1 /*
2  * jdcoefct.c
3  *
4  * This file was part of the Independent JPEG Group's software:
5  * Copyright (C) 1994-1997, Thomas G. Lane.
6  * libjpeg-turbo Modifications:
7  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
8  * Copyright (C) 2010, 2015-2016, D. R. Commander.
9  * Copyright (C) 2015, Google, Inc.
10  * For conditions of distribution and use, see the accompanying README.ijg
11  * file.
12  *
13  * This file contains the coefficient buffer controller for decompression.
14  * This controller is the top level of the JPEG decompressor proper.
15  * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
16  *
17  * In buffered-image mode, this controller is the interface between
18  * input-oriented processing and output-oriented processing.
19  * Also, the input side (only) is used when reading a file for transcoding.
20  */
21 
22 #include "jdcoefct.h"
23 #include "jpegcomp.h"
24 
25 
26 /* Forward declarations */
27 METHODDEF(int) decompress_onepass
28         (j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
29 #ifdef D_MULTISCAN_FILES_SUPPORTED
30 METHODDEF(int) decompress_data
31         (j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
32 #endif
33 #ifdef BLOCK_SMOOTHING_SUPPORTED
34 LOCAL(boolean) smoothing_ok (j_decompress_ptr cinfo);
35 METHODDEF(int) decompress_smooth_data
36         (j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
37 #endif
38 
39 
40 /*
41  * Initialize for an input processing pass.
42  */
43 
44 METHODDEF(void)
start_input_pass(j_decompress_ptr cinfo)45 start_input_pass (j_decompress_ptr cinfo)
46 {
47   cinfo->input_iMCU_row = 0;
48   start_iMCU_row(cinfo);
49 }
50 
51 
52 /*
53  * Initialize for an output processing pass.
54  */
55 
56 METHODDEF(void)
start_output_pass(j_decompress_ptr cinfo)57 start_output_pass (j_decompress_ptr cinfo)
58 {
59 #ifdef BLOCK_SMOOTHING_SUPPORTED
60   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
61 
62   /* If multipass, check to see whether to use block smoothing on this pass */
63   if (coef->pub.coef_arrays != NULL) {
64     if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
65       coef->pub.decompress_data = decompress_smooth_data;
66     else
67       coef->pub.decompress_data = decompress_data;
68   }
69 #endif
70   cinfo->output_iMCU_row = 0;
71 }
72 
73 
74 /*
75  * Decompress and return some data in the single-pass case.
76  * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
77  * Input and output must run in lockstep since we have only a one-MCU buffer.
78  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
79  *
80  * NB: output_buf contains a plane for each component in image,
81  * which we index according to the component's SOF position.
82  */
83 
84 METHODDEF(int)
decompress_onepass(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)85 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
86 {
87   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
88   JDIMENSION MCU_col_num;       /* index of current MCU within row */
89   JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
90   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
91   int blkn, ci, xindex, yindex, yoffset, useful_width;
92   JSAMPARRAY output_ptr;
93   JDIMENSION start_col, output_col;
94   jpeg_component_info *compptr;
95   inverse_DCT_method_ptr inverse_DCT;
96 
97   /* Loop to process as much as one whole iMCU row */
98   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
99        yoffset++) {
100     for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
101          MCU_col_num++) {
102       /* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */
103       jzero_far((void *) coef->MCU_buffer[0],
104                 (size_t) (cinfo->blocks_in_MCU * sizeof(JBLOCK)));
105       if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
106         /* Suspension forced; update state counters and exit */
107         coef->MCU_vert_offset = yoffset;
108         coef->MCU_ctr = MCU_col_num;
109         return JPEG_SUSPENDED;
110       }
111 
112       /* Only perform the IDCT on blocks that are contained within the desired
113        * cropping region.
114        */
115       if (MCU_col_num >= cinfo->master->first_iMCU_col &&
116           MCU_col_num <= cinfo->master->last_iMCU_col) {
117         /* Determine where data should go in output_buf and do the IDCT thing.
118          * We skip dummy blocks at the right and bottom edges (but blkn gets
119          * incremented past them!).  Note the inner loop relies on having
120          * allocated the MCU_buffer[] blocks sequentially.
