/[pcsx2_0.9.7]/branch/r3113_0.9.7_beta/3rdparty/libjpeg/jdcoefct.c
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Revision 32 - (hide annotations) (download)
Tue Sep 7 03:29:01 2010 UTC (10 years, 7 months ago) by william
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branching from upstream revision (http://pcsx2.googlecode.com/svn/trunk
): r3113 to
https://svn.netsolutions.dnsalias.com/websvn/ps2/pcsx2/pcsx2_0.9.7/branch/r3113_0.9.7_beta
1 william 31 /*
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    
28     typedef 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    
62     typedef my_coef_controller * my_coef_ptr;
63    
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));
70     #endif
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));
75     #endif
76    
77    
78     LOCAL(void)
79     start_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    
106     METHODDEF(void)
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)
119     start_output_pass (j_decompress_ptr cinfo)
120     {
121     #ifdef BLOCK_SMOOTHING_SUPPORTED
122     my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
123    
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;
128     else
129     coef->pub.decompress_data = decompress_data;
130     }
131     #endif
132     cinfo->output_iMCU_row = 0;
133     }
134    
135    
136     /*
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.
141     *
142     * NB: output_buf contains a plane for each component in image,
143     * which we index according to the component's SOF position.
144     */
145    
146     METHODDEF(int)
147     decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
148     {
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;
158    
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;
161     yoffset++) {
162     for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
163     MCU_col_num++) {
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;
172     }
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.
177     */
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;
184     continue;
185     }
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[compptr->component_index] +
190     yoffset * compptr->DCT_v_scaled_size;
191     start_col = MCU_col_num * compptr->MCU_sample_width;
192     for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
193     if (cinfo->input_iMCU_row < last_iMCU_row ||
194     yoffset+yindex < compptr->last_row_height) {
195     output_col = start_col;
196     for (xindex = 0; xindex < useful_width; xindex++) {
197     (*inverse_DCT) (cinfo, compptr,
198     (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
199     output_ptr, output_col);
200     output_col += compptr->DCT_h_scaled_size;
201     }
202     }
203     blkn += compptr->MCU_width;
204     output_ptr += compptr->DCT_v_scaled_size;
205     }
206     }
207     }
208     /* Completed an MCU row, but perhaps not an iMCU row */
209     coef->MCU_ctr = 0;
210     }
211     /* Completed the iMCU row, advance counters for next one */
212     cinfo->output_iMCU_row++;
213     if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
214     start_iMCU_row(cinfo);
215     return JPEG_ROW_COMPLETED;
216     }
217     /* Completed the scan */
218     (*cinfo->inputctl->finish_input_pass) (cinfo);
219     return JPEG_SCAN_COMPLETED;
220     }
221    
222    
223     /*
224     * Dummy consume-input routine for single-pass operation.
225     */
226    
227     METHODDEF(int)
228     dummy_consume_data (j_decompress_ptr cinfo)
229     {
230     return JPEG_SUSPENDED; /* Always indicate nothing was done */
231     }
232    
233    
234     #ifdef D_MULTISCAN_FILES_SUPPORTED
235    
236     /*
237     * Consume input data and store it in the full-image coefficient buffer.
238     * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
239     * ie, v_samp_factor block rows for each component in the scan.
240     * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
241     */
242    
243     METHODDEF(int)
244     consume_data (j_decompress_ptr cinfo)
245     {
246     my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
247     JDIMENSION MCU_col_num; /* index of current MCU within row */
248     int blkn, ci, xindex, yindex, yoffset;
249     JDIMENSION start_col;
250     JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
251     JBLOCKROW buffer_ptr;
252     jpeg_component_info *compptr;
253    
254     /* Align the virtual buffers for the components used in this scan. */
255     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
256     compptr = cinfo->cur_comp_info[ci];
257     buffer[ci] = (*cinfo->mem->access_virt_barray)
258     ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
259     cinfo->input_iMCU_row * compptr->v_samp_factor,
260     (JDIMENSION) compptr->v_samp_factor, TRUE);
261     /* Note: entropy decoder expects buffer to be zeroed,
262     * but this is handled automatically by the memory manager
263     * because we requested a pre-zeroed array.
