#if !defined(_FX_JPEG_TURBO_) | |
/* | |
* jdphuff.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 decoding routines for progressive JPEG. | |
* | |
* Much of the complexity here has to do with supporting input suspension. | |
* If the data source module demands suspension, we want to be able to back | |
* up to the start of the current MCU. To do this, we copy state variables | |
* into local working storage, and update them back to the permanent | |
* storage only upon successful completion of an MCU. | |
*/ | |
#define JPEG_INTERNALS | |
#include "jinclude.h" | |
#include "jpeglib.h" | |
#include "jdhuff.h" /* Declarations shared with jdhuff.c */ | |
#ifdef D_PROGRESSIVE_SUPPORTED | |
/* | |
* Expanded entropy decoder object for progressive Huffman decoding. | |
* | |
* The savable_state subrecord contains fields that change within an MCU, | |
* but must not be updated permanently until we complete the MCU. | |
*/ | |
typedef struct { | |
unsigned int EOBRUN; /* remaining EOBs in EOBRUN */ | |
int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ | |
} savable_state; | |
/* This macro is to work around compilers with missing or broken | |
* structure assignment. You'll need to fix this code if you have | |
* such a compiler and you change MAX_COMPS_IN_SCAN. | |
*/ | |
#ifndef NO_STRUCT_ASSIGN | |
#define ASSIGN_STATE(dest,src) ((dest) = (src)) | |
#else | |
#if MAX_COMPS_IN_SCAN == 4 | |
#define ASSIGN_STATE(dest,src) \ | |
((dest).EOBRUN = (src).EOBRUN, \ | |
(dest).last_dc_val[0] = (src).last_dc_val[0], \ | |
(dest).last_dc_val[1] = (src).last_dc_val[1], \ | |
(dest).last_dc_val[2] = (src).last_dc_val[2], \ | |
(dest).last_dc_val[3] = (src).last_dc_val[3]) | |
#endif | |
#endif | |
typedef struct { | |
struct jpeg_entropy_decoder pub; /* public fields */ | |
/* These fields are loaded into local variables at start of each MCU. | |
* In case of suspension, we exit WITHOUT updating them. | |
*/ | |
bitread_perm_state bitstate; /* Bit buffer at start of MCU */ | |
savable_state saved; /* Other state at start of MCU */ | |
/* These fields are NOT loaded into local working state. */ | |
unsigned int restarts_to_go; /* MCUs left in this restart interval */ | |
/* Pointers to derived tables (these workspaces have image lifespan) */ | |
d_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; | |
d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */ | |
} phuff_entropy_decoder; | |
typedef phuff_entropy_decoder * phuff_entropy_ptr; | |
/* Forward declarations */ | |
METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo, | |
JBLOCKROW *MCU_data)); | |
METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo, | |
JBLOCKROW *MCU_data)); | |
METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo, | |
JBLOCKROW *MCU_data)); | |
METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo, | |
JBLOCKROW *MCU_data)); | |
/* | |
* Initialize for a Huffman-compressed scan. | |
*/ | |
METHODDEF(void) | |
start_pass_phuff_decoder (j_decompress_ptr cinfo) | |
{ | |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
boolean is_DC_band, bad; | |
int ci, coefi, tbl; | |
int *coef_bit_ptr; | |
jpeg_component_info * compptr; | |
is_DC_band = (cinfo->Ss == 0); | |
/* Validate scan parameters */ | |
bad = FALSE; | |
if (is_DC_band) { | |
if (cinfo->Se != 0) | |
bad = TRUE; | |
} else { | |
/* need not check Ss/Se < 0 since they came from unsigned bytes */ | |
if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2) | |
bad = TRUE; | |
/* AC scans may have only one component */ | |
if (cinfo->comps_in_scan != 1) | |
bad = TRUE; | |
} | |
if (cinfo->Ah != 0) { | |
/* Successive approximation refinement scan: must have Al = Ah-1. */ | |
if (cinfo->Al != cinfo->Ah-1) | |
bad = TRUE; | |
} | |
if (cinfo->Al > 13) /* need not check for < 0 */ | |
bad = TRUE; | |
/* Arguably the maximum Al value should be less than 13 for 8-bit precision, | |
