1/*
2 * jdcoefct.c
3 *
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, D. R. Commander.
9 * Copyright (C) 2015, Google, Inc.
10 * For conditions of distribution and use, see the accompanying README.ijg
11 * file.
12 *
13 * This file contains the coefficient buffer controller for decompression.
14 * This controller is the top level of the JPEG decompressor proper.
15 * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
16 *
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.
20 */
21
22#include "jinclude.h"
23#include "jdcoefct.h"
24#include "jpegcomp.h"
25
26
27/* Forward declarations */
28METHODDEF(int) decompress_onepass(j_decompress_ptr cinfo,
29 JSAMPIMAGE output_buf);
30#ifdef D_MULTISCAN_FILES_SUPPORTED
31METHODDEF(int) decompress_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
32#endif
33#ifdef BLOCK_SMOOTHING_SUPPORTED
34LOCAL(boolean) smoothing_ok(j_decompress_ptr cinfo);
35METHODDEF(int) decompress_smooth_data(j_decompress_ptr cinfo,
36 JSAMPIMAGE output_buf);
37#endif
38
39
40/*
41 * Initialize for an input processing pass.
42 */
43
44METHODDEF(void)
45start_input_pass(j_decompress_ptr cinfo)
46{
47 cinfo->input_iMCU_row = 0;
48 start_iMCU_row(cinfo);
49}
50
51
52/*
53 * Initialize for an output processing pass.
54 */
55
56METHODDEF(void)
57start_output_pass(j_decompress_ptr cinfo)
58{
59#ifdef BLOCK_SMOOTHING_SUPPORTED
60 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
61
62 /* If multipass, check to see whether to use block smoothing on this pass */
63 if (coef->pub.coef_arrays != NULL) {
64 if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
65 coef->pub.decompress_data = decompress_smooth_data;
66 else
67 coef->pub.decompress_data = decompress_data;
68 }
69#endif
70 cinfo->output_iMCU_row = 0;
71}
72
73
74/*
75 * Decompress and return some data in the single-pass case.
76 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
77 * Input and output must run in lockstep since we have only a one-MCU buffer.
78 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
79 *
80 * NB: output_buf contains a plane for each component in image,
81 * which we index according to the component's SOF position.
82 */
83
84METHODDEF(int)
85decompress_onepass(j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
86{
87 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
88 JDIMENSION MCU_col_num; /* index of current MCU within row */
89 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
90 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
91 int blkn, ci, xindex, yindex, yoffset, useful_width;
92 JSAMPARRAY output_ptr;
93 JDIMENSION start_col, output_col;
94 jpeg_component_info *compptr;
95 inverse_DCT_method_ptr inverse_DCT;
96
97 /* Loop to process as much as one whole iMCU row */
98 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
99 yoffset++) {
100 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
101 MCU_col_num++) {
102 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
103 jzero_far((void *)coef->MCU_buffer[0],
104 (size_t)(cinfo->blocks_in_MCU * sizeof(JBLOCK)));
105 if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
106 /* Suspension forced; update state counters and exit */
107 coef->MCU_vert_offset = yoffset;
108 coef->MCU_ctr = MCU_col_num;
109 return JPEG_SUSPENDED;
110 }
111
112 /* Only perform the IDCT on blocks that are contained within the desired
113 * cropping region.
114 */
115 if (MCU_col_num >= cinfo->master->first_iMCU_col &&
116 MCU_col_num <= cinfo->master->last_iMCU_col) {
117 /* Determine where data should go in output_buf and do the IDCT thing.
118 * We skip dummy blocks at the right and bottom edges (but blkn gets
119 * incremented past them!). Note the inner loop relies on having
120 * allocated the MCU_buffer[] blocks sequentially.
121 */
122 blkn = 0; /* index of current DCT block within MCU */
123 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
124 compptr = cinfo->cur_comp_info[ci];
125 /* Don't bother to IDCT an uninteresting component. */
126 if (!compptr->component_needed) {
127 blkn += compptr->MCU_blocks;
128 continue;
129 }
130 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
131 useful_width = (MCU_col_num < last_MCU_col) ?