264     */
265     }
266    
267     /* Loop to process one whole iMCU row */
268     for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
269     yoffset++) {
270     for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
271     MCU_col_num++) {
272     /* Construct list of pointers to DCT blocks belonging to this MCU */
273     blkn = 0; /* index of current DCT block within MCU */
274     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
275     compptr = cinfo->cur_comp_info[ci];
276     start_col = MCU_col_num * compptr->MCU_width;
277     for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
278     buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
279     for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
280     coef->MCU_buffer[blkn++] = buffer_ptr++;
281     }
282     }
283     }
284     /* Try to fetch the MCU. */
285     if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
286     /* Suspension forced; update state counters and exit */
287     coef->MCU_vert_offset = yoffset;
288     coef->MCU_ctr = MCU_col_num;
289     return JPEG_SUSPENDED;
290     }
291     }
292     /* Completed an MCU row, but perhaps not an iMCU row */
293     coef->MCU_ctr = 0;
294     }
295     /* Completed the iMCU row, advance counters for next one */
296     if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
297     start_iMCU_row(cinfo);
298     return JPEG_ROW_COMPLETED;
299     }
300     /* Completed the scan */
301     (*cinfo->inputctl->finish_input_pass) (cinfo);
302     return JPEG_SCAN_COMPLETED;
303     }
304    
305    
306     /*
307     * Decompress and return some data in the multi-pass case.
308     * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
309     * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
310     *
311     * NB: output_buf contains a plane for each component in image.
312     */
313    
314     METHODDEF(int)
315     decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
316     {
317     my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
318     JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
319     JDIMENSION block_num;
320     int ci, block_row, block_rows;
321     JBLOCKARRAY buffer;
322     JBLOCKROW buffer_ptr;
323     JSAMPARRAY output_ptr;
324     JDIMENSION output_col;
325     jpeg_component_info *compptr;
326     inverse_DCT_method_ptr inverse_DCT;
327    
328     /* Force some input to be done if we are getting ahead of the input. */
329     while (cinfo->input_scan_number < cinfo->output_scan_number ||
330     (cinfo->input_scan_number == cinfo->output_scan_number &&
331     cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
332     if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
333     return JPEG_SUSPENDED;
334     }
335    
336     /* OK, output from the virtual arrays. */
337     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
338     ci++, compptr++) {
339     /* Don't bother to IDCT an uninteresting component. */
340     if (! compptr->component_needed)
341     continue;
342     /* Align the virtual buffer for this component. */
343     buffer = (*cinfo->mem->access_virt_barray)
344     ((j_common_ptr) cinfo, coef->whole_image[ci],
345     cinfo->output_iMCU_row * compptr->v_samp_factor,
346     (JDIMENSION) compptr->v_samp_factor, FALSE);
347     /* Count non-dummy DCT block rows in this iMCU row. */
348     if (cinfo->output_iMCU_row < last_iMCU_row)
349     block_rows = compptr->v_samp_factor;
350     else {
351     /* NB: can't use last_row_height here; it is input-side-dependent! */
352     block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
353     if (block_rows == 0) block_rows = compptr->v_samp_factor;
354     }
355     inverse_DCT = cinfo->idct->inverse_DCT[ci];
356     output_ptr = output_buf[ci];
357     /* Loop over all DCT blocks to be processed. */
358     for (block_row = 0; block_row < block_rows; block_row++) {
359     buffer_ptr = buffer[block_row];
360     output_col = 0;
361     for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
362     (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
363     output_ptr, output_col);
364     buffer_ptr++;
365     output_col += compptr->DCT_h_scaled_size;
366     }
367     output_ptr += compptr->DCT_v_scaled_size;
368     }
369     }
370    
371     if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
372     return JPEG_ROW_COMPLETED;
373     return JPEG_SCAN_COMPLETED;
374     }
375    
376     #endif /* D_MULTISCAN_FILES_SUPPORTED */
377    
378    
379     #ifdef BLOCK_SMOOTHING_SUPPORTED
380    
381     /*
382     * This code applies interblock smoothing as described by section K.8
383     * of the JPEG standard: the first 5 AC coefficients are estimated from
384     * the DC values of a DCT block and its 8 neighboring blocks.
385     * We apply smoothing only for progressive JPEG decoding, and only if
386     * the coefficients it can estimate are not yet known to full precision.
