4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1997, Thomas G. Lane.
6 * libjpeg-turbo Modifications:
7 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
8 * Copyright (C) 2010, 2015-2016, 2019-2020, 2022-2023, D. R. Commander.
9 * Copyright (C) 2015, 2020, Google, Inc.
10 * For conditions of distribution and use, see the accompanying README.ijg
13 * This file contains the coefficient buffer controller for decompression.
14 * This controller is the top level of the lossy JPEG decompressor proper.
15 * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
17 * In buffered-image mode, this controller is the interface between
18 * input-oriented processing and output-oriented processing.
19 * Also, the input side (only) is used when reading a file for transcoding.
24 #include "jpegapicomp.h"
25 #include "jsamplecomp.h"
28 /* Forward declarations */
29 METHODDEF(int) decompress_onepass(j_decompress_ptr cinfo,
30 _JSAMPIMAGE output_buf);
31 #ifdef D_MULTISCAN_FILES_SUPPORTED
32 METHODDEF(int) decompress_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf);
34 #ifdef BLOCK_SMOOTHING_SUPPORTED
35 LOCAL(boolean) smoothing_ok(j_decompress_ptr cinfo);
36 METHODDEF(int) decompress_smooth_data(j_decompress_ptr cinfo,
37 _JSAMPIMAGE output_buf);
42 * Initialize for an input processing pass.
46 start_input_pass(j_decompress_ptr cinfo)
48 cinfo->input_iMCU_row = 0;
49 start_iMCU_row(cinfo);
54 * Initialize for an output processing pass.
58 start_output_pass(j_decompress_ptr cinfo)
60 #ifdef BLOCK_SMOOTHING_SUPPORTED
61 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
63 /* If multipass, check to see whether to use block smoothing on this pass */
64 if (coef->pub.coef_arrays != NULL) {
65 if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
66 coef->pub._decompress_data = decompress_smooth_data;
68 coef->pub._decompress_data = decompress_data;
71 cinfo->output_iMCU_row = 0;
76 * Decompress and return some data in the single-pass case.
77 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
78 * Input and output must run in lockstep since we have only a one-MCU buffer.
79 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
81 * NB: output_buf contains a plane for each component in image,
82 * which we index according to the component's SOF position.
86 decompress_onepass(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf)
88 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
89 JDIMENSION MCU_col_num; /* index of current MCU within row */
90 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
91 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
92 int blkn, ci, xindex, yindex, yoffset, useful_width;
93 _JSAMPARRAY output_ptr;
94 JDIMENSION start_col, output_col;
95 jpeg_component_info *compptr;
96 _inverse_DCT_method_ptr inverse_DCT;
98 /* Loop to process as much as one whole iMCU row */
99 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
101 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
103 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
104 jzero_far((void *)coef->MCU_buffer[0],
105 (size_t)(cinfo->blocks_in_MCU * sizeof(JBLOCK)));
106 if (!cinfo->entropy->insufficient_data)
107 cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row;
108 if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
109 /* Suspension forced; update state counters and exit */
110 coef->MCU_vert_offset = yoffset;
111 coef->MCU_ctr = MCU_col_num;
112 return JPEG_SUSPENDED;
115 /* Only perform the IDCT on blocks that are contained within the desired
118 if (MCU_col_num >= cinfo->master->first_iMCU_col &&
119 MCU_col_num <= cinfo->master->last_iMCU_col) {
120 /* Determine where data should go in output_buf and do the IDCT thing.
121 * We skip dummy blocks at the right and bottom edges (but blkn gets
122 * incremented past them!). Note the inner loop relies on having
123 * allocated the MCU_buffer[] blocks sequentially.
125 blkn = 0; /* index of current DCT block within MCU */
126 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
127 compptr = cinfo->cur_comp_info[ci];
128 /* Don't bother to IDCT an uninteresting component. */
129 if (!compptr->component_needed) {
130 blkn += compptr->MCU_blocks;
133 inverse_DCT = cinfo->idct->_inverse_DCT[compptr->component_index];
134 useful_width = (MCU_col_num < last_MCU_col) ?