132 compptr->MCU_width : compptr->last_col_width;
133 output_ptr = output_buf[compptr->component_index] +
134 yoffset * compptr->_DCT_scaled_size;
135 start_col = (MCU_col_num - cinfo->master->first_iMCU_col) *
136 compptr->MCU_sample_width;
137 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
138 if (cinfo->input_iMCU_row < last_iMCU_row ||
139 yoffset + yindex < compptr->last_row_height) {
140 output_col = start_col;
141 for (xindex = 0; xindex < useful_width; xindex++) {
142 (*inverse_DCT) (cinfo, compptr,
143 (JCOEFPTR)coef->MCU_buffer[blkn + xindex],
144 output_ptr, output_col);
145 output_col += compptr->_DCT_scaled_size;
146 }
147 }
148 blkn += compptr->MCU_width;
149 output_ptr += compptr->_DCT_scaled_size;
150 }
151 }
152 }
153 }
154 /* Completed an MCU row, but perhaps not an iMCU row */
155 coef->MCU_ctr = 0;
156 }
157 /* Completed the iMCU row, advance counters for next one */
158 cinfo->output_iMCU_row++;
159 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
160 start_iMCU_row(cinfo);
161 return JPEG_ROW_COMPLETED;
162 }
163 /* Completed the scan */
164 (*cinfo->inputctl->finish_input_pass) (cinfo);
165 return JPEG_SCAN_COMPLETED;
166}
167
168
169/*
170 * Dummy consume-input routine for single-pass operation.
171 */
172
173METHODDEF(int)
174dummy_consume_data(j_decompress_ptr cinfo)
175{
176 return JPEG_SUSPENDED; /* Always indicate nothing was done */
177}
178
179
180#ifdef D_MULTISCAN_FILES_SUPPORTED
181
182/*
183 * Consume input data and store it in the full-image coefficient buffer.
184 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
185 * ie, v_samp_factor block rows for each component in the scan.
186 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
187 */
188
189METHODDEF(int)
190consume_data(j_decompress_ptr cinfo)
191{
192 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
193 JDIMENSION MCU_col_num; /* index of current MCU within row */
194 int blkn, ci, xindex, yindex, yoffset;
195 JDIMENSION start_col;
196 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
197 JBLOCKROW buffer_ptr;
198 jpeg_component_info *compptr;
199
200 /* Align the virtual buffers for the components used in this scan. */
201 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
202 compptr = cinfo->cur_comp_info[ci];
203 buffer[ci] = (*cinfo->mem->access_virt_barray)
204 ((j_common_ptr)cinfo, coef->whole_image[compptr->component_index],
205 cinfo->input_iMCU_row * compptr->v_samp_factor,
206 (JDIMENSION)compptr->v_samp_factor, TRUE);
207 /* Note: entropy decoder expects buffer to be zeroed,
208 * but this is handled automatically by the memory manager
209 * because we requested a pre-zeroed array.
210 */
211 }
212
213 /* Loop to process one whole iMCU row */
214 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
215 yoffset++) {
216 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
217 MCU_col_num++) {
218 /* Construct list of pointers to DCT blocks belonging to this MCU */
219 blkn = 0; /* index of current DCT block within MCU */
220 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
221 compptr = cinfo->cur_comp_info[ci];
222 start_col = MCU_col_num * compptr->MCU_width;
223 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
224 buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
225 for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
226 coef->MCU_buffer[blkn++] = buffer_ptr++;
227 }
228 }
229 }
230 /* Try to fetch the MCU. */
231 if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
232 /* Suspension forced; update state counters and exit */
233 coef->MCU_vert_offset = yoffset;
234 coef->MCU_ctr = MCU_col_num;
235 return JPEG_SUSPENDED;
236 }
237 }
238 /* Completed an MCU row, but perhaps not an iMCU row */
239 coef->MCU_ctr = 0;
240 }
241 /* Completed the iMCU row, advance counters for next one */
242 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
243 start_iMCU_row(cinfo);
244 return JPEG_ROW_COMPLETED;
245 }
246 /* Completed the scan */
247 (*cinfo->inputctl->finish_input_pass) (cinfo);
248 return JPEG_SCAN_COMPLETED;
249}
250
251
252/*
253 * Decompress and return some data in the multi-pass case.
254 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
255 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
256 *
257 * NB: output_buf contains a plane for each component in image.
