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Diffstat (limited to 'jcphuff.c')
| -rw-r--r-- | jcphuff.c | 831 |
1 files changed, 831 insertions, 0 deletions
diff --git a/jcphuff.c b/jcphuff.c new file mode 100644 index 0000000..3102871 --- /dev/null +++ b/jcphuff.c @@ -0,0 +1,831 @@ +/* + * 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. + */ + +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. + */ + +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 */ |