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https://github.com/ZDoom/raze-gles.git
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718112a8fe
Currently none of these is being used, but eventually they will, once more code gets ported over. So it's better to have them right away and avoid editing the project file too much, only to revert that later.
796 lines
24 KiB
C
796 lines
24 KiB
C
/*
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* jdarith.c
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*
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* Developed 1997-2015 by Guido Vollbeding.
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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 portable arithmetic entropy decoding routines for JPEG
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* (implementing the ISO/IEC IS 10918-1 and CCITT Recommendation ITU-T T.81).
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*
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* Both sequential and progressive modes are supported in this single module.
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*
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* Suspension is not currently supported in this module.
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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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/* Expanded entropy decoder object for arithmetic decoding. */
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typedef struct {
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struct jpeg_entropy_decoder pub; /* public fields */
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INT32 c; /* C register, base of coding interval + input bit buffer */
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INT32 a; /* A register, normalized size of coding interval */
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int ct; /* bit shift counter, # of bits left in bit buffer part of C */
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/* init: ct = -16 */
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/* run: ct = 0..7 */
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/* error: ct = -1 */
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int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
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int dc_context[MAX_COMPS_IN_SCAN]; /* context index for DC conditioning */
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unsigned int restarts_to_go; /* MCUs left in this restart interval */
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/* Pointers to statistics areas (these workspaces have image lifespan) */
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unsigned char * dc_stats[NUM_ARITH_TBLS];
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unsigned char * ac_stats[NUM_ARITH_TBLS];
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/* Statistics bin for coding with fixed probability 0.5 */
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unsigned char fixed_bin[4];
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} arith_entropy_decoder;
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typedef arith_entropy_decoder * arith_entropy_ptr;
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/* The following two definitions specify the allocation chunk size
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* for the statistics area.
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* According to sections F.1.4.4.1.3 and F.1.4.4.2, we need at least
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* 49 statistics bins for DC, and 245 statistics bins for AC coding.
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*
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* We use a compact representation with 1 byte per statistics bin,
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* thus the numbers directly represent byte sizes.
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* This 1 byte per statistics bin contains the meaning of the MPS
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* (more probable symbol) in the highest bit (mask 0x80), and the
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* index into the probability estimation state machine table
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* in the lower bits (mask 0x7F).
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*/
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#define DC_STAT_BINS 64
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#define AC_STAT_BINS 256
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LOCAL(int)
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get_byte (j_decompress_ptr cinfo)
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/* Read next input byte; we do not support suspension in this module. */
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{
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struct jpeg_source_mgr * src = cinfo->src;
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if (src->bytes_in_buffer == 0)
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if (! (*src->fill_input_buffer) (cinfo))
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ERREXIT(cinfo, JERR_CANT_SUSPEND);
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src->bytes_in_buffer--;
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return GETJOCTET(*src->next_input_byte++);
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}
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/*
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* The core arithmetic decoding routine (common in JPEG and JBIG).
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* This needs to go as fast as possible.
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* Machine-dependent optimization facilities
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* are not utilized in this portable implementation.
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* However, this code should be fairly efficient and
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* may be a good base for further optimizations anyway.
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*
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* Return value is 0 or 1 (binary decision).
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*
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* Note: I've changed the handling of the code base & bit
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* buffer register C compared to other implementations
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* based on the standards layout & procedures.
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* While it also contains both the actual base of the
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* coding interval (16 bits) and the next-bits buffer,
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* the cut-point between these two parts is floating
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* (instead of fixed) with the bit shift counter CT.
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* Thus, we also need only one (variable instead of
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* fixed size) shift for the LPS/MPS decision, and
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* we can do away with any renormalization update
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* of C (except for new data insertion, of course).
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*
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* I've also introduced a new scheme for accessing
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* the probability estimation state machine table,
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* derived from Markus Kuhn's JBIG implementation.
