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

Last change on this file since 80 was 80, checked in by Sam Hocevar, 12 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: 20.4 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 * jdphuff.c
11 *
12 * Copyright (C) 1995-1996, 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 Huffman entropy decoding routines for progressive JPEG.
17 *
18 * Much of the complexity here has to do with supporting input suspension.
19 * If the data source module demands suspension, we want to be able to back
20 * up to the start of the current MCU.  To do this, we copy state variables
21 * into local working storage, and update them back to the permanent
22 * storage only upon successful completion of an MCU.
23 */
24
25#define JPEG_INTERNALS
26#include "loaders/jpg/jinclude.h"
27#include "loaders/jpg/jpeglib.h"
28#include "loaders/jpg/jdhuff.h"         /* Declarations shared with jdhuff.c */
29
30
31#ifdef D_PROGRESSIVE_SUPPORTED
32
33/*
34 * Expanded entropy decoder object for progressive Huffman decoding.
35 *
36 * The savable_state subrecord contains fields that change within an MCU,
37 * but must not be updated permanently until we complete the MCU.
38 */
39
40typedef struct {
41  unsigned int EOBRUN;                  /* remaining EOBs in EOBRUN */
42  int last_dc_val[MAX_COMPS_IN_SCAN];   /* last DC coef for each component */
43} savable_state;
44
45/* This macro is to work around compilers with missing or broken
46 * structure assignment.  You'll need to fix this code if you have
47 * such a compiler and you change MAX_COMPS_IN_SCAN.
48 */
49
50#ifndef NO_STRUCT_ASSIGN
51#define ASSIGN_STATE(dest,src)  ((dest) = (src))
52#else
53#if MAX_COMPS_IN_SCAN == 4
54#define ASSIGN_STATE(dest,src)  \
55        ((dest).EOBRUN = (src).EOBRUN, \
56         (dest).last_dc_val[0] = (src).last_dc_val[0], \
57         (dest).last_dc_val[1] = (src).last_dc_val[1], \
58         (dest).last_dc_val[2] = (src).last_dc_val[2], \
59         (dest).last_dc_val[3] = (src).last_dc_val[3])
60#endif
61#endif
62
63
64typedef struct {
65  struct jpeg_entropy_decoder pub; /* public fields */
66
67  /* These fields are loaded into local variables at start of each MCU.
68   * In case of suspension, we exit WITHOUT updating them.
69   */
70  bitread_perm_state bitstate;  /* Bit buffer at start of MCU */
71  savable_state saved;          /* Other state at start of MCU */
72
73  /* These fields are NOT loaded into local working state. */
74  unsigned int restarts_to_go;  /* MCUs left in this restart interval */
75
76  /* Pointers to derived tables (these workspaces have image lifespan) */
77  d_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
78
79  d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */
80} phuff_entropy_decoder;
81
82typedef phuff_entropy_decoder * phuff_entropy_ptr;
83
84/* Forward declarations */
85METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo,
86                                            JBLOCKROW *MCU_data));
87METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo,
88                                            JBLOCKROW *MCU_data));
89METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo,
90                                             JBLOCKROW *MCU_data));
91METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo,
92                                             JBLOCKROW *MCU_data));
93
94
95/*
96 * Initialize for a Huffman-compressed scan.
97 */
98
99METHODDEF(void)
100start_pass_phuff_decoder (j_decompress_ptr cinfo)
101{
102  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
103  boolean is_DC_band, bad;
104  int ci, coefi, tbl;
105  int *coef_bit_ptr;
106  jpeg_component_info * compptr;
107
108  is_DC_band = (cinfo->Ss == 0);
109
110  /* Validate scan parameters */
111  bad = FALSE;
112  if (is_DC_band) {
113    if (cinfo->Se != 0)
114      bad = TRUE;
115  } else {
116    /* need not check Ss/Se < 0 since they came from unsigned bytes */
117    if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
118      bad = TRUE;
119    /* AC scans may have only one component */
120    if (cinfo->comps_in_scan != 1)
121      bad = TRUE;
122  }
123  if (cinfo->Ah != 0) {
124    /* Successive approximation refinement scan: must have Al = Ah-1. */
125    if (cinfo->Al != cinfo->Ah-1)
126      bad = TRUE;
127  }
128  if (cinfo->Al > 13)           /* need not check for < 0 */
129    bad = TRUE;
130  if (bad)
131    ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
132             cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
133  /* Update progression status, and verify that scan order is legal.
