4 * Copyright (C) 1994-1995, 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.
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.
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.
17 #define JPEG_INTERNALS
19 #include "radiant_jpeglib.h"
21 /* Block smoothing is only applicable for progressive JPEG, so: */
22 #ifndef D_PROGRESSIVE_SUPPORTED
23 #undef BLOCK_SMOOTHING_SUPPORTED
26 /* Private buffer controller object */
29 struct jpeg_d_coef_controller pub; /* public fields */
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 */
37 /* The output side's location is represented by cinfo->output_iMCU_row. */
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.
48 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];
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];
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] */
62 typedef my_coef_controller * my_coef_ptr;
64 /* Forward declarations */
65 METHODDEF int decompress_onepass
66 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
67 #ifdef D_MULTISCAN_FILES_SUPPORTED
68 METHODDEF int decompress_data
69 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
71 #ifdef BLOCK_SMOOTHING_SUPPORTED
72 LOCAL boolean smoothing_ok JPP((j_decompress_ptr cinfo));
73 METHODDEF int decompress_smooth_data
74 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
79 start_iMCU_row (j_decompress_ptr cinfo)
80 /* Reset within-iMCU-row counters for a new row (input side) */
82 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
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.
88 if (cinfo->comps_in_scan > 1) {
89 coef->MCU_rows_per_iMCU_row = 1;
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;
94 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
98 coef->MCU_vert_offset = 0;
103 * Initialize for an input processing pass.
107 start_input_pass (j_decompress_ptr cinfo)
109 cinfo->input_iMCU_row = 0;
110 start_iMCU_row(cinfo);
115 * Initialize for an output processing pass.
119 start_output_pass (j_decompress_ptr cinfo)
121 #ifdef BLOCK_SMOOTHING_SUPPORTED
122 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
124 /* If multipass, check to see whether to use block smoothing on this pass */
125 if (coef->pub.coef_arrays != NULL) {
126 if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
127 coef->pub.decompress_data = decompress_smooth_data;
129 coef->pub.decompress_data = decompress_data;
132 cinfo->output_iMCU_row = 0;
137 * Decompress and return some data in the single-pass case.
138 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
139 * Input and output must run in lockstep since we have only a one-MCU buffer.
140 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
142 * NB: output_buf contains a plane for each component in image.
143 * For single pass, this is the same as the components in the scan.
147 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
149 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
150 JDIMENSION MCU_col_num; /* index of current MCU within row */
151 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
152 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
153 int blkn, ci, xindex, yindex, yoffset, useful_width;
154 JSAMPARRAY output_ptr;
155 JDIMENSION start_col, output_col;
156 jpeg_component_info *compptr;
157 inverse_DCT_method_ptr inverse_DCT;
159 /* Loop to process as much as one whole iMCU row */
160 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
162 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
164 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
165 jzero_far((void FAR *) coef->MCU_buffer[0],
166 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));
167 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
168 /* Suspension forced; update state counters and exit */
169 coef->MCU_vert_offset = yoffset;
170 coef->MCU_ctr = MCU_col_num;
171 return JPEG_SUSPENDED;
173 /* Determine where data should go in output_buf and do the IDCT thing.
174 * We skip dummy blocks at the right and bottom edges (but blkn gets
175 * incremented past them!). Note the inner loop relies on having
176 * allocated the MCU_buffer[] blocks sequentially.
