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