ref: 13785bbbef60f5c13aa973c1e7d4277aa55f6a2d
dir: /sys/src/cmd/gs/jpeg/jcphuff.c/
/* * jcphuff.c * * Copyright (C) 1995-1997, Thomas G. Lane. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains Huffman entropy encoding routines for progressive JPEG. * * We do not support output suspension in this module, since the library * currently does not allow multiple-scan files to be written with output * suspension. */ #define JPEG_INTERNALS #include "jinclude.h" #include "jpeglib.h" #include "jchuff.h" /* Declarations shared with jchuff.c */ #ifdef C_PROGRESSIVE_SUPPORTED /* Expanded entropy encoder object for progressive Huffman encoding. */ typedef struct { struct jpeg_entropy_encoder pub; /* public fields */ /* Mode flag: TRUE for optimization, FALSE for actual data output */ boolean gather_statistics; /* Bit-level coding status. * next_output_byte/free_in_buffer are local copies of cinfo->dest fields. */ JOCTET * next_output_byte; /* => next byte to write in buffer */ size_t free_in_buffer; /* # of byte spaces remaining in buffer */ INT32 put_buffer; /* current bit-accumulation buffer */ int put_bits; /* # of bits now in it */ j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */ /* Coding status for DC components */ int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ /* Coding status for AC components */ int ac_tbl_no; /* the table number of the single component */ unsigned int EOBRUN; /* run length of EOBs */ unsigned int BE; /* # of buffered correction bits before MCU */ char * bit_buffer; /* buffer for correction bits (1 per char) */ /* packing correction bits tightly would save some space but cost time... */ unsigned int restarts_to_go; /* MCUs left in this restart interval */ int next_restart_num; /* next restart number to write (0-7) */ /* Pointers to derived tables (these workspaces have image lifespan). * Since any one scan codes only DC or only AC, we only need one set * of tables, not one for DC and one for AC. */ c_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; /* Statistics tables for optimization; again, one set is enough */ long * count_ptrs[NUM_HUFF_TBLS]; } phuff_entropy_encoder; typedef phuff_entropy_encoder * phuff_entropy_ptr; /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit * buffer can hold. Larger sizes may slightly improve compression, but * 1000 is already well into the realm of overkill. * The minimum safe size is 64 bits. */ #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */ /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32. * We assume that int right shift is unsigned if INT32 right shift is, * which should be safe. */ #ifdef RIGHT_SHIFT_IS_UNSIGNED #define ISHIFT_TEMPS int ishift_temp; #define IRIGHT_SHIFT(x,shft) \ ((ishift_temp = (x)) < 0 ? \ (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \ (ishift_temp >> (shft))) #else #define ISHIFT_TEMPS #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) #endif /* Forward declarations */ METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo, JBLOCKROW *MCU_data)); METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo, JBLOCKROW *MCU_data)); METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo, JBLOCKROW *MCU_data)); METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo, JBLOCKROW *MCU_data)); METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo)); METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo)); /* * Initialize for a Huffman-compressed scan using progressive JPEG. */ METHODDEF(void) start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics) { phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; boolean is_DC_band; int ci, tbl; jpeg_component_info * compptr; entropy->cinfo = cinfo; entropy->gather_statistics = gather_statistics; is_DC_band = (cinfo->Ss == 0); /* We assume jcmaster.c already validated the scan parameters. */ /* Select execution routines */ if (cinfo->Ah == 0) { if (is_DC_band) entropy->pub.encode_mcu = encode_mcu_DC_first; else entropy->pub.encode_mcu = encode_mcu_AC_first; } else { if (is_DC_band) entropy->pub.encode_mcu = encode_mcu_DC_refine; else { entropy->pub.encode_mcu = encode_mcu_AC_refine; /* AC refinement needs a correction bit buffer */ if (entropy->bit_buffer == NULL) entropy->bit_buffer = (char *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, MAX_CORR_BITS * SIZEOF(char)); } } if (gather_statistics) entropy->pub.finish_pass = finish_pass_gather_phuff; else entropy->pub.finish_pass = finish_pass_phuff; /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1 * for AC coefficients. */ for (ci = 0; ci < cinfo->comps_in_scan; ci++) { compptr = cinfo->cur_comp_info[ci]; /* Initialize DC predictions to 0 */ entropy->last_dc_val[ci] = 0; /* Get table index */ if (is_DC_band) { if (cinfo->Ah != 0) /* DC refinement needs no table */ continue; tbl = compptr->dc_tbl_no; } else { entropy->ac_tbl_no = tbl = compptr->ac_tbl_no; } if (gather_statistics) { /* Check for invalid table index */ /* (make_c_derived_tbl does this in the other path) */ if (tbl < 0 || tbl >= NUM_HUFF_TBLS) ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); /* Allocate and zero the statistics tables */ /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ if (entropy->count_ptrs[tbl] == NULL) entropy->count_ptrs[tbl] = (long *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 257 * SIZEOF(long)); MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long)); } else { /* Compute derived values for Huffman table */ /* We may do this more than once for a table, but it's not expensive */ jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl, & entropy->derived_tbls[tbl]); } } /* Initialize AC stuff */ entropy->EOBRUN = 0; entropy->BE = 0; /* Initialize bit buffer to empty */ entropy->put_buffer = 0; entropy->put_bits = 0; /* Initialize restart stuff */ entropy->restarts_to_go = cinfo->restart_interval; entropy->next_restart_num = 0; } /* Outputting bytes to the file. * NB: these must be called only when actually outputting, * that is, entropy->gather_statistics == FALSE. */ /* Emit a byte */ #define emit_byte(entropy,val) \ { *(entropy)->next_output_byte++ = (JOCTET) (val); \ if (--(entropy)->free_in_buffer == 0) \ dump_buffer(entropy); } LOCAL(void) dump_buffer (phuff_entropy_ptr entropy) /* Empty the output buffer; we do not support suspension in this module. */ { struct jpeg_destination_mgr * dest = entropy->cinfo->dest; if (! (*dest->empty_output_buffer) (entropy->cinfo)) ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND); /* After a successful buffer dump, must reset buffer pointers */ entropy->next_output_byte = dest->next_output_byte; entropy->free_in_buffer = dest->free_in_buffer; } /* Outputting bits to the file */ /* Only the right 24 bits of put_buffer are used; the valid bits are * left-justified in this part. At most 16 bits can be passed to emit_bits * in one call, and we never retain more than 7 bits in put_buffer * between calls, so 24 bits are sufficient. */ INLINE LOCAL(void) emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size) /* Emit some bits, unless we are in gather mode */ { /* This routine is heavily used, so it's worth coding tightly. */ register INT32 put_buffer = (INT32) code; register int put_bits = entropy->put_bits; /* if size is 0, caller used an invalid Huffman table entry */ if (size == 0) ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); if (entropy->gather_statistics) return; /* do nothing if we're only getting stats */ put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */ put_bits += size; /* new number of bits in buffer */ put_buffer <<= 24 - put_bits; /* align incoming bits */ put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */ while (put_bits >= 8) { int c = (int) ((put_buffer >> 16) & 0xFF); emit_byte(entropy, c); if (c == 0xFF) { /* need to stuff a zero byte? */ emit_byte(entropy, 0); } put_buffer <<= 8; put_bits -= 8; } entropy->put_buffer = put_buffer; /* update variables */ entropy->put_bits = put_bits; } LOCAL(void) flush_bits (phuff_entropy_ptr entropy) { emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */ entropy->put_buffer = 0; /* and reset bit-buffer to empty */ entropy->put_bits = 0; } /* * Emit (or just count) a Huffman symbol. */ INLINE LOCAL(void) emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol) { if (entropy->gather_statistics) entropy->count_ptrs[tbl_no][symbol]++; else { c_derived_tbl * tbl = entropy->derived_tbls[tbl_no]; emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]); } } /* * Emit bits from a correction bit buffer. */ LOCAL(void) emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart, unsigned int nbits) { if (entropy->gather_statistics) return; /* no real work */ while (nbits > 0) { emit_bits(entropy, (unsigned int) (*bufstart), 1); bufstart++; nbits--; } } /* * Emit any pending EOBRUN symbol. */ LOCAL(void) emit_eobrun (phuff_entropy_ptr entropy) { register int temp, nbits; if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */ temp = entropy->EOBRUN; nbits = 0; while ((temp >>= 1)) nbits++; /* safety check: shouldn't happen given limited correction-bit buffer */ if (nbits > 14) ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4); if (nbits) emit_bits(entropy, entropy->EOBRUN, nbits); entropy->EOBRUN = 0; /* Emit any buffered correction bits */ emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE); entropy->BE = 0; } } /* * Emit a restart marker & resynchronize predictions. */ LOCAL(void) emit_restart (phuff_entropy_ptr entropy, int restart_num) { int ci; emit_eobrun(entropy); if (! entropy->gather_statistics) { flush_bits(entropy); emit_byte(entropy, 0xFF); emit_byte(entropy, JPEG_RST0 + restart_num); } if (entropy->cinfo->Ss == 0) { /* Re-initialize DC predictions to 0 */ for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++) entropy->last_dc_val[ci] = 0; } else { /* Re-initialize all AC-related fields to 0 */ entropy->EOBRUN = 0; entropy->BE = 0; } } /* * MCU encoding for DC initial scan (either spectral selection, * or first pass of successive approximation). */ METHODDEF(boolean) encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) { phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; register int temp, temp2; register int nbits; int blkn, ci; int Al = cinfo->Al; JBLOCKROW block; jpeg_component_info * compptr; ISHIFT_TEMPS entropy->next_output_byte = cinfo->dest->next_output_byte; entropy->free_in_buffer = cinfo->dest->free_in_buffer; /* Emit restart marker if needed */ if (cinfo->restart_interval) if (entropy->restarts_to_go == 0) emit_restart(entropy, entropy->next_restart_num); /* Encode the MCU data blocks */ for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { block = MCU_data[blkn]; ci = cinfo->MCU_membership[blkn]; compptr = cinfo->cur_comp_info[ci]; /* Compute the DC value after the required point transform by Al. * This is simply an arithmetic right shift. */ temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al); /* DC differences are figured on the point-transformed values. */ temp = temp2 - entropy->last_dc_val[ci]; entropy->last_dc_val[ci] = temp2; /* Encode the DC coefficient difference per section G.1.2.1 */ temp2 = temp; if (temp < 0) { temp = -temp; /* temp is abs value of input */ /* For a negative input, want temp2 = bitwise complement of abs(input) */ /* This code assumes we are on a two's complement machine */ temp2--; } /* Find the number of bits needed for the magnitude of the coefficient */ nbits = 0; while (temp) { nbits++; temp >>= 1; } /* Check for out-of-range coefficient values. * Since we're encoding a difference, the range limit is twice as much. */ if (nbits > MAX_COEF_BITS+1) ERREXIT(cinfo, JERR_BAD_DCT_COEF); /* Count/emit the Huffman-coded symbol for the number of bits */ emit_symbol(entropy, compptr->dc_tbl_no, nbits); /* Emit that number of bits of the value, if positive, */ /* or the complement of its magnitude, if negative. */ if (nbits) /* emit_bits rejects calls with size 0 */ emit_bits(entropy, (unsigned int) temp2, nbits); } cinfo->dest->next_output_byte = entropy->next_output_byte; cinfo->dest->free_in_buffer = entropy->free_in_buffer; /* Update restart-interval state too */ if (cinfo->restart_interval) { if (entropy->restarts_to_go == 0) { entropy->restarts_to_go = cinfo->restart_interval; entropy->next_restart_num++; entropy->next_restart_num &= 7; } entropy->restarts_to_go--; } return TRUE; } /* * MCU encoding for AC initial scan (either spectral selection, * or first pass of successive approximation). */ METHODDEF(boolean) encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) { phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; register int temp, temp2; register int nbits; register int r, k; int Se = cinfo->Se; int Al = cinfo->Al; JBLOCKROW block; entropy->next_output_byte = cinfo->dest->next_output_byte; entropy->free_in_buffer = cinfo->dest->free_in_buffer; /* Emit restart marker if needed */ if (cinfo->restart_interval) if (entropy->restarts_to_go == 0) emit_restart(entropy, entropy->next_restart_num); /* Encode the MCU data block */ block = MCU_data[0]; /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */ r = 0; /* r = run length of zeros */ for (k = cinfo->Ss; k <= Se; k++) { if ((temp = (*block)[jpeg_natural_order[k]]) == 0) { r++; continue; } /* We must apply the point transform by Al. For AC coefficients this * is an integer division with rounding towards 0. To do this portably * in C, we shift after obtaining the absolute value; so the code is * interwoven with finding the abs value (temp) and output bits (temp2). */ if (temp < 0) { temp = -temp; /* temp is abs value of input */ temp >>= Al; /* apply the point transform */ /* For a negative coef, want temp2 = bitwise complement of abs(coef) */ temp2 = ~temp; } else { temp >>= Al; /* apply the point transform */ temp2 = temp; } /* Watch out for case that nonzero coef is zero after point transform */ if (temp == 0) { r++; continue; } /* Emit any pending EOBRUN */ if (entropy->EOBRUN > 0) emit_eobrun(entropy); /* if run length > 15, must emit special run-length-16 codes (0xF0) */ while (r > 15) { emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); r -= 16; } /* Find the number of bits needed for the magnitude of the coefficient */ nbits = 1; /* there must be at least one 1 bit */ while ((temp >>= 1)) nbits++; /* Check for out-of-range coefficient values */ if (nbits > MAX_COEF_BITS) ERREXIT(cinfo, JERR_BAD_DCT_COEF); /* Count/emit Huffman symbol for run length / number of bits */ emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits); /* Emit that number of bits of the value, if positive, */ /* or the complement of its magnitude, if negative. */ emit_bits(entropy, (unsigned int) temp2, nbits); r = 0; /* reset zero run length */ } if (r > 0) { /* If there are trailing zeroes, */ entropy->EOBRUN++; /* count an EOB */ if (entropy->EOBRUN == 0x7FFF) emit_eobrun(entropy); /* force it out to avoid overflow */ } cinfo->dest->next_output_byte = entropy->next_output_byte; cinfo->dest->free_in_buffer = entropy->free_in_buffer; /* Update restart-interval state too */ if (cinfo->restart_interval) { if (entropy->restarts_to_go == 0) { entropy->restarts_to_go = cinfo->restart_interval; entropy->next_restart_num++; entropy->next_restart_num &= 7; } entropy->restarts_to_go--; } return TRUE; } /* * MCU encoding for DC successive approximation refinement scan. * Note: we assume such scans can be multi-component, although the spec * is not very clear on the point. */ METHODDEF(boolean) encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) { phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; register int temp; int blkn; int Al = cinfo->Al; JBLOCKROW block; entropy->next_output_byte = cinfo->dest->next_output_byte; entropy->free_in_buffer = cinfo->dest->free_in_buffer; /* Emit restart marker if needed */ if (cinfo->restart_interval) if (entropy->restarts_to_go == 0) emit_restart(entropy, entropy->next_restart_num); /* Encode the MCU data blocks */ for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { block = MCU_data[blkn]; /* We simply emit the Al'th bit of the DC coefficient value. */ temp = (*block)[0]; emit_bits(entropy, (unsigned int) (temp >> Al), 1); } cinfo->dest->next_output_byte = entropy->next_output_byte; cinfo->dest->free_in_buffer = entropy->free_in_buffer; /* Update restart-interval state too */ if (cinfo->restart_interval) { if (entropy->restarts_to_go == 0) { entropy->restarts_to_go = cinfo->restart_interval; entropy->next_restart_num++; entropy->next_restart_num &= 7; } entropy->restarts_to_go--; } return TRUE; } /* * MCU encoding for AC successive approximation refinement scan. */ METHODDEF(boolean) encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) { phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; register int temp; register int r, k; int EOB; char *BR_buffer; unsigned int BR; int Se = cinfo->Se; int Al = cinfo->Al; JBLOCKROW block; int absvalues[DCTSIZE2]; entropy->next_output_byte = cinfo->dest->next_output_byte; entropy->free_in_buffer = cinfo->dest->free_in_buffer; /* Emit restart marker if needed */ if (cinfo->restart_interval) if (entropy->restarts_to_go == 0) emit_restart(entropy, entropy->next_restart_num); /* Encode the MCU data block */ block = MCU_data[0]; /* It is convenient to make a pre-pass to determine the transformed * coefficients' absolute values and the EOB position. */ EOB = 0; for (k = cinfo->Ss; k <= Se; k++) { temp = (*block)[jpeg_natural_order[k]]; /* We must apply the point transform by Al. For AC coefficients this * is an integer division with rounding towards 0. To do this portably * in C, we shift after obtaining the absolute value. */ if (temp < 0) temp = -temp; /* temp is abs value of input */ temp >>= Al; /* apply the point transform */ absvalues[k] = temp; /* save abs value for main pass */ if (temp == 1) EOB = k; /* EOB = index of last newly-nonzero coef */ } /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */ r = 0; /* r = run length of zeros */ BR = 0; /* BR = count of buffered