4 * Copyright (C) 1995, 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.
8 * This file contains Huffman entropy encoding routines for progressive JPEG.
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
15 #define JPEG_INTERNALS
18 #include "jchuff.h" /* Declarations shared with jchuff.c */
20 #ifdef C_PROGRESSIVE_SUPPORTED
22 /* Expanded entropy encoder object for progressive Huffman encoding. */
25 struct jpeg_entropy_encoder pub; /* public fields */
27 /* Mode flag: TRUE for optimization, FALSE for actual data output */
28 boolean gather_statistics;
30 /* Bit-level coding status.
31 * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
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) */
39 /* Coding status for DC components */
40 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
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... */
49 unsigned int restarts_to_go; /* MCUs left in this restart interval */
50 int next_restart_num; /* next restart number to write (0-7) */
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.
56 c_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
58 /* Statistics tables for optimization; again, one set is enough */
59 long * count_ptrs[NUM_HUFF_TBLS];
60 } phuff_entropy_encoder;
62 typedef phuff_entropy_encoder * phuff_entropy_ptr;
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.
70 #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */
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.
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)))
85 #define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
88 /* Forward declarations */
89 METHODDEF boolean encode_mcu_DC_first JPP((j_compress_ptr cinfo,
90 JBLOCKROW *MCU_data));
91 METHODDEF boolean encode_mcu_AC_first JPP((j_compress_ptr cinfo,
92 JBLOCKROW *MCU_data));
93 METHODDEF boolean encode_mcu_DC_refine JPP((j_compress_ptr cinfo,
94 JBLOCKROW *MCU_data));
95 METHODDEF boolean encode_mcu_AC_refine JPP((j_compress_ptr cinfo,
96 JBLOCKROW *MCU_data));
97 METHODDEF void finish_pass_phuff JPP((j_compress_ptr cinfo));
98 METHODDEF void finish_pass_gather_phuff JPP((j_compress_ptr cinfo));
102 * Initialize for a Huffman-compressed scan using progressive JPEG.
106 start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
108 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
111 jpeg_component_info * compptr;
113 entropy->cinfo = cinfo;
114 entropy->gather_statistics = gather_statistics;
116 is_DC_band = (cinfo->Ss == 0);
118 /* We assume jcmaster.c already validated the scan parameters. */
120 /* Select execution routines */
121 if (cinfo->Ah == 0) {
123 entropy->pub.encode_mcu = encode_mcu_DC_first;
125 entropy->pub.encode_mcu = encode_mcu_AC_first;
128 entropy->pub.encode_mcu = encode_mcu_DC_refine;
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));
138 if (gather_statistics)
139 entropy->pub.finish_pass = finish_pass_gather_phuff;
141 entropy->pub.finish_pass = finish_pass_phuff;
143 /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
144 * for AC coefficients.
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 /* Make sure requested tables are present */
151 /* (In gather mode, tables need not be allocated yet) */
153 if (cinfo->Ah != 0) /* DC refinement needs no table */
155 tbl = compptr->dc_tbl_no;
156 if (tbl < 0 || tbl >= NUM_HUFF_TBLS ||
157 (cinfo->dc_huff_tbl_ptrs[tbl] == NULL && !gather_statistics))
158 ERREXIT1(cinfo,JERR_NO_HUFF_TABLE, tbl);
160 entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
161 if (tbl < 0 || tbl >= NUM_HUFF_TBLS ||
162 (cinfo->ac_huff_tbl_ptrs[tbl] == NULL && !gather_statistics))
163 ERREXIT1(cinfo,JERR_NO_HUFF_TABLE, tbl);
165 if (gather_statistics) {
166 /* Allocate and zero the statistics tables */
167 /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
168 if (entropy->count_ptrs[tbl] == NULL)
169 entropy->count_ptrs[tbl] = (long *)
170 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
172 MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long));
174 /* Compute derived values for Huffman tables */
175 /* We may do this more than once for a table, but it's not expensive */
177 jpeg_make_c_derived_tbl(cinfo, cinfo->dc_huff_tbl_ptrs[tbl],
178 & entropy->derived_tbls[tbl]);
180 jpeg_make_c_derived_tbl(cinfo, cinfo->ac_huff_tbl_ptrs[tbl],
181 & entropy->derived_tbls[tbl]);
185 /* Initialize AC stuff */
189 /* Initialize bit buffer to empty */
190 entropy->put_buffer = 0;
191 entropy->put_bits = 0;
193 /* Initialize restart stuff */
194 entropy->restarts_to_go = cinfo->restart_interval;
195 entropy->next_restart_num = 0;
199 /* Outputting bytes to the file.