121          */
122         blkn = 0;                 /* index of current DCT block within MCU */
123         for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
124           compptr = cinfo->cur_comp_info[ci];
125           /* Don't bother to IDCT an uninteresting component. */
126           if (! compptr->component_needed) {
127             blkn += compptr->MCU_blocks;
128             continue;
129           }
130           inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
131           useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
132                                                       : compptr->last_col_width;
133           output_ptr = output_buf[compptr->component_index] +
134             yoffset * compptr->_DCT_scaled_size;
135           start_col = (MCU_col_num - cinfo->master->first_iMCU_col) *
136               compptr->MCU_sample_width;
137           for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
138             if (cinfo->input_iMCU_row < last_iMCU_row ||
139                 yoffset+yindex < compptr->last_row_height) {
140               output_col = start_col;
141               for (xindex = 0; xindex < useful_width; xindex++) {
142                 (*inverse_DCT) (cinfo, compptr,
143                                 (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
144                                 output_ptr, output_col);
145                 output_col += compptr->_DCT_scaled_size;
146               }
147             }
148             blkn += compptr->MCU_width;
149             output_ptr += compptr->_DCT_scaled_size;
150           }
151         }
152       }
153     }
154     /* Completed an MCU row, but perhaps not an iMCU row */
155     coef->MCU_ctr = 0;
156   }
157   /* Completed the iMCU row, advance counters for next one */
158   cinfo->output_iMCU_row++;
159   if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
160     start_iMCU_row(cinfo);
161     return JPEG_ROW_COMPLETED;
162   }
163   /* Completed the scan */
164   (*cinfo->inputctl->finish_input_pass) (cinfo);
165   return JPEG_SCAN_COMPLETED;
166 }
167 
168 
169 /*
170  * Dummy consume-input routine for single-pass operation.
171  */
172 
173 METHODDEF(int)
dummy_consume_data(j_decompress_ptr cinfo)174 dummy_consume_data (j_decompress_ptr cinfo)
175 {
176   return JPEG_SUSPENDED;        /* Always indicate nothing was done */
177 }
178 
179 
180 #ifdef D_MULTISCAN_FILES_SUPPORTED
181 
182 /*
183  * Consume input data and store it in the full-image coefficient buffer.
184  * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
185  * ie, v_samp_factor block rows for each component in the scan.
186  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
187  */
188 
189 METHODDEF(int)
consume_data(j_decompress_ptr cinfo)190 consume_data (j_decompress_ptr cinfo)
191 {
192   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
193   JDIMENSION MCU_col_num;       /* index of current MCU within row */
194   int blkn, ci, xindex, yindex, yoffset;
195   JDIMENSION start_col;
196   JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
197   JBLOCKROW buffer_ptr;
198   jpeg_component_info *compptr;
199 
200   /* Align the virtual buffers for the components used in this scan. */
201   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
202     compptr = cinfo->cur_comp_info[ci];
203     buffer[ci] = (*cinfo->mem->access_virt_barray)
204       ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
205        cinfo->input_iMCU_row * compptr->v_samp_factor,
206        (JDIMENSION) compptr->v_samp_factor, TRUE);
207     /* Note: entropy decoder expects buffer to be zeroed,
208      * but this is handled automatically by the memory manager
209      * because we requested a pre-zeroed array.
210      */
211   }
212 
213   /* Loop to process one whole iMCU row */
214   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
215        yoffset++) {
216     for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
217          MCU_col_num++) {
218       /* Construct list of pointers to DCT blocks belonging to this MCU */
219       blkn = 0;                 /* index of current DCT block within MCU */
220       for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
221         compptr = cinfo->cur_comp_info[ci];
222         start_col = MCU_col_num * compptr->MCU_width;
223         for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
224           buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
225           for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
226             coef->MCU_buffer[blkn++] = buffer_ptr++;
227           }
228         }
229       }
230       /* Try to fetch the MCU. */
231       if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
232         /* Suspension forced; update state counters and exit */
233         coef->MCU_vert_offset = yoffset;
234         coef->MCU_ctr = MCU_col_num;
235         return JPEG_SUSPENDED;
236       }
237     }
238     /* Completed an MCU row, but perhaps not an iMCU row */
239     coef->MCU_ctr = 0;
240   }
241   /* Completed the iMCU row, advance counters for next one */
242   if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
243     start_iMCU_row(cinfo);
244     return JPEG_ROW_COMPLETED;
245   }
246   /* Completed the scan */
247   (*cinfo->inputctl->finish_input_pass) (cinfo);
248   return JPEG_SCAN_COMPLETED;
249 }
250 
251 
252 /*
253  * Decompress and return some data in the multi-pass case.