134   * Note that inter-scan inconsistencies are treated as warnings
135   * not fatal errors ... not clear if this is right way to behave.
136   */
137  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
138    int cindex = cinfo->cur_comp_info[ci]->component_index;
139    coef_bit_ptr = & cinfo->coef_bits[cindex][0];
140    if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
141      WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
142    for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
143      int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
144      if (cinfo->Ah != expected)
145        WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
146      coef_bit_ptr[coefi] = cinfo->Al;
147    }
148  }
149
150  /* Select MCU decoding routine */
151  if (cinfo->Ah == 0) {
152    if (is_DC_band)
153      entropy->pub.decode_mcu = decode_mcu_DC_first;
154    else
155      entropy->pub.decode_mcu = decode_mcu_AC_first;
156  } else {
157    if (is_DC_band)
158      entropy->pub.decode_mcu = decode_mcu_DC_refine;
159    else
160      entropy->pub.decode_mcu = decode_mcu_AC_refine;
161  }
162
163  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
164    compptr = cinfo->cur_comp_info[ci];
165    /* Make sure requested tables are present, and compute derived tables.
166     * We may build same derived table more than once, but it's not expensive.
167     */
168    if (is_DC_band) {
169      if (cinfo->Ah == 0) {     /* DC refinement needs no table */
170        tbl = compptr->dc_tbl_no;
171        if (tbl < 0 || tbl >= NUM_HUFF_TBLS ||
172            cinfo->dc_huff_tbl_ptrs[tbl] == NULL)
173          ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
174        jpeg_make_d_derived_tbl(cinfo, cinfo->dc_huff_tbl_ptrs[tbl],
175                                & entropy->derived_tbls[tbl]);
176      }
177    } else {
178      tbl = compptr->ac_tbl_no;
179      if (tbl < 0 || tbl >= NUM_HUFF_TBLS ||
180          cinfo->ac_huff_tbl_ptrs[tbl] == NULL)
181        ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
182      jpeg_make_d_derived_tbl(cinfo, cinfo->ac_huff_tbl_ptrs[tbl],
183                              & entropy->derived_tbls[tbl]);
184      /* remember the single active table */
185      entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
186    }
187    /* Initialize DC predictions to 0 */
188    entropy->saved.last_dc_val[ci] = 0;
189  }
190
191  /* Initialize bitread state variables */
192  entropy->bitstate.bits_left = 0;
193  entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
194  entropy->bitstate.printed_eod = FALSE;
195
196  /* Initialize private state variables */
197  entropy->saved.EOBRUN = 0;
198
199  /* Initialize restart counter */
200  entropy->restarts_to_go = cinfo->restart_interval;
201}
202
203
204/*
205 * Figure F.12: extend sign bit.
206 * On some machines, a shift and add will be faster than a table lookup.
207 */
208
209#ifdef AVOID_TABLES
210
211#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
212
213#else
214
215#define HUFF_EXTEND(x,s)  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
216
217static const int extend_test[16] =   /* entry n is 2**(n-1) */
218  { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
219    0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
220
221static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
222  { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
223    ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
224    ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
225    ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
226
227#endif /* AVOID_TABLES */
228
229
230/*
231 * Check for a restart marker & resynchronize decoder.
232 * Returns FALSE if must suspend.
233 */
234
235LOCAL(boolean)
236process_restart (j_decompress_ptr cinfo)
237{
238  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
239  int ci;
240
241  /* Throw away any unused bits remaining in bit buffer; */
242  /* include any full bytes in next_marker's count of discarded bytes */
243  cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
244  entropy->bitstate.bits_left = 0;
245
246  /* Advance past the RSTn marker */
247  if (! (*cinfo->marker->read_restart_marker) (cinfo))
248    return FALSE;
249
250  /* Re-initialize DC predictions to 0 */
251  for (ci = 0; ci < cinfo->comps_in_scan; ci++)
252    entropy->saved.last_dc_val[ci] = 0;
253  /* Re-init EOB run count, too */
254  entropy->saved.EOBRUN = 0;
255
256  /* Reset restart counter */
257  entropy->restarts_to_go = cinfo->restart_interval;
258
259  /* Next segment can get another out-of-data warning */
260  entropy->bitstate.printed_eod = FALSE;
261
262  return TRUE;
263}
264
265
266/*
267 * Huffman MCU decoding.