258 */
259
260METHODDEF(int)
261decompress_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
262{
263 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
264 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
265 JDIMENSION block_num;
266 int ci, block_row, block_rows;
267 JBLOCKARRAY buffer;
268 JBLOCKROW buffer_ptr;
269 JSAMPARRAY output_ptr;
270 JDIMENSION output_col;
271 jpeg_component_info *compptr;
272 inverse_DCT_method_ptr inverse_DCT;
273
274 /* Force some input to be done if we are getting ahead of the input. */
275 while (cinfo->input_scan_number < cinfo->output_scan_number ||
276 (cinfo->input_scan_number == cinfo->output_scan_number &&
277 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
278 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
279 return JPEG_SUSPENDED;
280 }
281
282 /* OK, output from the virtual arrays. */
283 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
284 ci++, compptr++) {
285 /* Don't bother to IDCT an uninteresting component. */
286 if (!compptr->component_needed)
287 continue;
288 /* Align the virtual buffer for this component. */
289 buffer = (*cinfo->mem->access_virt_barray)
290 ((j_common_ptr)cinfo, coef->whole_image[ci],
291 cinfo->output_iMCU_row * compptr->v_samp_factor,
292 (JDIMENSION)compptr->v_samp_factor, FALSE);
293 /* Count non-dummy DCT block rows in this iMCU row. */
294 if (cinfo->output_iMCU_row < last_iMCU_row)
295 block_rows = compptr->v_samp_factor;
296 else {
297 /* NB: can't use last_row_height here; it is input-side-dependent! */
298 block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
299 if (block_rows == 0) block_rows = compptr->v_samp_factor;
300 }
301 inverse_DCT = cinfo->idct->inverse_DCT[ci];
302 output_ptr = output_buf[ci];
303 /* Loop over all DCT blocks to be processed. */
304 for (block_row = 0; block_row < block_rows; block_row++) {
305 buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
306 output_col = 0;
307 for (block_num = cinfo->master->first_MCU_col[ci];
308 block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
309 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)buffer_ptr, output_ptr,
310 output_col);
311 buffer_ptr++;
312 output_col += compptr->_DCT_scaled_size;
313 }
314 output_ptr += compptr->_DCT_scaled_size;
315 }
316 }
317
318 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
319 return JPEG_ROW_COMPLETED;
320 return JPEG_SCAN_COMPLETED;
321}
322
323#endif /* D_MULTISCAN_FILES_SUPPORTED */
324
325
326#ifdef BLOCK_SMOOTHING_SUPPORTED
327
328/*
329 * This code applies interblock smoothing as described by section K.8
330 * of the JPEG standard: the first 5 AC coefficients are estimated from
331 * the DC values of a DCT block and its 8 neighboring blocks.
332 * We apply smoothing only for progressive JPEG decoding, and only if
333 * the coefficients it can estimate are not yet known to full precision.
334 */
335
336/* Natural-order array positions of the first 5 zigzag-order coefficients */
337#define Q01_POS 1
338#define Q10_POS 8
339#define Q20_POS 16
340#define Q11_POS 9
341#define Q02_POS 2
342
343/*
344 * Determine whether block smoothing is applicable and safe.
345 * We also latch the current states of the coef_bits[] entries for the
346 * AC coefficients; otherwise, if the input side of the decompressor
347 * advances into a new scan, we might think the coefficients are known
348 * more accurately than they really are.
