1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * jcphuff.c
7 *
8 * Copyright (C) 1995-1997, Thomas G. Lane.
9 * This file is part of the Independent JPEG Group's software.
10 * For conditions of distribution and use, see the accompanying README file.
11 *
12 * This file contains Huffman entropy encoding routines for progressive JPEG.
13 *
14 * We do not support output suspension in this module, since the library
15 * currently does not allow multiple-scan files to be written with output
16 * suspension.
17 */
18
19#define JPEG_INTERNALS
20#include "jinclude.h"
21#include "jpeglib.h"
22#include "jchuff.h" /* Declarations shared with jchuff.c */
23
24#ifdef C_PROGRESSIVE_SUPPORTED
25
26/* Expanded entropy encoder object for progressive Huffman encoding. */
27
28typedef struct {
29 struct jpeg_entropy_encoder pub; /* public fields */
30
31 /* Mode flag: TRUE for optimization, FALSE for actual data output */
32 boolean gather_statistics;
33
34 /* Bit-level coding status.
35 * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
36 */
37 JOCTET * next_output_byte; /* => next byte to write in buffer */
38 size_t free_in_buffer; /* # of byte spaces remaining in buffer */
39 INT32 put_buffer; /* current bit-accumulation buffer */
40 int put_bits; /* # of bits now in it */
41 j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */
42
43 /* Coding status for DC components */
44 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
45
46 /* Coding status for AC components */
47 int ac_tbl_no; /* the table number of the single component */
48 unsigned int EOBRUN; /* run length of EOBs */
49 unsigned int BE; /* # of buffered correction bits before MCU */
50 char * bit_buffer; /* buffer for correction bits (1 per char) */
51 /* packing correction bits tightly would save some space but cost time... */
52
53 unsigned int restarts_to_go; /* MCUs left in this restart interval */
54 int next_restart_num; /* next restart number to write (0-7) */
55
56 /* Pointers to derived tables (these workspaces have image lifespan).
57 * Since any one scan codes only DC or only AC, we only need one set
58 * of tables, not one for DC and one for AC.
59 */
60 c_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
61
62 /* Statistics tables for optimization; again, one set is enough */
63 long * count_ptrs[NUM_HUFF_TBLS];
64} phuff_entropy_encoder;
65
66typedef phuff_entropy_encoder * phuff_entropy_ptr;
67
68/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
69 * buffer can hold. Larger sizes may slightly improve compression, but
70 * 1000 is already well into the realm of overkill.
71 * The minimum safe size is 64 bits.
72 */
73
74#define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */
75
76/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
77 * We assume that int right shift is unsigned if INT32 right shift is,
78 * which should be safe.
79 */
80
81#ifdef RIGHT_SHIFT_IS_UNSIGNED
82#define ISHIFT_TEMPS int ishift_temp;
83#define IRIGHT_SHIFT(x,shft) \
84 ((ishift_temp = (x)) < 0 ? \
85 (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
86 (ishift_temp >> (shft)))
87#else
88#define ISHIFT_TEMPS
89#define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
90#endif
91
92/* Forward declarations */
93METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo,
94 JBLOCKROW *MCU_data));
95METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo,
96 JBLOCKROW *MCU_data));
97METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo,
98 JBLOCKROW *MCU_data));
99METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo,
100 JBLOCKROW *MCU_data));
101METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo));
102METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo));
103
104
105/*
106 * Initialize for a Huffman-compressed scan using progressive JPEG.
107 */
108
109METHODDEF(void)
110start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
111{
112 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
113 boolean is_DC_band;
114 int ci, tbl;
115 jpeg_component_info * compptr;
116
117 entropy->cinfo = cinfo;
118 entropy->gather_statistics = gather_statistics;
119
120 is_DC_band = (cinfo->Ss == 0);
121
122 /* We assume jcmaster.c already validated the scan parameters. */
123
124 /* Select execution routines */
125 if (cinfo->Ah == 0) {
126 if (is_DC_band)
127 entropy->pub.encode_mcu = encode_mcu_DC_first;
128 else
129 entropy->pub.encode_mcu = encode_mcu_AC_first;
130 } else {
131 if (is_DC_band)
132 entropy->pub.encode_mcu = encode_mcu_DC_refine;
133 else {
134 entropy->pub.encode_mcu = encode_mcu_AC_refine;
135 /* AC refinement needs a correction bit buffer */
136 if (entropy->bit_buffer == NULL)
137 entropy->bit_buffer = (char *)
138 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
139 MAX_CORR_BITS * SIZEOF(char));
140 }
141 }
142 if (gather_statistics)
143 entropy->pub.finish_pass = finish_pass_gather_phuff;
144 else
145 entropy->pub.finish_pass = finish_pass_phuff;
146
147 /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
148 * for AC coefficients.