268 * Each of these routines decodes and returns one MCU's worth of
269 * Huffman-compressed coefficients.
270 * The coefficients are reordered from zigzag order into natural array order,
271 * but are not dequantized.
272 *
273 * The i'th block of the MCU is stored into the block pointed to by
274 * MCU_data[i].  WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
275 *
276 * We return FALSE if data source requested suspension.  In that case no
277 * changes have been made to permanent state.  (Exception: some output
278 * coefficients may already have been assigned.  This is harmless for
279 * spectral selection, since we'll just re-assign them on the next call.
280 * Successive approximation AC refinement has to be more careful, however.)
281 */
282
283/*
284 * MCU decoding for DC initial scan (either spectral selection,
285 * or first pass of successive approximation).
286 */
287
288METHODDEF(boolean)
289decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
290{   
291  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
292  int Al = cinfo->Al;
293  register int s, r;
294  int blkn, ci;
295  JBLOCKROW block;
296  BITREAD_STATE_VARS;
297  savable_state state;
298  d_derived_tbl * tbl;
299  jpeg_component_info * compptr;
300
301  /* Process restart marker if needed; may have to suspend */
302  if (cinfo->restart_interval) {
303    if (entropy->restarts_to_go == 0)
304      if (! process_restart(cinfo))
305        return FALSE;
306  }
307
308  /* Load up working state */
309  BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
310  ASSIGN_STATE(state, entropy->saved);
311
312  /* Outer loop handles each block in the MCU */
313
314  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
315    block = MCU_data[blkn];
316    ci = cinfo->MCU_membership[blkn];
317    compptr = cinfo->cur_comp_info[ci];
318    tbl = entropy->derived_tbls[compptr->dc_tbl_no];
319
320    /* Decode a single block's worth of coefficients */
321
322    /* Section F.2.2.1: decode the DC coefficient difference */
323    HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
324    if (s) {
325      CHECK_BIT_BUFFER(br_state, s, return FALSE);
326      r = GET_BITS(s);
327      s = HUFF_EXTEND(r, s);
328    }
329
330    /* Convert DC difference to actual value, update last_dc_val */
331    s += state.last_dc_val[ci];
332    state.last_dc_val[ci] = s;
333    /* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */
334    (*block)[0] = (JCOEF) (s << Al);
335  }
336
337  /* Completed MCU, so update state */
338  BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
339  ASSIGN_STATE(entropy->saved, state);
340
341  /* Account for restart interval (no-op if not using restarts) */
342  entropy->restarts_to_go--;
343
344  return TRUE;
345}
346
347
348/*
349 * MCU decoding for AC initial scan (either spectral selection,
350 * or first pass of successive approximation).
351 */
352
353METHODDEF(boolean)
354decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
355{   
356  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
357  int Se = cinfo->Se;
358  int Al = cinfo->Al;
359  register int s, k, r;
360  unsigned int EOBRUN;
361  JBLOCKROW block;
362  BITREAD_STATE_VARS;
363  d_derived_tbl * tbl;
364
365  /* Process restart marker if needed; may have to suspend */
366  if (cinfo->restart_interval) {
367    if (entropy->restarts_to_go == 0)
368      if (! process_restart(cinfo))
369        return FALSE;
370  }
371
372  /* Load up working state.
373   * We can avoid loading/saving bitread state if in an EOB run.