200 * NB: these must be called only when actually outputting,
201 * that is, entropy->gather_statistics == FALSE.
205 #define emit_byte(entropy,val) \
206 { *(entropy)->next_output_byte++ = (JOCTET) (val); \
207 if (--(entropy)->free_in_buffer == 0) \
208 dump_buffer(entropy); }
212 dump_buffer (phuff_entropy_ptr entropy)
213 /* Empty the output buffer; we do not support suspension in this module. */
215 struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
217 if (! (*dest->empty_output_buffer) (entropy->cinfo))
218 ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
219 /* After a successful buffer dump, must reset buffer pointers */
220 entropy->next_output_byte = dest->next_output_byte;
221 entropy->free_in_buffer = dest->free_in_buffer;
225 /* Outputting bits to the file */
227 /* Only the right 24 bits of put_buffer are used; the valid bits are
228 * left-justified in this part. At most 16 bits can be passed to emit_bits
229 * in one call, and we never retain more than 7 bits in put_buffer
230 * between calls, so 24 bits are sufficient.
235 emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
236 /* Emit some bits, unless we are in gather mode */
238 /* This routine is heavily used, so it's worth coding tightly. */
239 register INT32 put_buffer = (INT32) code;
240 register int put_bits = entropy->put_bits;
242 /* if size is 0, caller used an invalid Huffman table entry */
244 ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
246 if (entropy->gather_statistics)
247 return; /* do nothing if we're only getting stats */
249 put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
251 put_bits += size; /* new number of bits in buffer */
253 put_buffer <<= 24 - put_bits; /* align incoming bits */
255 put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */
257 while (put_bits >= 8) {
258 int c = (int) ((put_buffer >> 16) & 0xFF);
260 emit_byte(entropy, c);
261 if (c == 0xFF) { /* need to stuff a zero byte? */
262 emit_byte(entropy, 0);
268 entropy->put_buffer = put_buffer; /* update variables */
269 entropy->put_bits = put_bits;
274 flush_bits (phuff_entropy_ptr entropy)
276 emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
277 entropy->put_buffer = 0; /* and reset bit-buffer to empty */
278 entropy->put_bits = 0;
283 * Emit (or just count) a Huffman symbol.
288 emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol)
290 if (entropy->gather_statistics)
291 entropy->count_ptrs[tbl_no][symbol]++;
293 c_derived_tbl * tbl = entropy->derived_tbls[tbl_no];
294 emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
300 * Emit bits from a correction bit buffer.
304 emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart,
307 if (entropy->gather_statistics)
308 return; /* no real work */
311 emit_bits(entropy, (unsigned int) (*bufstart), 1);
319 * Emit any pending EOBRUN symbol.
323 emit_eobrun (phuff_entropy_ptr entropy)
325 register int temp, nbits;
327 if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */
328 temp = entropy->EOBRUN;
333 emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
335 emit_bits(entropy, entropy->EOBRUN, nbits);
339 /* Emit any buffered correction bits */
340 emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
347 * Emit a restart marker & resynchronize predictions.
351 emit_restart (phuff_entropy_ptr entropy, int restart_num)
355 emit_eobrun(entropy);
357 if (! entropy->gather_statistics) {
359 emit_byte(entropy, 0xFF);
360 emit_byte(entropy, JPEG_RST0 + restart_num);
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;
368 /* Re-initialize all AC-related fields to 0 */
376 * MCU encoding for DC initial scan (either spectral selection,
377 * or first pass of successive approximation).
381 encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
383 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
384 register int temp, temp2;
389 jpeg_component_info * compptr;
392 entropy->next_output_byte = cinfo->dest->next_output_byte;
393 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
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);
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];
406 /* Compute the DC value after the required point transform by Al.
407 * This is simply an arithmetic right shift.
409 temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
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;
415 /* Encode the DC coefficient difference per section G.1.2.1 */
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 */
424 /* Find the number of bits needed for the magnitude of the coefficient */
431 /* Count/emit the Huffman-coded symbol for the number of bits */
432 emit_symbol(entropy, compptr->dc_tbl_no, nbits);
434 /* Emit that number of bits of the value, if positive, */
435 /* or the complement of its magnitude, if negative. */
436 if (nbits) /* emit_bits rejects calls with size 0 */
437 emit_bits(entropy, (unsigned int) temp2, nbits);
440 cinfo->dest->next_output_byte = entropy->next_output_byte;
441 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
443 /* Update restart-interval state too */
444 if (cinfo->restart_interval) {
445 if (entropy->restarts_to_go == 0) {
446 entropy->restarts_to_go = cinfo->restart_interval;
447 entropy->next_restart_num++;
448 entropy->next_restart_num &= 7;
450 entropy->restarts_to_go--;
458 * MCU encoding for AC initial scan (either spectral selection,
459 * or first pass of successive approximation).