135 compptr->MCU_width : compptr->last_col_width;
136 output_ptr = output_buf[compptr->component_index] +
137 yoffset * compptr->_DCT_scaled_size;
138 start_col = (MCU_col_num - cinfo->master->first_iMCU_col) *
139 compptr->MCU_sample_width;
140 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
141 if (cinfo->input_iMCU_row < last_iMCU_row ||
142 yoffset + yindex < compptr->last_row_height) {
143 output_col = start_col;
144 for (xindex = 0; xindex < useful_width; xindex++) {
145 (*inverse_DCT) (cinfo, compptr,
146 (JCOEFPTR)coef->MCU_buffer[blkn + xindex],
147 output_ptr, output_col);
148 output_col += compptr->_DCT_scaled_size;
151 blkn += compptr->MCU_width;
152 output_ptr += compptr->_DCT_scaled_size;
157 /* Completed an MCU row, but perhaps not an iMCU row */
160 /* Completed the iMCU row, advance counters for next one */
161 cinfo->output_iMCU_row++;
162 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
163 start_iMCU_row(cinfo);
164 return JPEG_ROW_COMPLETED;
166 /* Completed the scan */
167 (*cinfo->inputctl->finish_input_pass) (cinfo);
168 return JPEG_SCAN_COMPLETED;
173 * Dummy consume-input routine for single-pass operation.
177 dummy_consume_data(j_decompress_ptr cinfo)
179 return JPEG_SUSPENDED; /* Always indicate nothing was done */
183 #ifdef D_MULTISCAN_FILES_SUPPORTED
186 * Consume input data and store it in the full-image coefficient buffer.
187 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
188 * ie, v_samp_factor block rows for each component in the scan.
189 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
193 consume_data(j_decompress_ptr cinfo)
195 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
196 JDIMENSION MCU_col_num; /* index of current MCU within row */
197 int blkn, ci, xindex, yindex, yoffset;
198 JDIMENSION start_col;
199 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
200 JBLOCKROW buffer_ptr;
201 jpeg_component_info *compptr;
203 /* Align the virtual buffers for the components used in this scan. */
204 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
205 compptr = cinfo->cur_comp_info[ci];
206 buffer[ci] = (*cinfo->mem->access_virt_barray)
207 ((j_common_ptr)cinfo, coef->whole_image[compptr->component_index],
208 cinfo->input_iMCU_row * compptr->v_samp_factor,
209 (JDIMENSION)compptr->v_samp_factor, TRUE);
210 /* Note: entropy decoder expects buffer to be zeroed,
211 * but this is handled automatically by the memory manager
212 * because we requested a pre-zeroed array.
216 /* Loop to process one whole iMCU row */
217 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
219 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
221 /* Construct list of pointers to DCT blocks belonging to this MCU */
222 blkn = 0; /* index of current DCT block within MCU */
223 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
224 compptr = cinfo->cur_comp_info[ci];
225 start_col = MCU_col_num * compptr->MCU_width;
226 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
227 buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
228 for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
229 coef->MCU_buffer[blkn++] = buffer_ptr++;
233 if (!cinfo->entropy->insufficient_data)
234 cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row;
235 /* Try to fetch the MCU. */
236 if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
237 /* Suspension forced; update state counters and exit */
238 coef->MCU_vert_offset = yoffset;
239 coef->MCU_ctr = MCU_col_num;
240 return JPEG_SUSPENDED;
243 /* Completed an MCU row, but perhaps not an iMCU row */
246 /* Completed the iMCU row, advance counters for next one */
247 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
248 start_iMCU_row(cinfo);
249 return JPEG_ROW_COMPLETED;
251 /* Completed the scan */
252 (*cinfo->inputctl->finish_input_pass) (cinfo);
253 return JPEG_SCAN_COMPLETED;
258 * Decompress and return some data in the multi-pass case.
259 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
260 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
262 * NB: output_buf contains a plane for each component in image.