178 blkn = 0; /* index of current DCT block within MCU */
179 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
180 compptr = cinfo->cur_comp_info[ci];
181 /* Don't bother to IDCT an uninteresting component. */
182 if (! compptr->component_needed) {
183 blkn += compptr->MCU_blocks;
186 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
187 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
188 : compptr->last_col_width;
189 output_ptr = output_buf[ci] + yoffset * compptr->DCT_scaled_size;
190 start_col = MCU_col_num * compptr->MCU_sample_width;
191 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
192 if (cinfo->input_iMCU_row < last_iMCU_row ||
193 yoffset+yindex < compptr->last_row_height) {
194 output_col = start_col;
195 for (xindex = 0; xindex < useful_width; xindex++) {
196 (*inverse_DCT) (cinfo, compptr,
197 (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
198 output_ptr, output_col);
199 output_col += compptr->DCT_scaled_size;
202 blkn += compptr->MCU_width;
203 output_ptr += compptr->DCT_scaled_size;
207 /* Completed an MCU row, but perhaps not an iMCU row */
210 /* Completed the iMCU row, advance counters for next one */
211 cinfo->output_iMCU_row++;
212 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
213 start_iMCU_row(cinfo);
214 return JPEG_ROW_COMPLETED;
216 /* Completed the scan */
217 (*cinfo->inputctl->finish_input_pass) (cinfo);
218 return JPEG_SCAN_COMPLETED;
223 * Dummy consume-input routine for single-pass operation.
227 dummy_consume_data (j_decompress_ptr cinfo)
229 return JPEG_SUSPENDED; /* Always indicate nothing was done */
233 #ifdef D_MULTISCAN_FILES_SUPPORTED
236 * Consume input data and store it in the full-image coefficient buffer.
237 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
238 * ie, v_samp_factor block rows for each component in the scan.
239 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
243 consume_data (j_decompress_ptr cinfo)
245 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
246 JDIMENSION MCU_col_num; /* index of current MCU within row */
247 int blkn, ci, xindex, yindex, yoffset;
248 JDIMENSION start_col;
249 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
250 JBLOCKROW buffer_ptr;
251 jpeg_component_info *compptr;
253 /* Align the virtual buffers for the components used in this scan. */
254 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
255 compptr = cinfo->cur_comp_info[ci];
256 buffer[ci] = (*cinfo->mem->access_virt_barray)
257 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
258 cinfo->input_iMCU_row * compptr->v_samp_factor,
259 (JDIMENSION) compptr->v_samp_factor, TRUE);
260 /* Note: entropy decoder expects buffer to be zeroed,
261 * but this is handled automatically by the memory manager
262 * because we requested a pre-zeroed array.
266 /* Loop to process one whole iMCU row */
267 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
269 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
271 /* Construct list of pointers to DCT blocks belonging to this MCU */
272 blkn = 0; /* index of current DCT block within MCU */
273 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
274 compptr = cinfo->cur_comp_info[ci];
275 start_col = MCU_col_num * compptr->MCU_width;
276 for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
277 buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
278 for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
279 coef->MCU_buffer[blkn++] = buffer_ptr++;
283 /* Try to fetch the MCU. */
284 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
285 /* Suspension forced; update state counters and exit */
286 coef->MCU_vert_offset = yoffset;
287 coef->MCU_ctr = MCU_col_num;
288 return JPEG_SUSPENDED;
291 /* Completed an MCU row, but perhaps not an iMCU row */
294 /* Completed the iMCU row, advance counters for next one */
295 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
296 start_iMCU_row(cinfo);
297 return JPEG_ROW_COMPLETED;
299 /* Completed the scan */
300 (*cinfo->inputctl->finish_input_pass) (cinfo);
301 return JPEG_SCAN_COMPLETED;
306 * Decompress and return some data in the multi-pass case.
307 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
308 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
310 * NB: output_buf contains a plane for each component in image.
