Bug 1852740: add tests for the `fetchpriority` attribute in Link headers. r=necko...
[gecko.git] / media / libjpeg / jdapistd.c
blob02cd0cb93a85ca4163e25b3893161182b9bfe548
1 /*
2 * jdapistd.c
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, 2015-2020, 2022, D. R. Commander.
8 * Copyright (C) 2015, Google, Inc.
9 * For conditions of distribution and use, see the accompanying README.ijg
10 * file.
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.
21 #include "jinclude.h"
22 #include "jdmainct.h"
23 #include "jdcoefct.h"
24 #include "jdmaster.h"
25 #include "jdmerge.h"
26 #include "jdsample.h"
27 #include "jmemsys.h"
29 /* Forward declarations */
30 LOCAL(boolean) output_pass_setup(j_decompress_ptr cinfo);
34 * Decompression initialization.
35 * jpeg_read_header must be completed before calling this.
37 * If a multipass operating mode was selected, this will do all but the
38 * last pass, and thus may take a great deal of time.
40 * Returns FALSE if suspended. The return value need be inspected only if
41 * a suspending data source is used.
44 GLOBAL(boolean)
45 jpeg_start_decompress(j_decompress_ptr cinfo)
47 if (cinfo->global_state == DSTATE_READY) {
48 /* First call: initialize master control, select active modules */
49 jinit_master_decompress(cinfo);
50 if (cinfo->buffered_image) {
51 /* No more work here; expecting jpeg_start_output next */
52 cinfo->global_state = DSTATE_BUFIMAGE;
53 return TRUE;
55 cinfo->global_state = DSTATE_PRELOAD;
57 if (cinfo->global_state == DSTATE_PRELOAD) {
58 /* If file has multiple scans, absorb them all into the coef buffer */
59 if (cinfo->inputctl->has_multiple_scans) {
60 #ifdef D_MULTISCAN_FILES_SUPPORTED
61 for (;;) {
62 int retcode;
63 /* Call progress monitor hook if present */
64 if (cinfo->progress != NULL)
65 (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
66 /* Absorb some more input */
67 retcode = (*cinfo->inputctl->consume_input) (cinfo);
68 if (retcode == JPEG_SUSPENDED)
69 return FALSE;
70 if (retcode == JPEG_REACHED_EOI)
71 break;
72 /* Advance progress counter if appropriate */
73 if (cinfo->progress != NULL &&
74 (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
75 if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
76 /* jdmaster underestimated number of scans; ratchet up one scan */
77 cinfo->progress->pass_limit += (long)cinfo->total_iMCU_rows;
81 #else
82 ERREXIT(cinfo, JERR_NOT_COMPILED);
83 #endif /* D_MULTISCAN_FILES_SUPPORTED */
85 cinfo->output_scan_number = cinfo->input_scan_number;
86 } else if (cinfo->global_state != DSTATE_PRESCAN)
87 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
88 /* Perform any dummy output passes, and set up for the final pass */
89 return output_pass_setup(cinfo);
94 * Set up for an output pass, and perform any dummy pass(es) needed.
95 * Common subroutine for jpeg_start_decompress and jpeg_start_output.
96 * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
97 * Exit: If done, returns TRUE and sets global_state for proper output mode.
98 * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
101 LOCAL(boolean)
102 output_pass_setup(j_decompress_ptr cinfo)
104 if (cinfo->global_state != DSTATE_PRESCAN) {
105 /* First call: do pass setup */
106 (*cinfo->master->prepare_for_output_pass) (cinfo);
107 cinfo->output_scanline = 0;
108 cinfo->global_state = DSTATE_PRESCAN;
110 /* Loop over any required dummy passes */
111 while (cinfo->master->is_dummy_pass) {
112 #ifdef QUANT_2PASS_SUPPORTED
113 /* Crank through the dummy pass */
114 while (cinfo->output_scanline < cinfo->output_height) {
115 JDIMENSION last_scanline;
116 /* Call progress monitor hook if present */
117 if (cinfo->progress != NULL) {
118 cinfo->progress->pass_counter = (long)cinfo->output_scanline;
119 cinfo->progress->pass_limit = (long)cinfo->output_height;
120 (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
122 /* Process some data */
123 last_scanline = cinfo->output_scanline;
124 (*cinfo->main->process_data) (cinfo, (JSAMPARRAY)NULL,
125 &cinfo->output_scanline, (JDIMENSION)0);
126 if (cinfo->output_scanline == last_scanline)
127 return FALSE; /* No progress made, must suspend */
129 /* Finish up dummy pass, and set up for another one */
130 (*cinfo->master->finish_output_pass) (cinfo);
131 (*cinfo->master->prepare_for_output_pass) (cinfo);
132 cinfo->output_scanline = 0;
133 #else
134 ERREXIT(cinfo, JERR_NOT_COMPILED);
135 #endif /* QUANT_2PASS_SUPPORTED */
137 /* Ready for application to drive output pass through
138 * jpeg_read_scanlines or jpeg_read_raw_data.