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*/
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LOCAL(int)
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arith_decode (j_decompress_ptr cinfo, unsigned char *st)
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{
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register arith_entropy_ptr e = (arith_entropy_ptr) cinfo->entropy;
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register unsigned char nl, nm;
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register INT32 qe, temp;
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register int sv, data;
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/* Renormalization & data input per section D.2.6 */
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while (e->a < 0x8000L) {
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if (--e->ct < 0) {
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/* Need to fetch next data byte */
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if (cinfo->unread_marker)
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data = 0; /* stuff zero data */
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else {
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data = get_byte(cinfo); /* read next input byte */
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if (data == 0xFF) { /* zero stuff or marker code */
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do data = get_byte(cinfo);
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while (data == 0xFF); /* swallow extra 0xFF bytes */
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if (data == 0)
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data = 0xFF; /* discard stuffed zero byte */
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else {
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/* Note: Different from the Huffman decoder, hitting
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* a marker while processing the compressed data
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* segment is legal in arithmetic coding.
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* The convention is to supply zero data
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* then until decoding is complete.
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*/
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cinfo->unread_marker = data;
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data = 0;
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}
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}
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}
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e->c = (e->c << 8) | data; /* insert data into C register */
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if ((e->ct += 8) < 0) /* update bit shift counter */
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/* Need more initial bytes */
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if (++e->ct == 0)
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/* Got 2 initial bytes -> re-init A and exit loop */
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e->a = 0x8000L; /* => e->a = 0x10000L after loop exit */
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}
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e->a <<= 1;
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}
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/* Fetch values from our compact representation of Table D.3(D.2):
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* Qe values and probability estimation state machine
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*/
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sv = *st;
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qe = jpeg_aritab[sv & 0x7F]; /* => Qe_Value */
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nl = qe & 0xFF; qe >>= 8; /* Next_Index_LPS + Switch_MPS */
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nm = qe & 0xFF; qe >>= 8; /* Next_Index_MPS */
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/* Decode & estimation procedures per sections D.2.4 & D.2.5 */
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temp = e->a - qe;
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e->a = temp;
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temp <<= e->ct;
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if (e->c >= temp) {
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e->c -= temp;
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/* Conditional LPS (less probable symbol) exchange */
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if (e->a < qe) {
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e->a = qe;
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*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
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} else {
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e->a = qe;
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*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
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sv ^= 0x80; /* Exchange LPS/MPS */
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}
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} else if (e->a < 0x8000L) {
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/* Conditional MPS (more probable symbol) exchange */
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if (e->a < qe) {
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*st = (sv & 0x80) ^ nl; /* Estimate_after_LPS */
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sv ^= 0x80; /* Exchange LPS/MPS */
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} else {
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*st = (sv & 0x80) ^ nm; /* Estimate_after_MPS */
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}
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}
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return sv >> 7;
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}
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/*
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* Check for a restart marker & resynchronize decoder.
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*/
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LOCAL(void)
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process_restart (j_decompress_ptr cinfo)
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{
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arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
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int ci;
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jpeg_component_info * compptr;
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/* Advance past the RSTn marker */
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if (! (*cinfo->marker->read_restart_marker) (cinfo))
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ERREXIT(cinfo, JERR_CANT_SUSPEND);
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/* Re-initialize statistics areas */
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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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if (! cinfo->progressive_mode || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
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MEMZERO(entropy->dc_stats[compptr->dc_tbl_no], DC_STAT_BINS);
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/* Reset DC predictions to 0 */
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entropy->last_dc_val[ci] = 0;
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entropy->dc_context[ci] = 0;
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}
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if ((! cinfo->progressive_mode && cinfo->lim_Se) ||
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(cinfo->progressive_mode && cinfo->Ss)) {
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MEMZERO(entropy->ac_stats[compptr->ac_tbl_no], AC_STAT_BINS);
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}
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}
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/* Reset arithmetic decoding variables */
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entropy->c = 0;
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entropy->a = 0;
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entropy->ct = -16; /* force reading 2 initial bytes to fill C */
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/* Reset restart counter */
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entropy->restarts_to_go = cinfo->restart_interval;
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}
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/*
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* Arithmetic MCU decoding.
