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1/*
2 * jdcoefct.c
3 *
4 * Copyright (C) 1994-1997, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains the coefficient buffer controller for decompression.
9 * This controller is the top level of the JPEG decompressor proper.
10 * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
11 *
12 * In buffered-image mode, this controller is the interface between
13 * input-oriented processing and output-oriented processing.
14 * Also, the input side (only) is used when reading a file for transcoding.
15 */
16
17#define JPEG_INTERNALS
18#include "jinclude.h"
19#include "jpeglib.h"
20
21/* Block smoothing is only applicable for progressive JPEG, so: */
22#ifndef D_PROGRESSIVE_SUPPORTED
23#undef BLOCK_SMOOTHING_SUPPORTED
24#endif
25
26/* Private buffer controller object */
27
28typedef struct {
29 struct jpeg_d_coef_controller pub; /* public fields */
30
31 /* These variables keep track of the current location of the input side. */
32 /* cinfo->input_iMCU_row is also used for this. */
33 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */
34 int MCU_vert_offset; /* counts MCU rows within iMCU row */
35 int MCU_rows_per_iMCU_row; /* number of such rows needed */
36
37 /* The output side's location is represented by cinfo->output_iMCU_row. */
38
39 /* In single-pass modes, it's sufficient to buffer just one MCU.
40 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
41 * and let the entropy decoder write into that workspace each time.
42 * (On 80x86, the workspace is FAR even though it's not really very big;
43 * this is to keep the module interfaces unchanged when a large coefficient
44 * buffer is necessary.)
45 * In multi-pass modes, this array points to the current MCU's blocks
46 * within the virtual arrays; it is used only by the input side.
47 */
48 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];
49
50#ifdef D_MULTISCAN_FILES_SUPPORTED
51 /* In multi-pass modes, we need a virtual block array for each component. */
52 jvirt_barray_ptr whole_image[MAX_COMPONENTS];
53#endif
54
55#ifdef BLOCK_SMOOTHING_SUPPORTED
56 /* When doing block smoothing, we latch coefficient Al values here */
57 int * coef_bits_latch;
58#define SAVED_COEFS 6 /* we save coef_bits[0..5] */
59#endif
60} my_coef_controller;
61
62typedef my_coef_controller * my_coef_ptr;
63
64/* Forward declarations */
65METHODDEF(int) decompress_onepass
66 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
67#ifdef D_MULTISCAN_FILES_SUPPORTED
68METHODDEF(int) decompress_data
69 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
70#endif
71#ifdef BLOCK_SMOOTHING_SUPPORTED
72LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo));
73METHODDEF(int) decompress_smooth_data
74 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
75#endif
76
77
78LOCAL(void)
79start_iMCU_row (j_decompress_ptr cinfo)
80/* Reset within-iMCU-row counters for a new row (input side) */
81{
82 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
83
84 /* In an interleaved scan, an MCU row is the same as an iMCU row.
85 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
86 * But at the bottom of the image, process only what's left.
87 */
88 if (cinfo->comps_in_scan > 1) {
89 coef->MCU_rows_per_iMCU_row = 1;
90 } else {
91 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
92 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
93 else
94 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
95 }
96
97 coef->MCU_ctr = 0;
98 coef->MCU_vert_offset = 0;
99}
100
101
102/*
103 * Initialize for an input processing pass.
104 */
105
106METHODDEF(void)
107#if defined(__VISAGECPP__)
108start_input_pass2 (j_decompress_ptr cinfo)
109#else
110start_input_pass (j_decompress_ptr cinfo)
111#endif
112{
113 cinfo->input_iMCU_row = 0;
114 start_iMCU_row(cinfo);
115}
116
117/*
118 * Initialize for an output processing pass.
119 */
120
121METHODDEF(void)
122start_output_pass (j_decompress_ptr cinfo)
123{
124#ifdef BLOCK_SMOOTHING_SUPPORTED
125 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
126
127 /* If multipass, check to see whether to use block smoothing on this pass */
128 if (coef->pub.coef_arrays != NULL) {
129 if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
130 coef->pub.decompress_data = decompress_smooth_data;
131 else
132 coef->pub.decompress_data = decompress_data;
133 }
134#endif
135 cinfo->output_iMCU_row = 0;
136}
137
138
139/*
140 * Decompress and return some data in the single-pass case.