266 decompress_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf)
268 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
269 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
270 JDIMENSION block_num;
271 int ci, block_row, block_rows;
273 JBLOCKROW buffer_ptr;
274 _JSAMPARRAY output_ptr;
275 JDIMENSION output_col;
276 jpeg_component_info *compptr;
277 _inverse_DCT_method_ptr inverse_DCT;
279 /* Force some input to be done if we are getting ahead of the input. */
280 while (cinfo->input_scan_number < cinfo->output_scan_number ||
281 (cinfo->input_scan_number == cinfo->output_scan_number &&
282 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
283 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
284 return JPEG_SUSPENDED;
287 /* OK, output from the virtual arrays. */
288 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
290 /* Don't bother to IDCT an uninteresting component. */
291 if (!compptr->component_needed)
293 /* Align the virtual buffer for this component. */
294 buffer = (*cinfo->mem->access_virt_barray)
295 ((j_common_ptr)cinfo, coef->whole_image[ci],
296 cinfo->output_iMCU_row * compptr->v_samp_factor,
297 (JDIMENSION)compptr->v_samp_factor, FALSE);
298 /* Count non-dummy DCT block rows in this iMCU row. */
299 if (cinfo->output_iMCU_row < last_iMCU_row)
300 block_rows = compptr->v_samp_factor;
302 /* NB: can't use last_row_height here; it is input-side-dependent! */
303 block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
304 if (block_rows == 0) block_rows = compptr->v_samp_factor;
306 inverse_DCT = cinfo->idct->_inverse_DCT[ci];
307 output_ptr = output_buf[ci];
308 /* Loop over all DCT blocks to be processed. */
309 for (block_row = 0; block_row < block_rows; block_row++) {
310 buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
312 for (block_num = cinfo->master->first_MCU_col[ci];
313 block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
314 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)buffer_ptr, output_ptr,
317 output_col += compptr->_DCT_scaled_size;
319 output_ptr += compptr->_DCT_scaled_size;
323 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
324 return JPEG_ROW_COMPLETED;
325 return JPEG_SCAN_COMPLETED;
328 #endif /* D_MULTISCAN_FILES_SUPPORTED */
331 #ifdef BLOCK_SMOOTHING_SUPPORTED
334 * This code applies interblock smoothing; the first 9 AC coefficients are
335 * estimated from the DC values of a DCT block and its 24 neighboring blocks.
336 * We apply smoothing only for progressive JPEG decoding, and only if
337 * the coefficients it can estimate are not yet known to full precision.
340 /* Natural-order array positions of the first 9 zigzag-order coefficients */
352 * Determine whether block smoothing is applicable and safe.
353 * We also latch the current states of the coef_bits[] entries for the
354 * AC coefficients; otherwise, if the input side of the decompressor
355 * advances into a new scan, we might think the coefficients are known
356 * more accurately than they really are.
360 smoothing_ok(j_decompress_ptr cinfo)
362 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
363 boolean smoothing_useful = FALSE;
365 jpeg_component_info *compptr;
367 int *coef_bits, *prev_coef_bits;
368 int *coef_bits_latch, *prev_coef_bits_latch;
370 if (!cinfo->progressive_mode || cinfo->coef_bits == NULL)
373 /* Allocate latch area if not already done */
374 if (coef->coef_bits_latch == NULL)
375 coef->coef_bits_latch = (int *)
376 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
377 cinfo->num_components * 2 *
378 (SAVED_COEFS * sizeof(int)));
379 coef_bits_latch = coef->coef_bits_latch;
380 prev_coef_bits_latch =
381 &coef->coef_bits_latch[cinfo->num_components * SAVED_COEFS];
383 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
385 /* All components' quantization values must already be latched. */
386 if ((qtable = compptr->quant_table) == NULL)
388 /* Verify DC & first 9 AC quantizers are nonzero to avoid zero-divide. */
389 if (qtable->quantval[0] == 0 ||
390 qtable->quantval[Q01_POS] == 0 ||
391 qtable->quantval[Q10_POS] == 0 ||
392 qtable->quantval[Q20_POS] == 0 ||
393 qtable->quantval[Q11_POS] == 0 ||
394 qtable->quantval[Q02_POS] == 0 ||
395 qtable->quantval[Q03_POS] == 0 ||
396 qtable->quantval[Q12_POS] == 0 ||
397 qtable->quantval[Q21_POS] == 0 ||
398 qtable->quantval[Q30_POS] == 0)
400 /* DC values must be at least partly known for all components. */
401 coef_bits = cinfo->coef_bits[ci];
402 prev_coef_bits = cinfo->coef_bits[ci + cinfo->num_components];
403 if (coef_bits[0] < 0)
405 coef_bits_latch[0] = coef_bits[0];
406 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
407 for (coefi = 1; coefi < SAVED_COEFS; coefi++) {
408 if (cinfo->input_scan_number > 1)
409 prev_coef_bits_latch[coefi] = prev_coef_bits[coefi];
411 prev_coef_bits_latch[coefi] = -1;
412 coef_bits_latch[coefi] = coef_bits[coefi];
413 if (coef_bits[coefi] != 0)
414 smoothing_useful = TRUE;
416 coef_bits_latch += SAVED_COEFS;
417 prev_coef_bits_latch += SAVED_COEFS;
420 return smoothing_useful;
425 * Variant of decompress_data for use when doing block smoothing.