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* Each of these routines decodes and returns one MCU's worth of
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* arithmetic-compressed coefficients.
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* The coefficients are reordered from zigzag order into natural array order,
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* but are not dequantized.
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*
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* The i'th block of the MCU is stored into the block pointed to by
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* MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
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*/
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/*
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* MCU decoding 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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decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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{
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arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
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JBLOCKROW block;
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unsigned char *st;
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int blkn, ci, tbl, sign;
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int v, m;
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/* Process 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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process_restart(cinfo);
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entropy->restarts_to_go--;
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}
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if (entropy->ct == -1) return TRUE; /* if error do nothing */
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/* Outer loop handles each block in the MCU */
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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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tbl = cinfo->cur_comp_info[ci]->dc_tbl_no;
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/* Sections F.2.4.1 & F.1.4.4.1: Decoding of DC coefficients */
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/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
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st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
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/* Figure F.19: Decode_DC_DIFF */
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if (arith_decode(cinfo, st) == 0)
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entropy->dc_context[ci] = 0;
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else {
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/* Figure F.21: Decoding nonzero value v */
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/* Figure F.22: Decoding the sign of v */
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sign = arith_decode(cinfo, st + 1);
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st += 2; st += sign;
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/* Figure F.23: Decoding the magnitude category of v */
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if ((m = arith_decode(cinfo, st)) != 0) {
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st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
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while (arith_decode(cinfo, st)) {
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if ((m <<= 1) == 0x8000) {
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WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
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entropy->ct = -1; /* magnitude overflow */
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return TRUE;
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}
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st += 1;
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}
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}
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/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
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if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1))
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entropy->dc_context[ci] = 0; /* zero diff category */
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else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1))
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entropy->dc_context[ci] = 12 + (sign * 4); /* large diff category */
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else
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entropy->dc_context[ci] = 4 + (sign * 4); /* small diff category */
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v = m;
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/* Figure F.24: Decoding the magnitude bit pattern of v */
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st += 14;
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while (m >>= 1)
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if (arith_decode(cinfo, st)) v |= m;
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v += 1; if (sign) v = -v;
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entropy->last_dc_val[ci] += v;
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}
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/* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */
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(*block)[0] = (JCOEF) (entropy->last_dc_val[ci] << cinfo->Al);
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}
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return TRUE;
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}
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/*
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* MCU decoding for AC 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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decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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{
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arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
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JBLOCKROW block;
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unsigned char *st;
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int tbl, sign, k;
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int v, m;
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const int * natural_order;
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/* Process 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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process_restart(cinfo);
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entropy->restarts_to_go--;
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}
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if (entropy->ct == -1) return TRUE; /* if error do nothing */
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natural_order = cinfo->natural_order;
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/* There is always only one block per MCU */
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block = MCU_data[0];
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tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
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/* Sections F.2.4.2 & F.1.4.4.2: Decoding of AC coefficients */
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/* Figure F.20: Decode_AC_coefficients */
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k = cinfo->Ss - 1;
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do {
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st = entropy->ac_stats[tbl] + 3 * k;
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if (arith_decode(cinfo, st)) break; /* EOB flag */
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for (;;) {
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k++;
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if (arith_decode(cinfo, st + 1)) break;
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st += 3;
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if (k >= cinfo->Se) {
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WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
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entropy->ct = -1; /* spectral overflow */
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return TRUE;
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}
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}
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/* Figure F.21: Decoding nonzero value v */
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/* Figure F.22: Decoding the sign of v */
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sign = arith_decode(cinfo, entropy->fixed_bin);
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st += 2;
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/* Figure F.23: Decoding the magnitude category of v */
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if ((m = arith_decode(cinfo, st)) != 0) {
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if (arith_decode(cinfo, st)) {
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m <<= 1;
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st = entropy->ac_stats[tbl] +
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(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
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while (arith_decode(cinfo, st)) {
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if ((m <<= 1) == 0x8000) {
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WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
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entropy->ct = -1; /* magnitude overflow */
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return TRUE;
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}
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st += 1;
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}
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}
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}
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v = m;
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/* Figure F.24: Decoding the magnitude bit pattern of v */
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st += 14;
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while (m >>= 1)
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if (arith_decode(cinfo, st)) v |= m;
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v += 1; if (sign) v = -v;
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/* Scale and output coefficient in natural (dezigzagged) order */
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(*block)[natural_order[k]] = (JCOEF) (v << cinfo->Al);
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} while (k < cinfo->Se);
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return TRUE;
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}
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/*
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* MCU decoding for DC successive approximation refinement scan.