314 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
316 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
317 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
318 JDIMENSION block_num;
319 int ci, block_row, block_rows;
321 JBLOCKROW buffer_ptr;
322 JSAMPARRAY output_ptr;
323 JDIMENSION output_col;
324 jpeg_component_info *compptr;
325 inverse_DCT_method_ptr inverse_DCT;
327 /* Force some input to be done if we are getting ahead of the input. */
328 while (cinfo->input_scan_number < cinfo->output_scan_number ||
329 (cinfo->input_scan_number == cinfo->output_scan_number &&
330 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
331 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
332 return JPEG_SUSPENDED;
335 /* OK, output from the virtual arrays. */
336 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
338 /* Don't bother to IDCT an uninteresting component. */
339 if (! compptr->component_needed)
341 /* Align the virtual buffer for this component. */
342 buffer = (*cinfo->mem->access_virt_barray)
343 ((j_common_ptr) cinfo, coef->whole_image[ci],
344 cinfo->output_iMCU_row * compptr->v_samp_factor,
345 (JDIMENSION) compptr->v_samp_factor, FALSE);
346 /* Count non-dummy DCT block rows in this iMCU row. */
347 if (cinfo->output_iMCU_row < last_iMCU_row)
348 block_rows = compptr->v_samp_factor;
350 /* NB: can't use last_row_height here; it is input-side-dependent! */
351 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
352 if (block_rows == 0) block_rows = compptr->v_samp_factor;
354 inverse_DCT = cinfo->idct->inverse_DCT[ci];
355 output_ptr = output_buf[ci];
356 /* Loop over all DCT blocks to be processed. */
357 for (block_row = 0; block_row < block_rows; block_row++) {
358 buffer_ptr = buffer[block_row];
360 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
361 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
362 output_ptr, output_col);
364 output_col += compptr->DCT_scaled_size;
366 output_ptr += compptr->DCT_scaled_size;
370 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
371 return JPEG_ROW_COMPLETED;
372 return JPEG_SCAN_COMPLETED;
375 #endif /* D_MULTISCAN_FILES_SUPPORTED */
378 #ifdef BLOCK_SMOOTHING_SUPPORTED
381 * This code applies interblock smoothing as described by section K.8
382 * of the JPEG standard: the first 5 AC coefficients are estimated from
383 * the DC values of a DCT block and its 8 neighboring blocks.
384 * We apply smoothing only for progressive JPEG decoding, and only if
385 * the coefficients it can estimate are not yet known to full precision.
389 * Determine whether block smoothing is applicable and safe.
390 * We also latch the current states of the coef_bits[] entries for the
391 * AC coefficients; otherwise, if the input side of the decompressor
392 * advances into a new scan, we might think the coefficients are known
393 * more accurately than they really are.
397 smoothing_ok (j_decompress_ptr cinfo)
399 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
400 boolean smoothing_useful = FALSE;
402 jpeg_component_info *compptr;
405 int * coef_bits_latch;
407 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
410 /* Allocate latch area if not already done */
411 if (coef->coef_bits_latch == NULL)
412 coef->coef_bits_latch = (int *)
413 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
414 cinfo->num_components *
415 (SAVED_COEFS * SIZEOF(int)));
416 coef_bits_latch = coef->coef_bits_latch;
418 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
420 /* All components' quantization values must already be latched. */
421 if ((qtable = compptr->quant_table) == NULL)
423 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
424 for (coefi = 0; coefi <= 5; coefi++) {
425 if (qtable->quantval[coefi] == 0)
428 /* DC values must be at least partly known for all components. */
429 coef_bits = cinfo->coef_bits[ci];
430 if (coef_bits[0] < 0)
432 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
433 for (coefi = 1; coefi <= 5; coefi++) {
434 coef_bits_latch[coefi] = coef_bits[coefi];
435 if (coef_bits[coefi] != 0)
436 smoothing_useful = TRUE;
438 coef_bits_latch += SAVED_COEFS;
441 return smoothing_useful;
446 * Variant of decompress_data for use when doing block smoothing.
