Line data Source code
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 */
28 : LOCAL(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 :
42 : GLOBAL(boolean)
43 0 : jpeg_start_decompress (j_decompress_ptr cinfo)
44 : {
45 0 : if (cinfo->global_state == DSTATE_READY) {
46 : /* First call: initialize master control, select active modules */
47 0 : jinit_master_decompress(cinfo);
48 0 : if (cinfo->buffered_image) {
49 : /* No more work here; expecting jpeg_start_output next */
50 0 : cinfo->global_state = DSTATE_BUFIMAGE;
51 0 : return TRUE;
52 : }
53 0 : cinfo->global_state = DSTATE_PRELOAD;
54 : }
55 0 : if (cinfo->global_state == DSTATE_PRELOAD) {
56 : /* If file has multiple scans, absorb them all into the coef buffer */
57 0 : if (cinfo->inputctl->has_multiple_scans) {
58 : #ifdef D_MULTISCAN_FILES_SUPPORTED
59 0 : for (;;) {
60 : int retcode;
61 : /* Call progress monitor hook if present */
62 0 : if (cinfo->progress != NULL)
63 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
64 : /* Absorb some more input */
65 0 : retcode = (*cinfo->inputctl->consume_input) (cinfo);
66 0 : if (retcode == JPEG_SUSPENDED)
67 0 : return FALSE;
68 0 : if (retcode == JPEG_REACHED_EOI)
69 0 : break;
70 : /* Advance progress counter if appropriate */
71 0 : if (cinfo->progress != NULL &&
72 0 : (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
73 0 : if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
74 : /* jdmaster underestimated number of scans; ratchet up one scan */
75 0 : 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 0 : cinfo->output_scan_number = cinfo->input_scan_number;
84 0 : } else if (cinfo->global_state != DSTATE_PRESCAN)
85 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
86 : /* Perform any dummy output passes, and set up for the final pass */
87 0 : 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 :
99 : LOCAL(boolean)
100 0 : output_pass_setup (j_decompress_ptr cinfo)
101 : {
102 0 : if (cinfo->global_state != DSTATE_PRESCAN) {
103 : /* First call: do pass setup */
104 0 : (*cinfo->master->prepare_for_output_pass) (cinfo);
105 0 : cinfo->output_scanline = 0;
106 0 : cinfo->global_state = DSTATE_PRESCAN;
107 : }
108 : /* Loop over any required dummy passes */
109 0 : while (cinfo->master->is_dummy_pass) {
110 : #ifdef QUANT_2PASS_SUPPORTED
111 : /* Crank through the dummy pass */
112 0 : while (cinfo->output_scanline < cinfo->output_height) {
113 : JDIMENSION last_scanline;
114 : /* Call progress monitor hook if present */
115 0 : if (cinfo->progress != NULL) {
116 0 : cinfo->progress->pass_counter = (long) cinfo->output_scanline;
117 0 : cinfo->progress->pass_limit = (long) cinfo->output_height;
118 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
119 : }
120 : /* Process some data */
121 0 : last_scanline = cinfo->output_scanline;
122 0 : (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
123 : &cinfo->output_scanline, (JDIMENSION) 0);
124 0 : if (cinfo->output_scanline == last_scanline)
125 0 : return FALSE; /* No progress made, must suspend */
126 : }
127 : /* Finish up dummy pass, and set up for another one */
128 0 : (*cinfo->master->finish_output_pass) (cinfo);
129 0 : (*cinfo->master->prepare_for_output_pass) (cinfo);
130 0 : 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 0 : cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
139 0 : 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 :
152 : GLOBAL(void)
153 0 : jpeg_crop_scanline (j_decompress_ptr cinfo, JDIMENSION *xoffset,
154 : JDIMENSION *width)
155 : {
156 : int ci, align, orig_downsampled_width;
157 : JDIMENSION input_xoffset;
158 0 : boolean reinit_upsampler = FALSE;
159 : jpeg_component_info *compptr;
160 :
161 0 : if (cinfo->global_state != DSTATE_SCANNING || cinfo->output_scanline != 0)
162 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