* but the spec doesn't say so, and we try to be liberal about what we | |
* accept. Note: large Al values could result in out-of-range DC | |
* coefficients during early scans, leading to bizarre displays due to | |
* overflows in the IDCT math. But we won't crash. | |
*/ | |
if (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 cindex = cinfo->cur_comp_info[ci]->component_index; | |
coef_bit_ptr = & cinfo->coef_bits[cindex][0]; | |
if (!is_DC_band && 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 (is_DC_band) | |
entropy->pub.decode_mcu = decode_mcu_DC_first; | |
else | |
entropy->pub.decode_mcu = decode_mcu_AC_first; | |
} else { | |
if (is_DC_band) | |
entropy->pub.decode_mcu = decode_mcu_DC_refine; | |
else | |
entropy->pub.decode_mcu = decode_mcu_AC_refine; | |
} | |
for (ci = 0; ci < cinfo->comps_in_scan; ci++) { | |
compptr = cinfo->cur_comp_info[ci]; | |
/* Make sure requested tables are present, and compute derived tables. | |
* We may build same derived table more than once, but it's not expensive. | |
*/ | |
if (is_DC_band) { | |
if (cinfo->Ah == 0) { /* DC refinement needs no table */ | |
tbl = compptr->dc_tbl_no; | |
jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, | |
& entropy->derived_tbls[tbl]); | |
} | |
} else { | |
tbl = compptr->ac_tbl_no; | |
jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, | |
& entropy->derived_tbls[tbl]); | |
/* remember the single active table */ | |
entropy->ac_derived_tbl = entropy->derived_tbls[tbl]; | |
} | |
/* Initialize DC predictions to 0 */ | |
entropy->saved.last_dc_val[ci] = 0; | |
} | |
/* Initialize bitread state variables */ | |
entropy->bitstate.bits_left = 0; | |
entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */ | |
entropy->pub.insufficient_data = FALSE; | |
/* Initialize private state variables */ | |
entropy->saved.EOBRUN = 0; | |
/* Initialize restart counter */ | |
entropy->restarts_to_go = cinfo->restart_interval; | |
} | |
/* | |
* Figure F.12: extend sign bit. | |
* On some machines, a shift and add will be faster than a table lookup. | |
*/ | |
#ifdef AVOID_TABLES | |
#define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x)) | |
#else | |
#define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x)) | |
static const int extend_test[16] = /* entry n is 2**(n-1) */ | |
{ 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, | |
0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; | |
static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ | |
{ 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1, | |
((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1, | |
((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1, | |
((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 }; | |
#endif /* AVOID_TABLES */ | |
/* | |
* Check for a restart marker & resynchronize decoder. | |
* Returns FALSE if must suspend. | |
*/ | |
LOCAL(boolean) | |
process_restart (j_decompress_ptr cinfo) | |
{ | |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
int ci; | |
/* Throw away any unused bits remaining in bit buffer; */ | |
/* include any full bytes in next_marker's count of discarded bytes */ | |
cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; | |
entropy->bitstate.bits_left = 0; | |
/* Advance past the RSTn marker */ | |
if (! (*cinfo->marker->read_restart_marker) (cinfo)) | |
return FALSE; | |
/* Re-initialize DC predictions to 0 */ | |
for (ci = 0; ci < cinfo->comps_in_scan; ci++) | |
entropy->saved.last_dc_val[ci] = 0; | |
/* Re-init EOB run count, too */ | |
entropy->saved.EOBRUN = 0; | |
/* Reset restart counter */ | |
entropy->restarts_to_go = cinfo->restart_interval; | |
/* Reset out-of-data flag, unless read_restart_marker left us smack up | |
* against a marker. In that case we will end up treating the next data | |
* segment as empty, and we can avoid producing bogus output pixels by | |
* leaving the flag set. | |
*/ | |
if (cinfo->unread_marker == 0) | |