463 encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
465 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
466 register int temp, temp2;
473 entropy->next_output_byte = cinfo->dest->next_output_byte;
474 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
476 /* Emit restart marker if needed */
477 if (cinfo->restart_interval)
478 if (entropy->restarts_to_go == 0)
479 emit_restart(entropy, entropy->next_restart_num);
481 /* Encode the MCU data block */
484 /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
486 r = 0; /* r = run length of zeros */
488 for (k = cinfo->Ss; k <= Se; k++) {
489 if ((temp = (*block)[jpeg_natural_order[k]]) == 0) {
493 /* We must apply the point transform by Al. For AC coefficients this
494 * is an integer division with rounding towards 0. To do this portably
495 * in C, we shift after obtaining the absolute value; so the code is
496 * interwoven with finding the abs value (temp) and output bits (temp2).
499 temp = -temp; /* temp is abs value of input */
500 temp >>= Al; /* apply the point transform */
501 /* For a negative coef, want temp2 = bitwise complement of abs(coef) */
504 temp >>= Al; /* apply the point transform */
507 /* Watch out for case that nonzero coef is zero after point transform */
513 /* Emit any pending EOBRUN */
514 if (entropy->EOBRUN > 0)
515 emit_eobrun(entropy);
516 /* if run length > 15, must emit special run-length-16 codes (0xF0) */
518 emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
522 /* Find the number of bits needed for the magnitude of the coefficient */
523 nbits = 1; /* there must be at least one 1 bit */
527 /* Count/emit Huffman symbol for run length / number of bits */
528 emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
530 /* Emit that number of bits of the value, if positive, */
531 /* or the complement of its magnitude, if negative. */
532 emit_bits(entropy, (unsigned int) temp2, nbits);
534 r = 0; /* reset zero run length */
537 if (r > 0) { /* If there are trailing zeroes, */
538 entropy->EOBRUN++; /* count an EOB */
539 if (entropy->EOBRUN == 0x7FFF)
540 emit_eobrun(entropy); /* force it out to avoid overflow */
543 cinfo->dest->next_output_byte = entropy->next_output_byte;
544 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
546 /* Update restart-interval state too */
547 if (cinfo->restart_interval) {
548 if (entropy->restarts_to_go == 0) {
549 entropy->restarts_to_go = cinfo->restart_interval;
550 entropy->next_restart_num++;
551 entropy->next_restart_num &= 7;
553 entropy->restarts_to_go--;
561 * MCU encoding for DC successive approximation refinement scan.
562 * Note: we assume such scans can be multi-component, although the spec
563 * is not very clear on the point.
567 encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
569 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
575 entropy->next_output_byte = cinfo->dest->next_output_byte;
576 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
578 /* Emit restart marker if needed */
579 if (cinfo->restart_interval)
580 if (entropy->restarts_to_go == 0)
581 emit_restart(entropy, entropy->next_restart_num);
583 /* Encode the MCU data blocks */
584 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
585 block = MCU_data[blkn];
587 /* We simply emit the Al'th bit of the DC coefficient value. */
589 emit_bits(entropy, (unsigned int) (temp >> Al), 1);
592 cinfo->dest->next_output_byte = entropy->next_output_byte;
593 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
595 /* Update restart-interval state too */
596 if (cinfo->restart_interval) {
597 if (entropy->restarts_to_go == 0) {
598 entropy->restarts_to_go = cinfo->restart_interval;
599 entropy->next_restart_num++;
600 entropy->next_restart_num &= 7;
602 entropy->restarts_to_go--;
610 * MCU encoding for AC successive approximation refinement scan.
614 encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
616 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
625 int absvalues[DCTSIZE2];
627 entropy->next_output_byte = cinfo->dest->next_output_byte;
628 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
630 /* Emit restart marker if needed */
631 if (cinfo->restart_interval)
632 if (entropy->restarts_to_go == 0)
633 emit_restart(entropy, entropy->next_restart_num);
635 /* Encode the MCU data block */
638 /* It is convenient to make a pre-pass to determine the transformed
639 * coefficients' absolute values and the EOB position.
642 for (k = cinfo->Ss; k <= Se; k++) {
643 temp = (*block)[jpeg_natural_order[k]];
644 /* We must apply the point transform by Al. For AC coefficients this
645 * is an integer division with rounding towards 0. To do this portably
646 * in C, we shift after obtaining the absolute value.