140 cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
141 return TRUE;
146 * Enable partial scanline decompression
148 * Must be called after jpeg_start_decompress() and before any calls to
149 * jpeg_read_scanlines() or jpeg_skip_scanlines().
151 * Refer to libjpeg.txt for more information.
154 GLOBAL(void)
155 jpeg_crop_scanline(j_decompress_ptr cinfo, JDIMENSION *xoffset,
156 JDIMENSION *width)
158 int ci, align, orig_downsampled_width;
159 JDIMENSION input_xoffset;
160 boolean reinit_upsampler = FALSE;
161 jpeg_component_info *compptr;
162 #ifdef UPSAMPLE_MERGING_SUPPORTED
163 my_master_ptr master = (my_master_ptr)cinfo->master;
164 #endif
166 if ((cinfo->global_state != DSTATE_SCANNING &&
167 cinfo->global_state != DSTATE_BUFIMAGE) || cinfo->output_scanline != 0)
168 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
170 if (!xoffset || !width)
171 ERREXIT(cinfo, JERR_BAD_CROP_SPEC);
173 /* xoffset and width must fall within the output image dimensions. */
174 if (*width == 0 || *xoffset + *width > cinfo->output_width)
175 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
177 /* No need to do anything if the caller wants the entire width. */
178 if (*width == cinfo->output_width)
179 return;
181 /* Ensuring the proper alignment of xoffset is tricky. At minimum, it
182 * must align with an MCU boundary, because:
184 * (1) The IDCT is performed in blocks, and it is not feasible to modify
185 * the algorithm so that it can transform partial blocks.
186 * (2) Because of the SIMD extensions, any input buffer passed to the
187 * upsampling and color conversion routines must be aligned to the
188 * SIMD word size (for instance, 128-bit in the case of SSE2.) The
189 * easiest way to accomplish this without copying data is to ensure
190 * that upsampling and color conversion begin at the start of the
191 * first MCU column that will be inverse transformed.
193 * In practice, we actually impose a stricter alignment requirement. We
194 * require that xoffset be a multiple of the maximum MCU column width of all
195 * of the components (the "iMCU column width.") This is to simplify the
196 * single-pass decompression case, allowing us to use the same MCU column
197 * width for all of the components.
199 if (cinfo->comps_in_scan == 1 && cinfo->num_components == 1)
200 align = cinfo->_min_DCT_scaled_size;
201 else
202 align = cinfo->_min_DCT_scaled_size * cinfo->max_h_samp_factor;
204 /* Adjust xoffset to the nearest iMCU boundary <= the requested value */
205 input_xoffset = *xoffset;
206 *xoffset = (input_xoffset / align) * align;
208 /* Adjust the width so that the right edge of the output image is as
209 * requested (only the left edge is altered.) It is important that calling
210 * programs check this value after this function returns, so that they can
211 * allocate an output buffer with the appropriate size.
213 *width = *width + input_xoffset - *xoffset;
214 cinfo->output_width = *width;
215 #ifdef UPSAMPLE_MERGING_SUPPORTED
216 if (master->using_merged_upsample && cinfo->max_v_samp_factor == 2) {
217 my_merged_upsample_ptr upsample = (my_merged_upsample_ptr)cinfo->upsample;
218 upsample->out_row_width =
219 cinfo->output_width * cinfo->out_color_components;
221 #endif
223 /* Set the first and last iMCU columns that we must decompress. These values
224 * will be used in single-scan decompressions.
226 cinfo->master->first_iMCU_col = (JDIMENSION)(long)(*xoffset) / (long)align;
227 cinfo->master->last_iMCU_col =
228 (JDIMENSION)jdiv_round_up((long)(*xoffset + cinfo->output_width),
229 (long)align) - 1;
231 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
232 ci++, compptr++) {
233 int hsf = (cinfo->comps_in_scan == 1 && cinfo->num_components == 1) ?
