1 /*
2 * jdcoefct.c
3 *
4 * Copyright (C) 1994-1997, Thomas G. Lane.
5 * Modified 2002-2011 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains the coefficient buffer controller for decompression.
10 * This controller is the top level of the JPEG decompressor proper.
11 * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
12 *
13 * In buffered-image mode, this controller is the interface between
14 * input-oriented processing and output-oriented processing.
15 * Also, the input side (only) is used when reading a file for transcoding.
16 */
17
18 #define JPEG_INTERNALS
19 #include "jinclude.h"
20 #include "jpeglib.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 struct jpeg_d_coef_controller pub; /* public fields */
31
32 /* These variables keep track of the current location of the input side. */
33 /* cinfo->input_iMCU_row is also used for this. */
34 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */
35 int MCU_vert_offset; /* counts MCU rows within iMCU row */
36 int MCU_rows_per_iMCU_row; /* number of such rows needed */
37
38 /* The output side's location is represented by cinfo->output_iMCU_row. */
39
40 /* In single-pass modes, it's sufficient to buffer just one MCU.
41 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
42 * and let the entropy decoder write into that workspace each time.
43 * (On 80x86, the workspace is FAR even though it's not really very big;
44 * this is to keep the module interfaces unchanged when a large coefficient
45 * buffer is necessary.)
46 * In multi-pass modes, this array points to the current MCU's blocks
47 * within the virtual arrays; it is used only by the input side.
48 */
49 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];
50
51 #ifdef D_MULTISCAN_FILES_SUPPORTED
52 /* In multi-pass modes, we need a virtual block array for each component. */
53 jvirt_barray_ptr whole_image[MAX_COMPONENTS];
54 #endif
55
56 #ifdef BLOCK_SMOOTHING_SUPPORTED
57 /* When doing block smoothing, we latch coefficient Al values here */
58 int * coef_bits_latch;
59 #define SAVED_COEFS 6 /* we save coef_bits[0..5] */
60 #endif
61 } my_coef_controller;
62
63 typedef my_coef_controller * my_coef_ptr;
64
65 /* Forward declarations */
66 METHODDEF(int) decompress_onepass
67 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
68 #ifdef D_MULTISCAN_FILES_SUPPORTED
69 METHODDEF(int) decompress_data
70 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
71 #endif
72 #ifdef BLOCK_SMOOTHING_SUPPORTED
73 LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo));
74 METHODDEF(int) decompress_smooth_data
75 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
76 #endif
77
78
79 LOCAL(void)
80 start_iMCU_row (j_decompress_ptr cinfo)
81 /* Reset within-iMCU-row counters for a new row (input side) */
82 {
83 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
84
85 /* In an interleaved scan, an MCU row is the same as an iMCU row.
86 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
87 * But at the bottom of the image, process only what's left.
88 */
89 if (cinfo->comps_in_scan > 1) {
90 coef->MCU_rows_per_iMCU_row = 1;
91 } else {
92 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
93 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
94 else
95 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
96 }
97
98 coef->MCU_ctr = 0;
99 coef->MCU_vert_offset = 0;
100 }
101
102
103 /*
104 * Initialize for an input processing pass.
105 */
106
107 METHODDEF(void)
108 start_input_pass (j_decompress_ptr cinfo)
109 {
110 cinfo->input_iMCU_row = 0;
111 start_iMCU_row(cinfo);
112 }
113
114
115 /*
116 * Initialize for an output processing pass.