254  * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
255  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
256  *
257  * NB: output_buf contains a plane for each component in image.
258  */
259 
260 METHODDEF(int)
decompress_data(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)261 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
262 {
263   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
264   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
265   JDIMENSION block_num;
266   int ci, block_row, block_rows;
267   JBLOCKARRAY buffer;
268   JBLOCKROW buffer_ptr;
269   JSAMPARRAY output_ptr;
270   JDIMENSION output_col;
271   jpeg_component_info *compptr;
272   inverse_DCT_method_ptr inverse_DCT;
273 
274   /* Force some input to be done if we are getting ahead of the input. */
275   while (cinfo->input_scan_number < cinfo->output_scan_number ||
276          (cinfo->input_scan_number == cinfo->output_scan_number &&
277           cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
278     if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
279       return JPEG_SUSPENDED;
280   }
281 
282   /* OK, output from the virtual arrays. */
283   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
284        ci++, compptr++) {
285     /* Don't bother to IDCT an uninteresting component. */
286     if (! compptr->component_needed)
287       continue;
288     /* Align the virtual buffer for this component. */
289     buffer = (*cinfo->mem->access_virt_barray)
290       ((j_common_ptr) cinfo, coef->whole_image[ci],
291        cinfo->output_iMCU_row * compptr->v_samp_factor,
292        (JDIMENSION) compptr->v_samp_factor, FALSE);
293     /* Count non-dummy DCT block rows in this iMCU row. */
294     if (cinfo->output_iMCU_row < last_iMCU_row)
295       block_rows = compptr->v_samp_factor;
296     else {
297       /* NB: can't use last_row_height here; it is input-side-dependent! */
298       block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
299       if (block_rows == 0) block_rows = compptr->v_samp_factor;
300     }
301     inverse_DCT = cinfo->idct->inverse_DCT[ci];
302     output_ptr = output_buf[ci];
303     /* Loop over all DCT blocks to be processed. */
304     for (block_row = 0; block_row < block_rows; block_row++) {
305       buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
306       output_col = 0;
307       for (block_num = cinfo->master->first_MCU_col[ci];
308            block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
309         (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
310                         output_ptr, output_col);
311         buffer_ptr++;
312         output_col += compptr->_DCT_scaled_size;
313       }
314       output_ptr += compptr->_DCT_scaled_size;
315     }
316   }
317 
318   if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
319     return JPEG_ROW_COMPLETED;
320   return JPEG_SCAN_COMPLETED;
321 }
322 
323 #endif /* D_MULTISCAN_FILES_SUPPORTED */
324 
325 
326 #ifdef BLOCK_SMOOTHING_SUPPORTED
327 
328 /*
329  * This code applies interblock smoothing as described by section K.8
330  * of the JPEG standard: the first 5 AC coefficients are estimated from
331  * the DC values of a DCT block and its 8 neighboring blocks.
332  * We apply smoothing only for progressive JPEG decoding, and only if
333  * the coefficients it can estimate are not yet known to full precision.
334  */
335 
336 /* Natural-order array positions of the first 5 zigzag-order coefficients */
337 #define Q01_POS  1
338 #define Q10_POS  8
339 #define Q20_POS  16
340 #define Q11_POS  9
341 #define Q02_POS  2
342 
343 /*
344  * Determine whether block smoothing is applicable and safe.
345  * We also latch the current states of the coef_bits[] entries for the
346  * AC coefficients; otherwise, if the input side of the decompressor
347  * advances into a new scan, we might think the coefficients are known
348  * more accurately than they really are.