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* Note: we assume such scans can be multi-component,
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* although the spec is not very clear on the point.
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*/
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METHODDEF(boolean)
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decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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{
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arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
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unsigned char *st;
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int p1, blkn;
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/* Process 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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process_restart(cinfo);
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entropy->restarts_to_go--;
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}
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st = entropy->fixed_bin; /* use fixed probability estimation */
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p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
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/* Outer loop handles each block in the MCU */
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for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
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/* Encoded data is simply the next bit of the two's-complement DC value */
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if (arith_decode(cinfo, st))
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MCU_data[blkn][0][0] |= p1;
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}
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return TRUE;
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}
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/*
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* MCU decoding for AC successive approximation refinement scan.
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*/
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METHODDEF(boolean)
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decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
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{
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arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
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JBLOCKROW block;
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JCOEFPTR thiscoef;
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unsigned char *st;
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int tbl, k, kex;
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int p1, m1;
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const int * natural_order;
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/* Process 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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process_restart(cinfo);
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entropy->restarts_to_go--;
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}
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if (entropy->ct == -1) return TRUE; /* if error do nothing */
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natural_order = cinfo->natural_order;
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/* There is always only one block per MCU */
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block = MCU_data[0];
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tbl = cinfo->cur_comp_info[0]->ac_tbl_no;
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p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
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m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */
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/* Establish EOBx (previous stage end-of-block) index */
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kex = cinfo->Se;
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do {
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if ((*block)[natural_order[kex]]) break;
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} while (--kex);
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k = cinfo->Ss - 1;
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do {
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st = entropy->ac_stats[tbl] + 3 * k;
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if (k >= kex)
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if (arith_decode(cinfo, st)) break; /* EOB flag */
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for (;;) {
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thiscoef = *block + natural_order[++k];
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if (*thiscoef) { /* previously nonzero coef */
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if (arith_decode(cinfo, st + 2)) {
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if (*thiscoef < 0)
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*thiscoef += m1;
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else
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*thiscoef += p1;
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}
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|
break;
|
|
}
|
|
if (arith_decode(cinfo, st + 1)) { /* newly nonzero coef */
|
|
if (arith_decode(cinfo, entropy->fixed_bin))
|
|
*thiscoef = m1;
|
|
else
|
|
*thiscoef = p1;
|
|
break;
|
|
}
|
|
st += 3;
|
|
if (k >= cinfo->Se) {
|
|
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
|
|
entropy->ct = -1; /* spectral overflow */
|
|
return TRUE;
|
|
}
|
|
}
|
|
} while (k < cinfo->Se);
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
|
|
/*
|
|
* Decode one MCU's worth of arithmetic-compressed coefficients.