234 1 : compptr->h_samp_factor;
236 /* Set downsampled_width to the new output width. */
237 orig_downsampled_width = compptr->downsampled_width;
238 compptr->downsampled_width =
239 (JDIMENSION)jdiv_round_up((long)(cinfo->output_width *
240 compptr->h_samp_factor),
241 (long)cinfo->max_h_samp_factor);
242 if (compptr->downsampled_width < 2 && orig_downsampled_width >= 2)
243 reinit_upsampler = TRUE;
245 /* Set the first and last iMCU columns that we must decompress. These
246 * values will be used in multi-scan decompressions.
248 cinfo->master->first_MCU_col[ci] =
249 (JDIMENSION)(long)(*xoffset * hsf) / (long)align;
250 cinfo->master->last_MCU_col[ci] =
251 (JDIMENSION)jdiv_round_up((long)((*xoffset + cinfo->output_width) * hsf),
252 (long)align) - 1;
255 if (reinit_upsampler) {
256 cinfo->master->jinit_upsampler_no_alloc = TRUE;
257 jinit_upsampler(cinfo);
258 cinfo->master->jinit_upsampler_no_alloc = FALSE;
264 * Read some scanlines of data from the JPEG decompressor.
266 * The return value will be the number of lines actually read.
267 * This may be less than the number requested in several cases,
268 * including bottom of image, data source suspension, and operating
269 * modes that emit multiple scanlines at a time.
271 * Note: we warn about excess calls to jpeg_read_scanlines() since
272 * this likely signals an application programmer error. However,
273 * an oversize buffer (max_lines > scanlines remaining) is not an error.
276 GLOBAL(JDIMENSION)
277 jpeg_read_scanlines(j_decompress_ptr cinfo, JSAMPARRAY scanlines,
278 JDIMENSION max_lines)
280 JDIMENSION row_ctr;
282 if (cinfo->global_state != DSTATE_SCANNING)
283 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
284 if (cinfo->output_scanline >= cinfo->output_height) {
285 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
286 return 0;
289 /* Call progress monitor hook if present */
290 if (cinfo->progress != NULL) {
291 cinfo->progress->pass_counter = (long)cinfo->output_scanline;
292 cinfo->progress->pass_limit = (long)cinfo->output_height;
293 (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
296 /* Process some data */
297 row_ctr = 0;
298 (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
299 cinfo->output_scanline += row_ctr;
300 return row_ctr;
304 /* Dummy color convert function used by jpeg_skip_scanlines() */
305 LOCAL(void)
306 noop_convert(j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
307 JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
312 /* Dummy quantize function used by jpeg_skip_scanlines() */
313 LOCAL(void)
314 noop_quantize(j_decompress_ptr cinfo, JSAMPARRAY input_buf,
315 JSAMPARRAY output_buf, int num_rows)
321 * In some cases, it is best to call jpeg_read_scanlines() and discard the
322 * output, rather than skipping the scanlines, because this allows us to
323 * maintain the internal state of the context-based upsampler. In these cases,
324 * we set up and tear down a dummy color converter in order to avoid valgrind
325 * errors and to achieve the best possible performance.
328 LOCAL(void)
329 read_and_discard_scanlines(j_decompress_ptr cinfo, JDIMENSION num_lines)
331 JDIMENSION n;
332 #ifdef UPSAMPLE_MERGING_SUPPORTED
333 my_master_ptr master = (my_master_ptr)cinfo->master;
334 #endif
335 JSAMPLE dummy_sample[1] = { 0 };
336 JSAMPROW dummy_row = dummy_sample;
337 JSAMPARRAY scanlines = NULL;
338 void (*color_convert) (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
339 JDIMENSION input_row, JSAMPARRAY output_buf,
340 int num_rows) = NULL;
341 void (*color_quantize) (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
342 JSAMPARRAY output_buf, int num_rows) = NULL;
344 if (cinfo->cconvert && cinfo->cconvert->color_convert) {
345 color_convert = cinfo->cconvert->color_convert;
346 cinfo->cconvert->color_convert = noop_convert;
347 /* This just prevents UBSan from complaining about adding 0 to a NULL
348 * pointer. The pointer isn't actually used.