429 decompress_smooth_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf)
431 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
432 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
433 JDIMENSION block_num, last_block_column;
434 int ci, block_row, block_rows, access_rows, image_block_row,
437 JBLOCKROW buffer_ptr, prev_prev_block_row, prev_block_row;
438 JBLOCKROW next_block_row, next_next_block_row;
439 _JSAMPARRAY output_ptr;
440 JDIMENSION output_col;
441 jpeg_component_info *compptr;
442 _inverse_DCT_method_ptr inverse_DCT;
446 JQUANT_TBL *quanttbl;
447 JLONG Q00, Q01, Q02, Q03 = 0, Q10, Q11, Q12 = 0, Q20, Q21 = 0, Q30 = 0, num;
448 int DC01, DC02, DC03, DC04, DC05, DC06, DC07, DC08, DC09, DC10, DC11, DC12,
449 DC13, DC14, DC15, DC16, DC17, DC18, DC19, DC20, DC21, DC22, DC23, DC24,
453 /* Keep a local variable to avoid looking it up more than once */
454 workspace = coef->workspace;
456 /* Force some input to be done if we are getting ahead of the input. */
457 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
458 !cinfo->inputctl->eoi_reached) {
459 if (cinfo->input_scan_number == cinfo->output_scan_number) {
460 /* If input is working on current scan, we ordinarily want it to
461 * have completed the current row. But if input scan is DC,
462 * we want it to keep two rows ahead so that next two block rows' DC
463 * values are up to date.
465 JDIMENSION delta = (cinfo->Ss == 0) ? 2 : 0;
466 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row + delta)
469 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
470 return JPEG_SUSPENDED;
473 /* OK, output from the virtual arrays. */
474 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
476 /* Don't bother to IDCT an uninteresting component. */
477 if (!compptr->component_needed)
479 /* Count non-dummy DCT block rows in this iMCU row. */
480 if (cinfo->output_iMCU_row + 1 < last_iMCU_row) {
481 block_rows = compptr->v_samp_factor;
482 access_rows = block_rows * 3; /* this and next two iMCU rows */
483 } else if (cinfo->output_iMCU_row < last_iMCU_row) {
484 block_rows = compptr->v_samp_factor;
485 access_rows = block_rows * 2; /* this and next iMCU row */
487 /* NB: can't use last_row_height here; it is input-side-dependent! */
488 block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
489 if (block_rows == 0) block_rows = compptr->v_samp_factor;
490 access_rows = block_rows; /* this iMCU row only */
492 /* Align the virtual buffer for this component. */
493 if (cinfo->output_iMCU_row > 1) {
494 access_rows += 2 * compptr->v_samp_factor; /* prior two iMCU rows too */
495 buffer = (*cinfo->mem->access_virt_barray)
496 ((j_common_ptr)cinfo, coef->whole_image[ci],
497 (cinfo->output_iMCU_row - 2) * compptr->v_samp_factor,
498 (JDIMENSION)access_rows, FALSE);
499 buffer += 2 * compptr->v_samp_factor; /* point to current iMCU row */
500 } else if (cinfo->output_iMCU_row > 0) {
501 access_rows += compptr->v_samp_factor; /* prior iMCU row too */
502 buffer = (*cinfo->mem->access_virt_barray)
503 ((j_common_ptr)cinfo, coef->whole_image[ci],
504 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
505 (JDIMENSION)access_rows, FALSE);
506 buffer += compptr->v_samp_factor; /* point to current iMCU row */
508 buffer = (*cinfo->mem->access_virt_barray)
509 ((j_common_ptr)cinfo, coef->whole_image[ci],
510 (JDIMENSION)0, (JDIMENSION)access_rows, FALSE);
512 /* Fetch component-dependent info.
