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Open Source Computer Vision Library
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834 lines
24 KiB
834 lines
24 KiB
15 years ago
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/*
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* jcphuff.c
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*
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* Copyright (C) 1995-1997, Thomas G. Lane.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This file contains Huffman entropy encoding routines for progressive JPEG.
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*
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* We do not support output suspension in this module, since the library
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* currently does not allow multiple-scan files to be written with output
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* suspension.
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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#include "jchuff.h" /* Declarations shared with jchuff.c */
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#ifdef C_PROGRESSIVE_SUPPORTED
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/* Expanded entropy encoder object for progressive Huffman encoding. */
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typedef struct {
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struct jpeg_entropy_encoder pub; /* public fields */
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/* Mode flag: TRUE for optimization, FALSE for actual data output */
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boolean gather_statistics;
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/* Bit-level coding status.
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* next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
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*/
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JOCTET * next_output_byte; /* => next byte to write in buffer */
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size_t free_in_buffer; /* # of byte spaces remaining in buffer */
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INT32 put_buffer; /* current bit-accumulation buffer */
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int put_bits; /* # of bits now in it */
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j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */
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/* Coding status for DC components */
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int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
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/* Coding status for AC components */
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int ac_tbl_no; /* the table number of the single component */
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unsigned int EOBRUN; /* run length of EOBs */
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unsigned int BE; /* # of buffered correction bits before MCU */
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char * bit_buffer; /* buffer for correction bits (1 per char) */
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/* packing correction bits tightly would save some space but cost time... */
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unsigned int restarts_to_go; /* MCUs left in this restart interval */
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int next_restart_num; /* next restart number to write (0-7) */
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/* Pointers to derived tables (these workspaces have image lifespan).
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* Since any one scan codes only DC or only AC, we only need one set
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* of tables, not one for DC and one for AC.
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*/
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c_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
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/* Statistics tables for optimization; again, one set is enough */
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long * count_ptrs[NUM_HUFF_TBLS];
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} phuff_entropy_encoder;
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typedef phuff_entropy_encoder * phuff_entropy_ptr;
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/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
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* buffer can hold. Larger sizes may slightly improve compression, but
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* 1000 is already well into the realm of overkill.
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* The minimum safe size is 64 bits.
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*/
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#define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */
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/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
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* We assume that int right shift is unsigned if INT32 right shift is,
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* which should be safe.
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*/
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#ifdef RIGHT_SHIFT_IS_UNSIGNED
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#define ISHIFT_TEMPS int ishift_temp;
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#define IRIGHT_SHIFT(x,shft) \
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((ishift_temp = (x)) < 0 ? \
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(ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
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(ishift_temp >> (shft)))
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#else
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#define ISHIFT_TEMPS
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#define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
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#endif
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/* Forward declarations */
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METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo,
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JBLOCKROW *MCU_data));
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METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo,
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JBLOCKROW *MCU_data));
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METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo,
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JBLOCKROW *MCU_data));
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METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo,
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JBLOCKROW *MCU_data));
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METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo));
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METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo));
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/*
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* Initialize for a Huffman-compressed scan using progressive JPEG.
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*/
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METHODDEF(void)
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start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
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{
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phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
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boolean is_DC_band;
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int ci, tbl;
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jpeg_component_info * compptr;
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entropy->cinfo = cinfo;
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entropy->gather_statistics = gather_statistics;
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is_DC_band = (cinfo->Ss == 0);
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/* We assume jcmaster.c already validated the scan parameters. */
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/* Select execution routines */
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if (cinfo->Ah == 0) {
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if (is_DC_band)
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entropy->pub.encode_mcu = encode_mcu_DC_first;
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else
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entropy->pub.encode_mcu = encode_mcu_AC_first;
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} else {
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if (is_DC_band)
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entropy->pub.encode_mcu = encode_mcu_DC_refine;
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else {
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entropy->pub.encode_mcu = encode_mcu_AC_refine;
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/* AC refinement needs a correction bit buffer */
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if (entropy->bit_buffer == NULL)
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entropy->bit_buffer = (char *)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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MAX_CORR_BITS * SIZEOF(char));
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}
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}
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if (gather_statistics)
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entropy->pub.finish_pass = finish_pass_gather_phuff;
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else
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entropy->pub.finish_pass = finish_pass_phuff;
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/* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
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* for AC coefficients.
