1 /*
2 * jdcoefct.c
3 *
4 * Copyright (C) 1994-1998, 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 lossy 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 "jinclude8.h"
19 #include "jpeglib8.h"
20 #include "jlossy8.h"
21
22 /* Block smoothing is only applicable for progressive JPEG, so: */
23 #ifndef D_PROGRESSIVE_SUPPORTED
24 #undef BLOCK_SMOOTHING_SUPPORTED
25 #endif
26
27 /* Private buffer controller object */
28
29 typedef struct {
30 /* These variables keep track of the current location of the input side. */
31 /* cinfo->input_iMCU_row is also used for this. */
32 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */
33 int MCU_vert_offset; /* counts MCU rows within iMCU row */
34 int MCU_rows_per_iMCU_row; /* number of such rows needed */
35
36 /* The output side's location is represented by cinfo->output_iMCU_row. */
37
38 /* In single-pass modes, it's sufficient to buffer just one MCU.
39 * We allocate a workspace of D_MAX_DATA_UNITS_IN_MCU coefficient blocks,
40 * and let the entropy decoder write into that workspace each time.
41 * (On 80x86, the workspace is FAR even though it's not really very big;
42 * this is to keep the module interfaces unchanged when a large coefficient
43 * buffer is necessary.)
44 * In multi-pass modes, this array points to the current MCU's blocks
45 * within the virtual arrays; it is used only by the input side.
46 */
47 JBLOCKROW MCU_buffer[D_MAX_DATA_UNITS_IN_MCU];
48
49 #ifdef D_MULTISCAN_FILES_SUPPORTED
50 /* In multi-pass modes, we need a virtual block array for each component. */
51 jvirt_barray_ptr whole_image[MAX_COMPONENTS];
52 #endif
53
54 #ifdef BLOCK_SMOOTHING_SUPPORTED
55 /* When doing block smoothing, we latch coefficient Al values here */
56 int * coef_bits_latch;
57 #define SAVED_COEFS 6 /* we save coef_bits[0..5] */
58 #endif
59 } d_coef_controller;
60
61 typedef d_coef_controller * d_coef_ptr;
62
63 /* Forward declarations */
64 METHODDEF(int) decompress_onepass
65 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
66 #ifdef D_MULTISCAN_FILES_SUPPORTED
67 METHODDEF(int) decompress_data
68 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
69 #endif
70 #ifdef BLOCK_SMOOTHING_SUPPORTED
71 LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo));
72 METHODDEF(int) decompress_smooth_data
73 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
74 #endif
75
76
77 LOCAL(void)
start_iMCU_row(j_decompress_ptr cinfo)78 start_iMCU_row (j_decompress_ptr cinfo)
79 /* Reset within-iMCU-row counters for a new row (input side) */
80 {
81 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
82 d_coef_ptr coef = (d_coef_ptr) lossyd->coef_private;
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
106 METHODDEF(void)
start_input_pass(j_decompress_ptr cinfo)107 start_input_pass (j_decompress_ptr cinfo)
108 {
109 cinfo->input_iMCU_row = 0;
110 start_iMCU_row(cinfo);
111 }
112
113
114 /*
115 * Initialize for an output processing pass.
116 */
117
118 METHODDEF(void)
start_output_pass(j_decompress_ptr cinfo)119 start_output_pass (j_decompress_ptr cinfo)
120 {
121 #ifdef BLOCK_SMOOTHING_SUPPORTED
122 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
123 /* d_coef_ptr coef = (d_coef_ptr) lossyd->coef_private; */
124
125 /* If multipass, check to see whether to use block smoothing on this pass */
126 if (lossyd->coef_arrays != NULL) {
127 if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
128 lossyd->pub.decompress_data = decompress_smooth_data;
129 else
130 lossyd->pub.decompress_data = decompress_data;
131 }
132 #endif
133 cinfo->output_iMCU_row = 0;
134 }
135
136
137 /*
138 * Decompress and return some data in the single-pass case.
139 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
140 * Input and output must run in lockstep since we have only a one-MCU buffer.
141 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
142 *
143 * NB: output_buf contains a plane for each component in image,
144 * which we index according to the component's SOF position.
145 */
146
147 METHODDEF(int)
decompress_onepass(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)148 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
149 {
150 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
151 d_coef_ptr coef = (d_coef_ptr) lossyd->coef_private;
152 JDIMENSION MCU_col_num; /* index of current MCU within row */
153 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
154 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
155 int blkn, ci, xindex, yindex, yoffset, useful_width;
156 JSAMPARRAY output_ptr;
157 JDIMENSION start_col, output_col;
158 jpeg_component_info *compptr;
159 inverse_DCT_method_ptr inverse_DCT;
160
161 /* Loop to process as much as one whole iMCU row */
162 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
163 yoffset++) {
164 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
165 MCU_col_num++) {
166 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
167 jzero_far((void FAR *) coef->MCU_buffer[0],
168 (size_t)cinfo->data_units_in_MCU * SIZEOF(JBLOCK));
169 if (! (*lossyd->entropy_decode_mcu) (cinfo, coef->MCU_buffer)) {
170 /* Suspension forced; update state counters and exit */
171 coef->MCU_vert_offset = yoffset;
172 coef->MCU_ctr = MCU_col_num;
173 return JPEG_SUSPENDED;
174 }
175 /* Determine where data should go in output_buf and do the IDCT thing.
176 * We skip dummy blocks at the right and bottom edges (but blkn gets
177 * incremented past them!). Note the inner loop relies on having
178 * allocated the MCU_buffer[] blocks sequentially.
179 */
180 blkn = 0; /* index of current DCT block within MCU */
181 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
182 compptr = cinfo->cur_comp_info[ci];
183 /* Don't bother to IDCT an uninteresting component. */
184 if (! compptr->component_needed) {
185 blkn += compptr->MCU_data_units;
186 continue;
187 }
188 inverse_DCT = lossyd->inverse_DCT[compptr->component_index];
189 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
190 : compptr->last_col_width;
191 output_ptr = output_buf[compptr->component_index] +
192 yoffset * compptr->codec_data_unit;
193 start_col = MCU_col_num * (JDIMENSION)compptr->MCU_sample_width;
194 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
195 if (cinfo->input_iMCU_row < last_iMCU_row ||
196 yoffset+yindex < compptr->last_row_height) {
197 output_col = start_col;
198 for (xindex = 0; xindex < useful_width; xindex++) {
199 (*inverse_DCT) (cinfo, compptr,
200 (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
201 output_ptr, output_col);
202 output_col += (JDIMENSION)compptr->codec_data_unit;
203 }
204 }
205 blkn += compptr->MCU_width;
206 output_ptr += compptr->codec_data_unit;
207 }
208 }
209 }
210 /* Completed an MCU row, but perhaps not an iMCU row */
211 coef->MCU_ctr = 0;
212 }
213 /* Completed the iMCU row, advance counters for next one */
214 cinfo->output_iMCU_row++;
215 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
216 start_iMCU_row(cinfo);
217 return JPEG_ROW_COMPLETED;
218 }
219 /* Completed the scan */
220 (*cinfo->inputctl->finish_input_pass) (cinfo);
221 return JPEG_SCAN_COMPLETED;
222 }
223
224
225 /*
226 * Dummy consume-input routine for single-pass operation.
227 */
228
229 METHODDEF(int)
dummy_consume_data(j_decompress_ptr cinfo)230 dummy_consume_data (j_decompress_ptr cinfo)
231 {
232 return JPEG_SUSPENDED; /* Always indicate nothing was done */
233 }
234
235
236 #ifdef D_MULTISCAN_FILES_SUPPORTED
237
238 /*
239 * Consume input data and store it in the full-image coefficient buffer.
240 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
241 * ie, v_samp_factor block rows for each component in the scan.
242 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
243 */
244
245 METHODDEF(int)
consume_data(j_decompress_ptr cinfo)246 consume_data (j_decompress_ptr cinfo)
247 {
248 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
249 d_coef_ptr coef = (d_coef_ptr) lossyd->coef_private;
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 * (JDIMENSION)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 * (JDIMENSION)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 (! (*lossyd->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
317 METHODDEF(int)
decompress_data(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)318 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
319 {
320 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
321 d_coef_ptr coef = (d_coef_ptr) lossyd->coef_private;
322 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
323 JDIMENSION block_num;
324 int ci, block_row, block_rows;
325 JBLOCKARRAY buffer;
326 JBLOCKROW buffer_ptr;
327 JSAMPARRAY output_ptr;
328 JDIMENSION output_col;
329 jpeg_component_info *compptr;
330 inverse_DCT_method_ptr inverse_DCT;
331
332 /* Force some input to be done if we are getting ahead of the input. */
333 while (cinfo->input_scan_number < cinfo->output_scan_number ||
334 (cinfo->input_scan_number == cinfo->output_scan_number &&
335 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
336 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
337 return JPEG_SUSPENDED;
338 }
339
340 /* OK, output from the virtual arrays. */
341 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
342 ci++, compptr++) {
343 /* Don't bother to IDCT an uninteresting component. */
344 if (! compptr->component_needed)
345 continue;
346 /* Align the virtual buffer for this component. */
347 buffer = (*cinfo->mem->access_virt_barray)
348 ((j_common_ptr) cinfo, coef->whole_image[ci],
349 cinfo->output_iMCU_row * (JDIMENSION)compptr->v_samp_factor,
350 (JDIMENSION) compptr->v_samp_factor, FALSE);
351 /* Count non-dummy DCT block rows in this iMCU row. */
352 if (cinfo->output_iMCU_row < last_iMCU_row)
353 block_rows = compptr->v_samp_factor;
354 else {
355 /* NB: can't use last_row_height here; it is input-side-dependent! */
356 block_rows = (int)compptr->height_in_data_units % compptr->v_samp_factor;
357 if (block_rows == 0) block_rows = compptr->v_samp_factor;
358 }
359 inverse_DCT = lossyd->inverse_DCT[ci];
360 output_ptr = output_buf[ci];
361 /* Loop over all DCT blocks to be processed. */
362 for (block_row = 0; block_row < block_rows; block_row++) {
363 buffer_ptr = buffer[block_row];
364 output_col = 0;
365 for (block_num = 0; block_num < compptr->width_in_data_units; block_num++) {
366 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
367 output_ptr, output_col);
368 buffer_ptr++;
369 output_col += (JDIMENSION)compptr->codec_data_unit;
370 }
371 output_ptr += compptr->codec_data_unit;
372 }
373 }
374
375 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
376 return JPEG_ROW_COMPLETED;
377 return JPEG_SCAN_COMPLETED;
378 }
379
380 #endif /* D_MULTISCAN_FILES_SUPPORTED */
381
382
383 #ifdef BLOCK_SMOOTHING_SUPPORTED
384
385 /*
386 * This code applies interblock smoothing as described by section K.8
387 * of the JPEG standard: the first 5 AC coefficients are estimated from
388 * the DC values of a DCT block and its 8 neighboring blocks.
389 * We apply smoothing only for progressive JPEG decoding, and only if
390 * the coefficients it can estimate are not yet known to full precision.
391 */
392
393 /* Natural-order array positions of the first 5 zigzag-order coefficients */
394 #define Q01_POS 1
395 #define Q10_POS 8
396 #define Q20_POS 16
397 #define Q11_POS 9
398 #define Q02_POS 2
399
400 /*
401 * Determine whether block smoothing is applicable and safe.
402 * We also latch the current states of the coef_bits[] entries for the
403 * AC coefficients; otherwise, if the input side of the decompressor
404 * advances into a new scan, we might think the coefficients are known
405 * more accurately than they really are.