141 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
142 * Input and output must run in lockstep since we have only a one-MCU buffer.
143 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
144 *
145 * NB: output_buf contains a plane for each component in image,
146 * which we index according to the component's SOF position.
147 */
148
149METHODDEF(int)
150decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
151{
152 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
153 JDIMENSION MCU_col_num; /* index of current MCU within row */
154 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
155 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
156 int blkn, ci, xindex, yindex, yoffset, useful_width;
157 JSAMPARRAY output_ptr;
158 JDIMENSION start_col, output_col;
159 jpeg_component_info *compptr;
160 inverse_DCT_method_ptr inverse_DCT;
161
162 /* Loop to process as much as one whole iMCU row */
163 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
164 yoffset++) {
165 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
166 MCU_col_num++) {
167 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
168 jzero_far((void FAR *) coef->MCU_buffer[0],
169 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));
170 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
171 /* Suspension forced; update state counters and exit */
172 coef->MCU_vert_offset = yoffset;
173 coef->MCU_ctr = MCU_col_num;
174 return JPEG_SUSPENDED;
175 }
176 /* Determine where data should go in output_buf and do the IDCT thing.
177 * We skip dummy blocks at the right and bottom edges (but blkn gets
178 * incremented past them!). Note the inner loop relies on having
179 * allocated the MCU_buffer[] blocks sequentially.
180 */
181 blkn = 0; /* index of current DCT block within MCU */
182 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
183 compptr = cinfo->cur_comp_info[ci];
184 /* Don't bother to IDCT an uninteresting component. */
185 if (! compptr->component_needed) {
186 blkn += compptr->MCU_blocks;
187 continue;
188 }
189 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
190 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
191 : compptr->last_col_width;
192 output_ptr = output_buf[compptr->component_index] +
193 yoffset * compptr->DCT_scaled_size;
194 start_col = MCU_col_num * compptr->MCU_sample_width;
195 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
196 if (cinfo->input_iMCU_row < last_iMCU_row ||
197 yoffset+yindex < compptr->last_row_height) {
198 output_col = start_col;
199 for (xindex = 0; xindex < useful_width; xindex++) {
200 (*inverse_DCT) (cinfo, compptr,
201 (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
202 output_ptr, output_col);
203 output_col += compptr->DCT_scaled_size;
204 }
205 }
206 blkn += compptr->MCU_width;
207 output_ptr += compptr->DCT_scaled_size;
208 }
209 }
210 }
211 /* Completed an MCU row, but perhaps not an iMCU row */
212 coef->MCU_ctr = 0;
213 }
214 /* Completed the iMCU row, advance counters for next one */
215 cinfo->output_iMCU_row++;
216 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
217 start_iMCU_row(cinfo);
218 return JPEG_ROW_COMPLETED;
219 }
220 /* Completed the scan */
221 (*cinfo->inputctl->finish_input_pass) (cinfo);
222 return JPEG_SCAN_COMPLETED;
223}
224
225
226/*
227 * Dummy consume-input routine for single-pass operation.
228 */
229
230METHODDEF(int)
231dummy_consume_data (j_decompress_ptr cinfo)
232{
233 return JPEG_SUSPENDED; /* Always indicate nothing was done */
234}
235
236
237#ifdef D_MULTISCAN_FILES_SUPPORTED
238
239/*
240 * Consume input data and store it in the full-image coefficient buffer.
241 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
242 * ie, v_samp_factor block rows for each component in the scan.
243 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
244 */
245
246METHODDEF(int)
247consume_data (j_decompress_ptr cinfo)
248{
249 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
250 JDIMENSION MCU_col_num; /* index of current MCU within row */
251 int blkn, ci, xindex, yindex, yoffset;
252 JDIMENSION start_col;
253 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
254 JBLOCKROW buffer_ptr;
255 jpeg_component_info *compptr;
256
257 /* Align the virtual buffers for the components used in this scan. */
258 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
259 compptr = cinfo->cur_comp_info[ci];
260 buffer[ci] = (*cinfo->mem->access_virt_barray)
261 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
262 cinfo->input_iMCU_row * compptr->v_samp_factor,
263 (JDIMENSION) compptr->v_samp_factor, TRUE);
264 /* Note: entropy decoder expects buffer to be zeroed,
265 * but this is handled automatically by the memory manager
266 * because we requested a pre-zeroed array.