450 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
452 my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
453 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
454 JDIMENSION block_num, last_block_column;
455 int ci, block_row, block_rows, access_rows;
457 JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
458 JSAMPARRAY output_ptr;
459 JDIMENSION output_col;
460 jpeg_component_info *compptr;
461 inverse_DCT_method_ptr inverse_DCT;
462 boolean first_row, last_row;
465 JQUANT_TBL *quanttbl;
466 INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
467 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
470 /* Force some input to be done if we are getting ahead of the input. */
471 while (cinfo->input_scan_number <= cinfo->output_scan_number &&
472 ! cinfo->inputctl->eoi_reached) {
473 if (cinfo->input_scan_number == cinfo->output_scan_number) {
474 /* If input is working on current scan, we ordinarily want it to
475 * have completed the current row. But if input scan is DC,
476 * we want it to keep one row ahead so that next block row's DC
477 * values are up to date.
479 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
480 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
483 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
484 return JPEG_SUSPENDED;
487 /* OK, output from the virtual arrays. */
488 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
490 /* Don't bother to IDCT an uninteresting component. */
491 if (! compptr->component_needed)
493 /* Count non-dummy DCT block rows in this iMCU row. */
494 if (cinfo->output_iMCU_row < last_iMCU_row) {
495 block_rows = compptr->v_samp_factor;
496 access_rows = block_rows * 2; /* this and next iMCU row */
499 /* NB: can't use last_row_height here; it is input-side-dependent! */
500 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
501 if (block_rows == 0) block_rows = compptr->v_samp_factor;
502 access_rows = block_rows; /* this iMCU row only */
505 /* Align the virtual buffer for this component. */
506 if (cinfo->output_iMCU_row > 0) {
507 access_rows += compptr->v_samp_factor; /* prior iMCU row too */
508 buffer = (*cinfo->mem->access_virt_barray)
509 ((j_common_ptr) cinfo, coef->whole_image[ci],
510 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
511 (JDIMENSION) access_rows, FALSE);
512 buffer += compptr->v_samp_factor; /* point to current iMCU row */
515 buffer = (*cinfo->mem->access_virt_barray)
516 ((j_common_ptr) cinfo, coef->whole_image[ci],
517 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
520 /* Fetch component-dependent info */
521 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
522 quanttbl = compptr->quant_table;
523 Q00 = quanttbl->quantval[0];
524 Q01 = quanttbl->quantval[1];
525 Q10 = quanttbl->quantval[2];
526 Q20 = quanttbl->quantval[3];
527 Q11 = quanttbl->quantval[4];
528 Q02 = quanttbl->quantval[5];
529 inverse_DCT = cinfo->idct->inverse_DCT[ci];
530 output_ptr = output_buf[ci];
531 /* Loop over all DCT blocks to be processed. */
532 for (block_row = 0; block_row < block_rows; block_row++) {
533 buffer_ptr = buffer[block_row];
534 if (first_row && block_row == 0)
535 prev_block_row = buffer_ptr;
537 prev_block_row = buffer[block_row-1];
538 if (last_row && block_row == block_rows-1)
539 next_block_row = buffer_ptr;
541 next_block_row = buffer[block_row+1];
542 /* We fetch the surrounding DC values using a sliding-register approach.
543 * Initialize all nine here so as to do the right thing on narrow pics.
545 DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
546 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
547 DC7 = DC8 = DC9 = (int) next_block_row[0][0];
549 last_block_column = compptr->width_in_blocks - 1;
550 for (block_num = 0; block_num <= last_block_column; block_num++) {
551 /* Fetch current DCT block into workspace so we can modify it. */
552 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
553 /* Update DC values */
554 if (block_num < last_block_column) {
555 DC3 = (int) prev_block_row[1][0];
556 DC6 = (int) buffer_ptr[1][0];
557 DC9 = (int) next_block_row[1][0];
559 /* Compute coefficient estimates per K.8.
560 * An estimate is applied only if coefficient is still zero,
561 * and is not known to be fully accurate.