149 */
150 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
151 compptr = cinfo->cur_comp_info[ci];
152 /* Initialize DC predictions to 0 */
153 entropy->last_dc_val[ci] = 0;
154 /* Get table index */
155 if (is_DC_band) {
156 if (cinfo->Ah != 0) /* DC refinement needs no table */
157 continue;
158 tbl = compptr->dc_tbl_no;
159 } else {
160 entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
161 }
162 if (gather_statistics) {
163 /* Check for invalid table index */
164 /* (make_c_derived_tbl does this in the other path) */
165 if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
166 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
167 /* Allocate and zero the statistics tables */
168 /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
169 if (entropy->count_ptrs[tbl] == NULL)
170 entropy->count_ptrs[tbl] = (long *)
171 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
172 257 * SIZEOF(long));
173 MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long));
174 } else {
175 /* Compute derived values for Huffman table */
176 /* We may do this more than once for a table, but it's not expensive */
177 jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl,
178 & entropy->derived_tbls[tbl]);
179 }
180 }
181
182 /* Initialize AC stuff */
183 entropy->EOBRUN = 0;
184 entropy->BE = 0;
185
186 /* Initialize bit buffer to empty */
187 entropy->put_buffer = 0;
188 entropy->put_bits = 0;
189
190 /* Initialize restart stuff */
191 entropy->restarts_to_go = cinfo->restart_interval;
192 entropy->next_restart_num = 0;
193}
194
195
196/* Outputting bytes to the file.
197 * NB: these must be called only when actually outputting,
198 * that is, entropy->gather_statistics == FALSE.
199 */
200
201/* Emit a byte */
202#define emit_byte(entropy,val) \
203 { *(entropy)->next_output_byte++ = (JOCTET) (val); \
204 if (--(entropy)->free_in_buffer == 0) \
205 dump_buffer(entropy); }
206
207
208LOCAL(void)
209dump_buffer (phuff_entropy_ptr entropy)
210/* Empty the output buffer; we do not support suspension in this module. */
211{
212 struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
213
214 if (! (*dest->empty_output_buffer) (entropy->cinfo))
215 ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
216 /* After a successful buffer dump, must reset buffer pointers */
217 entropy->next_output_byte = dest->next_output_byte;
218 entropy->free_in_buffer = dest->free_in_buffer;
219}
220
221
222/* Outputting bits to the file */
223
224/* Only the right 24 bits of put_buffer are used; the valid bits are
225 * left-justified in this part. At most 16 bits can be passed to emit_bits
226 * in one call, and we never retain more than 7 bits in put_buffer
227 * between calls, so 24 bits are sufficient.
228 */
229
230INLINE
231LOCAL(void)
232emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
233/* Emit some bits, unless we are in gather mode */
234{
235 /* This routine is heavily used, so it's worth coding tightly. */
236 register INT32 put_buffer = (INT32) code;
237 register int put_bits = entropy->put_bits;
238
239 /* if size is 0, caller used an invalid Huffman table entry */
240 if (size == 0)
241 ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
242
243 if (entropy->gather_statistics)
244 return; /* do nothing if we're only getting stats */
245
246 put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
247
248 put_bits += size; /* new number of bits in buffer */
249
250 put_buffer <<= 24 - put_bits; /* align incoming bits */
251
252 put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */
253
254 while (put_bits >= 8) {
255 int c = (int) ((put_buffer >> 16) & 0xFF);
256
257 emit_byte(entropy, c);
258 if (c == 0xFF) { /* need to stuff a zero byte? */
259 emit_byte(entropy, 0);
260 }
261 put_buffer <<= 8;
262 put_bits -= 8;
263 }
264
265 entropy->put_buffer = put_buffer; /* update variables */
266 entropy->put_bits = put_bits;
267}
268
269
270LOCAL(void)
271flush_bits (phuff_entropy_ptr entropy)
272{
273 emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
274 entropy->put_buffer = 0; /* and reset bit-buffer to empty */
275 entropy->put_bits = 0;
276}
277
278
279/*
280 * Emit (or just count) a Huffman symbol.