267 */
268 }
269
270 /* Loop to process one whole iMCU row */
271 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
272 yoffset++) {
273 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
274 MCU_col_num++) {
275 /* Construct list of pointers to DCT blocks belonging to this MCU */
276 blkn = 0; /* index of current DCT block within MCU */
277 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
278 compptr = cinfo->cur_comp_info[ci];
279 start_col = MCU_col_num * compptr->MCU_width;
280 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
281 buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
282 for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
283 coef->MCU_buffer[blkn++] = buffer_ptr++;
284 }
285 }
286 }
287 /* Try to fetch the MCU. */
288 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
289 /* Suspension forced; update state counters and exit */
290 coef->MCU_vert_offset = yoffset;
291 coef->MCU_ctr = MCU_col_num;
292 return JPEG_SUSPENDED;
293 }
294 }
295 /* Completed an MCU row, but perhaps not an iMCU row */
296 coef->MCU_ctr = 0;
297 }
298 /* Completed the iMCU row, advance counters for next one */
299 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
300 start_iMCU_row(cinfo);
301 return JPEG_ROW_COMPLETED;
302 }
303 /* Completed the scan */
304 (*cinfo->inputctl->finish_input_pass) (cinfo);
305 return JPEG_SCAN_COMPLETED;
306}
307
308
309/*
310 * Decompress and return some data in the multi-pass case.
311 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
312 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
313 *
314 * NB: output_buf contains a plane for each component in image.
315 */
316
317METHODDEF(int)
318decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
319{
320 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
321 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
322 JDIMENSION block_num;
323 int ci, block_row, block_rows;
324 JBLOCKARRAY buffer;
325 JBLOCKROW buffer_ptr;
326 JSAMPARRAY output_ptr;
327 JDIMENSION output_col;
328 jpeg_component_info *compptr;
329 inverse_DCT_method_ptr inverse_DCT;
330
331 /* Force some input to be done if we are getting ahead of the input. */
332 while (cinfo->input_scan_number < cinfo->output_scan_number ||
333 (cinfo->input_scan_number == cinfo->output_scan_number &&
334 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
335 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
336 return JPEG_SUSPENDED;
337 }
338
339 /* OK, output from the virtual arrays. */
340 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
341 ci++, compptr++) {
342 /* Don't bother to IDCT an uninteresting component. */
343 if (! compptr->component_needed)
344 continue;
345 /* Align the virtual buffer for this component. */
346 buffer = (*cinfo->mem->access_virt_barray)
347 ((j_common_ptr) cinfo, coef->whole_image[ci],
348 cinfo->output_iMCU_row * compptr->v_samp_factor,
349 (JDIMENSION) compptr->v_samp_factor, FALSE);
350 /* Count non-dummy DCT block rows in this iMCU row. */
351 if (cinfo->output_iMCU_row < last_iMCU_row)
352 block_rows = compptr->v_samp_factor;
353 else {
354 /* NB: can't use last_row_height here; it is input-side-dependent! */
355 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
356 if (block_rows == 0) block_rows = compptr->v_samp_factor;
357 }
358 inverse_DCT = cinfo->idct->inverse_DCT[ci];
359 output_ptr = output_buf[ci];
360 /* Loop over all DCT blocks to be processed. */
361 for (block_row = 0; block_row < block_rows; block_row++) {
362 buffer_ptr = buffer[block_row];
363 output_col = 0;
364 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
365 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
366 output_ptr, output_col);
367 buffer_ptr++;
368 output_col += compptr->DCT_scaled_size;
369 }
370 output_ptr += compptr->DCT_scaled_size;
371 }
372 }
373
374 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
375 return JPEG_ROW_COMPLETED;
376 return JPEG_SCAN_COMPLETED;
377}
378
379#endif /* D_MULTISCAN_FILES_SUPPORTED */
380
381
382#ifdef BLOCK_SMOOTHING_SUPPORTED
383
384/*
385 * This code applies interblock smoothing as described by section K.8
386 * of the JPEG standard: the first 5 AC coefficients are estimated from
387 * the DC values of a DCT block and its 8 neighboring blocks.