163 :
164 0 : if (!xoffset || !width)
165 0 : ERREXIT(cinfo, JERR_BAD_CROP_SPEC);
166 :
167 : /* xoffset and width must fall within the output image dimensions. */
168 0 : if (*width == 0 || *xoffset + *width > cinfo->output_width)
169 0 : ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
170 :
171 : /* No need to do anything if the caller wants the entire width. */
172 0 : if (*width == cinfo->output_width)
173 0 : 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 0 : align = cinfo->_min_DCT_scaled_size * cinfo->max_h_samp_factor;
194 :
195 : /* Adjust xoffset to the nearest iMCU boundary <= the requested value */
196 0 : input_xoffset = *xoffset;
197 0 : *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 0 : *width = *width + input_xoffset - *xoffset;
205 0 : 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 0 : cinfo->master->first_iMCU_col =
211 0 : (JDIMENSION) (long) (*xoffset) / (long) align;
212 0 : cinfo->master->last_iMCU_col =
213 0 : (JDIMENSION) jdiv_round_up((long) (*xoffset + cinfo->output_width),
214 0 : (long) align) - 1;
215 :
216 0 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
217 0 : ci++, compptr++) {
218 : /* Set downsampled_width to the new output width. */
219 0 : orig_downsampled_width = compptr->downsampled_width;
220 0 : compptr->downsampled_width =
221 0 : (JDIMENSION) jdiv_round_up((long) (cinfo->output_width *
222 0 : compptr->h_samp_factor),
223 0 : (long) cinfo->max_h_samp_factor);
224 0 : if (compptr->downsampled_width < 2 && orig_downsampled_width >= 2)
225 0 : 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 0 : cinfo->master->first_MCU_col[ci] =
231 0 : (JDIMENSION) (long) (*xoffset * compptr->h_samp_factor) /
232 0 : (long) align;
233 0 : cinfo->master->last_MCU_col[ci] =
234 0 : (JDIMENSION) jdiv_round_up((long) ((*xoffset + cinfo->output_width) *
235 0 : compptr->h_samp_factor),
236 0 : (long) align) - 1;
237 : }
238 :
239 0 : if (reinit_upsampler) {
240 0 : cinfo->master->jinit_upsampler_no_alloc = TRUE;
241 0 : jinit_upsampler(cinfo);
242 0 : 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 :
260 : GLOBAL(JDIMENSION)
261 0 : jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
262 : JDIMENSION max_lines)
263 : {
264 : JDIMENSION row_ctr;
265 :
266 0 : if (cinfo->global_state != DSTATE_SCANNING)
267 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
268 0 : if (cinfo->output_scanline >= cinfo->output_height) {
269 0 : WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
270 0 : return 0;
271 : }
272 :
273 : /* Call progress monitor hook if present */
274 0 : if (cinfo->progress != NULL) {
275 0 : cinfo->progress->pass_counter = (long) cinfo->output_scanline;
276 0 : cinfo->progress->pass_limit = (long) cinfo->output_height;
277 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
278 : }
279 :
280 : /* Process some data */
281 0 : row_ctr = 0;
282 0 : (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
283 0 : cinfo->output_scanline += row_ctr;
284 0 : return row_ctr;
285 : }
286 :
287 :
288 : /* Dummy color convert function used by jpeg_skip_scanlines() */
289 : LOCAL(void)
290 0 : noop_convert (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
291 : JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows)
292 : {
293 0 : }
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 :
304 : LOCAL(void)
305 0 : read_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 0 : color_convert = cinfo->cconvert->color_convert;
313 0 : cinfo->cconvert->color_convert = noop_convert;
314 :
315 0 : for (n = 0; n < num_lines; n++)
316 0 : jpeg_read_scanlines(cinfo, NULL, 1);
317 :
318 0 : cinfo->cconvert->color_convert = color_convert;
319 0 : }
320 :
321 :
322 : /*
323 : * Called by jpeg_skip_scanlines(). This partially skips a decompress block by
324 : * incrementing the rowgroup counter.