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*/
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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compptr = cinfo->cur_comp_info[ci];
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/* Initialize DC predictions to 0 */
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entropy->last_dc_val[ci] = 0;
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/* Get table index */
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if (is_DC_band) {
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if (cinfo->Ah != 0) /* DC refinement needs no table */
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continue;
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tbl = compptr->dc_tbl_no;
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} else {
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entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
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}
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if (gather_statistics) {
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/* Check for invalid table index */
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/* (make_c_derived_tbl does this in the other path) */
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if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
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ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
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/* Allocate and zero the statistics tables */
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/* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
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if (entropy->count_ptrs[tbl] == NULL)
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entropy->count_ptrs[tbl] = (long *)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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257 * SIZEOF(long));
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MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long));
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} else {
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/* Compute derived values for Huffman table */
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/* We may do this more than once for a table, but it's not expensive */
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jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl,
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& entropy->derived_tbls[tbl]);
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}
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}
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/* Initialize AC stuff */
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entropy->EOBRUN = 0;
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entropy->BE = 0;
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/* Initialize bit buffer to empty */
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entropy->put_buffer = 0;
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entropy->put_bits = 0;
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/* Initialize restart stuff */
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entropy->restarts_to_go = cinfo->restart_interval;
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entropy->next_restart_num = 0;
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}
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/* Outputting bytes to the file.
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* NB: these must be called only when actually outputting,
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* that is, entropy->gather_statistics == FALSE.
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*/
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/* Emit a byte */
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#define emit_byte(entropy,val) \
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{ *(entropy)->next_output_byte++ = (JOCTET) (val); \
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if (--(entropy)->free_in_buffer == 0) \
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dump_buffer(entropy); }
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LOCAL(void)
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dump_buffer (phuff_entropy_ptr entropy)
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/* Empty the output buffer; we do not support suspension in this module. */
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{
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struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
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if (! (*dest->empty_output_buffer) (entropy->cinfo))
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ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
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/* After a successful buffer dump, must reset buffer pointers */
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entropy->next_output_byte = dest->next_output_byte;
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entropy->free_in_buffer = dest->free_in_buffer;
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}
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/* Outputting bits to the file */
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/* Only the right 24 bits of put_buffer are used; the valid bits are
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* left-justified in this part. At most 16 bits can be passed to emit_bits
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* in one call, and we never retain more than 7 bits in put_buffer
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* between calls, so 24 bits are sufficient.
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*/
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INLINE
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LOCAL(void)
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emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
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/* Emit some bits, unless we are in gather mode */
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{
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/* This routine is heavily used, so it's worth coding tightly. */
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register INT32 put_buffer = (INT32) code;
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register int put_bits = entropy->put_bits;
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/* if size is 0, caller used an invalid Huffman table entry */
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if (size == 0)
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ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
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if (entropy->gather_statistics)
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return; /* do nothing if we're only getting stats */
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put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
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put_bits += size; /* new number of bits in buffer */
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put_buffer <<= 24 - put_bits; /* align incoming bits */
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put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */
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while (put_bits >= 8) {
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int c = (int) ((put_buffer >> 16) & 0xFF);
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emit_byte(entropy, c);
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if (c == 0xFF) { /* need to stuff a zero byte? */
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emit_byte(entropy, 0);
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}
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put_buffer <<= 8;
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put_bits -= 8;
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}
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entropy->put_buffer = put_buffer; /* update variables */
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entropy->put_bits = put_bits;
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}
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LOCAL(void)
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flush_bits (phuff_entropy_ptr entropy)
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{
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emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
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entropy->put_buffer = 0; /* and reset bit-buffer to empty */
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entropy->put_bits = 0;
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}
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/*
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* Emit (or just count) a Huffman symbol.
