source: golgotha/src/i4/loaders/jpg/jdcoefct.cc @ 80

Last change on this file since 80 was 80, checked in by Sam Hocevar, 11 years ago
  • Adding the Golgotha source code. Not sure what's going to be interesting in there, but since it's all public domain, there's certainly stuff to pick up.
File size: 25.8 KB
Line 
1/********************************************************************** <BR>
2  This file is part of Crack dot Com's free source code release of
3  Golgotha. <a href="http://www.crack.com/golgotha_release"> <BR> for
4  information about compiling & licensing issues visit this URL</a>
5  <PRE> If that doesn't help, contact Jonathan Clark at
6  golgotha_source@usa.net (Subject should have "GOLG" in it)
7***********************************************************************/
8
9/*
10 * jdcoefct.c
11 *
12 * Copyright (C) 1994-1996, Thomas G. Lane.
13 * This file is part of the Independent JPEG Group's software.
14 * For conditions of distribution and use, see the accompanying README file.
15 *
16 * This file contains the coefficient buffer controller for decompression.
17 * This controller is the top level of the JPEG decompressor proper.
18 * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
19 *
20 * In buffered-image mode, this controller is the interface between
21 * input-oriented processing and output-oriented processing.
22 * Also, the input side (only) is used when reading a file for transcoding.
23 */
24
25#define JPEG_INTERNALS
26#include "loaders/jpg/jinclude.h"
27#include "loaders/jpg/jpeglib.h"
28
29/* Block smoothing is only applicable for progressive JPEG, so: */
30#ifndef D_PROGRESSIVE_SUPPORTED
31#undef BLOCK_SMOOTHING_SUPPORTED
32#endif
33
34/* Private buffer controller object */
35
36typedef struct {
37  struct jpeg_d_coef_controller pub; /* public fields */
38
39  /* These variables keep track of the current location of the input side. */
40  /* cinfo->input_iMCU_row is also used for this. */
41  JDIMENSION MCU_ctr;           /* counts MCUs processed in current row */
42  int MCU_vert_offset;          /* counts MCU rows within iMCU row */
43  int MCU_rows_per_iMCU_row;    /* number of such rows needed */
44
45  /* The output side's location is represented by cinfo->output_iMCU_row. */
46
47  /* In single-pass modes, it's sufficient to buffer just one MCU.
48   * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
49   * and let the entropy decoder write into that workspace each time.
50   * (On 80x86, the workspace is FAR even though it's not really very big;
51   * this is to keep the module interfaces unchanged when a large coefficient
52   * buffer is necessary.)
53   * In multi-pass modes, this array points to the current MCU's blocks
54   * within the virtual arrays; it is used only by the input side.
55   */
56  JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];
57
58#ifdef D_MULTISCAN_FILES_SUPPORTED
59  /* In multi-pass modes, we need a virtual block array for each component. */
60  jvirt_barray_ptr whole_image[MAX_COMPONENTS];
61#endif
62
63#ifdef BLOCK_SMOOTHING_SUPPORTED
64  /* When doing block smoothing, we latch coefficient Al values here */
65  int * coef_bits_latch;
66#define SAVED_COEFS  6          /* we save coef_bits[0..5] */
67#endif
68} my_coef_controller;
69
70typedef my_coef_controller * my_coef_ptr;
71
72/* Forward declarations */
73METHODDEF(int) decompress_onepass
74        JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
75#ifdef D_MULTISCAN_FILES_SUPPORTED
76METHODDEF(int) decompress_data
77        JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
78#endif
79#ifdef BLOCK_SMOOTHING_SUPPORTED
80LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo));
81METHODDEF(int) decompress_smooth_data
82        JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
83#endif
84
85
86LOCAL(void)
87start_iMCU_row (j_decompress_ptr cinfo)
88/* Reset within-iMCU-row counters for a new row (input side) */
89{
90  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
91
92  /* In an interleaved scan, an MCU row is the same as an iMCU row.
93   * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
94   * But at the bottom of the image, process only what's left.
95   */
96  if (cinfo->comps_in_scan > 1) {
97    coef->MCU_rows_per_iMCU_row = 1;
98  } else {
99    if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
100      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
101    else
102      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
103  }
104
105  coef->MCU_ctr = 0;
106  coef->MCU_vert_offset = 0;
107}
108
109
110/*
111 * Initialize for an input processing pass.