117 */
118
119 METHODDEF(void)
120 start_output_pass (j_decompress_ptr cinfo)
121 {
122 #ifdef BLOCK_SMOOTHING_SUPPORTED
123 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
124
125 /* If multipass, check to see whether to use block smoothing on this pass */
126 if (coef->pub.coef_arrays != NULL) {
127 if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
128 coef->pub.decompress_data = decompress_smooth_data;
129 else
130 coef->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)
148 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
149 {
150 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
151 JDIMENSION MCU_col_num; /* index of current MCU within row */
152 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
153 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
154 int blkn, ci, xindex, yindex, yoffset, useful_width;
155 JSAMPARRAY output_ptr;
156 JDIMENSION start_col, output_col;
157 jpeg_component_info *compptr;
158 inverse_DCT_method_ptr inverse_DCT;
159
160 /* Loop to process as much as one whole iMCU row */
161 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
162 yoffset++) {
163 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
164 MCU_col_num++) {
165 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
166 if (cinfo->lim_Se) /* can bypass in DC only case */
167 FMEMZERO((void FAR *) coef->MCU_buffer[0],
168 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));
169 if (! (*cinfo->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_blocks;
186 continue;
187 }
188 inverse_DCT = cinfo->idct->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->DCT_v_scaled_size;
193 start_col = MCU_col_num * 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 += compptr->DCT_h_scaled_size;
203 }
204 }
205 blkn += compptr->MCU_width;
206 output_ptr += compptr->DCT_v_scaled_size;
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)
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)
246 consume_data (j_decompress_ptr cinfo)
247 {
248 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
249 JDIMENSION MCU_col_num; /* index of current MCU within row */
250 int blkn, ci, xindex, yindex, yoffset;
251 JDIMENSION start_col;
252 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
253 JBLOCKROW buffer_ptr;
254 jpeg_component_info *compptr;
255
256 /* Align the virtual buffers for the components used in this scan. */
257 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
258 compptr = cinfo->cur_comp_info[ci];
259 buffer[ci] = (*cinfo->mem->access_virt_barray)
260 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
261 cinfo->input_iMCU_row * compptr->v_samp_factor,
262 (JDIMENSION) compptr->v_samp_factor, TRUE);
263 /* Note: entropy decoder expects buffer to be zeroed,
264 * but this is handled automatically by the memory manager
265 * because we requested a pre-zeroed array.
266 */
267 }
268
269 /* Loop to process one whole iMCU row */
270 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
271 yoffset++) {
272 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
273 MCU_col_num++) {
274 /* Construct list of pointers to DCT blocks belonging to this MCU */
275 blkn = 0; /* index of current DCT block within MCU */
276 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
277 compptr = cinfo->cur_comp_info[ci];
278 start_col = MCU_col_num * compptr->MCU_width;
279 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
280 buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
281 for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
282 coef->MCU_buffer[blkn++] = buffer_ptr++;
283 }
284 }
285 }
286 /* Try to fetch the MCU. */
287 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
288 /* Suspension forced; update state counters and exit */
289 coef->MCU_vert_offset = yoffset;
290 coef->MCU_ctr = MCU_col_num;
291 return JPEG_SUSPENDED;
292 }
293 }
294 /* Completed an MCU row, but perhaps not an iMCU row */
295 coef->MCU_ctr = 0;
296 }
297 /* Completed the iMCU row, advance counters for next one */
298 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
299 start_iMCU_row(cinfo);
300 return JPEG_ROW_COMPLETED;
301 }
302 /* Completed the scan */
303 (*cinfo->inputctl->finish_input_pass) (cinfo);
304 return JPEG_SCAN_COMPLETED;
305 }
306
307
308 /*
309 * Decompress and return some data in the multi-pass case.
310 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
311 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
312 *
313 * NB: output_buf contains a plane for each component in image.
314 */
315
316 METHODDEF(int)
317 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
318 {
319 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
320 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
321 JDIMENSION block_num;
322 int ci, block_row, block_rows;
323 JBLOCKARRAY buffer;
324 JBLOCKROW buffer_ptr;
325 JSAMPARRAY output_ptr;
326 JDIMENSION output_col;
327 jpeg_component_info *compptr;
328 inverse_DCT_method_ptr inverse_DCT;
329
330 /* Force some input to be done if we are getting ahead of the input. */
331 while (cinfo->input_scan_number < cinfo->output_scan_number ||
332 (cinfo->input_scan_number == cinfo->output_scan_number &&
333 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
334 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
335 return JPEG_SUSPENDED;
336 }
337
338 /* OK, output from the virtual arrays. */
339 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
340 ci++, compptr++) {
341 /* Don't bother to IDCT an uninteresting component. */
342 if (! compptr->component_needed)
343 continue;
344 /* Align the virtual buffer for this component. */
345 buffer = (*cinfo->mem->access_virt_barray)
346 ((j_common_ptr) cinfo, coef->whole_image[ci],
347 cinfo->output_iMCU_row * compptr->v_samp_factor,
348 (JDIMENSION) compptr->v_samp_factor, FALSE);
349 /* Count non-dummy DCT block rows in this iMCU row. */
350 if (cinfo->output_iMCU_row < last_iMCU_row)
351 block_rows = compptr->v_samp_factor;
352 else {
353 /* NB: can't use last_row_height here; it is input-side-dependent! */
354 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
355 if (block_rows == 0) block_rows = compptr->v_samp_factor;
356 }
357 inverse_DCT = cinfo->idct->inverse_DCT[ci];
358 output_ptr = output_buf[ci];
359 /* Loop over all DCT blocks to be processed. */
360 for (block_row = 0; block_row < block_rows; block_row++) {
361 buffer_ptr = buffer[block_row];
362 output_col = 0;
363 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
364 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
365 output_ptr, output_col);
366 buffer_ptr++;
367 output_col += compptr->DCT_h_scaled_size;
368 }
369 output_ptr += compptr->DCT_v_scaled_size;
370 }
371 }
372
373 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
374 return JPEG_ROW_COMPLETED;
375 return JPEG_SCAN_COMPLETED;
376 }
377
378 #endif /* D_MULTISCAN_FILES_SUPPORTED */
379
380
381 #ifdef BLOCK_SMOOTHING_SUPPORTED
382
383 /*
384 * This code applies interblock smoothing as described by section K.8
385 * of the JPEG standard: the first 5 AC coefficients are estimated from
386 * the DC values of a DCT block and its 8 neighboring blocks.