387     */
388    
389     /* Natural-order array positions of the first 5 zigzag-order coefficients */
390     #define Q01_POS 1
391     #define Q10_POS 8
392     #define Q20_POS 16
393     #define Q11_POS 9
394     #define Q02_POS 2
395    
396     /*
397     * Determine whether block smoothing is applicable and safe.
398     * We also latch the current states of the coef_bits[] entries for the
399     * AC coefficients; otherwise, if the input side of the decompressor
400     * advances into a new scan, we might think the coefficients are known
401     * more accurately than they really are.
402     */
403    
404     LOCAL(boolean)
405     smoothing_ok (j_decompress_ptr cinfo)
406     {
407     my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
408     boolean smoothing_useful = FALSE;
409     int ci, coefi;
410     jpeg_component_info *compptr;
411     JQUANT_TBL * qtable;
412     int * coef_bits;
413     int * coef_bits_latch;
414    
415     if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
416     return FALSE;
417    
418     /* Allocate latch area if not already done */
419     if (coef->coef_bits_latch == NULL)
420     coef->coef_bits_latch = (int *)
421     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
422     cinfo->num_components *
423     (SAVED_COEFS * SIZEOF(int)));
424     coef_bits_latch = coef->coef_bits_latch;
425    
426     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
427     ci++, compptr++) {
428     /* All components' quantization values must already be latched. */
429     if ((qtable = compptr->quant_table) == NULL)
430     return FALSE;
431     /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
432     if (qtable->quantval[0] == 0 ||
433     qtable->quantval[Q01_POS] == 0 ||
434     qtable->quantval[Q10_POS] == 0 ||
435     qtable->quantval[Q20_POS] == 0 ||
436     qtable->quantval[Q11_POS] == 0 ||
437     qtable->quantval[Q02_POS] == 0)
438     return FALSE;
439     /* DC values must be at least partly known for all components. */
440     coef_bits = cinfo->coef_bits[ci];
441     if (coef_bits[0] < 0)
442     return FALSE;
443     /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
444     for (coefi = 1; coefi <= 5; coefi++) {
445     coef_bits_latch[coefi] = coef_bits[coefi];
446     if (coef_bits[coefi] != 0)
447     smoothing_useful = TRUE;
448     }
449     coef_bits_latch += SAVED_COEFS;
450     }
451    
452     return smoothing_useful;
453     }
454    
455    
456     /*
457     * Variant of decompress_data for use when doing block smoothing.
458     */
459    
460     METHODDEF(int)
461     decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
462     {
463     my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
464     JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
465     JDIMENSION block_num, last_block_column;
466     int ci, block_row, block_rows, access_rows;
467     JBLOCKARRAY buffer;
468     JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
469     JSAMPARRAY output_ptr;
470     JDIMENSION output_col;
471     jpeg_component_info *compptr;
472     inverse_DCT_method_ptr inverse_DCT;
473     boolean first_row, last_row;
474     JBLOCK workspace;
475     int *coef_bits;
476     JQUANT_TBL *quanttbl;
477     INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
478     int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
479     int Al, pred;
480    
481     /* Force some input to be done if we are getting ahead of the input. */
482     while (cinfo->input_scan_number <= cinfo->output_scan_number &&
483     ! cinfo->inputctl->eoi_reached) {
484     if (cinfo->input_scan_number == cinfo->output_scan_number) {
485     /* If input is working on current scan, we ordinarily want it to
486     * have completed the current row. But if input scan is DC,
487     * we want it to keep one row ahead so that next block row's DC
488     * values are up to date.