406 */
407
408 LOCAL(boolean)
smoothing_ok(j_decompress_ptr cinfo)409 smoothing_ok (j_decompress_ptr cinfo)
410 {
411 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
412 d_coef_ptr coef = (d_coef_ptr) lossyd->coef_private;
413 boolean smoothing_useful = FALSE;
414 int ci, coefi;
415 jpeg_component_info *compptr;
416 JQUANT_TBL * qtable;
417 int * coef_bits;
418 int * coef_bits_latch;
419
420 if ((! (cinfo->process == JPROC_PROGRESSIVE)) || cinfo->coef_bits == NULL)
421 return FALSE;
422
423 /* Allocate latch area if not already done */
424 if (coef->coef_bits_latch == NULL)
425 coef->coef_bits_latch = (int *)
426 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
427 (size_t)cinfo->num_components *
428 (SAVED_COEFS * SIZEOF(int)));
429 coef_bits_latch = coef->coef_bits_latch;
430
431 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
432 ci++, compptr++) {
433 /* All components' quantization values must already be latched. */
434 if ((qtable = compptr->quant_table) == NULL)
435 return FALSE;
436 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
437 if (qtable->quantval[0] == 0 ||
438 qtable->quantval[Q01_POS] == 0 ||
439 qtable->quantval[Q10_POS] == 0 ||
440 qtable->quantval[Q20_POS] == 0 ||
441 qtable->quantval[Q11_POS] == 0 ||
442 qtable->quantval[Q02_POS] == 0)
443 return FALSE;
444 /* DC values must be at least partly known for all components. */
445 coef_bits = cinfo->coef_bits[ci];
446 if (coef_bits[0] < 0)
447 return FALSE;
448 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
449 for (coefi = 1; coefi <= 5; coefi++) {
450 coef_bits_latch[coefi] = coef_bits[coefi];
451 if (coef_bits[coefi] != 0)
452 smoothing_useful = TRUE;
453 }
454 coef_bits_latch += SAVED_COEFS;
455 }
456
457 return smoothing_useful;
458 }
459
460
461 /*
462 * Variant of decompress_data for use when doing block smoothing.
463 */
464
465 METHODDEF(int)
decompress_smooth_data(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)466 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
467 {
468 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
469 d_coef_ptr coef = (d_coef_ptr) lossyd->coef_private;
470 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
471 JDIMENSION block_num, last_block_column;
472 int ci, block_row, block_rows, access_rows;
473 JBLOCKARRAY buffer;
474 JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
475 JSAMPARRAY output_ptr;
476 JDIMENSION output_col;
477 jpeg_component_info *compptr;
478 inverse_DCT_method_ptr inverse_DCT;
479 boolean first_row, last_row;
480 JBLOCK workspace;
481 int *coef_bits;
482 JQUANT_TBL *quanttbl;
483 IJG_INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
484 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
485 int Al, pred;
486
487 /* Force some input to be done if we are getting ahead of the input. */
488 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
489 ! cinfo->inputctl->eoi_reached) {
490 if (cinfo->input_scan_number == cinfo->output_scan_number) {
491 /* If input is working on current scan, we ordinarily want it to
492 * have completed the current row. But if input scan is DC,
493 * we want it to keep one row ahead so that next block row's DC
494 * values are up to date.
495 */
496 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
497 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
498 break;
499 }
500 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
501 return JPEG_SUSPENDED;
502 }
503
504 /* OK, output from the virtual arrays. */
505 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
506 ci++, compptr++) {
507 /* Don't bother to IDCT an uninteresting component. */
508 if (! compptr->component_needed)
509 continue;
510 /* Count non-dummy DCT block rows in this iMCU row. */
511 if (cinfo->output_iMCU_row < last_iMCU_row) {
512 block_rows = compptr->v_samp_factor;
513 access_rows = block_rows * 2; /* this and next iMCU row */
514 last_row = FALSE;
515 } else {