350 scanlines = &dummy_row;
353 if (cinfo->cquantize && cinfo->cquantize->color_quantize) {
354 color_quantize = cinfo->cquantize->color_quantize;
355 cinfo->cquantize->color_quantize = noop_quantize;
358 #ifdef UPSAMPLE_MERGING_SUPPORTED
359 if (master->using_merged_upsample && cinfo->max_v_samp_factor == 2) {
360 my_merged_upsample_ptr upsample = (my_merged_upsample_ptr)cinfo->upsample;
361 scanlines = &upsample->spare_row;
363 #endif
365 for (n = 0; n < num_lines; n++)
366 jpeg_read_scanlines(cinfo, scanlines, 1);
368 if (color_convert)
369 cinfo->cconvert->color_convert = color_convert;
371 if (color_quantize)
372 cinfo->cquantize->color_quantize = color_quantize;
377 * Called by jpeg_skip_scanlines(). This partially skips a decompress block by
378 * incrementing the rowgroup counter.
381 LOCAL(void)
382 increment_simple_rowgroup_ctr(j_decompress_ptr cinfo, JDIMENSION rows)
384 JDIMENSION rows_left;
385 my_main_ptr main_ptr = (my_main_ptr)cinfo->main;
386 my_master_ptr master = (my_master_ptr)cinfo->master;
388 if (master->using_merged_upsample && cinfo->max_v_samp_factor == 2) {
389 read_and_discard_scanlines(cinfo, rows);
390 return;
393 /* Increment the counter to the next row group after the skipped rows. */
394 main_ptr->rowgroup_ctr += rows / cinfo->max_v_samp_factor;
396 /* Partially skipping a row group would involve modifying the internal state
397 * of the upsampler, so read the remaining rows into a dummy buffer instead.
399 rows_left = rows % cinfo->max_v_samp_factor;
400 cinfo->output_scanline += rows - rows_left;
402 read_and_discard_scanlines(cinfo, rows_left);
406 * Skips some scanlines of data from the JPEG decompressor.
408 * The return value will be the number of lines actually skipped. If skipping
409 * num_lines would move beyond the end of the image, then the actual number of
410 * lines remaining in the image is returned. Otherwise, the return value will
411 * be equal to num_lines.
413 * Refer to libjpeg.txt for more information.
416 GLOBAL(JDIMENSION)
417 jpeg_skip_scanlines(j_decompress_ptr cinfo, JDIMENSION num_lines)
419 my_main_ptr main_ptr = (my_main_ptr)cinfo->main;
420 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
421 my_master_ptr master = (my_master_ptr)cinfo->master;
422 my_upsample_ptr upsample = (my_upsample_ptr)cinfo->upsample;
423 JDIMENSION i, x;
424 int y;
425 JDIMENSION lines_per_iMCU_row, lines_left_in_iMCU_row, lines_after_iMCU_row;
426 JDIMENSION lines_to_skip, lines_to_read;
428 /* Two-pass color quantization is not supported. */
429 if (cinfo->quantize_colors && cinfo->two_pass_quantize)
430 ERREXIT(cinfo, JERR_NOTIMPL);
432 if (cinfo->global_state != DSTATE_SCANNING)
433 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
435 /* Do not skip past the bottom of the image. */
436 if (cinfo->output_scanline + num_lines >= cinfo->output_height) {
437 num_lines = cinfo->output_height - cinfo->output_scanline;
438 cinfo->output_scanline = cinfo->output_height;
439 (*cinfo->inputctl->finish_input_pass) (cinfo);
440 cinfo->inputctl->eoi_reached = TRUE;
441 return num_lines;
444 if (num_lines == 0)
445 return 0;
447 lines_per_iMCU_row = cinfo->_min_DCT_scaled_size * cinfo->max_v_samp_factor;
448 lines_left_in_iMCU_row =
449 (lines_per_iMCU_row - (cinfo->output_scanline % lines_per_iMCU_row)) %
450 lines_per_iMCU_row;
451 lines_after_iMCU_row = num_lines - lines_left_in_iMCU_row;
453 /* Skip the lines remaining in the current iMCU row. When upsampling
454 * requires context rows, we need the previous and next rows in order to read
455 * the current row. This adds some complexity.
457 if (cinfo->upsample->need_context_rows) {
458 /* If the skipped lines would not move us past the current iMCU row, we
459 * read the lines and ignore them. There might be a faster way of doing
460 * this, but we are facing increasing complexity for diminishing returns.