entropy->pub.insufficient_data = FALSE; | |
return TRUE; | |
} | |
/* | |
* Huffman MCU decoding. | |
* Each of these routines decodes and returns one MCU's worth of | |
* Huffman-compressed coefficients. | |
* The coefficients are reordered from zigzag order into natural array order, | |
* but are not dequantized. | |
* | |
* The i'th block of the MCU is stored into the block pointed to by | |
* MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. | |
* | |
* We return FALSE if data source requested suspension. In that case no | |
* changes have been made to permanent state. (Exception: some output | |
* coefficients may already have been assigned. This is harmless for | |
* spectral selection, since we'll just re-assign them on the next call. | |
* Successive approximation AC refinement has to be more careful, however.) | |
*/ | |
/* | |
* MCU decoding for DC initial scan (either spectral selection, | |
* or first pass of successive approximation). | |
*/ | |
METHODDEF(boolean) | |
decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) | |
{ | |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
int Al = cinfo->Al; | |
register int s, r; | |
int blkn, ci; | |
JBLOCKROW block; | |
BITREAD_STATE_VARS; | |
savable_state state; | |
d_derived_tbl * tbl; | |
jpeg_component_info * compptr; | |
/* Process restart marker if needed; may have to suspend */ | |
if (cinfo->restart_interval) { | |
if (entropy->restarts_to_go == 0) | |
if (! process_restart(cinfo)) | |
return FALSE; | |
} | |
/* If we've run out of data, just leave the MCU set to zeroes. | |
* This way, we return uniform gray for the remainder of the segment. | |
*/ | |
if (! entropy->pub.insufficient_data) { | |
/* Load up working state */ | |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); | |
ASSIGN_STATE(state, entropy->saved); | |
/* 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]; | |
tbl = entropy->derived_tbls[compptr->dc_tbl_no]; | |
/* Decode a single block's worth of coefficients */ | |
/* Section F.2.2.1: decode the DC coefficient difference */ | |
HUFF_DECODE(s, br_state, tbl, return FALSE, label1); | |
if (s) { | |
CHECK_BIT_BUFFER(br_state, s, return FALSE); | |
r = GET_BITS(s); | |
s = HUFF_EXTEND(r, s); | |
} | |
/* Convert DC difference to actual value, update last_dc_val */ | |
s += state.last_dc_val[ci]; | |
state.last_dc_val[ci] = s; | |
/* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */ | |
(*block)[0] = (JCOEF) (s << Al); | |
} | |
/* Completed MCU, so update state */ | |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
ASSIGN_STATE(entropy->saved, state); | |
} | |
/* Account for restart interval (no-op if not using restarts) */ | |
entropy->restarts_to_go--; | |
return TRUE; | |
} | |
/* | |
* MCU decoding for AC initial scan (either spectral selection, | |
* or first pass of successive approximation). | |
*/ | |
METHODDEF(boolean) | |
decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) | |
{ | |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
int Se = cinfo->Se; | |
int Al = cinfo->Al; | |
register int s, k, r; | |
unsigned int EOBRUN; | |
JBLOCKROW block; | |
BITREAD_STATE_VARS; | |
d_derived_tbl * tbl; | |
/* Process restart marker if needed; may have to suspend */ | |
if (cinfo->restart_interval) { | |
if (entropy->restarts_to_go == 0) | |
if (! process_restart(cinfo)) | |
return FALSE; | |
} | |
/* If we've run out of data, just leave the MCU set to zeroes. | |
* This way, we return uniform gray for the remainder of the segment. | |
*/ | |
if (! entropy->pub.insufficient_data) { | |
/* Load up working state. | |
* We can avoid loading/saving bitread state if in an EOB run. | |
*/ | |
EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ | |
/* There is always only one block per MCU */ | |
if (EOBRUN > 0) /* if it's a band of zeroes... */ | |
EOBRUN--; /* ...process it now (we do nothing) */ | |
else { | |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); | |