516 /* NB: can't use last_row_height here; it is input-side-dependent! */
517 block_rows = (int)compptr->height_in_data_units % compptr->v_samp_factor;
518 if (block_rows == 0) block_rows = compptr->v_samp_factor;
519 access_rows = block_rows; /* this iMCU row only */
520 last_row = TRUE;
521 }
522 /* Align the virtual buffer for this component. */
523 if (cinfo->output_iMCU_row > 0) {
524 access_rows += compptr->v_samp_factor; /* prior iMCU row too */
525 buffer = (*cinfo->mem->access_virt_barray)
526 ((j_common_ptr) cinfo, coef->whole_image[ci],
527 (cinfo->output_iMCU_row - 1) * (JDIMENSION)compptr->v_samp_factor,
528 (JDIMENSION) access_rows, FALSE);
529 buffer += compptr->v_samp_factor; /* point to current iMCU row */
530 first_row = FALSE;
531 } else {
532 buffer = (*cinfo->mem->access_virt_barray)
533 ((j_common_ptr) cinfo, coef->whole_image[ci],
534 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
535 first_row = TRUE;
536 }
537 /* Fetch component-dependent info */
538 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
539 quanttbl = compptr->quant_table;
540 Q00 = quanttbl->quantval[0];
541 Q01 = quanttbl->quantval[Q01_POS];
542 Q10 = quanttbl->quantval[Q10_POS];
543 Q20 = quanttbl->quantval[Q20_POS];
544 Q11 = quanttbl->quantval[Q11_POS];
545 Q02 = quanttbl->quantval[Q02_POS];
546 inverse_DCT = lossyd->inverse_DCT[ci];
547 output_ptr = output_buf[ci];
548 /* Loop over all DCT blocks to be processed. */
549 for (block_row = 0; block_row < block_rows; block_row++) {
550 buffer_ptr = buffer[block_row];
551 if (first_row && block_row == 0)
552 prev_block_row = buffer_ptr;
553 else
554 prev_block_row = buffer[block_row-1];
555 if (last_row && block_row == block_rows-1)
556 next_block_row = buffer_ptr;
557 else
558 next_block_row = buffer[block_row+1];
559 /* We fetch the surrounding DC values using a sliding-register approach.
560 * Initialize all nine here so as to do the right thing on narrow pics.
561 */
562 DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
563 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
564 DC7 = DC8 = DC9 = (int) next_block_row[0][0];
565 output_col = 0;
566 last_block_column = compptr->width_in_data_units - 1;
567 for (block_num = 0; block_num <= last_block_column; block_num++) {
568 /* Fetch current DCT block into workspace so we can modify it. */
569 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
570 /* Update DC values */
571 if (block_num < last_block_column) {
572 DC3 = (int) prev_block_row[1][0];
573 DC6 = (int) buffer_ptr[1][0];
574 DC9 = (int) next_block_row[1][0];
575 }
576 /* Compute coefficient estimates per K.8.
577 * An estimate is applied only if coefficient is still zero,
578 * and is not known to be fully accurate.
579 */
580 /* AC01 */
581 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
582 num = 36 * Q00 * (DC4 - DC6);
583 if (num >= 0) {
584 pred = (int) (((Q01<<7) + num) / (Q01<<8));
585 if (Al > 0 && pred >= (1<<Al))
586 pred = (1<<Al)-1;
587 } else {
588 pred = (int) (((Q01<<7) - num) / (Q01<<8));
589 if (Al > 0 && pred >= (1<<Al))
590 pred = (1<<Al)-1;
591 pred = -pred;
592 }
593 workspace[1] = (JCOEF) pred;
594 }
595 /* AC10 */
596 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
597 num = 36 * Q00 * (DC2 - DC8);
598 if (num >= 0) {
599 pred = (int) (((Q10<<7) + num) / (Q10<<8));
600 if (Al > 0 && pred >= (1<<Al))
601 pred = (1<<Al)-1;
602 } else {
603 pred = (int) (((Q10<<7) - num) / (Q10<<8));
604 if (Al > 0 && pred >= (1<<Al))
605 pred = (1<<Al)-1;
606 pred = -pred;
607 }
608 workspace[8] = (JCOEF) pred;
609 }
610 /* AC20 */
611 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
612 num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
613 if (num >= 0) {
614 pred = (int) (((Q20<<7) + num) / (Q20<<8));
615 if (Al > 0 && pred >= (1<<Al))
616 pred = (1<<Al)-1;
617 } else {
618 pred = (int) (((Q20<<7) - num) / (Q20<<8));
619 if (Al > 0 && pred >= (1<<Al))
620 pred = (1<<Al)-1;