387 * We apply smoothing only for progressive JPEG decoding, and only if
388 * the coefficients it can estimate are not yet known to full precision.
389 */
390
391 /* Natural-order array positions of the first 5 zigzag-order coefficients */
392 #define Q01_POS 1
393 #define Q10_POS 8
394 #define Q20_POS 16
395 #define Q11_POS 9
396 #define Q02_POS 2
397
398 /*
399 * Determine whether block smoothing is applicable and safe.
400 * We also latch the current states of the coef_bits[] entries for the
401 * AC coefficients; otherwise, if the input side of the decompressor
402 * advances into a new scan, we might think the coefficients are known
403 * more accurately than they really are.
404 */
405
406 LOCAL(boolean)
407 smoothing_ok (j_decompress_ptr cinfo)
408 {
409 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
410 boolean smoothing_useful = FALSE;
411 int ci, coefi;
412 jpeg_component_info *compptr;
413 JQUANT_TBL * qtable;
414 int * coef_bits;
415 int * coef_bits_latch;
416
417 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
418 return FALSE;
419
420 /* Allocate latch area if not already done */
421 if (coef->coef_bits_latch == NULL)
422 coef->coef_bits_latch = (int *)
423 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
424 cinfo->num_components *
425 (SAVED_COEFS * SIZEOF(int)));
426 coef_bits_latch = coef->coef_bits_latch;
427
428 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
429 ci++, compptr++) {
430 /* All components' quantization values must already be latched. */
431 if ((qtable = compptr->quant_table) == NULL)
432 return FALSE;
433 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
434 if (qtable->quantval[0] == 0 ||
435 qtable->quantval[Q01_POS] == 0 ||
436 qtable->quantval[Q10_POS] == 0 ||
437 qtable->quantval[Q20_POS] == 0 ||
438 qtable->quantval[Q11_POS] == 0 ||
439 qtable->quantval[Q02_POS] == 0)
440 return FALSE;
441 /* DC values must be at least partly known for all components. */
442 coef_bits = cinfo->coef_bits[ci];
443 if (coef_bits[0] < 0)
444 return FALSE;
445 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
446 for (coefi = 1; coefi <= 5; coefi++) {
447 coef_bits_latch[coefi] = coef_bits[coefi];
448 if (coef_bits[coefi] != 0)
449 smoothing_useful = TRUE;
450 }
451 coef_bits_latch += SAVED_COEFS;
452 }
453
454 return smoothing_useful;
455 }
456
457
458 /*
459 * Variant of decompress_data for use when doing block smoothing.
460 */
461
462 METHODDEF(int)
463 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
464 {
465 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
466 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
467 JDIMENSION block_num, last_block_column;
468 int ci, block_row, block_rows, access_rows;
469 JBLOCKARRAY buffer;
470 JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
471 JSAMPARRAY output_ptr;
472 JDIMENSION output_col;
473 jpeg_component_info *compptr;
474 inverse_DCT_method_ptr inverse_DCT;
475 boolean first_row, last_row;
476 JBLOCK workspace;
477 int *coef_bits;
478 JQUANT_TBL *quanttbl;
479 INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
480 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
481 int Al, pred;
482
483 /* Force some input to be done if we are getting ahead of the input. */
484 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
485 ! cinfo->inputctl->eoi_reached) {
486 if (cinfo->input_scan_number == cinfo->output_scan_number) {
487 /* If input is working on current scan, we ordinarily want it to
488 * have completed the current row. But if input scan is DC,
489 * we want it to keep one row ahead so that next block row's DC
490 * values are up to date.
