jcphuff.c
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1 /*
2  * jcphuff.c
3  *
4  * Copyright (C) 1995-1997, 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 Huffman entropy encoding routines for progressive JPEG.
9  *
10  * We do not support output suspension in this module, since the library
11  * currently does not allow multiple-scan files to be written with output
12  * suspension.
13  */
14 
15 #define JPEG_INTERNALS
16 #include "jinclude.h"
17 #include "jpeglib.h"
18 #include "jchuff.h" /* Declarations shared with jchuff.c */
19 
20 #ifdef C_PROGRESSIVE_SUPPORTED
21 
22 /* Expanded entropy encoder object for progressive Huffman encoding. */
23 
24 typedef struct {
25  struct jpeg_entropy_encoder pub; /* public fields */
26 
27  /* Mode flag: TRUE for optimization, FALSE for actual data output */
29 
30  /* Bit-level coding status.
31  * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
32  */
33  JOCTET * next_output_byte; /* => next byte to write in buffer */
34  size_t free_in_buffer; /* # of byte spaces remaining in buffer */
35  INT32 put_buffer; /* current bit-accumulation buffer */
36  int put_bits; /* # of bits now in it */
37  j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */
38 
39  /* Coding status for DC components */
40  int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
41 
42  /* Coding status for AC components */
43  int ac_tbl_no; /* the table number of the single component */
44  unsigned int EOBRUN; /* run length of EOBs */
45  unsigned int BE; /* # of buffered correction bits before MCU */
46  char * bit_buffer; /* buffer for correction bits (1 per char) */
47  /* packing correction bits tightly would save some space but cost time... */
48 
49  unsigned int restarts_to_go; /* MCUs left in this restart interval */
50  int next_restart_num; /* next restart number to write (0-7) */
51 
52  /* Pointers to derived tables (these workspaces have image lifespan).
53  * Since any one scan codes only DC or only AC, we only need one set
54  * of tables, not one for DC and one for AC.
55  */
56  c_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
57 
58  /* Statistics tables for optimization; again, one set is enough */
59  long * count_ptrs[NUM_HUFF_TBLS];
61 
63 
64 /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
65  * buffer can hold. Larger sizes may slightly improve compression, but
66  * 1000 is already well into the realm of overkill.
67  * The minimum safe size is 64 bits.
68  */
69 
70 #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */
71 
72 /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
73  * We assume that int right shift is unsigned if INT32 right shift is,
74  * which should be safe.
75  */
76 
77 #ifdef RIGHT_SHIFT_IS_UNSIGNED
78 #define ISHIFT_TEMPS int ishift_temp;
79 #define IRIGHT_SHIFT(x,shft) \
80  ((ishift_temp = (x)) < 0 ? \
81  (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
82  (ishift_temp >> (shft)))
83 #else
84 #define ISHIFT_TEMPS
85 #define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
86 #endif
87 
88 /* Forward declarations */
90  JBLOCKROW *MCU_data));
92  JBLOCKROW *MCU_data));
94  JBLOCKROW *MCU_data));
96  JBLOCKROW *MCU_data));
99 
100 
101 /*
102  * Initialize for a Huffman-compressed scan using progressive JPEG.
103  */
104 
105 METHODDEF(void)
106 start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
107 {
108  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
109  boolean is_DC_band;
110  int ci, tbl;
112 
113  entropy->cinfo = cinfo;
114  entropy->gather_statistics = gather_statistics;
115 
116  is_DC_band = (cinfo->Ss == 0);
117 
118  /* We assume jcmaster.c already validated the scan parameters. */
119 
120  /* Select execution routines */
121  if (cinfo->Ah == 0) {
122  if (is_DC_band)
123  entropy->pub.encode_mcu = encode_mcu_DC_first;
124  else
125  entropy->pub.encode_mcu = encode_mcu_AC_first;
126  } else {
127  if (is_DC_band)
128  entropy->pub.encode_mcu = encode_mcu_DC_refine;
129  else {
130  entropy->pub.encode_mcu = encode_mcu_AC_refine;
131  /* AC refinement needs a correction bit buffer */
132  if (entropy->bit_buffer == NULL)
133  entropy->bit_buffer = (char *)
134  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
135  MAX_CORR_BITS * SIZEOF(char));
136  }
137  }
138  if (gather_statistics)
139  entropy->pub.finish_pass = finish_pass_gather_phuff;
140  else
141  entropy->pub.finish_pass = finish_pass_phuff;
142 
143  /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
144  * for AC coefficients.