374   */
375  EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we care about */
376
377  /* There is always only one block per MCU */
378
379  if (EOBRUN > 0)               /* if it's a band of zeroes... */
380    EOBRUN--;                   /* ...process it now (we do nothing) */
381  else {
382    BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
383    block = MCU_data[0];
384    tbl = entropy->ac_derived_tbl;
385
386    for (k = cinfo->Ss; k <= Se; k++) {
387      HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
388      r = s >> 4;
389      s &= 15;
390      if (s) {
391        k += r;
392        CHECK_BIT_BUFFER(br_state, s, return FALSE);
393        r = GET_BITS(s);
394        s = HUFF_EXTEND(r, s);
395        /* Scale and output coefficient in natural (dezigzagged) order */
396        (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al);
397      } else {
398        if (r == 15) {          /* ZRL */
399          k += 15;              /* skip 15 zeroes in band */
400        } else {                /* EOBr, run length is 2^r + appended bits */
401          EOBRUN = 1 << r;
402          if (r) {              /* EOBr, r > 0 */
403            CHECK_BIT_BUFFER(br_state, r, return FALSE);
404            r = GET_BITS(r);
405            EOBRUN += r;
406          }
407          EOBRUN--;             /* this band is processed at this moment */
408          break;                /* force end-of-band */
409        }
410      }
411    }
412
413    BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
414  }
415
416  /* Completed MCU, so update state */
417  entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we care about */
418
419  /* Account for restart interval (no-op if not using restarts) */
420  entropy->restarts_to_go--;
421
422  return TRUE;
423}
424
425
426/*
427 * MCU decoding for DC successive approximation refinement scan.
428 * Note: we assume such scans can be multi-component, although the spec
429 * is not very clear on the point.
430 */
431
432METHODDEF(boolean)
433decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
434{   
435  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
436  int p1 = 1 << cinfo->Al;      /* 1 in the bit position being coded */
437  int blkn;
438  JBLOCKROW block;
439  BITREAD_STATE_VARS;
440
441  /* Process restart marker if needed; may have to suspend */
442  if (cinfo->restart_interval) {
443    if (entropy->restarts_to_go == 0)
444      if (! process_restart(cinfo))
445        return FALSE;
446  }
447
448  /* Load up working state */
449  BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
450
451  /* Outer loop handles each block in the MCU */
452
453  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
454    block = MCU_data[blkn];
455
456    /* Encoded data is simply the next bit of the two's-complement DC value */
457    CHECK_BIT_BUFFER(br_state, 1, return FALSE);
458    if (GET_BITS(1))
459      (*block)[0] |= p1;
460    /* Note: since we use |=, repeating the assignment later is safe */
461  }
462
463  /* Completed MCU, so update state */
464  BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
465
466  /* Account for restart interval (no-op if not using restarts) */
467  entropy->restarts_to_go--;
468
469  return TRUE;
470}
471
472
473/*
474 * MCU decoding for AC successive approximation refinement scan.
475 */
476
477METHODDEF(boolean)
478decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
479{   
480  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
481  int Se = cinfo->Se;
482  int p1 = 1 << cinfo->Al;      /* 1 in the bit position being coded */
483  int m1 = (-1) << cinfo->Al;   /* -1 in the bit position being coded */
484  register int s, k, r;
485  unsigned int EOBRUN;
486  JBLOCKROW block;
487  JCOEFPTR thiscoef;
488  BITREAD_STATE_VARS;
489  d_derived_tbl * tbl;
490  int num_newnz;
491  int newnz_pos[DCTSIZE2];
492
493  /* Process restart marker if needed; may have to suspend */
494  if (cinfo->restart_interval) {
495    if (entropy->restarts_to_go == 0)
496      if (! process_restart(cinfo))
497        return FALSE;
498  }
499
500  /* Load up working state */
501  BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
502  EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we care about */
503
504  /* There is always only one block per MCU */
505  block = MCU_data[0];
506  tbl = entropy->ac_derived_tbl;
507
508  /* If we are forced to suspend, we must undo the assignments to any newly
509   * nonzero coefficients in the block, because otherwise we'd get confused
510   * next time about which coefficients were already nonzero.
511   * But we need not undo addition of bits to already-nonzero coefficients;
512   * instead, we can test the current bit position to see if we already did it.