112 */
113
114METHODDEF(void)
115start_input_pass (j_decompress_ptr cinfo)
116{
117  cinfo->input_iMCU_row = 0;
118  start_iMCU_row(cinfo);
119}
120
121
122/*
123 * Initialize for an output processing pass.
124 */
125
126METHODDEF(void)
127start_output_pass (j_decompress_ptr cinfo)
128{
129#ifdef BLOCK_SMOOTHING_SUPPORTED
130  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
131
132  /* If multipass, check to see whether to use block smoothing on this pass */
133  if (coef->pub.coef_arrays != NULL) {
134    if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
135      coef->pub.decompress_data = decompress_smooth_data;
136    else
137      coef->pub.decompress_data = decompress_data;
138  }
139#endif
140  cinfo->output_iMCU_row = 0;
141}
142
143
144/*
145 * Decompress and return some data in the single-pass case.
146 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
147 * Input and output must run in lockstep since we have only a one-MCU buffer.
148 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
149 *
150 * NB: output_buf contains a plane for each component in image.
151 * For single pass, this is the same as the components in the scan.
152 */
153
154METHODDEF(int)
155decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
156{
157  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
158  JDIMENSION MCU_col_num;       /* index of current MCU within row */
159  JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
160  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
161  int blkn, ci, xindex, yindex, yoffset, useful_width;
162  JSAMPARRAY output_ptr;
163  JDIMENSION start_col, output_col;
164  jpeg_component_info *compptr;
165  inverse_DCT_method_ptr inverse_DCT;
166
167  /* Loop to process as much as one whole iMCU row */
168  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
169       yoffset++) {
170    for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
171         MCU_col_num++) {
172      /* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */
173      jzero_far((void FAR *) coef->MCU_buffer[0],
174                (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));
175      if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
176        /* Suspension forced; update state counters and exit */
177        coef->MCU_vert_offset = yoffset;
178        coef->MCU_ctr = MCU_col_num;
179        return JPEG_SUSPENDED;
180      }
181      /* Determine where data should go in output_buf and do the IDCT thing.
182       * We skip dummy blocks at the right and bottom edges (but blkn gets
183       * incremented past them!).  Note the inner loop relies on having
184       * allocated the MCU_buffer[] blocks sequentially.
185       */
186      blkn = 0;                 /* index of current DCT block within MCU */
187      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
188        compptr = cinfo->cur_comp_info[ci];
189        /* Don't bother to IDCT an uninteresting component. */
190        if (! compptr->component_needed) {
191          blkn += compptr->MCU_blocks;
192          continue;
193        }
194        inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
195        useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
196                                                    : compptr->last_col_width;
197        output_ptr = output_buf[ci] + yoffset * compptr->DCT_scaled_size;
198        start_col = MCU_col_num * compptr->MCU_sample_width;
199        for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
200          if (cinfo->input_iMCU_row < last_iMCU_row ||
201              yoffset+yindex < compptr->last_row_height) {
202            output_col = start_col;
203            for (xindex = 0; xindex < useful_width; xindex++) {
204              (*inverse_DCT) (cinfo, compptr,
205                              (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
206                              output_ptr, output_col);
207              output_col += compptr->DCT_scaled_size;
208            }
209          }
210          blkn += compptr->MCU_width;
211          output_ptr += compptr->DCT_scaled_size;
212        }
213      }
214    }
215    /* Completed an MCU row, but perhaps not an iMCU row */
216    coef->MCU_ctr = 0;
217  }
218  /* Completed the iMCU row, advance counters for next one */
219  cinfo->output_iMCU_row++;
220  if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
221    start_iMCU_row(cinfo);
222    return JPEG_ROW_COMPLETED;
223  }
224  /* Completed the scan */
225  (*cinfo->inputctl->finish_input_pass) (cinfo);
226  return JPEG_SCAN_COMPLETED;
227}
228
229
230/*
231 * Dummy consume-input routine for single-pass operation.
232 */
233
234METHODDEF(int)
235dummy_consume_data (j_decompress_ptr cinfo)
236{
237  return JPEG_SUSPENDED;        /* Always indicate nothing was done */
238}
239
240
241#ifdef D_MULTISCAN_FILES_SUPPORTED
242
243/*
244 * Consume input data and store it in the full-image coefficient buffer.
245 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
246 * ie, v_samp_factor block rows for each component in the scan.