281 */
282
283INLINE
284LOCAL(void)
285emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol)
286{
287 if (entropy->gather_statistics)
288 entropy->count_ptrs[tbl_no][symbol]++;
289 else {
290 c_derived_tbl * tbl = entropy->derived_tbls[tbl_no];
291 emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
292 }
293}
294
295
296/*
297 * Emit bits from a correction bit buffer.
298 */
299
300LOCAL(void)
301emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart,
302 unsigned int nbits)
303{
304 if (entropy->gather_statistics)
305 return; /* no real work */
306
307 while (nbits > 0) {
308 emit_bits(entropy, (unsigned int) (*bufstart), 1);
309 bufstart++;
310 nbits--;
311 }
312}
313
314
315/*
316 * Emit any pending EOBRUN symbol.
317 */
318
319LOCAL(void)
320emit_eobrun (phuff_entropy_ptr entropy)
321{
322 register int temp, nbits;
323
324 if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */
325 temp = entropy->EOBRUN;
326 nbits = 0;
327 while ((temp >>= 1))
328 nbits++;
329 /* safety check: shouldn't happen given limited correction-bit buffer */
330 if (nbits > 14)
331 ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
332
333 emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
334 if (nbits)
335 emit_bits(entropy, entropy->EOBRUN, nbits);
336
337 entropy->EOBRUN = 0;
338
339 /* Emit any buffered correction bits */
340 emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
341 entropy->BE = 0;
342 }
343}
344
345
346/*
347 * Emit a restart marker & resynchronize predictions.
348 */
349
350LOCAL(void)
351emit_restart (phuff_entropy_ptr entropy, int restart_num)
352{
353 int ci;
354
355 emit_eobrun(entropy);
356
357 if (! entropy->gather_statistics) {
358 flush_bits(entropy);
359 emit_byte(entropy, 0xFF);
360 emit_byte(entropy, JPEG_RST0 + restart_num);
361 }
362
363 if (entropy->cinfo->Ss == 0) {
364 /* Re-initialize DC predictions to 0 */
365 for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
366 entropy->last_dc_val[ci] = 0;
367 } else {
368 /* Re-initialize all AC-related fields to 0 */
369 entropy->EOBRUN = 0;
370 entropy->BE = 0;
371 }
372}
373
374
375/*
376 * MCU encoding for DC initial scan (either spectral selection,
377 * or first pass of successive approximation).
378 */
379
380METHODDEF(boolean)
381encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
382{
383 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
384 register int temp, temp2;
385 register int nbits;
386 int blkn, ci;
387 int Al = cinfo->Al;
388 JBLOCKROW block;
389 jpeg_component_info * compptr;
390 ISHIFT_TEMPS
391
392 entropy->next_output_byte = cinfo->dest->next_output_byte;
393 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
394
395 /* Emit restart marker if needed */
396 if (cinfo->restart_interval)
397 if (entropy->restarts_to_go == 0)
398 emit_restart(entropy, entropy->next_restart_num);
399
400 /* Encode the MCU data blocks */
401 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
402 block = MCU_data[blkn];
403 ci = cinfo->MCU_membership[blkn];
404 compptr = cinfo->cur_comp_info[ci];
405
406 /* Compute the DC value after the required point transform by Al.
407 * This is simply an arithmetic right shift.
408 */
409 temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
410
411 /* DC differences are figured on the point-transformed values. */
412 temp = temp2 - entropy->last_dc_val[ci];
413 entropy->last_dc_val[ci] = temp2;
414
415 /* Encode the DC coefficient difference per section G.1.2.1 */
416 temp2 = temp;
417 if (temp < 0) {
418 temp = -temp; /* temp is abs value of input */
419 /* For a negative input, want temp2 = bitwise complement of abs(input) */
420 /* This code assumes we are on a two's complement machine */
421 temp2--;
422 }
423
424 /* Find the number of bits needed for the magnitude of the coefficient */
425 nbits = 0;
426 while (temp) {
427 nbits++;
428 temp >>= 1;
429 }
430 /* Check for out-of-range coefficient values.