349 */
350
351LOCAL(boolean)
352smoothing_ok(j_decompress_ptr cinfo)
353{
354 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
355 boolean smoothing_useful = FALSE;
356 int ci, coefi;
357 jpeg_component_info *compptr;
358 JQUANT_TBL *qtable;
359 int *coef_bits;
360 int *coef_bits_latch;
361
362 if (!cinfo->progressive_mode || cinfo->coef_bits == NULL)
363 return FALSE;
364
365 /* Allocate latch area if not already done */
366 if (coef->coef_bits_latch == NULL)
367 coef->coef_bits_latch = (int *)
368 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
369 cinfo->num_components *
370 (SAVED_COEFS * sizeof(int)));
371 coef_bits_latch = coef->coef_bits_latch;
372
373 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
374 ci++, compptr++) {
375 /* All components' quantization values must already be latched. */
376 if ((qtable = compptr->quant_table) == NULL)
377 return FALSE;
378 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
379 if (qtable->quantval[0] == 0 ||
380 qtable->quantval[Q01_POS] == 0 ||
381 qtable->quantval[Q10_POS] == 0 ||
382 qtable->quantval[Q20_POS] == 0 ||
383 qtable->quantval[Q11_POS] == 0 ||
384 qtable->quantval[Q02_POS] == 0)
385 return FALSE;
386 /* DC values must be at least partly known for all components. */
387 coef_bits = cinfo->coef_bits[ci];
388 if (coef_bits[0] < 0)
389 return FALSE;
390 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
391 for (coefi = 1; coefi <= 5; coefi++) {
392 coef_bits_latch[coefi] = coef_bits[coefi];
393 if (coef_bits[coefi] != 0)
394 smoothing_useful = TRUE;
395 }
396 coef_bits_latch += SAVED_COEFS;
397 }
398
399 return smoothing_useful;
400}
401
402
403/*
404 * Variant of decompress_data for use when doing block smoothing.
405 */
406
407METHODDEF(int)
408decompress_smooth_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
409{
410 my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
411 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
412 JDIMENSION block_num, last_block_column;
413 int ci, block_row, block_rows, access_rows;
414 JBLOCKARRAY buffer;
415 JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
416 JSAMPARRAY output_ptr;
417 JDIMENSION output_col;
418 jpeg_component_info *compptr;
419 inverse_DCT_method_ptr inverse_DCT;
420 boolean first_row, last_row;
421 JCOEF *workspace;
422 int *coef_bits;
423 JQUANT_TBL *quanttbl;
424 JLONG Q00, Q01, Q02, Q10, Q11, Q20, num;
425 int DC1, DC2, DC3, DC4, DC5, DC6, DC7, DC8, DC9;
426 int Al, pred;
427
428 /* Keep a local variable to avoid looking it up more than once */
429 workspace = coef->workspace;
430
431 /* Force some input to be done if we are getting ahead of the input. */
432 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
433 !cinfo->inputctl->eoi_reached) {
434 if (cinfo->input_scan_number == cinfo->output_scan_number) {
435 /* If input is working on current scan, we ordinarily want it to
436 * have completed the current row. But if input scan is DC,
437 * we want it to keep one row ahead so that next block row's DC
438 * values are up to date.
439 */
440 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
441 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row + delta)
442 break;
443 }
444 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
445 return JPEG_SUSPENDED;
446 }
447
448 /* OK, output from the virtual arrays. */
449 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
450 ci++, compptr++) {
451 /* Don't bother to IDCT an uninteresting component. */
452 if (!compptr->component_needed)
453 continue;
454 /* Count non-dummy DCT block rows in this iMCU row. */
455 if (cinfo->output_iMCU_row < last_iMCU_row) {
456 block_rows = compptr->v_samp_factor;
457 access_rows = block_rows * 2; /* this and next iMCU row */
458 last_row = FALSE;
459 } else {
460 /* NB: can't use last_row_height here; it is input-side-dependent! */
461 block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
462 if (block_rows == 0) block_rows = compptr->v_samp_factor;
463 access_rows = block_rows; /* this iMCU row only */
464 last_row = TRUE;
465 }
466 /* Align the virtual buffer for this component. */
467 if (cinfo->output_iMCU_row > 0) {
468 access_rows += compptr->v_samp_factor; /* prior iMCU row too */
469 buffer = (*cinfo->mem->access_virt_barray)
470 ((j_common_ptr)cinfo, coef->whole_image[ci],
471 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
472 (JDIMENSION)access_rows, FALSE);
473 buffer += compptr->v_samp_factor; /* point to current iMCU row */
474 first_row = FALSE;
475 } else {
476 buffer = (*cinfo->mem->access_virt_barray)
477 ((j_common_ptr)cinfo, coef->whole_image[ci],
478 (JDIMENSION)0, (JDIMENSION)access_rows, FALSE);
479 first_row = TRUE;
480 }
481 /* Fetch component-dependent info */
482 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
483 quanttbl = compptr->quant_table;
484 Q00 = quanttbl->quantval[0];
485 Q01 = quanttbl->quantval[Q01_POS];
486 Q10 = quanttbl->quantval[Q10_POS];
487 Q20 = quanttbl->quantval[Q20_POS];
488 Q11 = quanttbl->quantval[Q11_POS];
489 Q02 = quanttbl->quantval[Q02_POS];
490 inverse_DCT = cinfo->idct->inverse_DCT[ci];
491 output_ptr = output_buf[ci];
492 /* Loop over all DCT blocks to be processed. */
493 for (block_row = 0; block_row < block_rows; block_row++) {
494 buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
495 if (first_row && block_row == 0)
496 prev_block_row = buffer_ptr;
497 else
498 prev_block_row = buffer[block_row - 1];
499 if (last_row && block_row == block_rows - 1)
500 next_block_row = buffer_ptr;
501 else
502 next_block_row = buffer[block_row + 1];
503 /* We fetch the surrounding DC values using a sliding-register approach.