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*/
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INLINE
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LOCAL(void)
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emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol)
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{
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if (entropy->gather_statistics)
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entropy->count_ptrs[tbl_no][symbol]++;
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else {
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c_derived_tbl * tbl = entropy->derived_tbls[tbl_no];
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emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
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}
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}
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/*
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* Emit bits from a correction bit buffer.
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*/
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LOCAL(void)
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emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart,
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unsigned int nbits)
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{
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if (entropy->gather_statistics)
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return; /* no real work */
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while (nbits > 0) {
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emit_bits(entropy, (unsigned int) (*bufstart), 1);
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bufstart++;
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nbits--;
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}
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}
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/*
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* Emit any pending EOBRUN symbol.
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*/
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LOCAL(void)
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emit_eobrun (phuff_entropy_ptr entropy)
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{
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register int temp, nbits;
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if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */
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temp = entropy->EOBRUN;
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nbits = 0;
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while ((temp >>= 1))
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nbits++;
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/* safety check: shouldn't happen given limited correction-bit buffer */
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if (nbits > 14)
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ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
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emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
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if (nbits)
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emit_bits(entropy, entropy->EOBRUN, nbits);
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entropy->EOBRUN = 0;
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/* Emit any buffered correction bits */
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emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
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entropy->BE = 0;
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}
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}
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/*
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* Emit a restart marker & resynchronize predictions.
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*/
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LOCAL(void)
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emit_restart (phuff_entropy_ptr entropy, int restart_num)
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{
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int ci;
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emit_eobrun(entropy);
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if (! entropy->gather_statistics) {
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flush_bits(entropy);
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emit_byte(entropy, 0xFF);
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emit_byte(entropy, JPEG_RST0 + restart_num);
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}
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if (entropy->cinfo->Ss == 0) {
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/* Re-initialize DC predictions to 0 */
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for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
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entropy->last_dc_val[ci] = 0;
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} else {
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/* Re-initialize all AC-related fields to 0 */
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entropy->EOBRUN = 0;
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entropy->BE = 0;
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}
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}
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/*
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* MCU encoding for DC initial scan (either spectral selection,
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* or first pass of successive approximation).
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*/
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METHODDEF(boolean)
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encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
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{
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phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
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register int temp, temp2;
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register int nbits;
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int blkn, ci;
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int Al = cinfo->Al;
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JBLOCKROW block;
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jpeg_component_info * compptr;
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ISHIFT_TEMPS
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entropy->next_output_byte = cinfo->dest->next_output_byte;
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entropy->free_in_buffer = cinfo->dest->free_in_buffer;
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/* Emit restart marker if needed */
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if (cinfo->restart_interval)
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if (entropy->restarts_to_go == 0)
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emit_restart(entropy, entropy->next_restart_num);
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/* Encode the MCU data blocks */
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for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
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block = MCU_data[blkn];
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ci = cinfo->MCU_membership[blkn];
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compptr = cinfo->cur_comp_info[ci];
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/* Compute the DC value after the required point transform by Al.
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* This is simply an arithmetic right shift.
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*/
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temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
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/* DC differences are figured on the point-transformed values. */
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temp = temp2 - entropy->last_dc_val[ci];
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entropy->last_dc_val[ci] = temp2;
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/* Encode the DC coefficient difference per section G.1.2.1 */
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temp2 = temp;
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if (temp < 0) {
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temp = -temp; /* temp is abs value of input */
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||
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/* For a negative input, want temp2 = bitwise complement of abs(input) */
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||
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/* This code assumes we are on a two's complement machine */
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||
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temp2--;
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}
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||
|
/* 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 */
|