145  */
146  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
147  compptr = cinfo->cur_comp_info[ci];
148  /* Initialize DC predictions to 0 */
149  entropy->last_dc_val[ci] = 0;
150  /* Get table index */
151  if (is_DC_band) {
152  if (cinfo->Ah != 0) /* DC refinement needs no table */
153  continue;
154  tbl = compptr->dc_tbl_no;
155  } else {
156  entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
157  }
158  if (gather_statistics) {
159  /* Check for invalid table index */
160  /* (make_c_derived_tbl does this in the other path) */
161  if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
162  ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
163  /* Allocate and zero the statistics tables */
164  /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
165  if (entropy->count_ptrs[tbl] == NULL)
166  entropy->count_ptrs[tbl] = (long *)
167  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
168  257 * SIZEOF(long));
169  MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long));
170  } else {
171  /* Compute derived values for Huffman table */
172  /* We may do this more than once for a table, but it's not expensive */
173  jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl,
174  & entropy->derived_tbls[tbl]);
175  }
176  }
177 
178  /* Initialize AC stuff */
179  entropy->EOBRUN = 0;
180  entropy->BE = 0;
181 
182  /* Initialize bit buffer to empty */
183  entropy->put_buffer = 0;
184  entropy->put_bits = 0;
185 
186  /* Initialize restart stuff */
187  entropy->restarts_to_go = cinfo->restart_interval;
188  entropy->next_restart_num = 0;
189 }
190 
191 
192 /* Outputting bytes to the file.
193  * NB: these must be called only when actually outputting,
194  * that is, entropy->gather_statistics == FALSE.
195  */
196 
197 /* Emit a byte */
198 #define emit_byte(entropy,val) \
199  { *(entropy)->next_output_byte++ = (JOCTET) (val); \
200  if (--(entropy)->free_in_buffer == 0) \
201  dump_buffer(entropy); }
202 
203 
204 LOCAL(void)
206 /* Empty the output buffer; we do not support suspension in this module. */
207 {
208  struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
209 
210  if (! (*dest->empty_output_buffer) (entropy->cinfo))
211  ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
212  /* After a successful buffer dump, must reset buffer pointers */
213  entropy->next_output_byte = dest->next_output_byte;
214  entropy->free_in_buffer = dest->free_in_buffer;
215 }
216 
217 
218 /* Outputting bits to the file */
219 
220 /* Only the right 24 bits of put_buffer are used; the valid bits are
221  * left-justified in this part. At most 16 bits can be passed to emit_bits
222  * in one call, and we never retain more than 7 bits in put_buffer
223  * between calls, so 24 bits are sufficient.
224  */
225 
226 INLINE
227 LOCAL(void)
228 emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
229 /* Emit some bits, unless we are in gather mode */
230 {
231  /* This routine is heavily used, so it's worth coding tightly. */
232  register INT32 put_buffer = (INT32) code;
233  register int put_bits = entropy->put_bits;
234 
235  /* if size is 0, caller used an invalid Huffman table entry */
236  if (size == 0)
237  ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
238 
239  if (entropy->gather_statistics)
240  return; /* do nothing if we're only getting stats */
241 
242  put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
243 
244  put_bits += size; /* new number of bits in buffer */
245 
246  put_buffer <<= 24 - put_bits; /* align incoming bits */
247 
248  put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */
249 
250  while (put_bits >= 8) {
251  int c = (int) ((put_buffer >> 16) & 0xFF);
252 
253  emit_byte(entropy, c);
254  if (c == 0xFF) { /* need to stuff a zero byte? */
255  emit_byte(entropy, 0);
256  }
257  put_buffer <<= 8;
258  put_bits -= 8;
259  }
260 
261  entropy->put_buffer = put_buffer; /* update variables */
262  entropy->put_bits = put_bits;
263 }
264 
265 
266 LOCAL(void)
268 {
269  emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
270  entropy->put_buffer = 0; /* and reset bit-buffer to empty */
271  entropy->put_bits = 0;
272 }
273 
274 
275 /*
276  * Emit (or just count) a Huffman symbol.
277  */
278 
279 INLINE
280 LOCAL(void)
281 emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol)
282 {
283  if (entropy->gather_statistics)
284  entropy->count_ptrs[tbl_no][symbol]++;
285  else {
286  c_derived_tbl * tbl = entropy->derived_tbls[tbl_no];
287  emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
288  }
289 }
290 
291 
292 /*
293  * Emit bits from a correction bit buffer.