489     */
490     JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
491     if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
492     break;
493     }
494     if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
495     return JPEG_SUSPENDED;
496     }
497    
498     /* OK, output from the virtual arrays. */
499     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
500     ci++, compptr++) {
501     /* Don't bother to IDCT an uninteresting component. */
502     if (! compptr->component_needed)
503     continue;
504     /* Count non-dummy DCT block rows in this iMCU row. */
505     if (cinfo->output_iMCU_row < last_iMCU_row) {
506     block_rows = compptr->v_samp_factor;
507     access_rows = block_rows * 2; /* this and next iMCU row */
508     last_row = FALSE;
509     } else {
510     /* NB: can't use last_row_height here; it is input-side-dependent! */
511     block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
512     if (block_rows == 0) block_rows = compptr->v_samp_factor;
513     access_rows = block_rows; /* this iMCU row only */
514     last_row = TRUE;
515     }
516     /* Align the virtual buffer for this component. */
517     if (cinfo->output_iMCU_row > 0) {
518     access_rows += compptr->v_samp_factor; /* prior iMCU row too */
519     buffer = (*cinfo->mem->access_virt_barray)
520     ((j_common_ptr) cinfo, coef->whole_image[ci],
521     (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
522     (JDIMENSION) access_rows, FALSE);
523     buffer += compptr->v_samp_factor; /* point to current iMCU row */
524     first_row = FALSE;
525     } else {
526     buffer = (*cinfo->mem->access_virt_barray)
527     ((j_common_ptr) cinfo, coef->whole_image[ci],
528     (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
529     first_row = TRUE;
530     }
531     /* Fetch component-dependent info */
532     coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
533     quanttbl = compptr->quant_table;
534     Q00 = quanttbl->quantval[0];
535     Q01 = quanttbl->quantval[Q01_POS];
536     Q10 = quanttbl->quantval[Q10_POS];
537     Q20 = quanttbl->quantval[Q20_POS];
538     Q11 = quanttbl->quantval[Q11_POS];
539     Q02 = quanttbl->quantval[Q02_POS];
540     inverse_DCT = cinfo->idct->inverse_DCT[ci];
541     output_ptr = output_buf[ci];
542     /* Loop over all DCT blocks to be processed. */
543     for (block_row = 0; block_row < block_rows; block_row++) {
544     buffer_ptr = buffer[block_row];
545     if (first_row && block_row == 0)
546     prev_block_row = buffer_ptr;
547     else
548     prev_block_row = buffer[block_row-1];
549     if (last_row && block_row == block_rows-1)
550     next_block_row = buffer_ptr;
551     else
552     next_block_row = buffer[block_row+1];
553     /* We fetch the surrounding DC values using a sliding-register approach.
554     * Initialize all nine here so as to do the right thing on narrow pics.
555     */
556     DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
557     DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
558     DC7 = DC8 = DC9 = (int) next_block_row[0][0];
559     output_col = 0;
560     last_block_column = compptr->width_in_blocks - 1;
561     for (block_num = 0; block_num <= last_block_column; block_num++) {
562     /* Fetch current DCT block into workspace so we can modify it. */
563     jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
564     /* Update DC values */
565     if (block_num < last_block_column) {
566     DC3 = (int) prev_block_row[1][0];
567     DC6 = (int) buffer_ptr[1][0];
568     DC9 = (int) next_block_row[1][0];
569     }
570     /* Compute coefficient estimates per K.8.
571     * An estimate is applied only if coefficient is still zero,
572     * and is not known to be fully accurate.
573     */
574     /* AC01 */
575     if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
576     num = 36 * Q00 * (DC4 - DC6);
577     if (num >= 0) {
578     pred = (int) (((Q01<<7) + num) / (Q01<<8));
579     if (Al > 0 && pred >= (1<<Al))
580     pred = (1<<Al)-1;
581     } else {
582     pred = (int) (((Q01<<7) - num) / (Q01<<8));
583     if (Al > 0 && pred >= (1<<Al))
584     pred = (1<<Al)-1;
585     pred = -pred;
586     }
587     workspace[1] = (JCOEF) pred;
588     }
589     /* AC10 */
590     if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
591     num = 36 * Q00 * (DC2 - DC8);
592     if (num >= 0) {
593     pred = (int) (((Q10<<7) + num) / (Q10<<8));
594     if (Al > 0 && pred >= (1<<Al))
595     pred = (1<<Al)-1;
596     } else {
597     pred = (int) (((Q10<<7) - num) / (Q10<<8));
598     if (Al > 0 && pred >= (1<<Al))
599     pred = (1<<Al)-1;
600     pred = -pred;
601     }
602     workspace[8] = (JCOEF) pred;
603     }