491 */
492 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
493 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
494 break;
495 }
496 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
497 return JPEG_SUSPENDED;
498 }
499
500 /* OK, output from the virtual arrays. */
501 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
502 ci++, compptr++) {
503 /* Don't bother to IDCT an uninteresting component. */
504 if (! compptr->component_needed)
505 continue;
506 /* Count non-dummy DCT block rows in this iMCU row. */
507 if (cinfo->output_iMCU_row < last_iMCU_row) {
508 block_rows = compptr->v_samp_factor;
509 access_rows = block_rows * 2; /* this and next iMCU row */
510 last_row = FALSE;
511 } else {
512 /* NB: can't use last_row_height here; it is input-side-dependent! */
513 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
514 if (block_rows == 0) block_rows = compptr->v_samp_factor;
515 access_rows = block_rows; /* this iMCU row only */
516 last_row = TRUE;
517 }
518 /* Align the virtual buffer for this component. */
519 if (cinfo->output_iMCU_row > 0) {
520 access_rows += compptr->v_samp_factor; /* prior iMCU row too */
521 buffer = (*cinfo->mem->access_virt_barray)
522 ((j_common_ptr) cinfo, coef->whole_image[ci],
523 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
524 (JDIMENSION) access_rows, FALSE);
525 buffer += compptr->v_samp_factor; /* point to current iMCU row */
526 first_row = FALSE;
527 } else {
528 buffer = (*cinfo->mem->access_virt_barray)
529 ((j_common_ptr) cinfo, coef->whole_image[ci],
530 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
531 first_row = TRUE;
532 }
533 /* Fetch component-dependent info */
534 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
535 quanttbl = compptr->quant_table;
536 Q00 = quanttbl->quantval[0];
537 Q01 = quanttbl->quantval[Q01_POS];
538 Q10 = quanttbl->quantval[Q10_POS];
539 Q20 = quanttbl->quantval[Q20_POS];
540 Q11 = quanttbl->quantval[Q11_POS];
541 Q02 = quanttbl->quantval[Q02_POS];
542 inverse_DCT = cinfo->idct->inverse_DCT[ci];
543 output_ptr = output_buf[ci];
544 /* Loop over all DCT blocks to be processed. */
545 for (block_row = 0; block_row < block_rows; block_row++) {
546 buffer_ptr = buffer[block_row];
547 if (first_row && block_row == 0)
548 prev_block_row = buffer_ptr;
549 else
550 prev_block_row = buffer[block_row-1];
551 if (last_row && block_row == block_rows-1)
552 next_block_row = buffer_ptr;
553 else
554 next_block_row = buffer[block_row+1];
555 /* We fetch the surrounding DC values using a sliding-register approach.
556 * Initialize all nine here so as to do the right thing on narrow pics.
557 */
558 DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
559 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
560 DC7 = DC8 = DC9 = (int) next_block_row[0][0];
561 output_col = 0;
562 last_block_column = compptr->width_in_blocks - 1;
563 for (block_num = 0; block_num <= last_block_column; block_num++) {
564 /* Fetch current DCT block into workspace so we can modify it. */
565 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
566 /* Update DC values */
567 if (block_num < last_block_column) {
568 DC3 = (int) prev_block_row[1][0];
569 DC6 = (int) buffer_ptr[1][0];
570 DC9 = (int) next_block_row[1][0];
571 }
572 /* Compute coefficient estimates per K.8.
573 * An estimate is applied only if coefficient is still zero,
574 * and is not known to be fully accurate.