504 * Initialize all nine here so as to do the right thing on narrow pics.
505 */
506 DC1 = DC2 = DC3 = (int)prev_block_row[0][0];
507 DC4 = DC5 = DC6 = (int)buffer_ptr[0][0];
508 DC7 = DC8 = DC9 = (int)next_block_row[0][0];
509 output_col = 0;
510 last_block_column = compptr->width_in_blocks - 1;
511 for (block_num = cinfo->master->first_MCU_col[ci];
512 block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
513 /* Fetch current DCT block into workspace so we can modify it. */
514 jcopy_block_row(buffer_ptr, (JBLOCKROW)workspace, (JDIMENSION)1);
515 /* Update DC values */
516 if (block_num < last_block_column) {
517 DC3 = (int)prev_block_row[1][0];
518 DC6 = (int)buffer_ptr[1][0];
519 DC9 = (int)next_block_row[1][0];
520 }
521 /* Compute coefficient estimates per K.8.
522 * An estimate is applied only if coefficient is still zero,
523 * and is not known to be fully accurate.
524 */
525 /* AC01 */
526 if ((Al = coef_bits[1]) != 0 && workspace[1] == 0) {
527 num = 36 * Q00 * (DC4 - DC6);
528 if (num >= 0) {
529 pred = (int)(((Q01 << 7) + num) / (Q01 << 8));
530 if (Al > 0 && pred >= (1 << Al))
531 pred = (1 << Al) - 1;
532 } else {
533 pred = (int)(((Q01 << 7) - num) / (Q01 << 8));
534 if (Al > 0 && pred >= (1 << Al))
535 pred = (1 << Al) - 1;
536 pred = -pred;
537 }
538 workspace[1] = (JCOEF)pred;
539 }
540 /* AC10 */
541 if ((Al = coef_bits[2]) != 0 && workspace[8] == 0) {
542 num = 36 * Q00 * (DC2 - DC8);
543 if (num >= 0) {
544 pred = (int)(((Q10 << 7) + num) / (Q10 << 8));
545 if (Al > 0 && pred >= (1 << Al))
546 pred = (1 << Al) - 1;
547 } else {
548 pred = (int)(((Q10 << 7) - num) / (Q10 << 8));
549 if (Al > 0 && pred >= (1 << Al))
550 pred = (1 << Al) - 1;
551 pred = -pred;
552 }
553 workspace[8] = (JCOEF)pred;
554 }
555 /* AC20 */
556 if ((Al = coef_bits[3]) != 0 && workspace[16] == 0) {
557 num = 9 * Q00 * (DC2 + DC8 - 2 * DC5);
558 if (num >= 0) {
559 pred = (int)(((Q20 << 7) + num) / (Q20 << 8));
560 if (Al > 0 && pred >= (1 << Al))
561 pred = (1 << Al) - 1;
562 } else {
563 pred = (int)(((Q20 << 7) - num) / (Q20 << 8));
564 if (Al > 0 && pred >= (1 << Al))
565 pred = (1 << Al) - 1;
566 pred = -pred;
567 }
568 workspace[16] = (JCOEF)pred;
569 }
570 /* AC11 */
571 if ((Al = coef_bits[4]) != 0 && workspace[9] == 0) {
572 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
573 if (num >= 0) {
574 pred = (int)(((Q11 << 7) + num) / (Q11 << 8));
575 if (Al > 0 && pred >= (1 << Al))
576 pred = (1 << Al) - 1;
577 } else {
578 pred = (int)(((Q11 << 7) - num) / (Q11 << 8));
579 if (Al > 0 && pred >= (1 << Al))
580 pred = (1 << Al) - 1;
581 pred = -pred;
582 }
583 workspace[9] = (JCOEF)pred;
584 }
585 /* AC02 */
586 if ((Al = coef_bits[5]) != 0 && workspace[2] == 0) {
587 num = 9 * Q00 * (DC4 + DC6 - 2 * DC5);
588 if (num >= 0) {
589 pred = (int)(((Q02 << 7) + num) / (Q02 << 8));
590 if (Al > 0 && pred >= (1 << Al))
591 pred = (1 << Al) - 1;
592 } else {
593 pred = (int)(((Q02 << 7) - num) / (Q02 << 8));
594 if (Al > 0 && pred >= (1 << Al))
595 pred = (1 << Al) - 1;
596 pred = -pred;