247 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
248 */
249
250METHODDEF(int)
251consume_data (j_decompress_ptr cinfo)
252{
253  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
254  JDIMENSION MCU_col_num;       /* index of current MCU within row */
255  int blkn, ci, xindex, yindex, yoffset;
256  JDIMENSION start_col;
257  JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
258  JBLOCKROW buffer_ptr;
259  jpeg_component_info *compptr;
260
261  /* Align the virtual buffers for the components used in this scan. */
262  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
263    compptr = cinfo->cur_comp_info[ci];
264    buffer[ci] = (*cinfo->mem->access_virt_barray)
265      ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
266       cinfo->input_iMCU_row * compptr->v_samp_factor,
267       (JDIMENSION) compptr->v_samp_factor, TRUE);
268    /* Note: entropy decoder expects buffer to be zeroed,
269     * but this is handled automatically by the memory manager
270     * because we requested a pre-zeroed array.
271     */
272  }
273
274  /* Loop to process one whole iMCU row */
275  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
276       yoffset++) {
277    for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
278         MCU_col_num++) {
279      /* Construct list of pointers to DCT blocks belonging to this MCU */
280      blkn = 0;                 /* index of current DCT block within MCU */
281      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
282        compptr = cinfo->cur_comp_info[ci];
283        start_col = MCU_col_num * compptr->MCU_width;
284        for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
285          buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
286          for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
287            coef->MCU_buffer[blkn++] = buffer_ptr++;
288          }
289        }
290      }
291      /* Try to fetch the MCU. */
292      if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
293        /* Suspension forced; update state counters and exit */
294        coef->MCU_vert_offset = yoffset;
295        coef->MCU_ctr = MCU_col_num;
296        return JPEG_SUSPENDED;
297      }
298    }
299    /* Completed an MCU row, but perhaps not an iMCU row */
300    coef->MCU_ctr = 0;
301  }
302  /* Completed the iMCU row, advance counters for next one */
303  if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
304    start_iMCU_row(cinfo);
305    return JPEG_ROW_COMPLETED;
306  }
307  /* Completed the scan */
308  (*cinfo->inputctl->finish_input_pass) (cinfo);
309  return JPEG_SCAN_COMPLETED;
310}
311
312
313/*
314 * Decompress and return some data in the multi-pass case.
315 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
316 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
317 *
318 * NB: output_buf contains a plane for each component in image.
319 */
320
321METHODDEF(int)
322decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
323{
324  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
325  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
326  JDIMENSION block_num;
327  int ci, block_row, block_rows;
328  JBLOCKARRAY buffer;
329  JBLOCKROW buffer_ptr;
330  JSAMPARRAY output_ptr;
331  JDIMENSION output_col;
332  jpeg_component_info *compptr;
333  inverse_DCT_method_ptr inverse_DCT;
334
335  /* Force some input to be done if we are getting ahead of the input. */
336  while (cinfo->input_scan_number < cinfo->output_scan_number ||
337         (cinfo->input_scan_number == cinfo->output_scan_number &&
338          cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
339    if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
340      return JPEG_SUSPENDED;
341  }
342
343  /* OK, output from the virtual arrays. */
344  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
345       ci++, compptr++) {
346    /* Don't bother to IDCT an uninteresting component. */
347    if (! compptr->component_needed)
348      continue;
349    /* Align the virtual buffer for this component. */
350    buffer = (*cinfo->mem->access_virt_barray)
351      ((j_common_ptr) cinfo, coef->whole_image[ci],
352       cinfo->output_iMCU_row * compptr->v_samp_factor,
353       (JDIMENSION) compptr->v_samp_factor, FALSE);
354    /* Count non-dummy DCT block rows in this iMCU row. */
355    if (cinfo->output_iMCU_row < last_iMCU_row)
356      block_rows = compptr->v_samp_factor;
357    else {
358      /* NB: can't use last_row_height here; it is input-side-dependent! */
359      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
360      if (block_rows == 0) block_rows = compptr->v_samp_factor;
361    }
362    inverse_DCT = cinfo->idct->inverse_DCT[ci];
363    output_ptr = output_buf[ci];
364    /* Loop over all DCT blocks to be processed. */
365    for (block_row = 0; block_row < block_rows; block_row++) {
366      buffer_ptr = buffer[block_row];
367      output_col = 0;
368      for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
369        (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
370                        output_ptr, output_col);
371        buffer_ptr++;
372        output_col += compptr->DCT_scaled_size;
373      }
374      output_ptr += compptr->DCT_scaled_size;
375    }
376  }
377
378  if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
379    return JPEG_ROW_COMPLETED;
380  return JPEG_SCAN_COMPLETED;
381}
382
383#endif /* D_MULTISCAN_FILES_SUPPORTED */
384
385
386#ifdef BLOCK_SMOOTHING_SUPPORTED
387
388/*
389 * This code applies interblock smoothing as described by section K.8
390 * of the JPEG standard: the first 5 AC coefficients are estimated from
391 * the DC values of a DCT block and its 8 neighboring blocks.