388 * We apply smoothing only for progressive JPEG decoding, and only if
389 * the coefficients it can estimate are not yet known to full precision.
390 */
391
392/* Natural-order array positions of the first 5 zigzag-order coefficients */
393#define Q01_POS 1
394#define Q10_POS 8
395#define Q20_POS 16
396#define Q11_POS 9
397#define Q02_POS 2
398
399/*
400 * Determine whether block smoothing is applicable and safe.
401 * We also latch the current states of the coef_bits[] entries for the
402 * AC coefficients; otherwise, if the input side of the decompressor
403 * advances into a new scan, we might think the coefficients are known
404 * more accurately than they really are.
405 */
406
407LOCAL(boolean)
408smoothing_ok (j_decompress_ptr cinfo)
409{
410 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
411 boolean smoothing_useful = FALSE;
412 int ci, coefi;
413 jpeg_component_info *compptr;
414 JQUANT_TBL * qtable;
415 int * coef_bits;
416 int * coef_bits_latch;
417
418 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
419 return FALSE;
420
421 /* Allocate latch area if not already done */
422 if (coef->coef_bits_latch == NULL)
423 coef->coef_bits_latch = (int *)
424 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
425 cinfo->num_components *
426 (SAVED_COEFS * SIZEOF(int)));
427 coef_bits_latch = coef->coef_bits_latch;
428
429 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
430 ci++, compptr++) {
431 /* All components' quantization values must already be latched. */
432 if ((qtable = compptr->quant_table) == NULL)
433 return FALSE;
434 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
435 if (qtable->quantval[0] == 0 ||
436 qtable->quantval[Q01_POS] == 0 ||
437 qtable->quantval[Q10_POS] == 0 ||
438 qtable->quantval[Q20_POS] == 0 ||
439 qtable->quantval[Q11_POS] == 0 ||
440 qtable->quantval[Q02_POS] == 0)
441 return FALSE;
442 /* DC values must be at least partly known for all components. */
443 coef_bits = cinfo->coef_bits[ci];
444 if (coef_bits[0] < 0)
445 return FALSE;
446 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
447 for (coefi = 1; coefi <= 5; coefi++) {
448 coef_bits_latch[coefi] = coef_bits[coefi];
449 if (coef_bits[coefi] != 0)
450 smoothing_useful = TRUE;
451 }
452 coef_bits_latch += SAVED_COEFS;
453 }
454
455 return smoothing_useful;
456}
457
458
459/*
460 * Variant of decompress_data for use when doing block smoothing.
461 */
462
463METHODDEF(int)
464decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
465{
466 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
467 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
468 JDIMENSION block_num, last_block_column;
469 int ci, block_row, block_rows, access_rows;
470 JBLOCKARRAY buffer;
471 JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
472 JSAMPARRAY output_ptr;
473 JDIMENSION output_col;
474 jpeg_component_info *compptr;
475 inverse_DCT_method_ptr inverse_DCT;
476 boolean first_row, last_row;
477 JBLOCK workspace;
478 int *coef_bits;
479 JQUANT_TBL *quanttbl;
480 JPEG_INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
481 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
482 int Al, pred;
483
484 /* Force some input to be done if we are getting ahead of the input. */
485 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
486 ! cinfo->inputctl->eoi_reached) {
487 if (cinfo->input_scan_number == cinfo->output_scan_number) {
488 /* If input is working on current scan, we ordinarily want it to
489 * have completed the current row. But if input scan is DC,
490 * we want it to keep one row ahead so that next block row's DC
491 * values are up to date.