431 * Since we're encoding a difference, the range limit is twice as much.
432 */
433 if (nbits > MAX_COEF_BITS+1)
434 ERREXIT(cinfo, JERR_BAD_DCT_COEF);
435
436 /* Count/emit the Huffman-coded symbol for the number of bits */
437 emit_symbol(entropy, compptr->dc_tbl_no, nbits);
438
439 /* Emit that number of bits of the value, if positive, */
440 /* or the complement of its magnitude, if negative. */
441 if (nbits) /* emit_bits rejects calls with size 0 */
442 emit_bits(entropy, (unsigned int) temp2, nbits);
443 }
444
445 cinfo->dest->next_output_byte = entropy->next_output_byte;
446 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
447
448 /* Update restart-interval state too */
449 if (cinfo->restart_interval) {
450 if (entropy->restarts_to_go == 0) {
451 entropy->restarts_to_go = cinfo->restart_interval;
452 entropy->next_restart_num++;
453 entropy->next_restart_num &= 7;
454 }
455 entropy->restarts_to_go--;
456 }
457
458 return TRUE;
459}
460
461
462/*
463 * MCU encoding for AC initial scan (either spectral selection,
464 * or first pass of successive approximation).
465 */
466
467METHODDEF(boolean)
468encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
469{
470 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
471 register int temp, temp2;
472 register int nbits;
473 register int r, k;
474 int Se = cinfo->Se;
475 int Al = cinfo->Al;
476 JBLOCKROW block;
477
478 entropy->next_output_byte = cinfo->dest->next_output_byte;
479 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
480
481 /* Emit restart marker if needed */
482 if (cinfo->restart_interval)
483 if (entropy->restarts_to_go == 0)
484 emit_restart(entropy, entropy->next_restart_num);
485
486 /* Encode the MCU data block */
487 block = MCU_data[0];
488
489 /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
490
491 r = 0; /* r = run length of zeros */
492
493 for (k = cinfo->Ss; k <= Se; k++) {
494 if ((temp = (*block)[jpeg_natural_order[k]]) == 0) {
495 r++;
496 continue;
497 }
498 /* We must apply the point transform by Al. For AC coefficients this
499 * is an integer division with rounding towards 0. To do this portably
500 * in C, we shift after obtaining the absolute value; so the code is
501 * interwoven with finding the abs value (temp) and output bits (temp2).
502 */
503 if (temp < 0) {
504 temp = -temp; /* temp is abs value of input */
505 temp >>= Al; /* apply the point transform */
506 /* For a negative coef, want temp2 = bitwise complement of abs(coef) */
507 temp2 = ~temp;
508 } else {
509 temp >>= Al; /* apply the point transform */
510 temp2 = temp;
511 }
512 /* Watch out for case that nonzero coef is zero after point transform */
513 if (temp == 0) {
514 r++;
515 continue;
516 }
517
518 /* Emit any pending EOBRUN */
519 if (entropy->EOBRUN > 0)
520 emit_eobrun(entropy);
521 /* if run length > 15, must emit special run-length-16 codes (0xF0) */
522 while (r > 15) {
523 emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
524 r -= 16;
525 }
526
527 /* Find the number of bits needed for the magnitude of the coefficient */
528 nbits = 1; /* there must be at least one 1 bit */
529 while ((temp >>= 1))
530 nbits++;
531 /* Check for out-of-range coefficient values */
532 if (nbits > MAX_COEF_BITS)
533 ERREXIT(cinfo, JERR_BAD_DCT_COEF);
534
535 /* Count/emit Huffman symbol for run length / number of bits */
536 emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
537
538 /* Emit that number of bits of the value, if positive, */
539 /* or the complement of its magnitude, if negative. */
540 emit_bits(entropy, (unsigned int) temp2, nbits);
541
542 r = 0; /* reset zero run length */
543 }
544
545 if (r > 0) { /* If there are trailing zeroes, */
546 entropy->EOBRUN++; /* count an EOB */
547 if (entropy->EOBRUN == 0x7FFF)
548 emit_eobrun(entropy); /* force it out to avoid overflow */
549 }
550
551 cinfo->dest->next_output_byte = entropy->next_output_byte;
552 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
553
554 /* Update restart-interval state too */
555 if (cinfo->restart_interval) {
556 if (entropy->restarts_to_go == 0) {
557 entropy->restarts_to_go = cinfo->restart_interval;
558 entropy->next_restart_num++;
559 entropy->next_restart_num &= 7;
560 }
561 entropy->restarts_to_go--;
562 }
563
564 return TRUE;
565}
566
567
568/*
569 * MCU encoding for DC successive approximation refinement scan.