|
|
*/
|
|
|
|
METHODDEF(boolean)
|
|
decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
|
|
{
|
|
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
|
|
jpeg_component_info * compptr;
|
|
JBLOCKROW block;
|
|
unsigned char *st;
|
|
int blkn, ci, tbl, sign, k;
|
|
int v, m;
|
|
const int * natural_order;
|
|
|
|
/* Process restart marker if needed */
|
|
if (cinfo->restart_interval) {
|
|
if (entropy->restarts_to_go == 0)
|
|
process_restart(cinfo);
|
|
entropy->restarts_to_go--;
|
|
}
|
|
|
|
if (entropy->ct == -1) return TRUE; /* if error do nothing */
|
|
|
|
natural_order = cinfo->natural_order;
|
|
|
|
/* Outer loop handles each block in the MCU */
|
|
|
|
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
|
|
block = MCU_data[blkn];
|
|
ci = cinfo->MCU_membership[blkn];
|
|
compptr = cinfo->cur_comp_info[ci];
|
|
|
|
/* Sections F.2.4.1 & F.1.4.4.1: Decoding of DC coefficients */
|
|
|
|
tbl = compptr->dc_tbl_no;
|
|
|
|
/* Table F.4: Point to statistics bin S0 for DC coefficient coding */
|
|
st = entropy->dc_stats[tbl] + entropy->dc_context[ci];
|
|
|
|
/* Figure F.19: Decode_DC_DIFF */
|
|
if (arith_decode(cinfo, st) == 0)
|
|
entropy->dc_context[ci] = 0;
|
|
else {
|
|
/* Figure F.21: Decoding nonzero value v */
|
|
/* Figure F.22: Decoding the sign of v */
|
|
sign = arith_decode(cinfo, st + 1);
|
|
st += 2; st += sign;
|
|
/* Figure F.23: Decoding the magnitude category of v */
|
|
if ((m = arith_decode(cinfo, st)) != 0) {
|
|
st = entropy->dc_stats[tbl] + 20; /* Table F.4: X1 = 20 */
|
|
while (arith_decode(cinfo, st)) {
|
|
if ((m <<= 1) == 0x8000) {
|
|
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
|
|
entropy->ct = -1; /* magnitude overflow */
|
|
return TRUE;
|
|
}
|
|
st += 1;
|
|
}
|
|
}
|
|
/* Section F.1.4.4.1.2: Establish dc_context conditioning category */
|
|
if (m < (int) ((1L << cinfo->arith_dc_L[tbl]) >> 1))
|
|
entropy->dc_context[ci] = 0; /* zero diff category */
|
|
else if (m > (int) ((1L << cinfo->arith_dc_U[tbl]) >> 1))
|
|
entropy->dc_context[ci] = 12 + (sign * 4); /* large diff category */
|
|
else
|
|
entropy->dc_context[ci] = 4 + (sign * 4); /* small diff category */
|
|
v = m;
|
|
/* Figure F.24: Decoding the magnitude bit pattern of v */
|
|
st += 14;
|
|
while (m >>= 1)
|
|
if (arith_decode(cinfo, st)) v |= m;
|
|
v += 1; if (sign) v = -v;
|
|
entropy->last_dc_val[ci] += v;
|
|
}
|
|
|
|
(*block)[0] = (JCOEF) entropy->last_dc_val[ci];
|
|
|
|
/* Sections F.2.4.2 & F.1.4.4.2: Decoding of AC coefficients */
|
|
|
|
if (cinfo->lim_Se == 0) continue;
|
|
tbl = compptr->ac_tbl_no;
|
|
k = 0;
|
|
|
|
/* Figure F.20: Decode_AC_coefficients */
|
|
do {
|
|
st = entropy->ac_stats[tbl] + 3 * k;
|
|
if (arith_decode(cinfo, st)) break; /* EOB flag */
|
|
for (;;) {
|
|
k++;
|
|
if (arith_decode(cinfo, st + 1)) break;
|
|
st += 3;
|
|
if (k >= cinfo->lim_Se) {
|
|
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
|
|
entropy->ct = -1; /* spectral overflow */
|
|
return TRUE;
|
|
}
|
|
}
|
|
/* Figure F.21: Decoding nonzero value v */
|
|
/* Figure F.22: Decoding the sign of v */
|
|
sign = arith_decode(cinfo, entropy->fixed_bin);
|
|
st += 2;
|
|
/* Figure F.23: Decoding the magnitude category of v */
|
|
if ((m = arith_decode(cinfo, st)) != 0) {
|
|
if (arith_decode(cinfo, st)) {
|
|
m <<= 1;
|
|
st = entropy->ac_stats[tbl] +
|
|
(k <= cinfo->arith_ac_K[tbl] ? 189 : 217);
|
|
while (arith_decode(cinfo, st)) {
|
|
if ((m <<= 1) == 0x8000) {
|
|
WARNMS(cinfo, JWRN_ARITH_BAD_CODE);
|
|
entropy->ct = -1; /* magnitude overflow */
|
|
return TRUE;
|
|
}
|
|
st += 1;
|
|
}
|
|
}
|
|
}
|
|
v = m;
|
|
/* Figure F.24: Decoding the magnitude bit pattern of v */
|
|
st += 14;
|
|
while (m >>= 1)
|
|
if (arith_decode(cinfo, st)) v |= m;
|
|
v += 1; if (sign) v = -v;
|
|
(*block)[natural_order[k]] = (JCOEF) v;
|
|
} while (k < cinfo->lim_Se);
|
|
}
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
|
|
/*
|
|
* Initialize for an arithmetic-compressed scan.