bits added now */ BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */ for (k = cinfo->Ss; k <= Se; k++) { if ((temp = absvalues[k]) == 0) { r++; continue; } /* Emit any required ZRLs, but not if they can be folded into EOB */ while (r > 15 && k <= EOB) { /* emit any pending EOBRUN and the BE correction bits */ emit_eobrun(entropy); /* Emit ZRL */ emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); r -= 16; /* Emit buffered correction bits that must be associated with ZRL */ emit_buffered_bits(entropy, BR_buffer, BR); BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ BR = 0; } /* If the coef was previously nonzero, it only needs a correction bit. * NOTE: a straight translation of the spec's figure G.7 would suggest * that we also need to test r > 15. But if r > 15, we can only get here * if k > EOB, which implies that this coefficient is not 1. */ if (temp > 1) { /* The correction bit is the next bit of the absolute value. */ BR_buffer[BR++] = (char) (temp & 1); continue; } /* Emit any pending EOBRUN and the BE correction bits */ emit_eobrun(entropy); /* Count/emit Huffman symbol for run length / number of bits */ emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1); /* Emit output bit for newly-nonzero coef */ temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1; emit_bits(entropy, (unsigned int) temp, 1); /* Emit buffered correction bits that must be associated with this code */ emit_buffered_bits(entropy, BR_buffer, BR); BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ BR = 0; r = 0; /* reset zero run length */ } if (r > 0 || BR > 0) { /* If there are trailing zeroes, */ entropy->EOBRUN++; /* count an EOB */ entropy->BE += BR; /* concat my correction bits to older ones */ /* We force out the EOB if we risk either: * 1. overflow of the EOB counter; * 2. overflow of the correction bit buffer during the next MCU. */ if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1)) emit_eobrun(entropy); } cinfo->dest->next_output_byte = entropy->next_output_byte; cinfo->dest->free_in_buffer = entropy->free_in_buffer; /* Update restart-interval state too */ if (cinfo->restart_interval) { if (entropy->restarts_to_go == 0) { entropy->restarts_to_go = cinfo->restart_interval; entropy->next_restart_num++; entropy->next_restart_num &= 7; } entropy->restarts_to_go--; } return TRUE; } /* * Finish up at the end of a Huffman-compressed progressive scan. */ METHODDEF(void) finish_pass_phuff (j_compress_ptr cinfo) { phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; entropy->next_output_byte = cinfo->dest->next_output_byte; entropy->free_in_buffer = cinfo->dest->free_in_buffer; /* Flush out any buffered data */ emit_eobrun(entropy); flush_bits(entropy); cinfo->dest->next_output_byte = entropy->next_output_byte; cinfo->dest->free_in_buffer = entropy->free_in_buffer; } /* * Finish up a statistics-gathering pass and create the new Huffman tables. */ METHODDEF(void) finish_pass_gather_phuff (j_compress_ptr cinfo) { phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; boolean is_DC_band; int ci, tbl; jpeg_component_info * compptr; JHUFF_TBL **htblptr; boolean did[NUM_HUFF_TBLS]; /* Flush out buffered data (all we care about is counting the EOB symbol) */ emit_eobrun(entropy); is_DC_band = (cinfo->Ss == 0); /* It's important not to apply jpeg_gen_optimal_table more than once * per table, because it clobbers the input frequency counts! */ MEMZERO(did, SIZEOF(did)); for (ci = 0; ci < cinfo->comps_in_scan; ci++) { compptr = cinfo->cur_comp_info[ci]; if (is_DC_band) { if (cinfo->Ah != 0) /* DC refinement needs no table */ continue; tbl = compptr->dc_tbl_no; } else { tbl = compptr->ac_tbl_no; } if (! did[tbl]) { if (is_DC_band) htblptr = & cinfo->dc_huff_tbl_ptrs[tbl]; else htblptr = & cinfo->ac_huff_tbl_ptrs[tbl]; if (*htblptr == NULL) *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]); did[tbl] = TRUE; } } } /* * Module initialization routine for progressive Huffman entropy encoding. */ GLOBAL(void) jinit_phuff_encoder (j_compress_ptr cinfo) { phuff_entropy_ptr entropy; int i; entropy = (phuff_entropy_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(phuff_entropy_encoder)); cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; entropy->pub.start_pass = start_pass_phuff; /* Mark tables unallocated */ for (i = 0; i < NUM_HUFF_TBLS; i++) { entropy->derived_tbls[i] = NULL; entropy->count_ptrs[i] = NULL; } entropy->bit_buffer = NULL; /* needed only in AC refinement scan */ } #endif /* C_PROGRESSIVE_SUPPORTED */