392 * We apply smoothing only for progressive JPEG decoding, and only if
393 * the coefficients it can estimate are not yet known to full precision.
394 */
395
396/* Natural-order array positions of the first 5 zigzag-order coefficients */
397#define Q01_POS  1
398#define Q10_POS  8
399#define Q20_POS  16
400#define Q11_POS  9
401#define Q02_POS  2
402
403/*
404 * Determine whether block smoothing is applicable and safe.
405 * We also latch the current states of the coef_bits[] entries for the
406 * AC coefficients; otherwise, if the input side of the decompressor
407 * advances into a new scan, we might think the coefficients are known
408 * more accurately than they really are.
409 */
410
411LOCAL(boolean)
412smoothing_ok (j_decompress_ptr cinfo)
413{
414  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
415  boolean smoothing_useful = FALSE;
416  int ci, coefi;
417  jpeg_component_info *compptr;
418  JQUANT_TBL * qtable;
419  int * coef_bits;
420  int * coef_bits_latch;
421
422  if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
423    return FALSE;
424
425  /* Allocate latch area if not already done */
426  if (coef->coef_bits_latch == NULL)
427    coef->coef_bits_latch = (int *)
428      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
429                                  cinfo->num_components *
430                                  (SAVED_COEFS * SIZEOF(int)));
431  coef_bits_latch = coef->coef_bits_latch;
432
433  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
434       ci++, compptr++) {
435    /* All components' quantization values must already be latched. */
436    if ((qtable = compptr->quant_table) == NULL)
437      return FALSE;
438    /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
439    if (qtable->quantval[0] == 0 ||
440        qtable->quantval[Q01_POS] == 0 ||
441        qtable->quantval[Q10_POS] == 0 ||
442        qtable->quantval[Q20_POS] == 0 ||
443        qtable->quantval[Q11_POS] == 0 ||
444        qtable->quantval[Q02_POS] == 0)
445      return FALSE;
446    /* DC values must be at least partly known for all components. */
447    coef_bits = cinfo->coef_bits[ci];
448    if (coef_bits[0] < 0)
449      return FALSE;
450    /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
451    for (coefi = 1; coefi <= 5; coefi++) {
452      coef_bits_latch[coefi] = coef_bits[coefi];
453      if (coef_bits[coefi] != 0)
454        smoothing_useful = TRUE;
455    }
456    coef_bits_latch += SAVED_COEFS;
457  }
458
459  return smoothing_useful;
460}
461
462
463/*
464 * Variant of decompress_data for use when doing block smoothing.
465 */
466
467METHODDEF(int)
468decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
469{
470  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
471  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
472  JDIMENSION block_num, last_block_column;
473  int ci, block_row, block_rows, access_rows;
474  JBLOCKARRAY buffer;
475  JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
476  JSAMPARRAY output_ptr;
477  JDIMENSION output_col;
478  jpeg_component_info *compptr;
479  inverse_DCT_method_ptr inverse_DCT;
480  boolean first_row, last_row;
481  JBLOCK workspace;
482  int *coef_bits;
483  JQUANT_TBL *quanttbl;
484  INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
485  int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
486  int Al, pred;
487
488  /* Force some input to be done if we are getting ahead of the input. */
489  while (cinfo->input_scan_number <= cinfo->output_scan_number &&
490         ! cinfo->inputctl->eoi_reached) {
491    if (cinfo->input_scan_number == cinfo->output_scan_number) {
492      /* If input is working on current scan, we ordinarily want it to
493       * have completed the current row.  But if input scan is DC,
494       * we want it to keep one row ahead so that next block row's DC
495       * values are up to date.
496       */
497      JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
498      if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
499        break;
500    }
501    if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
502      return JPEG_SUSPENDED;
503  }
504
505  /* OK, output from the virtual arrays. */
506  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
507       ci++, compptr++) {
508    /* Don't bother to IDCT an uninteresting component. */
509    if (! compptr->component_needed)
510      continue;
511    /* Count non-dummy DCT block rows in this iMCU row. */
512    if (cinfo->output_iMCU_row < last_iMCU_row) {
513      block_rows = compptr->v_samp_factor;
514      access_rows = block_rows * 2; /* this and next iMCU row */
515      last_row = FALSE;
516    } else {
517      /* NB: can't use last_row_height here; it is input-side-dependent! */
518      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
519      if (block_rows == 0) block_rows = compptr->v_samp_factor;
520      access_rows = block_rows; /* this iMCU row only */
521      last_row = TRUE;
522    }
523    /* Align the virtual buffer for this component. */
524    if (cinfo->output_iMCU_row > 0) {
525      access_rows += compptr->v_samp_factor; /* prior iMCU row too */
526      buffer = (*cinfo->mem->access_virt_barray)
527        ((j_common_ptr) cinfo, coef->whole_image[ci],
528         (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
529         (JDIMENSION) access_rows, FALSE);
530      buffer += compptr->v_samp_factor; /* point to current iMCU row */
531      first_row = FALSE;
532    } else {
533      buffer = (*cinfo->mem->access_virt_barray)
534        ((j_common_ptr) cinfo, coef->whole_image[ci],
535         (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
536      first_row = TRUE;
537    }
538    /* Fetch component-dependent info */
539    coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
540    quanttbl = compptr->quant_table;
541    Q00 = quanttbl->quantval[0];
542    Q01 = quanttbl->quantval[Q01_POS];
543    Q10 = quanttbl->quantval[Q10_POS];
544    Q20 = quanttbl->quantval[Q20_POS];
545    Q11 = quanttbl->quantval[Q11_POS];
546    Q02 = quanttbl->quantval[Q02_POS];
547    inverse_DCT = cinfo->idct->inverse_DCT[ci];
548    output_ptr = output_buf[ci];
549    /* Loop over all DCT blocks to be processed. */
550    for (block_row = 0; block_row < block_rows; block_row++) {
551      buffer_ptr = buffer[block_row];
552      if (first_row && block_row == 0)
553        prev_block_row = buffer_ptr;
554      else
555        prev_block_row = buffer[block_row-1];
556      if (last_row && block_row == block_rows-1)
557        next_block_row = buffer_ptr;
558      else
559        next_block_row = buffer[block_row+1];
560      /* We fetch the surrounding DC values using a sliding-register approach.
561       * Initialize all nine here so as to do the right thing on narrow pics.
562       */
563      DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
564      DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
565      DC7 = DC8 = DC9 = (int) next_block_row[0][0];
566      output_col = 0;
567      last_block_column = compptr->width_in_blocks - 1;
568      for (block_num = 0; block_num <= last_block_column; block_num++) {
569        /* Fetch current DCT block into workspace so we can modify it. */
570        jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
571        /* Update DC values */
572        if (block_num < last_block_column) {
573          DC3 = (int) prev_block_row[1][0];
574          DC6 = (int) buffer_ptr[1][0];
575          DC9 = (int) next_block_row[1][0];
576        }
577        /* Compute coefficient estimates per K.8.
578         * An estimate is applied only if coefficient is still zero,
579         * and is not known to be fully accurate.
580         */
581        /* AC01 */
582        if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
583          num = 36 * Q00 * (DC4 - DC6);
584          if (num >= 0) {
585            pred = (int) (((Q01<<7) + num) / (Q01<<8));
586            if (Al > 0 && pred >= (1<<Al))
587              pred = (1<<Al)-1;
588          } else {
589            pred = (int) (((Q01<<7) - num) / (Q01<<8));
590            if (Al > 0 && pred >= (1<<Al))
591              pred = (1<<Al)-1;
592            pred = -pred;
593          }
594          workspace[1] = (JCOEF) pred;
595        }
596        /* AC10 */
597        if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
598          num = 36 * Q00 * (DC2 - DC8);
599          if (num >= 0) {
600            pred = (int) (((Q10<<7) + num) / (Q10<<8));
601            if (Al > 0 && pred >= (1<<Al))
602              pred = (1<<Al)-1;
603          } else {
604            pred = (int) (((Q10<<7) - num) / (Q10<<8));
605            if (Al > 0 && pred >= (1<<Al))
606              pred = (1<<Al)-1;
607            pred = -pred;
608          }
609          workspace[8] = (JCOEF) pred;
610        }
611        /* AC20 */
612        if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
613          num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
614          if (num >= 0) {
615            pred = (int) (((Q20<<7) + num) / (Q20<<8));
616            if (Al > 0 && pred >= (1<<Al))
617              pred = (1<<Al)-1;
618          } else {
619            pred = (int) (((Q20<<7) - num) / (Q20<<8));
620            if (Al > 0 && pred >= (1<<Al))
621              pred = (1<<Al)-1;
622            pred = -pred;
623          }
624          workspace[16] = (JCOEF) pred;
625        }
626        /* AC11 */
627        if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
628          num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
629          if (num >= 0) {
630            pred = (int) (((Q11<<7) + num) / (Q11<<8));
631            if (Al > 0 && pred >= (1<<Al))
632              pred = (1<<Al)-1;
633          } else {
634            pred = (int) (((Q11<<7) - num) / (Q11<<8));
635            if (Al > 0 && pred >= (1<<Al))
636              pred = (1<<Al)-1;
637            pred = -pred;
638          }
639          workspace[9] = (JCOEF) pred;
640        }
641        /* AC02 */
642        if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
643          num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
644          if (num >= 0) {
645            pred = (int) (((Q02<<7) + num) / (Q02<<8));
646            if (Al > 0 && pred >= (1<<Al))
647              pred = (1<<Al)-1;
648          } else {
649            pred = (int) (((Q02<<7) - num) / (Q02<<8));
650            if (Al > 0 && pred >= (1<<Al))
651              pred = (1<<Al)-1;
652            pred = -pred;
653          }
654          workspace[2] = (JCOEF) pred;
655        }
656        /* OK, do the IDCT */
657        (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
658                        output_ptr, output_col);
659        /* Advance for next column */
660        DC1 = DC2; DC2 = DC3;
661        DC4 = DC5; DC5 = DC6;
662        DC7 = DC8; DC8 = DC9;
663        buffer_ptr++, prev_block_row++, next_block_row++;
664        output_col += compptr->DCT_scaled_size;
665      }
666      output_ptr += compptr->DCT_scaled_size;
667    }
668  }
669
670  if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
671    return JPEG_ROW_COMPLETED;
672  return JPEG_SCAN_COMPLETED;
673}
674
675#endif /* BLOCK_SMOOTHING_SUPPORTED */
676
677
678/*
679 * Initialize coefficient buffer controller.
680 */
681
682GLOBAL(void)
683jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
684{
685  my_coef_ptr coef;
686
687  coef = (my_coef_ptr)
688    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
689                                SIZEOF(my_coef_controller));
690  cinfo->coef = (struct jpeg_d_coef_controller *) coef;
691  coef->pub.start_input_pass = start_input_pass;
692  coef->pub.start_output_pass = start_output_pass;
693#ifdef BLOCK_SMOOTHING_SUPPORTED
694  coef->coef_bits_latch = NULL;
695#endif
696
697  /* Create the coefficient buffer. */
698  if (need_full_buffer) {
699#ifdef D_MULTISCAN_FILES_SUPPORTED
700    /* Allocate a full-image virtual array for each component, */
701    /* padded to a multiple of samp_factor DCT blocks in each direction. */
702    /* Note we ask for a pre-zeroed array. */
703    int ci, access_rows;
704    jpeg_component_info *compptr;
705
706    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
707         ci++, compptr++) {
708      access_rows = compptr->v_samp_factor;
709#ifdef BLOCK_SMOOTHING_SUPPORTED
710      /* If block smoothing could be used, need a bigger window */
711      if (cinfo->progressive_mode)
712        access_rows *= 3;
713#endif
714      coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
715        ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
716         (JDIMENSION) jround_up((long) compptr->width_in_blocks,
717                                (long) compptr->h_samp_factor),
718         (JDIMENSION) jround_up((long) compptr->height_in_blocks,
719                                (long) compptr->v_samp_factor),
720         (JDIMENSION) access_rows);
721    }
722    coef->pub.consume_data = consume_data;
723    coef->pub.decompress_data = decompress_data;
724    coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
725#else
726    ERREXIT(cinfo, JERR_NOT_COMPILED);
727#endif
728  } else {
729    /* We only need a single-MCU buffer. */
730    JBLOCKROW buffer;
731    int i;
732
733    buffer = (JBLOCKROW)
734      (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
735                                  D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
736    for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
737      coef->MCU_buffer[i] = buffer + i;
738    }
739    coef->pub.consume_data = dummy_consume_data;
740    coef->pub.decompress_data = decompress_onepass;
741    coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
742  }
743}
Note: See TracBrowser for help on using the repository browser.