|
|
*/
|
|
|
|
METHODDEF(void)
|
|
start_pass (j_decompress_ptr cinfo)
|
|
{
|
|
arith_entropy_ptr entropy = (arith_entropy_ptr) cinfo->entropy;
|
|
int ci, tbl;
|
|
jpeg_component_info * compptr;
|
|
|
|
if (cinfo->progressive_mode) {
|
|
/* Validate progressive scan parameters */
|
|
if (cinfo->Ss == 0) {
|
|
if (cinfo->Se != 0)
|
|
goto bad;
|
|
} else {
|
|
/* need not check Ss/Se < 0 since they came from unsigned bytes */
|
|
if (cinfo->Se < cinfo->Ss || cinfo->Se > cinfo->lim_Se)
|
|
goto bad;
|
|
/* AC scans may have only one component */
|
|
if (cinfo->comps_in_scan != 1)
|
|
goto bad;
|
|
}
|
|
if (cinfo->Ah != 0) {
|
|
/* Successive approximation refinement scan: must have Al = Ah-1. */
|
|
if (cinfo->Ah-1 != cinfo->Al)
|
|
goto bad;
|
|
}
|
|
if (cinfo->Al > 13) { /* need not check for < 0 */
|
|
bad:
|
|
ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
|
|
cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
|
|
}
|
|
/* Update progression status, and verify that scan order is legal.
|
|
* Note that inter-scan inconsistencies are treated as warnings
|
|
* not fatal errors ... not clear if this is right way to behave.
|
|
*/
|
|
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
|
|
int coefi, cindex = cinfo->cur_comp_info[ci]->component_index;
|
|
int *coef_bit_ptr = & cinfo->coef_bits[cindex][0];
|
|
if (cinfo->Ss && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
|
|
WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
|
|
for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
|
|
int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
|
|
if (cinfo->Ah != expected)
|
|
WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
|
|
coef_bit_ptr[coefi] = cinfo->Al;
|
|
}
|
|
}
|
|
/* Select MCU decoding routine */
|
|
if (cinfo->Ah == 0) {
|
|
if (cinfo->Ss == 0)
|
|
entropy->pub.decode_mcu = decode_mcu_DC_first;
|
|
else
|
|
entropy->pub.decode_mcu = decode_mcu_AC_first;
|
|
} else {
|
|
if (cinfo->Ss == 0)
|
|
entropy->pub.decode_mcu = decode_mcu_DC_refine;
|
|
else
|
|
entropy->pub.decode_mcu = decode_mcu_AC_refine;
|
|
}
|
|
} else {
|
|
/* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
|
|
* This ought to be an error condition, but we make it a warning.