294  */
295 
296 LOCAL(void)
297 emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart,
298  unsigned int nbits)
299 {
300  if (entropy->gather_statistics)
301  return; /* no real work */
302 
303  while (nbits > 0) {
304  emit_bits(entropy, (unsigned int) (*bufstart), 1);
305  bufstart++;
306  nbits--;
307  }
308 }
309 
310 
311 /*
312  * Emit any pending EOBRUN symbol.
313  */
314 
315 LOCAL(void)
317 {
318  register int temp, nbits;
319 
320  if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */
321  temp = entropy->EOBRUN;
322  nbits = 0;
323  while ((temp >>= 1))
324  nbits++;
325  /* safety check: shouldn't happen given limited correction-bit buffer */
326  if (nbits > 14)
327  ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
328 
329  emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
330  if (nbits)
331  emit_bits(entropy, entropy->EOBRUN, nbits);
332 
333  entropy->EOBRUN = 0;
334 
335  /* Emit any buffered correction bits */
336  emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
337  entropy->BE = 0;
338  }
339 }
340 
341 
342 /*
343  * Emit a restart marker & resynchronize predictions.
344  */
345 
346 LOCAL(void)
347 emit_restart (phuff_entropy_ptr entropy, int restart_num)
348 {
349  int ci;
350 
351  emit_eobrun(entropy);
352 
353  if (! entropy->gather_statistics) {
354  flush_bits(entropy);
355  emit_byte(entropy, 0xFF);
356  emit_byte(entropy, JPEG_RST0 + restart_num);
357  }
358 
359  if (entropy->cinfo->Ss == 0) {
360  /* Re-initialize DC predictions to 0 */
361  for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
362  entropy->last_dc_val[ci] = 0;
363  } else {
364  /* Re-initialize all AC-related fields to 0 */
365  entropy->EOBRUN = 0;
366  entropy->BE = 0;
367  }
368 }
369 
370 
371 /*
372  * MCU encoding for DC initial scan (either spectral selection,
373  * or first pass of successive approximation).
374  */
375 
376 METHODDEF(boolean)
378 {
379  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
380  register int temp, temp2;
381  register int nbits;
382  int blkn, ci;
383  int Al = cinfo->Al;
384  JBLOCKROW block;
387 
388  entropy->next_output_byte = cinfo->dest->next_output_byte;
389  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
390 
391  /* Emit restart marker if needed */
392  if (cinfo->restart_interval)
393  if (entropy->restarts_to_go == 0)
394  emit_restart(entropy, entropy->next_restart_num);
395 
396  /* Encode the MCU data blocks */
397  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
398  block = MCU_data[blkn];
399  ci = cinfo->MCU_membership[blkn];
400  compptr = cinfo->cur_comp_info[ci];
401 
402  /* Compute the DC value after the required point transform by Al.
403  * This is simply an arithmetic right shift.
404  */
405  temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
406 
407  /* DC differences are figured on the point-transformed values. */
408  temp = temp2 - entropy->last_dc_val[ci];
409  entropy->last_dc_val[ci] = temp2;
410 
411  /* Encode the DC coefficient difference per section G.1.2.1 */
412  temp2 = temp;
413  if (temp < 0) {
414  temp = -temp; /* temp is abs value of input */
415  /* For a negative input, want temp2 = bitwise complement of abs(input) */
416  /* This code assumes we are on a two's complement machine */
417  temp2--;
418  }
419 
420  /* Find the number of bits needed for the magnitude of the coefficient */
421  nbits = 0;
422  while (temp) {
423  nbits++;
424  temp >>= 1;
425  }
426  /* Check for out-of-range coefficient values.
427  * Since we're encoding a difference, the range limit is twice as much.