513 * If the current scan is incomplete, then we use the component-dependent
514 * info from the previous scan.
516 if (cinfo->output_iMCU_row > cinfo->master->last_good_iMCU_row)
518 coef->coef_bits_latch + ((ci + cinfo->num_components) * SAVED_COEFS);
520 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
522 /* We only do DC interpolation if no AC coefficient data is available. */
524 coef_bits[1] == -1 && coef_bits[2] == -1 && coef_bits[3] == -1 &&
525 coef_bits[4] == -1 && coef_bits[5] == -1 && coef_bits[6] == -1 &&
526 coef_bits[7] == -1 && coef_bits[8] == -1 && coef_bits[9] == -1;
528 quanttbl = compptr->quant_table;
529 Q00 = quanttbl->quantval[0];
530 Q01 = quanttbl->quantval[Q01_POS];
531 Q10 = quanttbl->quantval[Q10_POS];
532 Q20 = quanttbl->quantval[Q20_POS];
533 Q11 = quanttbl->quantval[Q11_POS];
534 Q02 = quanttbl->quantval[Q02_POS];
536 Q03 = quanttbl->quantval[Q03_POS];
537 Q12 = quanttbl->quantval[Q12_POS];
538 Q21 = quanttbl->quantval[Q21_POS];
539 Q30 = quanttbl->quantval[Q30_POS];
541 inverse_DCT = cinfo->idct->_inverse_DCT[ci];
542 output_ptr = output_buf[ci];
543 /* Loop over all DCT blocks to be processed. */
544 image_block_rows = block_rows * cinfo->total_iMCU_rows;
545 for (block_row = 0; block_row < block_rows; block_row++) {
546 image_block_row = cinfo->output_iMCU_row * block_rows + block_row;
547 buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
549 if (image_block_row > 0)
551 buffer[block_row - 1] + cinfo->master->first_MCU_col[ci];
553 prev_block_row = buffer_ptr;
555 if (image_block_row > 1)
556 prev_prev_block_row =
557 buffer[block_row - 2] + cinfo->master->first_MCU_col[ci];
559 prev_prev_block_row = prev_block_row;
561 if (image_block_row < image_block_rows - 1)
563 buffer[block_row + 1] + cinfo->master->first_MCU_col[ci];
565 next_block_row = buffer_ptr;
567 if (image_block_row < image_block_rows - 2)
568 next_next_block_row =
569 buffer[block_row + 2] + cinfo->master->first_MCU_col[ci];
571 next_next_block_row = next_block_row;
573 /* We fetch the surrounding DC values using a sliding-register approach.
574 * Initialize all 25 here so as to do the right thing on narrow pics.
576 DC01 = DC02 = DC03 = DC04 = DC05 = (int)prev_prev_block_row[0][0];
577 DC06 = DC07 = DC08 = DC09 = DC10 = (int)prev_block_row[0][0];
578 DC11 = DC12 = DC13 = DC14 = DC15 = (int)buffer_ptr[0][0];
579 DC16 = DC17 = DC18 = DC19 = DC20 = (int)next_block_row[0][0];
580 DC21 = DC22 = DC23 = DC24 = DC25 = (int)next_next_block_row[0][0];
582 last_block_column = compptr->width_in_blocks - 1;
583 for (block_num = cinfo->master->first_MCU_col[ci];
584 block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
585 /* Fetch current DCT block into workspace so we can modify it. */
586 jcopy_block_row(buffer_ptr, (JBLOCKROW)workspace, (JDIMENSION)1);
587 /* Update DC values */
588 if (block_num == cinfo->master->first_MCU_col[ci] &&
589 block_num < last_block_column) {
590 DC04 = DC05 = (int)prev_prev_block_row[1][0];
591 DC09 = DC10 = (int)prev_block_row[1][0];
592 DC14 = DC15 = (int)buffer_ptr[1][0];
593 DC19 = DC20 = (int)next_block_row[1][0];
594 DC24 = DC25 = (int)next_next_block_row[1][0];
596 if (block_num + 1 < last_block_column) {
597 DC05 = (int)prev_prev_block_row[2][0];
598 DC10 = (int)prev_block_row[2][0];
599 DC15 = (int)buffer_ptr[2][0];
600 DC20 = (int)next_block_row[2][0];
601 DC25 = (int)next_next_block_row[2][0];
603 /* If DC interpolation is enabled, compute coefficient estimates using
604 * a Gaussian-like kernel, keeping the averages of the DC values.