492 */
493 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
494 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
495 break;
496 }
497 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
498 return JPEG_SUSPENDED;
499 }
500
501 /* OK, output from the virtual arrays. */
502 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
503 ci++, compptr++) {
504 /* Don't bother to IDCT an uninteresting component. */
505 if (! compptr->component_needed)
506 continue;
507 /* Count non-dummy DCT block rows in this iMCU row. */
508 if (cinfo->output_iMCU_row < last_iMCU_row) {
509 block_rows = compptr->v_samp_factor;
510 access_rows = block_rows * 2; /* this and next iMCU row */
511 last_row = FALSE;
512 } else {
513 /* NB: can't use last_row_height here; it is input-side-dependent! */
514 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
515 if (block_rows == 0) block_rows = compptr->v_samp_factor;
516 access_rows = block_rows; /* this iMCU row only */
517 last_row = TRUE;
518 }
519 /* Align the virtual buffer for this component. */
520 if (cinfo->output_iMCU_row > 0) {
521 access_rows += compptr->v_samp_factor; /* prior iMCU row too */
522 buffer = (*cinfo->mem->access_virt_barray)
523 ((j_common_ptr) cinfo, coef->whole_image[ci],
524 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
525 (JDIMENSION) access_rows, FALSE);
526 buffer += compptr->v_samp_factor; /* point to current iMCU row */
527 first_row = FALSE;
528 } else {
529 buffer = (*cinfo->mem->access_virt_barray)
530 ((j_common_ptr) cinfo, coef->whole_image[ci],
531 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
532 first_row = TRUE;
533 }
534 /* Fetch component-dependent info */
535 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
536 quanttbl = compptr->quant_table;
537 Q00 = quanttbl->quantval[0];
538 Q01 = quanttbl->quantval[Q01_POS];
539 Q10 = quanttbl->quantval[Q10_POS];
540 Q20 = quanttbl->quantval[Q20_POS];
541 Q11 = quanttbl->quantval[Q11_POS];
542 Q02 = quanttbl->quantval[Q02_POS];
543 inverse_DCT = cinfo->idct->inverse_DCT[ci];
544 output_ptr = output_buf[ci];
545 /* Loop over all DCT blocks to be processed. */
546 for (block_row = 0; block_row < block_rows; block_row++) {
547 buffer_ptr = buffer[block_row];
548 if (first_row && block_row == 0)
549 prev_block_row = buffer_ptr;
550 else
551 prev_block_row = buffer[block_row-1];
552 if (last_row && block_row == block_rows-1)
553 next_block_row = buffer_ptr;
554 else
555 next_block_row = buffer[block_row+1];
556 /* We fetch the surrounding DC values using a sliding-register approach.
557 * Initialize all nine here so as to do the right thing on narrow pics.
558 */
559 DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
560 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
561 DC7 = DC8 = DC9 = (int) next_block_row[0][0];
562 output_col = 0;
563 last_block_column = compptr->width_in_blocks - 1;
564 for (block_num = 0; block_num <= last_block_column; block_num++) {
565 /* Fetch current DCT block into workspace so we can modify it. */
566 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
567 /* Update DC values */
568 if (block_num < last_block_column) {
569 DC3 = (int) prev_block_row[1][0];
570 DC6 = (int) buffer_ptr[1][0];
571 DC9 = (int) next_block_row[1][0];
572 }
573 /* Compute coefficient estimates per K.8.
574 * An estimate is applied only if coefficient is still zero,
575 * and is not known to be fully accurate.
576 */
577 /* AC01 */
578 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
579 num = 36 * Q00 * (DC4 - DC6);
580 if (num >= 0) {
581 pred = (int) (((Q01<<7) + num) / (Q01<<8));
582 if (Al > 0 && pred >= (1<<Al))
583 pred = (1<<Al)-1;
584 } else {
585 pred = (int) (((Q01<<7) - num) / (Q01<<8));
586 if (Al > 0 && pred >= (1<<Al))
587 pred = (1<<Al)-1;
588 pred = -pred;
589 }
590 workspace[1] = (JCOEF) pred;
591 }
592 /* AC10 */
593 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
594 num = 36 * Q00 * (DC2 - DC8);
595 if (num >= 0) {
596 pred = (int) (((Q10<<7) + num) / (Q10<<8));
597 if (Al > 0 && pred >= (1<<Al))
598 pred = (1<<Al)-1;
599 } else {
600 pred = (int) (((Q10<<7) - num) / (Q10<<8));
601 if (Al > 0 && pred >= (1<<Al))
602 pred = (1<<Al)-1;
603 pred = -pred;
604 }
605 workspace[8] = (JCOEF) pred;