428  */
429  if (nbits > MAX_COEF_BITS+1)
430  ERREXIT(cinfo, JERR_BAD_DCT_COEF);
431 
432  /* Count/emit the Huffman-coded symbol for the number of bits */
433  emit_symbol(entropy, compptr->dc_tbl_no, nbits);
434 
435  /* Emit that number of bits of the value, if positive, */
436  /* or the complement of its magnitude, if negative. */
437  if (nbits) /* emit_bits rejects calls with size 0 */
438  emit_bits(entropy, (unsigned int) temp2, nbits);
439  }
440 
441  cinfo->dest->next_output_byte = entropy->next_output_byte;
442  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
443 
444  /* Update restart-interval state too */
445  if (cinfo->restart_interval) {
446  if (entropy->restarts_to_go == 0) {
447  entropy->restarts_to_go = cinfo->restart_interval;
448  entropy->next_restart_num++;
449  entropy->next_restart_num &= 7;
450  }
451  entropy->restarts_to_go--;
452  }
453 
454  return TRUE;
455 }
456 
457 
458 /*
459  * MCU encoding for AC initial scan (either spectral selection,
460  * or first pass of successive approximation).
461  */
462 
463 METHODDEF(boolean)
465 {
466  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
467  register int temp, temp2;
468  register int nbits;
469  register int r, k;
470  int Se = cinfo->Se;
471  int Al = cinfo->Al;
472  JBLOCKROW block;
473 
474  entropy->next_output_byte = cinfo->dest->next_output_byte;
475  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
476 
477  /* Emit restart marker if needed */
478  if (cinfo->restart_interval)
479  if (entropy->restarts_to_go == 0)
480  emit_restart(entropy, entropy->next_restart_num);
481 
482  /* Encode the MCU data block */
483  block = MCU_data[0];
484 
485  /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
486 
487  r = 0; /* r = run length of zeros */
488 
489  for (k = cinfo->Ss; k <= Se; k++) {
490  if ((temp = (*block)[jpeg_natural_order[k]]) == 0) {
491  r++;
492  continue;
493  }
494  /* We must apply the point transform by Al. For AC coefficients this
495  * is an integer division with rounding towards 0. To do this portably
496  * in C, we shift after obtaining the absolute value; so the code is
497  * interwoven with finding the abs value (temp) and output bits (temp2).
498  */
499  if (temp < 0) {
500  temp = -temp; /* temp is abs value of input */
501  temp >>= Al; /* apply the point transform */
502  /* For a negative coef, want temp2 = bitwise complement of abs(coef) */
503  temp2 = ~temp;
504  } else {
505  temp >>= Al; /* apply the point transform */
506  temp2 = temp;
507  }
508  /* Watch out for case that nonzero coef is zero after point transform */
509  if (temp == 0) {
510  r++;
511  continue;
512  }
513 
514  /* Emit any pending EOBRUN */
515  if (entropy->EOBRUN > 0)
516  emit_eobrun(entropy);
517  /* if run length > 15, must emit special run-length-16 codes (0xF0) */
518  while (r > 15) {
519  emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
520  r -= 16;
521  }
522 
523  /* Find the number of bits needed for the magnitude of the coefficient */
524  nbits = 1; /* there must be at least one 1 bit */
525  while ((temp >>= 1))
526  nbits++;
527  /* Check for out-of-range coefficient values */
528  if (nbits > MAX_COEF_BITS)
529  ERREXIT(cinfo, JERR_BAD_DCT_COEF);
530 
531  /* Count/emit Huffman symbol for run length / number of bits */
532  emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
533 
534  /* Emit that number of bits of the value, if positive, */
535  /* or the complement of its magnitude, if negative. */
536  emit_bits(entropy, (unsigned int) temp2, nbits);
537 
538  r = 0; /* reset zero run length */
539  }
540 
541  if (r > 0) { /* If there are trailing zeroes, */
542  entropy->EOBRUN++; /* count an EOB */
543  if (entropy->EOBRUN == 0x7FFF)
544  emit_eobrun(entropy); /* force it out to avoid overflow */
545  }
546 
547  cinfo->dest->next_output_byte = entropy->next_output_byte;
548  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
549 
550  /* Update restart-interval state too */
551  if (cinfo->restart_interval) {
552  if (entropy->restarts_to_go == 0) {
553  entropy->restarts_to_go = cinfo->restart_interval;
554  entropy->next_restart_num++;
555  entropy->next_restart_num &= 7;
556  }
557  entropy->restarts_to_go--;
558  }
559 
560  return TRUE;
561 }
562 
563 
564 /*
565  * MCU encoding for DC successive approximation refinement scan.
566  * Note: we assume such scans can be multi-component, although the spec
567  * is not very clear on the point.