349  */
350 
351 LOCAL(boolean)
smoothing_ok(j_decompress_ptr cinfo)352 smoothing_ok (j_decompress_ptr cinfo)
353 {
354   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
355   boolean smoothing_useful = FALSE;
356   int ci, coefi;
357   jpeg_component_info *compptr;
358   JQUANT_TBL * qtable;
359   int * coef_bits;
360   int * coef_bits_latch;
361 
362   if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
363     return FALSE;
364 
365   /* Allocate latch area if not already done */
366   if (coef->coef_bits_latch == NULL)
367     coef->coef_bits_latch = (int *)
368       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
369                                   cinfo->num_components *
370                                   (SAVED_COEFS * sizeof(int)));
371   coef_bits_latch = coef->coef_bits_latch;
372 
373   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
374        ci++, compptr++) {
375     /* All components' quantization values must already be latched. */
376     if ((qtable = compptr->quant_table) == NULL)
377       return FALSE;
378     /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
379     if (qtable->quantval[0] == 0 ||
380         qtable->quantval[Q01_POS] == 0 ||
381         qtable->quantval[Q10_POS] == 0 ||
382         qtable->quantval[Q20_POS] == 0 ||
383         qtable->quantval[Q11_POS] == 0 ||
384         qtable->quantval[Q02_POS] == 0)
385       return FALSE;
386     /* DC values must be at least partly known for all components. */
387     coef_bits = cinfo->coef_bits[ci];
388     if (coef_bits[0] < 0)
389       return FALSE;
390     /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
391     for (coefi = 1; coefi <= 5; coefi++) {
392       coef_bits_latch[coefi] = coef_bits[coefi];
393       if (coef_bits[coefi] != 0)
394         smoothing_useful = TRUE;
395     }
396     coef_bits_latch += SAVED_COEFS;
397   }
398 
399   return smoothing_useful;
400 }
401 
402 
403 /*
404  * Variant of decompress_data for use when doing block smoothing.
405  */
406 
407 METHODDEF(int)
decompress_smooth_data(j_decompress_ptr cinfo,JSAMPIMAGE output_buf)408 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
409 {
410   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
411   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
412   JDIMENSION block_num, last_block_column;
413   int ci, block_row, block_rows, access_rows;
414   JBLOCKARRAY buffer;
415   JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
416   JSAMPARRAY output_ptr;
417   JDIMENSION output_col;
418   jpeg_component_info *compptr;
419   inverse_DCT_method_ptr inverse_DCT;
420   boolean first_row, last_row;
421   JCOEF * workspace;
422   int *coef_bits;
423   JQUANT_TBL *quanttbl;
424   INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
425   int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
426   int Al, pred;
427 
428   /* Keep a local variable to avoid looking it up more than once */
429   workspace = coef->workspace;
430 
431   /* Force some input to be done if we are getting ahead of the input. */
432   while (cinfo->input_scan_number <= cinfo->output_scan_number &&
433          ! cinfo->inputctl->eoi_reached) {
434     if (cinfo->input_scan_number == cinfo->output_scan_number) {
435       /* If input is working on current scan, we ordinarily want it to
436        * have completed the current row.  But if input scan is DC,
437        * we want it to keep one row ahead so that next block row's DC
438        * values are up to date.