325 : */
326 :
327 : LOCAL(void)
328 0 : increment_simple_rowgroup_ctr (j_decompress_ptr cinfo, JDIMENSION rows)
329 : {
330 : JDIMENSION rows_left;
331 0 : 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 0 : 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 0 : rows_left = rows % cinfo->max_v_samp_factor;
340 0 : cinfo->output_scanline += rows - rows_left;
341 :
342 0 : read_and_discard_scanlines(cinfo, rows_left);
343 0 : }
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 :
356 : GLOBAL(JDIMENSION)
357 0 : jpeg_skip_scanlines (j_decompress_ptr cinfo, JDIMENSION num_lines)
358 : {
359 0 : my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
360 0 : my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
361 0 : 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 0 : if (cinfo->global_state != DSTATE_SCANNING)
368 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
369 :
370 : /* Do not skip past the bottom of the image. */
371 0 : if (cinfo->output_scanline + num_lines >= cinfo->output_height) {
372 0 : cinfo->output_scanline = cinfo->output_height;
373 0 : return cinfo->output_height - cinfo->output_scanline;
374 : }
375 :
376 0 : if (num_lines == 0)
377 0 : return 0;
378 :
379 0 : lines_per_iMCU_row = cinfo->_min_DCT_scaled_size * cinfo->max_v_samp_factor;
380 0 : lines_left_in_iMCU_row =
381 0 : (lines_per_iMCU_row - (cinfo->output_scanline % lines_per_iMCU_row)) %
382 : lines_per_iMCU_row;
383 0 : 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 0 : 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 0 : if ((num_lines < lines_left_in_iMCU_row + 1) ||
399 0 : (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full &&
400 0 : lines_after_iMCU_row < lines_per_iMCU_row + 1)) {
401 0 : read_and_discard_scanlines(cinfo, num_lines);
402 0 : 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 0 : if (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full) {
409 0 : cinfo->output_scanline += lines_left_in_iMCU_row + lines_per_iMCU_row;
410 0 : lines_after_iMCU_row -= lines_per_iMCU_row;
411 : } else {
412 0 : cinfo->output_scanline += lines_left_in_iMCU_row;
413 : }
414 :
415 : /* If we have just completed the first block, adjust the buffer pointers */
416 0 : if (main_ptr->iMCU_row_ctr == 0 ||
417 0 : (main_ptr->iMCU_row_ctr == 1 && lines_left_in_iMCU_row > 2))
418 0 : set_wraparound_pointers(cinfo);
419 0 : main_ptr->buffer_full = FALSE;
420 0 : main_ptr->rowgroup_ctr = 0;
421 0 : main_ptr->context_state = CTX_PREPARE_FOR_IMCU;
422 0 : upsample->next_row_out = cinfo->max_v_samp_factor;
423 0 : 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 0 : if (num_lines < lines_left_in_iMCU_row) {
429 0 : increment_simple_rowgroup_ctr(cinfo, num_lines);
430 0 : return num_lines;
431 : } else {
432 0 : cinfo->output_scanline += lines_left_in_iMCU_row;
433 0 : main_ptr->buffer_full = FALSE;
434 0 : main_ptr->rowgroup_ctr = 0;
435 0 : upsample->next_row_out = cinfo->max_v_samp_factor;
436 0 : upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
437 : }
438 : }
439 :
440 : /* Calculate how many full iMCU rows we can skip. */
441 0 : if (cinfo->upsample->need_context_rows)
442 0 : lines_to_skip = ((lines_after_iMCU_row - 1) / lines_per_iMCU_row) *
443 : lines_per_iMCU_row;
444 : else
445 0 : 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 0 : 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 0 : if (cinfo->inputctl->has_multiple_scans) {
458 0 : if (cinfo->upsample->need_context_rows) {
459 0 : cinfo->output_scanline += lines_to_skip;
460 0 : cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row;
461 0 : 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 0 : read_and_discard_scanlines(cinfo, lines_to_read);
466 : } else {
467 0 : cinfo->output_scanline += lines_to_skip;
468 0 : cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row;
469 0 : increment_simple_rowgroup_ctr(cinfo, lines_to_read);
470 : }
471 0 : upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
472 0 : return num_lines;
473 : }
474 :