564 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
565 num = 36 * Q00 * (DC4 - DC6);
567 pred = (int) (((Q01<<7) + num) / (Q01<<8));
568 if (Al > 0 && pred >= (1<<Al))
571 pred = (int) (((Q01<<7) - num) / (Q01<<8));
572 if (Al > 0 && pred >= (1<<Al))
576 workspace[1] = (JCOEF) pred;
579 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
580 num = 36 * Q00 * (DC2 - DC8);
582 pred = (int) (((Q10<<7) + num) / (Q10<<8));
583 if (Al > 0 && pred >= (1<<Al))
586 pred = (int) (((Q10<<7) - num) / (Q10<<8));
587 if (Al > 0 && pred >= (1<<Al))
591 workspace[8] = (JCOEF) pred;
594 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
595 num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
597 pred = (int) (((Q20<<7) + num) / (Q20<<8));
598 if (Al > 0 && pred >= (1<<Al))
601 pred = (int) (((Q20<<7) - num) / (Q20<<8));
602 if (Al > 0 && pred >= (1<<Al))
606 workspace[16] = (JCOEF) pred;
609 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
610 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
612 pred = (int) (((Q11<<7) + num) / (Q11<<8));
613 if (Al > 0 && pred >= (1<<Al))
616 pred = (int) (((Q11<<7) - num) / (Q11<<8));
617 if (Al > 0 && pred >= (1<<Al))
621 workspace[9] = (JCOEF) pred;
624 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
625 num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
627 pred = (int) (((Q02<<7) + num) / (Q02<<8));
628 if (Al > 0 && pred >= (1<<Al))
631 pred = (int) (((Q02<<7) - num) / (Q02<<8));
632 if (Al > 0 && pred >= (1<<Al))
636 workspace[2] = (JCOEF) pred;
638 /* OK, do the IDCT */
639 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
640 output_ptr, output_col);
641 /* Advance for next column */
642 DC1 = DC2; DC2 = DC3;
643 DC4 = DC5; DC5 = DC6;
644 DC7 = DC8; DC8 = DC9;
645 buffer_ptr++, prev_block_row++, next_block_row++;
646 output_col += compptr->DCT_scaled_size;
648 output_ptr += compptr->DCT_scaled_size;
652 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
653 return JPEG_ROW_COMPLETED;
654 return JPEG_SCAN_COMPLETED;
657 #endif /* BLOCK_SMOOTHING_SUPPORTED */
661 * Initialize coefficient buffer controller.
665 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
670 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
671 SIZEOF(my_coef_controller));
672 cinfo->coef = (struct jpeg_d_coef_controller *) coef;
673 coef->pub.start_input_pass = start_input_pass;
674 coef->pub.start_output_pass = start_output_pass;
675 #ifdef BLOCK_SMOOTHING_SUPPORTED
676 coef->coef_bits_latch = NULL;
679 /* Create the coefficient buffer. */
680 if (need_full_buffer) {
681 #ifdef D_MULTISCAN_FILES_SUPPORTED
682 /* Allocate a full-image virtual array for each component, */
683 /* padded to a multiple of samp_factor DCT blocks in each direction. */
684 /* Note we ask for a pre-zeroed array. */
686 jpeg_component_info *compptr;
688 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
690 access_rows = compptr->v_samp_factor;
691 #ifdef BLOCK_SMOOTHING_SUPPORTED
692 /* If block smoothing could be used, need a bigger window */
693 if (cinfo->progressive_mode)
696 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
697 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
698 (JDIMENSION) jround_up((long) compptr->width_in_blocks,
699 (long) compptr->h_samp_factor),
700 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
701 (long) compptr->v_samp_factor),
702 (JDIMENSION) access_rows);
704 coef->pub.consume_data = consume_data;
705 coef->pub.decompress_data = decompress_data;
706 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
708 ERREXIT(cinfo, JERR_NOT_COMPILED);
711 /* We only need a single-MCU buffer. */
716 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
717 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
718 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
719 coef->MCU_buffer[i] = buffer + i;
721 coef->pub.consume_data = dummy_consume_data;
722 coef->pub.decompress_data = decompress_onepass;
723 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */