_skip;
452
453 /* For images requiring multiple scans (progressive, non-interleaved, etc.),
454 * all of the entropy decoding occurs in jpeg_start_decompress(), assuming
455 * that the input data source is non-suspending. This makes skipping easy.
456 */
457 if (cinfo->inputctl->has_multiple_scans) {
458 if (cinfo->upsample->need_context_rows) {
459 cinfo->output_scanline += lines_to_skip;
460 cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row;
461 main_ptr->iMCU_row_ctr += lines_after_iMCU_row / lines_per_iMCU_row;
462 /* It is complex to properly move to the middle of a context block, so
463 * read the remaining lines instead of skipping them.
464 */
465 read_and_discard_scanlines(cinfo, lines_to_read);
466 } else {
467 cinfo->output_scanline += lines_to_skip;
468 cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row;
469 increment_simple_rowgroup_ctr(cinfo, lines_to_read);
470 }
471 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
472 return num_lines;
473 }
474
475 /* Skip the iMCU rows that we can safely skip. */
476 for (i = 0; i < lines_to_skip; i += lines_per_iMCU_row) {
477 for (y = 0; y < coef->MCU_rows_per_iMCU_row; y++) {
478 for (x = 0; x < cinfo->MCUs_per_row; x++) {
479 /* Calling decode_mcu() with a NULL pointer causes it to discard the
480 * decoded coefficients. This is ~5% faster for large subsets, but
481 * it's tough to tell a difference for smaller images.
482 */
483 (*cinfo->entropy->decode_mcu) (cinfo, NULL);
484 }
485 }
486 cinfo->input_iMCU_row++;
487 cinfo->output_iMCU_row++;
488 if (cinfo->input_iMCU_row < cinfo->total_iMCU_rows)
489 start_iMCU_row(cinfo);
490 else
491 (*cinfo->inputctl->finish_input_pass) (cinfo);
492 }
493 cinfo->output_scanline += lines_to_skip;
494
495 if (cinfo->upsample->need_context_rows) {
496 /* Context-based upsampling keeps track of iMCU rows. */
497 main_ptr->iMCU_row_ctr += lines_to_skip / lines_per_iMCU_row;
498
499 /* It is complex to properly move to the middle of a context block, so
500 * read the remaining lines instead of skipping them.
501 */
502 read_and_discard_scanlines(cinfo, lines_to_read);
503 } else {
504 increment_simple_rowgroup_ctr(cinfo, lines_to_read);
505 }
506
507 /* Since skipping lines involves skipping the upsampling step, the value of
508 * "rows_to_go" will become invalid unless we set it here. NOTE: This is a
509 * bit odd, since "rows_to_go" seems to be redundantly keeping track of
510 * output_scanline.
511 */
512 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
513
514 /* Always skip the requested number of lines. */
515 return num_lines;
516}
517
518/*
519 * Alternate entry point to read raw data.
520 * Processes exactly one iMCU row per call, unless suspended.
521 */
522
523GLOBAL(JDIMENSION)
524jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
525 JDIMENSION max_lines)
526{
527 JDIMENSION lines_per_iMCU_row;
528
529 if (cinfo->global_state != DSTATE_RAW_OK)
530 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
531 if (cinfo->output_scanline >= cinfo->output_height) {
532 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
533 return 0;
534 }
535
536 /* Call progress monitor hook if present */
537 if (cinfo->progress != NULL) {
538 cinfo->progress->pass_counter = (long) cinfo->output_scanline;
539 cinfo->progress->pass_limit = (long) cinfo->output_height;
540 (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
541 }
542
543 /* Verify that at least one iMCU row can be returned. */
544 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size;
545 if (max_lines < lines_per_iMCU_row)
546 ERREXIT(cinfo, JERR_BUFFER_SIZE);
547
548 /* Decompress directly into user's buffer. */
549 if (! (*cinfo->coef->decompress_data) (cinfo, data))
550 return 0; /* suspension forced, can do nothing more */
551
552 /* OK, we processed one iMCU row. */
553 cinfo->output_scanline += lines_per_iMCU_row;
554 return lines_per_iMCU_row;
555}
556
557
558/* Additional entry points for buffered-image mode. */
559
560#ifdef D_MULTISCAN_FILES_SUPPORTED
561
562/*
563 * Initialize for an output pass in buffered-image mode.
564 */
565
566GLOBAL(boolean)
567jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
568{
569 if (cinfo->global_state != DSTATE_BUFIMAGE &&
570 cinfo->global_state != DSTATE_PRESCAN)
571 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
572 /* Limit scan number to valid range */
573 if (scan_number <= 0)
574 scan_number = 1;
575 if (cinfo->inputctl->eoi_reached &&
576 scan_number > cinfo->input_scan_number)
577 scan_number = cinfo->input_scan_number;
578 cinfo->output_scan_number = scan_number;
579 /* Perform any dummy output passes, and set up for the real pass */
580 return output_pass_setup(cinfo);
581}
582
583
584/*
585 * Finish up after an output pass in buffered-image mode.
586 *
587 * Returns FALSE if suspended. The return value need be inspected only if
588 * a suspending data source is used.
589 */
590
591GLOBAL(boolean)
592jpeg_finish_output (j_decompress_ptr cinfo)
593{
594 if ((cinfo->global_state == DSTATE_SCANNING ||
595 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
596 /* Terminate this pass. */
597 /* We do not require the whole pass to have been completed. */
598 (*cinfo->master->finish_output_pass) (cinfo);
599 cinfo->global_state = DSTATE_BUFPOST;
600 } else if (cinfo->global_state != DSTATE_BUFPOST) {
601 /* BUFPOST = repeat call after a suspension, anything else is error */
602 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
603 }
604 /* Read markers looking for SOS or EOI */
605 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
606 ! cinfo->inputctl->eoi_reached) {
607 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
608 return FALSE; /* Suspend, come back later */
609 }
610 cinfo->global_state = DSTATE_BUFIMAGE;
611 return TRUE;
612}
613
614#endif /* D_MULTISCAN_FILES_SUPPORTED */
615