575 */
576 /* AC01 */
577 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
578 num = 36 * Q00 * (DC4 - DC6);
579 if (num >= 0) {
580 pred = (int) (((Q01<<7) + num) / (Q01<<8));
581 if (Al > 0 && pred >= (1<<Al))
582 pred = (1<<Al)-1;
583 } else {
584 pred = (int) (((Q01<<7) - num) / (Q01<<8));
585 if (Al > 0 && pred >= (1<<Al))
586 pred = (1<<Al)-1;
587 pred = -pred;
588 }
589 workspace[1] = (JCOEF) pred;
590 }
591 /* AC10 */
592 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
593 num = 36 * Q00 * (DC2 - DC8);
594 if (num >= 0) {
595 pred = (int) (((Q10<<7) + num) / (Q10<<8));
596 if (Al > 0 && pred >= (1<<Al))
597 pred = (1<<Al)-1;
598 } else {
599 pred = (int) (((Q10<<7) - num) / (Q10<<8));
600 if (Al > 0 && pred >= (1<<Al))
601 pred = (1<<Al)-1;
602 pred = -pred;
603 }
604 workspace[8] = (JCOEF) pred;
605 }
606 /* AC20 */
607 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
608 num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
609 if (num >= 0) {
610 pred = (int) (((Q20<<7) + num) / (Q20<<8));
611 if (Al > 0 && pred >= (1<<Al))
612 pred = (1<<Al)-1;
613 } else {
614 pred = (int) (((Q20<<7) - num) / (Q20<<8));
615 if (Al > 0 && pred >= (1<<Al))
616 pred = (1<<Al)-1;
617 pred = -pred;
618 }
619 workspace[16] = (JCOEF) pred;
620 }
621 /* AC11 */
622 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
623 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
624 if (num >= 0) {
625 pred = (int) (((Q11<<7) + num) / (Q11<<8));
626 if (Al > 0 && pred >= (1<<Al))
627 pred = (1<<Al)-1;
628 } else {
629 pred = (int) (((Q11<<7) - num) / (Q11<<8));
630 if (Al > 0 && pred >= (1<<Al))
631 pred = (1<<Al)-1;
632 pred = -pred;
633 }
634 workspace[9] = (JCOEF) pred;
635 }
636 /* AC02 */
637 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
638 num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
639 if (num >= 0) {
640 pred = (int) (((Q02<<7) + num) / (Q02<<8));
641 if (Al > 0 && pred >= (1<<Al))
642 pred = (1<<Al)-1;
643 } else {
644 pred = (int) (((Q02<<7) - num) / (Q02<<8));
645 if (Al > 0 && pred >= (1<<Al))
646 pred = (1<<Al)-1;
647 pred = -pred;
648 }
649 workspace[2] = (JCOEF) pred;
650 }
651 /* OK, do the IDCT */
652 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
653 output_ptr, output_col);
654 /* Advance for next column */
655 DC1 = DC2; DC2 = DC3;
656 DC4 = DC5; DC5 = DC6;
657 DC7 = DC8; DC8 = DC9;
658 buffer_ptr++, prev_block_row++, next_block_row++;
659 output_col += compptr->DCT_h_scaled_size;
660 }
661 output_ptr += compptr->DCT_v_scaled_size;
662 }
663 }
664
665 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
666 return JPEG_ROW_COMPLETED;
667 return JPEG_SCAN_COMPLETED;
668 }
669
670 #endif /* BLOCK_SMOOTHING_SUPPORTED */
671
672
673 /*
674 * Initialize coefficient buffer controller.
675 */
676
677 GLOBAL(void)
678 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
679 {
680 my_coef_ptr coef;
681
682 coef = (my_coef_ptr)
683 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
684 SIZEOF(my_coef_controller));
685 cinfo->coef = (struct jpeg_d_coef_controller *) coef;
686 coef->pub.start_input_pass = start_input_pass;
687 coef->pub.start_output_pass = start_output_pass;
688 #ifdef BLOCK_SMOOTHING_SUPPORTED
689 coef->coef_bits_latch = NULL;
690 #endif
691
692 /* Create the coefficient buffer. */
693 if (need_full_buffer) {
694 #ifdef D_MULTISCAN_FILES_SUPPORTED
695 /* Allocate a full-image virtual array for each component, */
696 /* padded to a multiple of samp_factor DCT blocks in each direction. */
697 /* Note we ask for a pre-zeroed array. */
698 int ci, access_rows;
699 jpeg_component_info *compptr;
700
701 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
702 ci++, compptr++) {
703 access_rows = compptr->v_samp_factor;
704 #ifdef BLOCK_SMOOTHING_SUPPORTED
705 /* If block smoothing could be used, need a bigger window */
706 if (cinfo->progressive_mode)
707 access_rows *= 3;
708 #endif
709 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
710 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
711 (JDIMENSION) jround_up((long) compptr->width_in_blocks,
712 (long) compptr->h_samp_factor),
713 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
714 (long) compptr->v_samp_factor),
715 (JDIMENSION) access_rows);
716 }
717 coef->pub.consume_data = consume_data;
718 coef->pub.decompress_data = decompress_data;
719 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
720 #else
721 ERREXIT(cinfo, JERR_NOT_COMPILED);
722 #endif
723 } else {
724 /* We only need a single-MCU buffer. */
725 JBLOCKROW buffer;
726 int i;
727
728 buffer = (JBLOCKROW)
729 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
730 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
731 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
732 coef->MCU_buffer[i] = buffer + i;
733 }
734 if (cinfo->lim_Se == 0) /* DC only case: want to bypass later */
735 FMEMZERO((void FAR *) buffer,
736 (size_t) (D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)));
737 coef->pub.consume_data = dummy_consume_data;
738 coef->pub.decompress_data = decompress_onepass;
739 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
740 }
741 }