604     /* AC20 */
605     if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
606     num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
607     if (num >= 0) {
608     pred = (int) (((Q20<<7) + num) / (Q20<<8));
609     if (Al > 0 && pred >= (1<<Al))
610     pred = (1<<Al)-1;
611     } else {
612     pred = (int) (((Q20<<7) - num) / (Q20<<8));
613     if (Al > 0 && pred >= (1<<Al))
614     pred = (1<<Al)-1;
615     pred = -pred;
616     }
617     workspace[16] = (JCOEF) pred;
618     }
619     /* AC11 */
620     if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
621     num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
622     if (num >= 0) {
623     pred = (int) (((Q11<<7) + num) / (Q11<<8));
624     if (Al > 0 && pred >= (1<<Al))
625     pred = (1<<Al)-1;
626     } else {
627     pred = (int) (((Q11<<7) - num) / (Q11<<8));
628     if (Al > 0 && pred >= (1<<Al))
629     pred = (1<<Al)-1;
630     pred = -pred;
631     }
632     workspace[9] = (JCOEF) pred;
633     }
634     /* AC02 */
635     if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
636     num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
637     if (num >= 0) {
638     pred = (int) (((Q02<<7) + num) / (Q02<<8));
639     if (Al > 0 && pred >= (1<<Al))
640     pred = (1<<Al)-1;
641     } else {
642     pred = (int) (((Q02<<7) - num) / (Q02<<8));
643     if (Al > 0 && pred >= (1<<Al))
644     pred = (1<<Al)-1;
645     pred = -pred;
646     }
647     workspace[2] = (JCOEF) pred;
648     }
649     /* OK, do the IDCT */
650     (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
651     output_ptr, output_col);
652     /* Advance for next column */
653     DC1 = DC2; DC2 = DC3;
654     DC4 = DC5; DC5 = DC6;
655     DC7 = DC8; DC8 = DC9;
656     buffer_ptr++, prev_block_row++, next_block_row++;
657     output_col += compptr->DCT_h_scaled_size;
658     }
659     output_ptr += compptr->DCT_v_scaled_size;
660     }
661     }
662    
663     if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
664     return JPEG_ROW_COMPLETED;
665     return JPEG_SCAN_COMPLETED;
666     }
667    
668     #endif /* BLOCK_SMOOTHING_SUPPORTED */
669    
670    
671     /*
672     * Initialize coefficient buffer controller.
673     */
674    
675     GLOBAL(void)
676     jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
677     {
678     my_coef_ptr coef;
679    
680     coef = (my_coef_ptr)
681     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
682     SIZEOF(my_coef_controller));
683     cinfo->coef = (struct jpeg_d_coef_controller *) coef;
684     coef->pub.start_input_pass = start_input_pass;
685     coef->pub.start_output_pass = start_output_pass;
686     #ifdef BLOCK_SMOOTHING_SUPPORTED
687     coef->coef_bits_latch = NULL;
688     #endif
689    
690     /* Create the coefficient buffer. */
691     if (need_full_buffer) {
692     #ifdef D_MULTISCAN_FILES_SUPPORTED
693     /* Allocate a full-image virtual array for each component, */
694     /* padded to a multiple of samp_factor DCT blocks in each direction. */
695     /* Note we ask for a pre-zeroed array. */
696     int ci, access_rows;
697     jpeg_component_info *compptr;
698    
699     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
700     ci++, compptr++) {
701     access_rows = compptr->v_samp_factor;
702     #ifdef BLOCK_SMOOTHING_SUPPORTED
703     /* If block smoothing could be used, need a bigger window */
704     if (cinfo->progressive_mode)
705     access_rows *= 3;
706     #endif
707     coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
708     ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
709     (JDIMENSION) jround_up((long) compptr->width_in_blocks,
710     (long) compptr->h_samp_factor),
711     (JDIMENSION) jround_up((long) compptr->height_in_blocks,
712     (long) compptr->v_samp_factor),
713     (JDIMENSION) access_rows);
714     }
715     coef->pub.consume_data = consume_data;
716     coef->pub.decompress_data = decompress_data;
717     coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
718     #else
719     ERREXIT(cinfo, JERR_NOT_COMPILED);
720     #endif
721     } else {
722     /* We only need a single-MCU buffer. */
723     JBLOCKROW buffer;
724     int i;
725    
726     buffer = (JBLOCKROW)
727     (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
728     D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
729     for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
730     coef->MCU_buffer[i] = buffer + i;
731     }
732     coef->pub.consume_data = dummy_consume_data;
733     coef->pub.decompress_data = decompress_onepass;
734     coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
735     }
736     }

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