513   */
514  num_newnz = 0;
515
516  /* initialize coefficient loop counter to start of band */
517  k = cinfo->Ss;
518
519  if (EOBRUN == 0) {
520    for (; k <= Se; k++) {
521      HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
522      r = s >> 4;
523      s &= 15;
524      if (s) {
525        if (s != 1)             /* size of new coef should always be 1 */
526          WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
527        CHECK_BIT_BUFFER(br_state, 1, goto undoit);
528        if (GET_BITS(1))
529          s = p1;               /* newly nonzero coef is positive */
530        else
531          s = m1;               /* newly nonzero coef is negative */
532      } else {
533        if (r != 15) {
534          EOBRUN = 1 << r;      /* EOBr, run length is 2^r + appended bits */
535          if (r) {
536            CHECK_BIT_BUFFER(br_state, r, goto undoit);
537            r = GET_BITS(r);
538            EOBRUN += r;
539          }
540          break;                /* rest of block is handled by EOB logic */
541        }
542        /* note s = 0 for processing ZRL */
543      }
544      /* Advance over already-nonzero coefs and r still-zero coefs,
545       * appending correction bits to the nonzeroes.  A correction bit is 1
546       * if the absolute value of the coefficient must be increased.
547       */
548      do {
549        thiscoef = *block + jpeg_natural_order[k];
550        if (*thiscoef != 0) {
551          CHECK_BIT_BUFFER(br_state, 1, goto undoit);
552          if (GET_BITS(1)) {
553            if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
554              if (*thiscoef >= 0)
555                *thiscoef += p1;
556              else
557                *thiscoef += m1;
558            }
559          }
560        } else {
561          if (--r < 0)
562            break;              /* reached target zero coefficient */
563        }
564        k++;
565      } while (k <= Se);
566      if (s) {
567        int pos = jpeg_natural_order[k];
568        /* Output newly nonzero coefficient */
569        (*block)[pos] = (JCOEF) s;
570        /* Remember its position in case we have to suspend */
571        newnz_pos[num_newnz++] = pos;
572      }
573    }
574  }
575
576  if (EOBRUN > 0) {
577    /* Scan any remaining coefficient positions after the end-of-band
578     * (the last newly nonzero coefficient, if any).  Append a correction
579     * bit to each already-nonzero coefficient.  A correction bit is 1
580     * if the absolute value of the coefficient must be increased.
581     */
582    for (; k <= Se; k++) {
583      thiscoef = *block + jpeg_natural_order[k];
584      if (*thiscoef != 0) {
585        CHECK_BIT_BUFFER(br_state, 1, goto undoit);
586        if (GET_BITS(1)) {
587          if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
588            if (*thiscoef >= 0)
589              *thiscoef += p1;
590            else
591              *thiscoef += m1;
592          }
593        }
594      }
595    }
596    /* Count one block completed in EOB run */
597    EOBRUN--;
598  }
599
600  /* Completed MCU, so update state */
601  BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
602  entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we care about */
603
604  /* Account for restart interval (no-op if not using restarts) */
605  entropy->restarts_to_go--;
606
607  return TRUE;
608
609undoit:
610  /* Re-zero any output coefficients that we made newly nonzero */
611  while (num_newnz > 0)
612    (*block)[newnz_pos[--num_newnz]] = 0;
613
614  return FALSE;
615}
616
617
618/*
619 * Module initialization routine for progressive Huffman entropy decoding.
620 */
621
622GLOBAL(void)
623jinit_phuff_decoder (j_decompress_ptr cinfo)
624{
625  phuff_entropy_ptr entropy;
626  int *coef_bit_ptr;
627  int ci, i;
628
629  entropy = (phuff_entropy_ptr)
630    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
631                                SIZEOF(phuff_entropy_decoder));
632  cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
633  entropy->pub.start_pass = start_pass_phuff_decoder;
634
635  /* Mark derived tables unallocated */
636  for (i = 0; i < NUM_HUFF_TBLS; i++) {
637    entropy->derived_tbls[i] = NULL;
638  }
639
640  /* Create progression status table */
641  cinfo->coef_bits = (int (*)[DCTSIZE2])
642    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
643                                cinfo->num_components*DCTSIZE2*SIZEOF(int));
644  coef_bit_ptr = & cinfo->coef_bits[0][0];
645  for (ci = 0; ci < cinfo->num_components; ci++)
646    for (i = 0; i < DCTSIZE2; i++)
647      *coef_bit_ptr++ = -1;
648}
649
650#endif /* D_PROGRESSIVE_SUPPORTED */
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