461 * The increasing complexity would be a by-product of meddling with the
462 * state machine used to skip context rows. Near the end of an iMCU row,
463 * the next iMCU row may have already been entropy-decoded. In this unique
464 * case, we will read the next iMCU row if we cannot skip past it as well.
466 if ((num_lines < lines_left_in_iMCU_row + 1) ||
467 (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full &&
468 lines_after_iMCU_row < lines_per_iMCU_row + 1)) {
469 read_and_discard_scanlines(cinfo, num_lines);
470 return num_lines;
473 /* If the next iMCU row has already been entropy-decoded, make sure that
474 * we do not skip too far.
476 if (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full) {
477 cinfo->output_scanline += lines_left_in_iMCU_row + lines_per_iMCU_row;
478 lines_after_iMCU_row -= lines_per_iMCU_row;
479 } else {
480 cinfo->output_scanline += lines_left_in_iMCU_row;
483 /* If we have just completed the first block, adjust the buffer pointers */
484 if (main_ptr->iMCU_row_ctr == 0 ||
485 (main_ptr->iMCU_row_ctr == 1 && lines_left_in_iMCU_row > 2))
486 set_wraparound_pointers(cinfo);
487 main_ptr->buffer_full = FALSE;
488 main_ptr->rowgroup_ctr = 0;
489 main_ptr->context_state = CTX_PREPARE_FOR_IMCU;
490 if (!master->using_merged_upsample) {
491 upsample->next_row_out = cinfo->max_v_samp_factor;
492 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
496 /* Skipping is much simpler when context rows are not required. */
497 else {
498 if (num_lines < lines_left_in_iMCU_row) {
499 increment_simple_rowgroup_ctr(cinfo, num_lines);
500 return num_lines;
501 } else {
502 cinfo->output_scanline += lines_left_in_iMCU_row;
503 main_ptr->buffer_full = FALSE;
504 main_ptr->rowgroup_ctr = 0;
505 if (!master->using_merged_upsample) {
506 upsample->next_row_out = cinfo->max_v_samp_factor;
507 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
512 /* Calculate how many full iMCU rows we can skip. */
513 if (cinfo->upsample->need_context_rows)
514 lines_to_skip = ((lines_after_iMCU_row - 1) / lines_per_iMCU_row) *
515 lines_per_iMCU_row;
516 else
517 lines_to_skip = (lines_after_iMCU_row / lines_per_iMCU_row) *
518 lines_per_iMCU_row;
519 /* Calculate the number of lines that remain to be skipped after skipping all
520 * of the full iMCU rows that we can. We will not read these lines unless we
521 * have to.
523 lines_to_read = lines_after_iMCU_row - lines_to_skip;
525 /* For images requiring multiple scans (progressive, non-interleaved, etc.),
526 * all of the entropy decoding occurs in jpeg_start_decompress(), assuming
527 * that the input data source is non-suspending. This makes skipping easy.
529 if (cinfo->inputctl->has_multiple_scans || cinfo->buffered_image) {
530 if (cinfo->upsample->need_context_rows) {
531 cinfo->output_scanline += lines_to_skip;
532 cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row;
533 main_ptr->iMCU_row_ctr += lines_to_skip / lines_per_iMCU_row;
534 /* It is complex to properly move to the middle of a context block, so
535 * read the remaining lines instead of skipping them.
537 read_and_discard_scanlines(cinfo, lines_to_read);
538 } else {
539 cinfo->output_scanline += lines_to_skip;
540 cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row;
541 increment_simple_rowgroup_ctr(cinfo, lines_to_read);
543 if (!master->using_merged_upsample)
544 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
545 return num_lines;
548 /* Skip the iMCU rows that we can safely skip. */
549 for (i = 0; i < lines_to_skip; i += lines_per_iMCU_row) {
550 for (y = 0; y < coef->MCU_rows_per_iMCU_row; y++) {
551 for (x = 0; x < cinfo->MCUs_per_row; x++) {
552 /* Calling decode_mcu() with a NULL pointer causes it to discard the
553 * decoded coefficients. This is ~5% faster for large subsets, but
554 * it's tough to tell a difference for smaller images.