439        */
440       JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
441       if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
442         break;
443     }
444     if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
445       return JPEG_SUSPENDED;
446   }
447 
448   /* OK, output from the virtual arrays. */
449   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
450        ci++, compptr++) {
451     /* Don't bother to IDCT an uninteresting component. */
452     if (! compptr->component_needed)
453       continue;
454     /* Count non-dummy DCT block rows in this iMCU row. */
455     if (cinfo->output_iMCU_row < last_iMCU_row) {
456       block_rows = compptr->v_samp_factor;
457       access_rows = block_rows * 2; /* this and next iMCU row */
458       last_row = FALSE;
459     } else {
460       /* NB: can't use last_row_height here; it is input-side-dependent! */
461       block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
462       if (block_rows == 0) block_rows = compptr->v_samp_factor;
463       access_rows = block_rows; /* this iMCU row only */
464       last_row = TRUE;
465     }
466     /* Align the virtual buffer for this component. */
467     if (cinfo->output_iMCU_row > 0) {
468       access_rows += compptr->v_samp_factor; /* prior iMCU row too */
469       buffer = (*cinfo->mem->access_virt_barray)
470         ((j_common_ptr) cinfo, coef->whole_image[ci],
471          (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
472          (JDIMENSION) access_rows, FALSE);
473       buffer += compptr->v_samp_factor; /* point to current iMCU row */
474       first_row = FALSE;
475     } else {
476       buffer = (*cinfo->mem->access_virt_barray)
477         ((j_common_ptr) cinfo, coef->whole_image[ci],
478          (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
479       first_row = TRUE;
480     }
481     /* Fetch component-dependent info */
482     coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
483     quanttbl = compptr->quant_table;
484     Q00 = quanttbl->quantval[0];
485     Q01 = quanttbl->quantval[Q01_POS];
486     Q10 = quanttbl->quantval[Q10_POS];
487     Q20 = quanttbl->quantval[Q20_POS];
488     Q11 = quanttbl->quantval[Q11_POS];
489     Q02 = quanttbl->quantval[Q02_POS];
490     inverse_DCT = cinfo->idct->inverse_DCT[ci];
491     output_ptr = output_buf[ci];
492     /* Loop over all DCT blocks to be processed. */
493     for (block_row = 0; block_row < block_rows; block_row++) {
494       buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
495       if (first_row && block_row == 0)
496         prev_block_row = buffer_ptr;
497       else
498         prev_block_row = buffer[block_row-1];
499       if (last_row && block_row == block_rows-1)
500         next_block_row = buffer_ptr;
501       else
502         next_block_row = buffer[block_row+1];
503       /* We fetch the surrounding DC values using a sliding-register approach.
504        * Initialize all nine here so as to do the right thing on narrow pics.
505        */
506       DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
507       DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
508       DC7 = DC8 = DC9 = (int) next_block_row[0][0];
509       output_col = 0;
510       last_block_column = compptr->width_in_blocks - 1;
511       for (block_num = cinfo->master->first_MCU_col[ci];
512            block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
513         /* Fetch current DCT block into workspace so we can modify it. */
514         jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
515         /* Update DC values */
516         if (block_num < last_block_column) {
517           DC3 = (int) prev_block_row[1][0];
518           DC6 = (int) buffer_ptr[1][0];
519           DC9 = (int) next_block_row[1][0];
520         }
521         /* Compute coefficient estimates per K.8.
522          * An estimate is applied only if coefficient is still zero,
523          * and is not known to be fully accurate.
524          */
525         /* AC01 */
526         if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
527           num = 36 * Q00 * (DC4 - DC6);
528           if (num >= 0) {
529             pred = (int) (((Q01<<7) + num) / (Q01<<8));
530             if (Al > 0 && pred >= (1<<Al))
531               pred = (1<<Al)-1;
532           } else {
533             pred = (int) (((Q01<<7) - num) / (Q01<<8));
534             if (Al > 0 && pred >= (1<<Al))
535               pred = (1<<Al)-1;
536             pred = -pred;
537           }
538           workspace[1] = (JCOEF) pred;
539         }
540         /* AC10 */
541         if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
542           num = 36 * Q00 * (DC2 - DC8);
543           if (num >= 0) {
544             pred = (int) (((Q10<<7) + num) / (Q10<<8));
545             if (Al > 0 && pred >= (1<<Al))
546               pred = (1<<Al)-1;
547           } else {
548             pred = (int) (((Q10<<7) - num) / (Q10<<8));
549             if (Al > 0 && pred >= (1<<Al))
550               pred = (1<<Al)-1;
551             pred = -pred;
552           }
553           workspace[8] = (JCOEF) pred;
554         }
555         /* AC20 */
556         if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