|
|
*/
|
|
if (cinfo->Ss != 0 || cinfo->Ah != 0 || cinfo->Al != 0 ||
|
|
(cinfo->Se < DCTSIZE2 && cinfo->Se != cinfo->lim_Se))
|
|
WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
|
|
/* Select MCU decoding routine */
|
|
entropy->pub.decode_mcu = decode_mcu;
|
|
}
|
|
|
|
/* Allocate & initialize requested statistics areas */
|
|
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
|
|
compptr = cinfo->cur_comp_info[ci];
|
|
if (! cinfo->progressive_mode || (cinfo->Ss == 0 && cinfo->Ah == 0)) {
|
|
tbl = compptr->dc_tbl_no;
|
|
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
|
|
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
|
|
if (entropy->dc_stats[tbl] == NULL)
|
|
entropy->dc_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
|
|
((j_common_ptr) cinfo, JPOOL_IMAGE, DC_STAT_BINS);
|
|
MEMZERO(entropy->dc_stats[tbl], DC_STAT_BINS);
|
|
/* Initialize DC predictions to 0 */
|
|
entropy->last_dc_val[ci] = 0;
|
|
entropy->dc_context[ci] = 0;
|
|
}
|
|
if ((! cinfo->progressive_mode && cinfo->lim_Se) ||
|
|
(cinfo->progressive_mode && cinfo->Ss)) {
|
|
tbl = compptr->ac_tbl_no;
|
|
if (tbl < 0 || tbl >= NUM_ARITH_TBLS)
|
|
ERREXIT1(cinfo, JERR_NO_ARITH_TABLE, tbl);
|
|
if (entropy->ac_stats[tbl] == NULL)
|
|
entropy->ac_stats[tbl] = (unsigned char *) (*cinfo->mem->alloc_small)
|
|
((j_common_ptr) cinfo, JPOOL_IMAGE, AC_STAT_BINS);
|
|
MEMZERO(entropy->ac_stats[tbl], AC_STAT_BINS);
|
|
}
|
|
}
|
|
|
|
/* Initialize arithmetic decoding variables */
|
|
entropy->c = 0;
|
|
entropy->a = 0;
|
|
entropy->ct = -16; /* force reading 2 initial bytes to fill C */
|
|
|
|
/* Initialize restart counter */
|
|
entropy->restarts_to_go = cinfo->restart_interval;
|
|
}
|
|
|
|
|
|
/*
|
|
* Finish up at the end of an arithmetic-compressed scan.
|
|
*/
|
|
|
|
METHODDEF(void)
|
|
finish_pass (j_decompress_ptr cinfo)
|
|
{
|
|
/* no work necessary here */
|
|
}
|
|
|
|
|
|
/*
|
|
* Module initialization routine for arithmetic entropy decoding.
|
|
*/
|
|
|
|
GLOBAL(void)
|
|
jinit_arith_decoder (j_decompress_ptr cinfo)
|
|
{
|
|
arith_entropy_ptr entropy;
|
|
int i;
|
|
|
|
entropy = (arith_entropy_ptr)
|
|
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
|
SIZEOF(arith_entropy_decoder));
|
|
cinfo->entropy = &entropy->pub;
|
|
entropy->pub.start_pass = start_pass;
|
|
entropy->pub.finish_pass = finish_pass;
|
|
|
|
/* Mark tables unallocated */
|
|
for (i = 0; i < NUM_ARITH_TBLS; i++) {
|
|
entropy->dc_stats[i] = NULL;
|
|
entropy->ac_stats[i] = NULL;
|
|
}
|
|
|
|
/* Initialize index for fixed probability estimation */
|
|
entropy->fixed_bin[0] = 113;
|
|
|
|
if (cinfo->progressive_mode) {
|
|
/* Create progression status table */
|
|
int *coef_bit_ptr, ci;
|
|
cinfo->coef_bits = (int (*)[DCTSIZE2])
|
|
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
|
cinfo->num_components*DCTSIZE2*SIZEOF(int));
|
|
coef_bit_ptr = & cinfo->coef_bits[0][0];
|
|
for (ci = 0; ci < cinfo->num_components; ci++)
|
|
for (i = 0; i < DCTSIZE2; i++)
|
|
*coef_bit_ptr++ = -1;
|
|
}
|
|
}
|