606 * If DC interpolation is disabled, compute coefficient estimates using
607 * an algorithm similar to the one described in Section K.8 of the JPEG
608 * standard, except applied to a 5x5 window rather than a 3x3 window.
610 * An estimate is applied only if the coefficient is still zero and is
611 * not known to be fully accurate.
614 if ((Al = coef_bits[1]) != 0 && workspace[1] == 0) {
615 num = Q00 * (change_dc ?
616 (-DC01 - DC02 + DC04 + DC05 - 3 * DC06 + 13 * DC07 -
617 13 * DC09 + 3 * DC10 - 3 * DC11 + 38 * DC12 - 38 * DC14 +
618 3 * DC15 - 3 * DC16 + 13 * DC17 - 13 * DC19 + 3 * DC20 -
619 DC21 - DC22 + DC24 + DC25) :
620 (-7 * DC11 + 50 * DC12 - 50 * DC14 + 7 * DC15));
622 pred = (int)(((Q01 << 7) + num) / (Q01 << 8));
623 if (Al > 0 && pred >= (1 << Al))
624 pred = (1 << Al) - 1;
626 pred = (int)(((Q01 << 7) - num) / (Q01 << 8));
627 if (Al > 0 && pred >= (1 << Al))
628 pred = (1 << Al) - 1;
631 workspace[1] = (JCOEF)pred;
634 if ((Al = coef_bits[2]) != 0 && workspace[8] == 0) {
635 num = Q00 * (change_dc ?
636 (-DC01 - 3 * DC02 - 3 * DC03 - 3 * DC04 - DC05 - DC06 +
637 13 * DC07 + 38 * DC08 + 13 * DC09 - DC10 + DC16 -
638 13 * DC17 - 38 * DC18 - 13 * DC19 + DC20 + DC21 +
639 3 * DC22 + 3 * DC23 + 3 * DC24 + DC25) :
640 (-7 * DC03 + 50 * DC08 - 50 * DC18 + 7 * DC23));
642 pred = (int)(((Q10 << 7) + num) / (Q10 << 8));
643 if (Al > 0 && pred >= (1 << Al))
644 pred = (1 << Al) - 1;
646 pred = (int)(((Q10 << 7) - num) / (Q10 << 8));
647 if (Al > 0 && pred >= (1 << Al))
648 pred = (1 << Al) - 1;
651 workspace[8] = (JCOEF)pred;
654 if ((Al = coef_bits[3]) != 0 && workspace[16] == 0) {
655 num = Q00 * (change_dc ?
656 (DC03 + 2 * DC07 + 7 * DC08 + 2 * DC09 - 5 * DC12 - 14 * DC13 -
657 5 * DC14 + 2 * DC17 + 7 * DC18 + 2 * DC19 + DC23) :
658 (-DC03 + 13 * DC08 - 24 * DC13 + 13 * DC18 - DC23));
660 pred = (int)(((Q20 << 7) + num) / (Q20 << 8));
661 if (Al > 0 && pred >= (1 << Al))
662 pred = (1 << Al) - 1;
664 pred = (int)(((Q20 << 7) - num) / (Q20 << 8));
665 if (Al > 0 && pred >= (1 << Al))
666 pred = (1 << Al) - 1;
669 workspace[16] = (JCOEF)pred;
672 if ((Al = coef_bits[4]) != 0 && workspace[9] == 0) {
673 num = Q00 * (change_dc ?