556 if (!cinfo->entropy->insufficient_data)
557 cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row;
558 (*cinfo->entropy->decode_mcu) (cinfo, NULL);
561 cinfo->input_iMCU_row++;
562 cinfo->output_iMCU_row++;
563 if (cinfo->input_iMCU_row < cinfo->total_iMCU_rows)
564 start_iMCU_row(cinfo);
565 else
566 (*cinfo->inputctl->finish_input_pass) (cinfo);
568 cinfo->output_scanline += lines_to_skip;
570 if (cinfo->upsample->need_context_rows) {
571 /* Context-based upsampling keeps track of iMCU rows. */
572 main_ptr->iMCU_row_ctr += lines_to_skip / lines_per_iMCU_row;
574 /* It is complex to properly move to the middle of a context block, so
575 * read the remaining lines instead of skipping them.
577 read_and_discard_scanlines(cinfo, lines_to_read);
578 } else {
579 increment_simple_rowgroup_ctr(cinfo, lines_to_read);
582 /* Since skipping lines involves skipping the upsampling step, the value of
583 * "rows_to_go" will become invalid unless we set it here. NOTE: This is a
584 * bit odd, since "rows_to_go" seems to be redundantly keeping track of
585 * output_scanline.
587 if (!master->using_merged_upsample)
588 upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
590 /* Always skip the requested number of lines. */
591 return num_lines;
595 * Alternate entry point to read raw data.
596 * Processes exactly one iMCU row per call, unless suspended.
599 GLOBAL(JDIMENSION)
600 jpeg_read_raw_data(j_decompress_ptr cinfo, JSAMPIMAGE data,
601 JDIMENSION max_lines)
603 JDIMENSION lines_per_iMCU_row;
605 if (cinfo->global_state != DSTATE_RAW_OK)
606 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
607 if (cinfo->output_scanline >= cinfo->output_height) {
608 WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
609 return 0;
612 /* Call progress monitor hook if present */
613 if (cinfo->progress != NULL) {
614 cinfo->progress->pass_counter = (long)cinfo->output_scanline;
615 cinfo->progress->pass_limit = (long)cinfo->output_height;
616 (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo);
619 /* Verify that at least one iMCU row can be returned. */
620 lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size;
621 if (max_lines < lines_per_iMCU_row)
622 ERREXIT(cinfo, JERR_BUFFER_SIZE);
624 /* Decompress directly into user's buffer. */
625 if (!(*cinfo->coef->decompress_data) (cinfo, data))
626 return 0; /* suspension forced, can do nothing more */
628 /* OK, we processed one iMCU row. */
629 cinfo->output_scanline += lines_per_iMCU_row;
630 return lines_per_iMCU_row;
634 /* Additional entry points for buffered-image mode. */
636 #ifdef D_MULTISCAN_FILES_SUPPORTED
639 * Initialize for an output pass in buffered-image mode.
642 GLOBAL(boolean)
643 jpeg_start_output(j_decompress_ptr cinfo, int scan_number)
645 if (cinfo->global_state != DSTATE_BUFIMAGE &&
646 cinfo->global_state != DSTATE_PRESCAN)
647 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
648 /* Limit scan number to valid range */
649 if (scan_number <= 0)
650 scan_number = 1;
651 if (cinfo->inputctl->eoi_reached && scan_number > cinfo->input_scan_number)
652 scan_number = cinfo->input_scan_number;
653 cinfo->output_scan_number = scan_number;
654 /* Perform any dummy output passes, and set up for the real pass */
655 return output_pass_setup(cinfo);
660 * Finish up after an output pass in buffered-image mode.
662 * Returns FALSE if suspended. The return value need be inspected only if
663 * a suspending data source is used.
666 GLOBAL(boolean)
667 jpeg_finish_output(j_decompress_ptr cinfo)
669 if ((cinfo->global_state == DSTATE_SCANNING ||
670 cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
671 /* Terminate this pass. */
672 /* We do not require the whole pass to have been completed. */
673 (*cinfo->master->finish_output_pass) (cinfo);
674 cinfo->global_state = DSTATE_BUFPOST;
675 } else if (cinfo->global_state != DSTATE_BUFPOST) {
676 /* BUFPOST = repeat call after a suspension, anything else is error */
677 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
679 /* Read markers looking for SOS or EOI */
680 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
681 !cinfo->inputctl->eoi_reached) {
682 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
683 return FALSE; /* Suspend, come back later */
685 cinfo->global_state = DSTATE_BUFIMAGE;
686 return TRUE;
689 #endif /* D_MULTISCAN_FILES_SUPPORTED */