568  */
569 
570 METHODDEF(boolean)
572 {
573  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
574  register int temp;
575  int blkn;
576  int Al = cinfo->Al;
577  JBLOCKROW block;
578 
579  entropy->next_output_byte = cinfo->dest->next_output_byte;
580  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
581 
582  /* Emit restart marker if needed */
583  if (cinfo->restart_interval)
584  if (entropy->restarts_to_go == 0)
585  emit_restart(entropy, entropy->next_restart_num);
586 
587  /* Encode the MCU data blocks */
588  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
589  block = MCU_data[blkn];
590 
591  /* We simply emit the Al'th bit of the DC coefficient value. */
592  temp = (*block)[0];
593  emit_bits(entropy, (unsigned int) (temp >> Al), 1);
594  }
595 
596  cinfo->dest->next_output_byte = entropy->next_output_byte;
597  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
598 
599  /* Update restart-interval state too */
600  if (cinfo->restart_interval) {
601  if (entropy->restarts_to_go == 0) {
602  entropy->restarts_to_go = cinfo->restart_interval;
603  entropy->next_restart_num++;
604  entropy->next_restart_num &= 7;
605  }
606  entropy->restarts_to_go--;
607  }
608 
609  return TRUE;
610 }
611 
612 
613 /*
614  * MCU encoding for AC successive approximation refinement scan.
615  */
616 
617 METHODDEF(boolean)
619 {
620  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
621  register int temp;
622  register int r, k;
623  int EOB;
624  char *BR_buffer;
625  unsigned int BR;
626  int Se = cinfo->Se;
627  int Al = cinfo->Al;
628  JBLOCKROW block;
629  int absvalues[DCTSIZE2];
630 
631  entropy->next_output_byte = cinfo->dest->next_output_byte;
632  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
633 
634  /* Emit restart marker if needed */
635  if (cinfo->restart_interval)
636  if (entropy->restarts_to_go == 0)
637  emit_restart(entropy, entropy->next_restart_num);
638 
639  /* Encode the MCU data block */
640  block = MCU_data[0];
641 
642  /* It is convenient to make a pre-pass to determine the transformed
643  * coefficients' absolute values and the EOB position.
644  */
645  EOB = 0;
646  for (k = cinfo->Ss; k <= Se; k++) {
647  temp = (*block)[jpeg_natural_order[k]];
648  /* We must apply the point transform by Al. For AC coefficients this
649  * is an integer division with rounding towards 0. To do this portably
650  * in C, we shift after obtaining the absolute value.
651  */
652  if (temp < 0)
653  temp = -temp; /* temp is abs value of input */
654  temp >>= Al; /* apply the point transform */
655  absvalues[k] = temp; /* save abs value for main pass */
656  if (temp == 1)
657  EOB = k; /* EOB = index of last newly-nonzero coef */
658  }
659 
660  /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
661 
662  r = 0; /* r = run length of zeros */
663  BR = 0; /* BR = count of buffered bits added now */
664  BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
665 
666  for (k = cinfo->Ss; k <= Se; k++) {
667  if ((temp = absvalues[k]) == 0) {
668  r++;
669  continue;
670  }
671 
672  /* Emit any required ZRLs, but not if they can be folded into EOB */
673  while (r > 15 && k <= EOB) {
674  /* emit any pending EOBRUN and the BE correction bits */
675  emit_eobrun(entropy);
676  /* Emit ZRL */
677  emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
678  r -= 16;
679  /* Emit buffered correction bits that must be associated with ZRL */
680  emit_buffered_bits(entropy, BR_buffer, BR);
681  BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
682  BR = 0;
683  }
684 
685  /* If the coef was previously nonzero, it only needs a correction bit.
686  * NOTE: a straight translation of the spec's figure G.7 would suggest
687  * that we also need to test r > 15. But if r > 15, we can only get here
688  * if k > EOB, which implies that this coefficient is not 1.
689  */
690  if (temp > 1) {
691  /* The correction bit is the next bit of the absolute value. */
692  BR_buffer[BR++] = (char) (temp & 1);
693  continue;
694  }
695 
696  /* Emit any pending EOBRUN and the BE correction bits */
697  emit_eobrun(entropy);
698 
699  /* Count/emit Huffman symbol for run length / number of bits */
700  emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
701 
702  /* Emit output bit for newly-nonzero coef */
703  temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
704  emit_bits(entropy, (unsigned int) temp, 1);
705 
706  /* Emit buffered correction bits that must be associated with this code */
707  emit_buffered_bits(entropy, BR_buffer, BR);
708  BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
709  BR = 0;
710  r = 0; /* reset zero run length */
711  }
712 
713  if (r > 0 || BR > 0) { /* If there are trailing zeroes, */
714  entropy->EOBRUN++; /* count an EOB */
715  entropy->BE += BR; /* concat my correction bits to older ones */
716  /* We force out the EOB if we risk either:
717  * 1. overflow of the EOB counter;
718  * 2. overflow of the correction bit buffer during the next MCU.