606 }
607 /* AC20 */
608 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
609 num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
610 if (num >= 0) {
611 pred = (int) (((Q20<<7) + num) / (Q20<<8));
612 if (Al > 0 && pred >= (1<<Al))
613 pred = (1<<Al)-1;
614 } else {
615 pred = (int) (((Q20<<7) - num) / (Q20<<8));
616 if (Al > 0 && pred >= (1<<Al))
617 pred = (1<<Al)-1;
618 pred = -pred;
619 }
620 workspace[16] = (JCOEF) pred;
621 }
622 /* AC11 */
623 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
624 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
625 if (num >= 0) {
626 pred = (int) (((Q11<<7) + num) / (Q11<<8));
627 if (Al > 0 && pred >= (1<<Al))
628 pred = (1<<Al)-1;
629 } else {
630 pred = (int) (((Q11<<7) - num) / (Q11<<8));
631 if (Al > 0 && pred >= (1<<Al))
632 pred = (1<<Al)-1;
633 pred = -pred;
634 }
635 workspace[9] = (JCOEF) pred;
636 }
637 /* AC02 */
638 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
639 num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
640 if (num >= 0) {
641 pred = (int) (((Q02<<7) + num) / (Q02<<8));
642 if (Al > 0 && pred >= (1<<Al))
643 pred = (1<<Al)-1;
644 } else {
645 pred = (int) (((Q02<<7) - num) / (Q02<<8));
646 if (Al > 0 && pred >= (1<<Al))
647 pred = (1<<Al)-1;
648 pred = -pred;
649 }
650 workspace[2] = (JCOEF) pred;
651 }
652 /* OK, do the IDCT */
653 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
654 output_ptr, output_col);
655 /* Advance for next column */
656 DC1 = DC2; DC2 = DC3;
657 DC4 = DC5; DC5 = DC6;
658 DC7 = DC8; DC8 = DC9;
659 buffer_ptr++, prev_block_row++, next_block_row++;
660 output_col += compptr->DCT_scaled_size;
661 }
662 output_ptr += compptr->DCT_scaled_size;
663 }
664 }
665
666 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
667 return JPEG_ROW_COMPLETED;
668 return JPEG_SCAN_COMPLETED;
669}
670
671#endif /* BLOCK_SMOOTHING_SUPPORTED */
672
673
674/*
675 * Initialize coefficient buffer controller.
676 */
677
678GLOBAL(void)
679jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
680{
681 my_coef_ptr coef;
682
683 coef = (my_coef_ptr)
684 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
685 SIZEOF(my_coef_controller));
686 cinfo->coef = (struct jpeg_d_coef_controller *) coef;
687#if defined(__VISAGECPP__)
688 coef->pub.start_input_pass2 = start_input_pass2;
689#else
690 coef->pub.start_input_pass = start_input_pass;
691#endif
692
693 coef->pub.start_output_pass = start_output_pass;
694#ifdef BLOCK_SMOOTHING_SUPPORTED
695 coef->coef_bits_latch = NULL;
696#endif
697
698 /* Create the coefficient buffer. */
699 if (need_full_buffer) {
700#ifdef D_MULTISCAN_FILES_SUPPORTED
701 /* Allocate a full-image virtual array for each component, */
702 /* padded to a multiple of samp_factor DCT blocks in each direction. */
703 /* Note we ask for a pre-zeroed array. */
704 int ci, access_rows;
705 jpeg_component_info *compptr;
706
707 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
708 ci++, compptr++) {
709 access_rows = compptr->v_samp_factor;
710#ifdef BLOCK_SMOOTHING_SUPPORTED
711 /* If block smoothing could be used, need a bigger window */
712 if (cinfo->progressive_mode)
713 access_rows *= 3;
714#endif
715 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
716 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
717 (JDIMENSION) jround_up((long) compptr->width_in_blocks,
718 (long) compptr->h_samp_factor),
719 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
720 (long) compptr->v_samp_factor),
721 (JDIMENSION) access_rows);
722 }
723 coef->pub.consume_data = consume_data;
724 coef->pub.decompress_data = decompress_data;
725 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
726#else
727 ERREXIT(cinfo, JERR_NOT_COMPILED);
728#endif
729 } else {
730 /* We only need a single-MCU buffer. */
731 JBLOCKROW buffer;
732 int i;
733
734 buffer = (JBLOCKROW)
735 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
736 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
737 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
738 coef->MCU_buffer[i] = buffer + i;
739 }
740 coef->pub.consume_data = dummy_consume_data;
741 coef->pub.decompress_data = decompress_onepass;
742 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
743 }
744}
745