475 : /* Skip the iMCU rows that we can safely skip. */
476 0 : for (i = 0; i < lines_to_skip; i += lines_per_iMCU_row) {
477 0 : for (y = 0; y < coef->MCU_rows_per_iMCU_row; y++) {
478 0 : 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 0 : (*cinfo->entropy->decode_mcu) (cinfo, NULL);
484 : }
485 : }
486 0 : cinfo->input_iMCU_row++;
487 0 : cinfo->output_iMCU_row++;
488 0 : if (cinfo->input_iMCU_row < cinfo->total_iMCU_rows)
489 0 : start_iMCU_row(cinfo);
490 : else
491 0 : (*cinfo->inputctl->finish_input_pass) (cinfo);
492 : }
493 0 : cinfo->output_scanline += lines_to_skip;
494 :
495 0 : if (cinfo->upsample->need_context_rows) {
496 : /* Context-based upsampling keeps track of iMCU rows. */
497 0 : 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 0 : read_and_discard_scanlines(cinfo, lines_to_read);
503 : } else {
504 0 : 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 0 : upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline;
513 :
514 : /* Always skip the requested number of lines. */
515 0 : 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 :
523 : GLOBAL(JDIMENSION)
524 0 : jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
525 : JDIMENSION max_lines)
526 : {
527 : JDIMENSION lines_per_iMCU_row;
528 :
529 0 : if (cinfo->global_state != DSTATE_RAW_OK)
530 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
531 0 : if (cinfo->output_scanline >= cinfo->output_height) {
532 0 : WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
533 0 : return 0;
534 : }
535 :
536 : /* Call progress monitor hook if present */
537 0 : if (cinfo->progress != NULL) {
538 0 : cinfo->progress->pass_counter = (long) cinfo->output_scanline;
539 0 : cinfo->progress->pass_limit = (long) cinfo->output_height;
540 0 : (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
541 : }
542 :
543 : /* Verify that at least one iMCU row can be returned. */
544 0 : lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size;
545 0 : if (max_lines < lines_per_iMCU_row)
546 0 : ERREXIT(cinfo, JERR_BUFFER_SIZE);
547 :
548 : /* Decompress directly into user's buffer. */
549 0 : if (! (*cinfo->coef->decompress_data) (cinfo, data))
550 0 : return 0; /* suspension forced, can do nothing more */
551 :
552 : /* OK, we processed one iMCU row. */
553 0 : cinfo->output_scanline += lines_per_iMCU_row;
554 0 : 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 :
566 : GLOBAL(boolean)
567 0 : jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
568 : {
569 0 : if (cinfo->global_state != DSTATE_BUFIMAGE &&
570 0 : cinfo->global_state != DSTATE_PRESCAN)
571 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
572 : /* Limit scan number to valid range */
573 0 : if (scan_number <= 0)
574 0 : scan_number = 1;
575 0 : if (cinfo->inputctl->eoi_reached &&
576 0 : scan_number > cinfo->input_scan_number)
577 0 : scan_number = cinfo->input_scan_number;
578 0 : cinfo->output_scan_number = scan_number;
579 : /* Perform any dummy output passes, and set up for the real pass */
580 0 : 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 :
591 : GLOBAL(boolean)
592 0 : jpeg_finish_output (j_decompress_ptr cinfo)
593 : {
594 0 : if ((cinfo->global_state == DSTATE_SCANNING ||
595 0 : 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 0 : (*cinfo->master->finish_output_pass) (cinfo);
599 0 : cinfo->global_state = DSTATE_BUFPOST;
600 0 : } else if (cinfo->global_state != DSTATE_BUFPOST) {
601 : /* BUFPOST = repeat call after a suspension, anything else is error */
602 0 : ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
603 : }
604 : /* Read markers looking for SOS or EOI */
605 0 : while (cinfo->input_scan_number <= cinfo->output_scan_number &&
606 0 : ! cinfo->inputctl->eoi_reached) {
607 0 : if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
608 0 : return FALSE; /* Suspend, come back later */
609 : }
610 0 : cinfo->global_state = DSTATE_BUFIMAGE;
611 0 : return TRUE;
612 : }
613 :
614 : #endif /* D_MULTISCAN_FILES_SUPPORTED */
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