570 * Note: we assume such scans can be multi-component, although the spec
571 * is not very clear on the point.
572 */
573
574METHODDEF(boolean)
575encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
576{
577 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
578 register int temp;
579 int blkn;
580 int Al = cinfo->Al;
581 JBLOCKROW block;
582
583 entropy->next_output_byte = cinfo->dest->next_output_byte;
584 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
585
586 /* Emit restart marker if needed */
587 if (cinfo->restart_interval)
588 if (entropy->restarts_to_go == 0)
589 emit_restart(entropy, entropy->next_restart_num);
590
591 /* Encode the MCU data blocks */
592 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
593 block = MCU_data[blkn];
594
595 /* We simply emit the Al'th bit of the DC coefficient value. */
596 temp = (*block)[0];
597 emit_bits(entropy, (unsigned int) (temp >> Al), 1);
598 }
599
600 cinfo->dest->next_output_byte = entropy->next_output_byte;
601 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
602
603 /* Update restart-interval state too */
604 if (cinfo->restart_interval) {
605 if (entropy->restarts_to_go == 0) {
606 entropy->restarts_to_go = cinfo->restart_interval;
607 entropy->next_restart_num++;
608 entropy->next_restart_num &= 7;
609 }
610 entropy->restarts_to_go--;
611 }
612
613 return TRUE;
614}
615
616
617/*
618 * MCU encoding for AC successive approximation refinement scan.
619 */
620
621METHODDEF(boolean)
622encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
623{
624 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
625 register int temp;
626 register int r, k;
627 int EOB;
628 char *BR_buffer;
629 unsigned int BR;
630 int Se = cinfo->Se;
631 int Al = cinfo->Al;
632 JBLOCKROW block;
633 int absvalues[DCTSIZE2];
634
635 entropy->next_output_byte = cinfo->dest->next_output_byte;
636 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
637
638 /* Emit restart marker if needed */
639 if (cinfo->restart_interval)
640 if (entropy->restarts_to_go == 0)
641 emit_restart(entropy, entropy->next_restart_num);
642
643 /* Encode the MCU data block */
644 block = MCU_data[0];
645
646 /* It is convenient to make a pre-pass to determine the transformed
647 * coefficients' absolute values and the EOB position.
648 */
649 EOB = 0;
650 for (k = cinfo->Ss; k <= Se; k++) {
651 temp = (*block)[jpeg_natural_order[k]];
652 /* We must apply the point transform by Al. For AC coefficients this
653 * is an integer division with rounding towards 0. To do this portably
654 * in C, we shift after obtaining the absolute value.
655 */
656 if (temp < 0)
657 temp = -temp; /* temp is abs value of input */
658 temp >>= Al; /* apply the point transform */
659 absvalues[k] = temp; /* save abs value for main pass */
660 if (temp == 1)
661 EOB = k; /* EOB = index of last newly-nonzero coef */
662 }
663
664 /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
665
666 r = 0; /* r = run length of zeros */
667 BR = 0; /* BR = count of buffered bits added now */
668 BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
669
670 for (k = cinfo->Ss; k <= Se; k++) {
671 if ((temp = absvalues[k]) == 0) {
672 r++;
673 continue;
674 }
675
676 /* Emit any required ZRLs, but not if they can be folded into EOB */
677 while (r > 15 && k <= EOB) {
678 /* emit any pending EOBRUN and the BE correction bits */
679 emit_eobrun(entropy);
680 /* Emit ZRL */
681 emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
682 r -= 16;
683 /* Emit buffered correction bits that must be associated with ZRL */
684 emit_buffered_bits(entropy, BR_buffer, BR);
685 BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
686 BR = 0;
687 }
688
689 /* If the coef was previously nonzero, it only needs a correction bit.
690 * NOTE: a straight translation of the spec's figure G.7 would suggest
691 * that we also need to test r > 15. But if r > 15, we can only get here
692 * if k > EOB, which implies that this coefficient is not 1.