674 (-DC01 + DC05 + 9 * DC07 - 9 * DC09 - 9 * DC17 +
675 9 * DC19 + DC21 - DC25) :
676 (DC10 + DC16 - 10 * DC17 + 10 * DC19 - DC02 - DC20 + DC22 -
677 DC24 + DC04 - DC06 + 10 * DC07 - 10 * DC09));
679 pred = (int)(((Q11 << 7) + num) / (Q11 << 8));
680 if (Al > 0 && pred >= (1 << Al))
681 pred = (1 << Al) - 1;
683 pred = (int)(((Q11 << 7) - num) / (Q11 << 8));
684 if (Al > 0 && pred >= (1 << Al))
685 pred = (1 << Al) - 1;
688 workspace[9] = (JCOEF)pred;
691 if ((Al = coef_bits[5]) != 0 && workspace[2] == 0) {
692 num = Q00 * (change_dc ?
693 (2 * DC07 - 5 * DC08 + 2 * DC09 + DC11 + 7 * DC12 - 14 * DC13 +
694 7 * DC14 + DC15 + 2 * DC17 - 5 * DC18 + 2 * DC19) :
695 (-DC11 + 13 * DC12 - 24 * DC13 + 13 * DC14 - DC15));
697 pred = (int)(((Q02 << 7) + num) / (Q02 << 8));
698 if (Al > 0 && pred >= (1 << Al))
699 pred = (1 << Al) - 1;
701 pred = (int)(((Q02 << 7) - num) / (Q02 << 8));
702 if (Al > 0 && pred >= (1 << Al))
703 pred = (1 << Al) - 1;
706 workspace[2] = (JCOEF)pred;
710 if ((Al = coef_bits[6]) != 0 && workspace[3] == 0) {
711 num = Q00 * (DC07 - DC09 + 2 * DC12 - 2 * DC14 + DC17 - DC19);
713 pred = (int)(((Q03 << 7) + num) / (Q03 << 8));
714 if (Al > 0 && pred >= (1 << Al))
715 pred = (1 << Al) - 1;
717 pred = (int)(((Q03 << 7) - num) / (Q03 << 8));
718 if (Al > 0 && pred >= (1 << Al))
719 pred = (1 << Al) - 1;
722 workspace[3] = (JCOEF)pred;
725 if ((Al = coef_bits[7]) != 0 && workspace[10] == 0) {
726 num = Q00 * (DC07 - 3 * DC08 + DC09 - DC17 + 3 * DC18 - DC19);
728 pred = (int)(((Q12 << 7) + num) / (Q12 << 8));
729 if (Al > 0 && pred >= (1 << Al))
730 pred = (1 << Al) - 1;
732 pred = (int)(((Q12 << 7) - num) / (Q12 << 8));
733 if (Al > 0 && pred >= (1 << Al))
734 pred = (1 << Al) - 1;
737 workspace[10] = (JCOEF)pred;
740 if ((Al = coef_bits[8]) != 0 && workspace[17] == 0) {
741 num = Q00 * (DC07 - DC09 - 3 * DC12 + 3 * DC14 + DC17 - DC19);
743 pred = (int)(((Q21 << 7) + num) / (Q21 << 8));
744 if (Al > 0 && pred >= (1 << Al))
745 pred = (1 << Al) - 1;
747 pred = (int)(((Q21 << 7) - num) / (Q21 << 8));
748 if (Al > 0 && pred >= (1 << Al))
749 pred = (1 << Al) - 1;
752 workspace[17] = (JCOEF)pred;
755 if ((Al = coef_bits[9]) != 0 && workspace[24] == 0) {
756 num = Q00 * (DC07 + 2 * DC08 + DC09 - DC17 - 2 * DC18 - DC19);
758 pred = (int)(((Q30 << 7) + num) / (Q30 << 8));
759 if (Al > 0 && pred >= (1 << Al))
760 pred = (1 << Al) - 1;
762 pred = (int)(((Q30 << 7) - num) / (Q30 << 8));
763 if (Al > 0 && pred >= (1 << Al))
764 pred = (1 << Al) - 1;
767 workspace[24] = (JCOEF)pred;
769 /* coef_bits[0] is non-negative. Otherwise this function would not
773 (-2 * DC01 - 6 * DC02 - 8 * DC03 - 6 * DC04 - 2 * DC05 -
774 6 * DC06 + 6 * DC07 + 42 * DC08 + 6 * DC09 - 6 * DC10 -
775 8 * DC11 + 42 * DC12 + 152 * DC13 + 42 * DC14 - 8 * DC15 -
776 6 * DC16 + 6 * DC17 + 42 * DC18 + 6 * DC19 - 6 * DC20 -
777 2 * DC21 - 6 * DC22 - 8 * DC23 - 6 * DC24 - 2 * DC25);
779 pred = (int)(((Q00 << 7) + num) / (Q00 << 8));
781 pred = (int)(((Q00 << 7) - num) / (Q00 << 8));