719  */
720  if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
721  emit_eobrun(entropy);
722  }
723 
724  cinfo->dest->next_output_byte = entropy->next_output_byte;
725  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
726 
727  /* Update restart-interval state too */
728  if (cinfo->restart_interval) {
729  if (entropy->restarts_to_go == 0) {
730  entropy->restarts_to_go = cinfo->restart_interval;
731  entropy->next_restart_num++;
732  entropy->next_restart_num &= 7;
733  }
734  entropy->restarts_to_go--;
735  }
736 
737  return TRUE;
738 }
739 
740 
741 /*
742  * Finish up at the end of a Huffman-compressed progressive scan.
743  */
744 
745 METHODDEF(void)
747 {
748  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
749 
750  entropy->next_output_byte = cinfo->dest->next_output_byte;
751  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
752 
753  /* Flush out any buffered data */
754  emit_eobrun(entropy);
755  flush_bits(entropy);
756 
757  cinfo->dest->next_output_byte = entropy->next_output_byte;
758  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
759 }
760 
761 
762 /*
763  * Finish up a statistics-gathering pass and create the new Huffman tables.
764  */
765 
766 METHODDEF(void)
768 {
769  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
770  boolean is_DC_band;
771  int ci, tbl;
773  JHUFF_TBL **htblptr;
774  boolean did[NUM_HUFF_TBLS];
775 
776  /* Flush out buffered data (all we care about is counting the EOB symbol) */
777  emit_eobrun(entropy);
778 
779  is_DC_band = (cinfo->Ss == 0);
780 
781  /* It's important not to apply jpeg_gen_optimal_table more than once
782  * per table, because it clobbers the input frequency counts!
783  */
784  MEMZERO(did, SIZEOF(did));
785 
786  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
787  compptr = cinfo->cur_comp_info[ci];
788  if (is_DC_band) {
789  if (cinfo->Ah != 0) /* DC refinement needs no table */
790  continue;
791  tbl = compptr->dc_tbl_no;
792  } else {
793  tbl = compptr->ac_tbl_no;
794  }
795  if (! did[tbl]) {
796  if (is_DC_band)
797  htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
798  else
799  htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
800  if (*htblptr == NULL)
801  *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
802  jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
803  did[tbl] = TRUE;
804  }
805  }
806 }
807 
808 
809 /*
810  * Module initialization routine for progressive Huffman entropy encoding.
811  */
812 
813 GLOBAL(void)
815 {
816  phuff_entropy_ptr entropy;
817  int i;
818 
819  entropy = (phuff_entropy_ptr)
820  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
822  cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
823  entropy->pub.start_pass = start_pass_phuff;
824 
825  /* Mark tables unallocated */
826  for (i = 0; i < NUM_HUFF_TBLS; i++) {
827  entropy->derived_tbls[i] = NULL;
828  entropy->count_ptrs[i] = NULL;
829  }
830  entropy->bit_buffer = NULL; /* needed only in AC refinement scan */
831 }
832 
833 #endif /* C_PROGRESSIVE_SUPPORTED */
unsigned int restarts_to_go
Definition: jcphuff.c:49
int c
Definition: autoplay.py:16
unsigned int BE
Definition: jcphuff.c:45
#define emit_byte(entropy, val)
Definition: jcphuff.c:198
emit_buffered_bits(phuff_entropy_ptr entropy, char *bufstart, unsigned int nbits)
Definition: jcphuff.c:297
const int jpeg_natural_order[]
Definition: jutils.c:53
unsigned int ehufco[256]
Definition: jchuff.h:28
struct jpeg_common_struct * j_common_ptr
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size_t free_in_buffer
Definition: jpeglib.h:715
png_uint_32 size
Definition: png.h:1521