597 }
598 workspace[2] = (JCOEF)pred;
599 }
600 /* OK, do the IDCT */
601 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)workspace, output_ptr,
602 output_col);
603 /* Advance for next column */
604 DC1 = DC2; DC2 = DC3;
605 DC4 = DC5; DC5 = DC6;
606 DC7 = DC8; DC8 = DC9;
607 buffer_ptr++, prev_block_row++, next_block_row++;
608 output_col += compptr->_DCT_scaled_size;
609 }
610 output_ptr += compptr->_DCT_scaled_size;
611 }
612 }
613
614 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
615 return JPEG_ROW_COMPLETED;
616 return JPEG_SCAN_COMPLETED;
617}
618
619#endif /* BLOCK_SMOOTHING_SUPPORTED */
620
621
622/*
623 * Initialize coefficient buffer controller.
624 */
625
626GLOBAL(void)
627jinit_d_coef_controller(j_decompress_ptr cinfo, boolean need_full_buffer)
628{
629 my_coef_ptr coef;
630
631 coef = (my_coef_ptr)
632 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
633 sizeof(my_coef_controller));
634 cinfo->coef = (struct jpeg_d_coef_controller *)coef;
635 coef->pub.start_input_pass = start_input_pass;
636 coef->pub.start_output_pass = start_output_pass;
637#ifdef BLOCK_SMOOTHING_SUPPORTED
638 coef->coef_bits_latch = NULL;
639#endif
640
641 /* Create the coefficient buffer. */
642 if (need_full_buffer) {
643#ifdef D_MULTISCAN_FILES_SUPPORTED
644 /* Allocate a full-image virtual array for each component, */
645 /* padded to a multiple of samp_factor DCT blocks in each direction. */
646 /* Note we ask for a pre-zeroed array. */
647 int ci, access_rows;
648 jpeg_component_info *compptr;
649
650 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
651 ci++, compptr++) {
652 access_rows = compptr->v_samp_factor;
653#ifdef BLOCK_SMOOTHING_SUPPORTED
654 /* If block smoothing could be used, need a bigger window */
655 if (cinfo->progressive_mode)
656 access_rows *= 3;
657#endif
658 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
659 ((j_common_ptr)cinfo, JPOOL_IMAGE, TRUE,
660 (JDIMENSION)jround_up((long)compptr->width_in_blocks,
661 (long)compptr->h_samp_factor),
662 (JDIMENSION)jround_up((long)compptr->height_in_blocks,
663 (long)compptr->v_samp_factor),
664 (JDIMENSION)access_rows);
665 }
666 coef->pub.consume_data = consume_data;
667 coef->pub.decompress_data = decompress_data;
668 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
669#else
670 ERREXIT(cinfo, JERR_NOT_COMPILED);
671#endif
672 } else {
673 /* We only need a single-MCU buffer. */
674 JBLOCKROW buffer;
675 int i;
676
677 buffer = (JBLOCKROW)
678 (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE,
679 D_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
680 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
681 coef->MCU_buffer[i] = buffer + i;
682 }
683 coef->pub.consume_data = dummy_consume_data;
684 coef->pub.decompress_data = decompress_onepass;
685 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
686 }
687
688 /* Allocate the workspace buffer */
689 coef->workspace = (JCOEF *)
690 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
691 sizeof(JCOEF) * DCTSIZE2);
692}
693