784 workspace[0] = (JCOEF)pred;
787 /* OK, do the IDCT */
788 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)workspace, output_ptr,
790 /* Advance for next column */
791 DC01 = DC02; DC02 = DC03; DC03 = DC04; DC04 = DC05;
792 DC06 = DC07; DC07 = DC08; DC08 = DC09; DC09 = DC10;
793 DC11 = DC12; DC12 = DC13; DC13 = DC14; DC14 = DC15;
794 DC16 = DC17; DC17 = DC18; DC18 = DC19; DC19 = DC20;
795 DC21 = DC22; DC22 = DC23; DC23 = DC24; DC24 = DC25;
796 buffer_ptr++, prev_block_row++, next_block_row++,
797 prev_prev_block_row++, next_next_block_row++;
798 output_col += compptr->_DCT_scaled_size;
800 output_ptr += compptr->_DCT_scaled_size;
804 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
805 return JPEG_ROW_COMPLETED;
806 return JPEG_SCAN_COMPLETED;
809 #endif /* BLOCK_SMOOTHING_SUPPORTED */
813 * Initialize coefficient buffer controller.
817 _jinit_d_coef_controller(j_decompress_ptr cinfo, boolean need_full_buffer)
821 if (cinfo->data_precision != BITS_IN_JSAMPLE)
822 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
825 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
826 sizeof(my_coef_controller));
827 cinfo->coef = (struct jpeg_d_coef_controller *)coef;
828 coef->pub.start_input_pass = start_input_pass;
829 coef->pub.start_output_pass = start_output_pass;
830 #ifdef BLOCK_SMOOTHING_SUPPORTED
831 coef->coef_bits_latch = NULL;
834 /* Create the coefficient buffer. */
835 if (need_full_buffer) {
836 #ifdef D_MULTISCAN_FILES_SUPPORTED
837 /* Allocate a full-image virtual array for each component, */
838 /* padded to a multiple of samp_factor DCT blocks in each direction. */
839 /* Note we ask for a pre-zeroed array. */
841 jpeg_component_info *compptr;
843 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
845 access_rows = compptr->v_samp_factor;
846 #ifdef BLOCK_SMOOTHING_SUPPORTED
847 /* If block smoothing could be used, need a bigger window */
848 if (cinfo->progressive_mode)
851 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
852 ((j_common_ptr)cinfo, JPOOL_IMAGE, TRUE,
853 (JDIMENSION)jround_up((long)compptr->width_in_blocks,
854 (long)compptr->h_samp_factor),
855 (JDIMENSION)jround_up((long)compptr->height_in_blocks,
856 (long)compptr->v_samp_factor),
857 (JDIMENSION)access_rows);
859 coef->pub.consume_data = consume_data;
860 coef->pub._decompress_data = decompress_data;
861 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
863 ERREXIT(cinfo, JERR_NOT_COMPILED);
866 /* We only need a single-MCU buffer. */
871 (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE,
872 D_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
873 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
874 coef->MCU_buffer[i] = buffer + i;
876 coef->pub.consume_data = dummy_consume_data;
877 coef->pub._decompress_data = decompress_onepass;
878 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
881 /* Allocate the workspace buffer */
882 coef->workspace = (JCOEF *)
883 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
884 sizeof(JCOEF) * DCTSIZE2);