621 pred = -pred;
622 }
623 workspace[16] = (JCOEF) pred;
624 }
625 /* AC11 */
626 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
627 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
628 if (num >= 0) {
629 pred = (int) (((Q11<<7) + num) / (Q11<<8));
630 if (Al > 0 && pred >= (1<<Al))
631 pred = (1<<Al)-1;
632 } else {
633 pred = (int) (((Q11<<7) - num) / (Q11<<8));
634 if (Al > 0 && pred >= (1<<Al))
635 pred = (1<<Al)-1;
636 pred = -pred;
637 }
638 workspace[9] = (JCOEF) pred;
639 }
640 /* AC02 */
641 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
642 num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
643 if (num >= 0) {
644 pred = (int) (((Q02<<7) + num) / (Q02<<8));
645 if (Al > 0 && pred >= (1<<Al))
646 pred = (1<<Al)-1;
647 } else {
648 pred = (int) (((Q02<<7) - num) / (Q02<<8));
649 if (Al > 0 && pred >= (1<<Al))
650 pred = (1<<Al)-1;
651 pred = -pred;
652 }
653 workspace[2] = (JCOEF) pred;
654 }
655 /* OK, do the IDCT */
656 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
657 output_ptr, output_col);
658 /* Advance for next column */
659 DC1 = DC2; DC2 = DC3;
660 DC4 = DC5; DC5 = DC6;
661 DC7 = DC8; DC8 = DC9;
662 buffer_ptr++, prev_block_row++, next_block_row++;
663 output_col += (JDIMENSION)compptr->codec_data_unit;
664 }
665 output_ptr += compptr->codec_data_unit;
666 }
667 }
668
669 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
670 return JPEG_ROW_COMPLETED;
671 return JPEG_SCAN_COMPLETED;
672 }
673
674 #endif /* BLOCK_SMOOTHING_SUPPORTED */
675
676
677 /*
678 * Initialize coefficient buffer controller.
679 */
680
681 GLOBAL(void)
jinit_d_coef_controller(j_decompress_ptr cinfo,boolean need_full_buffer)682 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
683 {
684 j_lossy_d_ptr lossyd = (j_lossy_d_ptr) cinfo->codec;
685 d_coef_ptr coef;
686
687 coef = (d_coef_ptr)
688 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
689 SIZEOF(d_coef_controller));
690 lossyd->coef_private = (void *) coef;
691 lossyd->coef_start_input_pass = start_input_pass;
692 lossyd->coef_start_output_pass = start_output_pass;
693 #ifdef BLOCK_SMOOTHING_SUPPORTED
694 coef->coef_bits_latch = NULL;
695 #endif
696
697 /* Create the coefficient buffer. */
698 if (need_full_buffer) {
699 #ifdef D_MULTISCAN_FILES_SUPPORTED
700 /* Allocate a full-image virtual array for each component, */
701 /* padded to a multiple of samp_factor DCT blocks in each direction. */
702 /* Note we ask for a pre-zeroed array. */
703 int ci, access_rows;
704 jpeg_component_info *compptr;
705
706 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
707 ci++, compptr++) {
708 access_rows = compptr->v_samp_factor;
709 #ifdef BLOCK_SMOOTHING_SUPPORTED
710 /* If block smoothing could be used, need a bigger window */
711 if (cinfo->process == JPROC_PROGRESSIVE)
712 access_rows *= 3;
713 #endif
714 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
715 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
716 (JDIMENSION) jround_up((long) compptr->width_in_data_units,
717 (long) compptr->h_samp_factor),
718 (JDIMENSION) jround_up((long) compptr->height_in_data_units,
719 (long) compptr->v_samp_factor),
720 (JDIMENSION) access_rows);
721 }
722 lossyd->pub.consume_data = consume_data;
723 lossyd->pub.decompress_data = decompress_data;
724 lossyd->coef_arrays = coef->whole_image; /* link to virtual arrays */
725 #else
726 ERREXIT(cinfo, JERR_NOT_COMPILED);
727 #endif
728 } else {
729 /* We only need a single-MCU buffer. */
730 JBLOCKROW buffer;
731 int i;
732
733 buffer = (JBLOCKROW)
734 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
735 D_MAX_DATA_UNITS_IN_MCU * SIZEOF(JBLOCK));
736 for (i = 0; i < D_MAX_DATA_UNITS_IN_MCU; i++) {
737 coef->MCU_buffer[i] = buffer + i;
738 }
739 lossyd->pub.consume_data = dummy_consume_data;
740 lossyd->pub.decompress_data = decompress_onepass;
741 lossyd->coef_arrays = NULL; /* flag for no virtual arrays */
742 }
743 }
744