557           num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
558           if (num >= 0) {
559             pred = (int) (((Q20<<7) + num) / (Q20<<8));
560             if (Al > 0 && pred >= (1<<Al))
561               pred = (1<<Al)-1;
562           } else {
563             pred = (int) (((Q20<<7) - num) / (Q20<<8));
564             if (Al > 0 && pred >= (1<<Al))
565               pred = (1<<Al)-1;
566             pred = -pred;
567           }
568           workspace[16] = (JCOEF) pred;
569         }
570         /* AC11 */
571         if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
572           num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
573           if (num >= 0) {
574             pred = (int) (((Q11<<7) + num) / (Q11<<8));
575             if (Al > 0 && pred >= (1<<Al))
576               pred = (1<<Al)-1;
577           } else {
578             pred = (int) (((Q11<<7) - num) / (Q11<<8));
579             if (Al > 0 && pred >= (1<<Al))
580               pred = (1<<Al)-1;
581             pred = -pred;
582           }
583           workspace[9] = (JCOEF) pred;
584         }
585         /* AC02 */
586         if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
587           num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
588           if (num >= 0) {
589             pred = (int) (((Q02<<7) + num) / (Q02<<8));
590             if (Al > 0 && pred >= (1<<Al))
591               pred = (1<<Al)-1;
592           } else {
593             pred = (int) (((Q02<<7) - num) / (Q02<<8));
594             if (Al > 0 && pred >= (1<<Al))
595               pred = (1<<Al)-1;
596             pred = -pred;
597           }
598           workspace[2] = (JCOEF) pred;
599         }
600         /* OK, do the IDCT */
601         (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
602                         output_ptr, output_col);
603         /* Advance for next column */
604         DC1 = DC2; DC2 = DC3;
605         DC4 = DC5; DC5 = DC6;
606         DC7 = DC8; DC8 = DC9;
607         buffer_ptr++, prev_block_row++, next_block_row++;
608         output_col += compptr->_DCT_scaled_size;
609       }
610       output_ptr += compptr->_DCT_scaled_size;
611     }
612   }
613 
614   if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
615     return JPEG_ROW_COMPLETED;
616   return JPEG_SCAN_COMPLETED;
617 }
618 
619 #endif /* BLOCK_SMOOTHING_SUPPORTED */
620 
621 
622 /*
623  * Initialize coefficient buffer controller.
624  */
625 
626 GLOBAL(void)
jinit_d_coef_controller(j_decompress_ptr cinfo,boolean need_full_buffer)627 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
628 {
629   my_coef_ptr coef;
630 
631   coef = (my_coef_ptr)
632     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
633                                 sizeof(my_coef_controller));
634   cinfo->coef = (struct jpeg_d_coef_controller *) coef;
635   coef->pub.start_input_pass = start_input_pass;
636   coef->pub.start_output_pass = start_output_pass;
637 #ifdef BLOCK_SMOOTHING_SUPPORTED
638   coef->coef_bits_latch = NULL;
639 #endif
640 
641   /* Create the coefficient buffer. */
642   if (need_full_buffer) {
643 #ifdef D_MULTISCAN_FILES_SUPPORTED
644     /* Allocate a full-image virtual array for each component, */
645     /* padded to a multiple of samp_factor DCT blocks in each direction. */
646     /* Note we ask for a pre-zeroed array. */
647     int ci, access_rows;
648     jpeg_component_info *compptr;
649 
650     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
651          ci++, compptr++) {
652       access_rows = compptr->v_samp_factor;
653 #ifdef BLOCK_SMOOTHING_SUPPORTED
654       /* If block smoothing could be used, need a bigger window */
655       if (cinfo->progressive_mode)
656         access_rows *= 3;
657 #endif
658       coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
659         ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
660          (JDIMENSION) jround_up((long) compptr->width_in_blocks,
661                                 (long) compptr->h_samp_factor),
662          (JDIMENSION) jround_up((long) compptr->height_in_blocks,
663                                 (long) compptr->v_samp_factor),
664          (JDIMENSION) access_rows);
665     }
666     coef->pub.consume_data = consume_data;
667     coef->pub.decompress_data = decompress_data;
668     coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
669 #else
670     ERREXIT(cinfo, JERR_NOT_COMPILED);
671 #endif
672   } else {
673     /* We only need a single-MCU buffer. */
674     JBLOCKROW buffer;
675     int i;
676 
677     buffer = (JBLOCKROW)
678       (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
679                                   D_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
680     for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
681       coef->MCU_buffer[i] = buffer + i;
682     }
683     coef->pub.consume_data = dummy_consume_data;
684     coef->pub.decompress_data = decompress_onepass;
685     coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
686   }
687 
688   /* Allocate the workspace buffer */
689   coef->workspace = (JCOEF *)
690     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
691                                 sizeof(JCOEF) * DCTSIZE2);
692 }
693