649 temp = -temp; /* temp is abs value of input */
650 temp >>= Al; /* apply the point transform */
651 absvalues[k] = temp; /* save abs value for main pass */
653 EOB = k; /* EOB = index of last newly-nonzero coef */
656 /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
658 r = 0; /* r = run length of zeros */
659 BR = 0; /* BR = count of buffered bits added now */
660 BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
662 for (k = cinfo->Ss; k <= Se; k++) {
663 if ((temp = absvalues[k]) == 0) {
668 /* Emit any required ZRLs, but not if they can be folded into EOB */
669 while (r > 15 && k <= EOB) {
670 /* emit any pending EOBRUN and the BE correction bits */
671 emit_eobrun(entropy);
673 emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
675 /* Emit buffered correction bits that must be associated with ZRL */
676 emit_buffered_bits(entropy, BR_buffer, BR);
677 BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
681 /* If the coef was previously nonzero, it only needs a correction bit.
682 * NOTE: a straight translation of the spec's figure G.7 would suggest
683 * that we also need to test r > 15. But if r > 15, we can only get here
684 * if k > EOB, which implies that this coefficient is not 1.
687 /* The correction bit is the next bit of the absolute value. */
688 BR_buffer[BR++] = (char) (temp & 1);
692 /* Emit any pending EOBRUN and the BE correction bits */
693 emit_eobrun(entropy);
695 /* Count/emit Huffman symbol for run length / number of bits */
696 emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
698 /* Emit output bit for newly-nonzero coef */
699 temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
700 emit_bits(entropy, (unsigned int) temp, 1);
702 /* Emit buffered correction bits that must be associated with this code */
703 emit_buffered_bits(entropy, BR_buffer, BR);
704 BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
706 r = 0; /* reset zero run length */
709 if (r > 0 || BR > 0) { /* If there are trailing zeroes, */
710 entropy->EOBRUN++; /* count an EOB */
711 entropy->BE += BR; /* concat my correction bits to older ones */
712 /* We force out the EOB if we risk either:
713 * 1. overflow of the EOB counter;
714 * 2. overflow of the correction bit buffer during the next MCU.
716 if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
717 emit_eobrun(entropy);
720 cinfo->dest->next_output_byte = entropy->next_output_byte;
721 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
723 /* Update restart-interval state too */
724 if (cinfo->restart_interval) {
725 if (entropy->restarts_to_go == 0) {
726 entropy->restarts_to_go = cinfo->restart_interval;
727 entropy->next_restart_num++;
728 entropy->next_restart_num &= 7;
730 entropy->restarts_to_go--;
738 * Finish up at the end of a Huffman-compressed progressive scan.
742 finish_pass_phuff (j_compress_ptr cinfo)
744 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
746 entropy->next_output_byte = cinfo->dest->next_output_byte;
747 entropy->free_in_buffer = cinfo->dest->free_in_buffer;
749 /* Flush out any buffered data */
750 emit_eobrun(entropy);
753 cinfo->dest->next_output_byte = entropy->next_output_byte;
754 cinfo->dest->free_in_buffer = entropy->free_in_buffer;
759 * Finish up a statistics-gathering pass and create the new Huffman tables.
763 finish_pass_gather_phuff (j_compress_ptr cinfo)
765 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
768 jpeg_component_info * compptr;
770 boolean did[NUM_HUFF_TBLS];
772 /* Flush out buffered data (all we care about is counting the EOB symbol) */
773 emit_eobrun(entropy);
775 is_DC_band = (cinfo->Ss == 0);
777 /* It's important not to apply jpeg_gen_optimal_table more than once
778 * per table, because it clobbers the input frequency counts!
780 MEMZERO(did, SIZEOF(did));
782 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
783 compptr = cinfo->cur_comp_info[ci];
785 if (cinfo->Ah != 0) /* DC refinement needs no table */
787 tbl = compptr->dc_tbl_no;
789 tbl = compptr->ac_tbl_no;
793 htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
795 htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
796 if (*htblptr == NULL)
797 *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
798 jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
806 * Module initialization routine for progressive Huffman entropy encoding.
810 jinit_phuff_encoder (j_compress_ptr cinfo)
812 phuff_entropy_ptr entropy;
815 entropy = (phuff_entropy_ptr)
816 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
817 SIZEOF(phuff_entropy_encoder));
818 cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
819 entropy->pub.start_pass = start_pass_phuff;
821 /* Mark tables unallocated */
822 for (i = 0; i < NUM_HUFF_TBLS; i++) {
823 entropy->derived_tbls[i] = NULL;
824 entropy->count_ptrs[i] = NULL;
826 entropy->bit_buffer = NULL; /* needed only in AC refinement scan */
829 #endif /* C_PROGRESSIVE_SUPPORTED */