693 */
694 if (temp > 1) {
695 /* The correction bit is the next bit of the absolute value. */
696 BR_buffer[BR++] = (char) (temp & 1);
697 continue;
698 }
699
700 /* Emit any pending EOBRUN and the BE correction bits */
701 emit_eobrun(entropy);
702
703 /* Count/emit Huffman symbol for run length / number of bits */
704 emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
705
706 /* Emit output bit for newly-nonzero coef */
707 temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
708 emit_bits(entropy, (unsigned int) temp, 1);
709
710 /* Emit buffered correction bits that must be associated with this code */
711 emit_buffered_bits(entropy, BR_buffer, BR);
712 BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
713 BR = 0;
714 r = 0; /* reset zero run length */
715 }
716
717 if (r > 0 || BR > 0) { /* If there are trailing zeroes, */
718 entropy->EOBRUN++; /* count an EOB */
719 entropy->BE += BR; /* concat my correction bits to older ones */
720 /* We force out the EOB if we risk either:
721 * 1. overflow of the EOB counter;
722 * 2. overflow of the correction bit buffer during the next MCU.
723 */
724 if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
725 emit_eobrun(entropy);
726 }
727
728 cinfo->dest->next_output_byte = entropy->next_output_byte;
729 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
730
731 /* Update restart-interval state too */
732 if (cinfo->restart_interval) {
733 if (entropy->restarts_to_go == 0) {
734 entropy->restarts_to_go = cinfo->restart_interval;
735 entropy->next_restart_num++;
736 entropy->next_restart_num &= 7;
737 }
738 entropy->restarts_to_go--;
739 }
740
741 return TRUE;
742}
743
744
745/*
746 * Finish up at the end of a Huffman-compressed progressive scan.
747 */
748
749METHODDEF(void)
750finish_pass_phuff (j_compress_ptr cinfo)
751{
752 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
753
754 entropy->next_output_byte = cinfo->dest->next_output_byte;
755 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
756
757 /* Flush out any buffered data */
758 emit_eobrun(entropy);
759 flush_bits(entropy);
760
761 cinfo->dest->next_output_byte = entropy->next_output_byte;
762 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
763}
764
765
766/*
767 * Finish up a statistics-gathering pass and create the new Huffman tables.
768 */
769
770METHODDEF(void)
771finish_pass_gather_phuff (j_compress_ptr cinfo)
772{
773 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
774 boolean is_DC_band;
775 int ci, tbl;
776 jpeg_component_info * compptr;
777 JHUFF_TBL **htblptr;
778 boolean did[NUM_HUFF_TBLS];
779
780 /* Flush out buffered data (all we care about is counting the EOB symbol) */
781 emit_eobrun(entropy);
782
783 is_DC_band = (cinfo->Ss == 0);
784
785 /* It's important not to apply jpeg_gen_optimal_table more than once
786 * per table, because it clobbers the input frequency counts!
787 */
788 MEMZERO(did, SIZEOF(did));
789
790 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
791 compptr = cinfo->cur_comp_info[ci];
792 if (is_DC_band) {
793 if (cinfo->Ah != 0) /* DC refinement needs no table */
794 continue;
795 tbl = compptr->dc_tbl_no;
796 } else {
797 tbl = compptr->ac_tbl_no;
798 }
799 if (! did[tbl]) {
800 if (is_DC_band)
801 htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
802 else
803 htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
804 if (*htblptr == NULL)
805 *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
806 jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
807 did[tbl] = TRUE;
808 }
809 }
810}
811
812
813/*
814 * Module initialization routine for progressive Huffman entropy encoding.
815 */
816
817GLOBAL(void)
818jinit_phuff_encoder (j_compress_ptr cinfo)
819{
820 phuff_entropy_ptr entropy;
821 int i;
822
823 entropy = (phuff_entropy_ptr)
824 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
825 SIZEOF(phuff_entropy_encoder));
826 cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
827 entropy->pub.start_pass = start_pass_phuff;
828
829 /* Mark tables unallocated */
830 for (i = 0; i < NUM_HUFF_TBLS; i++) {
831 entropy->derived_tbls[i] = NULL;
832 entropy->count_ptrs[i] = NULL;
833 }
834 entropy->bit_buffer = NULL; /* needed only in AC refinement scan */
835}
836
837#endif /* C_PROGRESSIVE_SUPPORTED */
838