#define NUM_HUFF_TBLS
Definition: jpeglib.h:44
encode_mcu_AC_first(j_compress_ptr cinfo, JBLOCKROW *MCU_data)
Definition: jcphuff.c:464
encode_mcu_AC_refine(j_compress_ptr cinfo, JBLOCKROW *MCU_data)
Definition: jcphuff.c:618
#define ERREXIT(cinfo, code)
Definition: jerror.h:205
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Definition: jcomapi.c:98
#define TRUE
Definition: OPC_IceHook.h:13
#define SIZEOF(object)
Definition: jinclude.h:80
encode_mcu_DC_first(j_compress_ptr cinfo, JBLOCKROW *MCU_data)
Definition: jcphuff.c:377
finish_pass_gather_phuff(j_compress_ptr cinfo)
Definition: jcphuff.c:767
emit_eobrun(phuff_entropy_ptr entropy)
Definition: jcphuff.c:316
c_derived_tbl * derived_tbls[NUM_HUFF_TBLS]
Definition: jcphuff.c:56
long INT32
Definition: jmorecfg.h:161
JOCTET * next_output_byte
Definition: jcphuff.c:33
struct jpeg_entropy_encoder * entropy
Definition: jpeglib.h:403
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Definition: png.h:2735
#define IRIGHT_SHIFT(x, shft)
Definition: jcphuff.c:85
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Definition: jdct.h:102
size_t free_in_buffer
Definition: jcphuff.c:34
#define MAX_CORR_BITS
Definition: jcphuff.c:70
#define JPOOL_IMAGE
Definition: jpeglib.h:749
#define ISHIFT_TEMPS
Definition: jcphuff.c:84
#define JPEG_RST0
Definition: jpeglib.h:1045
finish_pass_phuff(j_compress_ptr cinfo)
Definition: jcphuff.c:746
#define DCTSIZE2
Definition: jpeglib.h:42
#define LOCAL(type)
Definition: jmorecfg.h:186
struct jpeg_entropy_encoder pub
Definition: jcphuff.c:25
INLINE emit_bits(phuff_entropy_ptr entropy, unsigned int code, int size)
Definition: jcphuff.c:228
flush_bits(phuff_entropy_ptr entropy)
Definition: jcphuff.c:267
phuff_entropy_encoder * phuff_entropy_ptr
Definition: jcphuff.c:62
JBLOCK FAR * JBLOCKROW
Definition: jpeglib.h:71
#define MAX_COEF_BITS
Definition: jchuff.h:22
register bit_buf_type register int int nbits
Definition: jdhuff.h:155
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Definition: jcphuff.c:814
jpeg_make_c_derived_tbl(j_compress_ptr cinfo, boolean isDC, int tblno, c_derived_tbl **pdtbl)
Definition: jchuff.c:179
unsigned int restart_interval
Definition: jpeglib.h:332
j_compress_ptr cinfo
Definition: jcphuff.c:37
#define JPP(arglist)
Definition: jpeglib.h:818
#define ERREXIT1(cinfo, code, p1)
Definition: jerror.h:208
Definition: inftrees.h:24
emit_restart(phuff_entropy_ptr entropy, int restart_num)
Definition: jcphuff.c:347
typedef int
Definition: png.h:1113
#define GLOBAL(type)
Definition: jmorecfg.h:188
METHODDEF(boolean)
Definition: jcphuff.c:89
unsigned int EOBRUN
Definition: jcphuff.c:44
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Definition: jpeglib.h:379
jpeg_gen_optimal_table(j_compress_ptr cinfo, JHUFF_TBL *htbl, long freq[])
Definition: jchuff.c:705
boolean gather_statistics
Definition: jcphuff.c:28
encode_mcu_DC_refine(j_compress_ptr cinfo, JBLOCKROW *MCU_data)
Definition: jcphuff.c:571
char JOCTET
Definition: jmorecfg.h:115
INLINE emit_symbol(phuff_entropy_ptr entropy, int tbl_no, int symbol)
Definition: jcphuff.c:281
int last_dc_val[MAX_COMPS_IN_SCAN]
Definition: jcphuff.c:40
dump_buffer(phuff_entropy_ptr entropy)
Definition: jcphuff.c:205
char ehufsi[256]
Definition: jchuff.h:29
JOCTET * next_output_byte
Definition: jpeglib.h:714
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Definition: jcphuff.c:59
#define MAX_COMPS_IN_SCAN
Definition: jpeglib.h:46
#define MEMZERO(target, size)
Definition: jinclude.h:67


openhrp3
Author(s): AIST, General Robotix Inc., Nakamura Lab of Dept. of Mechano Informatics at University of Tokyo
autogenerated on Thu Sep 8 2022 02:24:04