block = MCU_data[0]; | |
tbl = entropy->ac_derived_tbl; | |
for (k = cinfo->Ss; k <= Se; k++) { | |
HUFF_DECODE(s, br_state, tbl, return FALSE, label2); | |
r = s >> 4; | |
s &= 15; | |
if (s) { | |
k += r; | |
CHECK_BIT_BUFFER(br_state, s, return FALSE); | |
r = GET_BITS(s); | |
s = HUFF_EXTEND(r, s); | |
/* Scale and output coefficient in natural (dezigzagged) order */ | |
(*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al); | |
} else { | |
if (r == 15) { /* ZRL */ | |
k += 15; /* skip 15 zeroes in band */ | |
} else { /* EOBr, run length is 2^r + appended bits */ | |
EOBRUN = 1 << r; | |
if (r) { /* EOBr, r > 0 */ | |
CHECK_BIT_BUFFER(br_state, r, return FALSE); | |
r = GET_BITS(r); | |
EOBRUN += r; | |
} | |
EOBRUN--; /* this band is processed at this moment */ | |
break; /* force end-of-band */ | |
} | |
} | |
} | |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
} | |
/* Completed MCU, so update state */ | |
entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ | |
} | |
/* Account for restart interval (no-op if not using restarts) */ | |
entropy->restarts_to_go--; | |
return TRUE; | |
} | |
/* | |
* MCU decoding 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) | |
decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) | |
{ | |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ | |
int blkn; | |
JBLOCKROW block; | |
BITREAD_STATE_VARS; | |
/* Process restart marker if needed; may have to suspend */ | |
if (cinfo->restart_interval) { | |
if (entropy->restarts_to_go == 0) | |
if (! process_restart(cinfo)) | |
return FALSE; | |
} | |
/* Not worth the cycles to check insufficient_data here, | |
* since we will not change the data anyway if we read zeroes. | |
*/ | |
/* Load up working state */ | |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); | |
/* Outer loop handles each block in the MCU */ | |
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { | |
block = MCU_data[blkn]; | |
/* Encoded data is simply the next bit of the two's-complement DC value */ | |
CHECK_BIT_BUFFER(br_state, 1, return FALSE); | |
if (GET_BITS(1)) | |
(*block)[0] |= p1; | |
/* Note: since we use |=, repeating the assignment later is safe */ | |
} | |
/* Completed MCU, so update state */ | |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
/* Account for restart interval (no-op if not using restarts) */ | |
entropy->restarts_to_go--; | |
return TRUE; | |
} | |
/* | |
* MCU decoding for AC successive approximation refinement scan. | |
*/ | |
METHODDEF(boolean) | |
decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) | |
{ | |
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
int Se = cinfo->Se; | |
int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ | |
int m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */ | |
register int s, k, r; | |
unsigned int EOBRUN; | |
JBLOCKROW block; | |
JCOEFPTR thiscoef; | |
BITREAD_STATE_VARS; | |
d_derived_tbl * tbl; | |
int num_newnz; | |
int newnz_pos[DCTSIZE2]; | |
/* Process restart marker if needed; may have to suspend */ | |
if (cinfo->restart_interval) { | |
if (entropy->restarts_to_go == 0) | |
if (! process_restart(cinfo)) | |
return FALSE; | |
} | |
/* If we've run out of data, don't modify the MCU. | |
*/ | |
if (! entropy->pub.insufficient_data) { | |
/* Load up working state */ | |
BITREAD_LOAD_STATE(cinfo,entropy->bitstate); | |
EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ | |
/* There is always only one block per MCU */ | |
block = MCU_data[0]; | |
tbl = entropy->ac_derived_tbl; | |
/* If we are forced to suspend, we must undo the assignments to any newly | |
* nonzero coefficients in the block, because otherwise we'd get confused | |
* next time about which coefficients were already nonzero. | |
* But we need not undo addition of bits to already-nonzero coefficients; | |
* instead, we can test the current bit to see if we already did it. | |
*/ | |
num_newnz = 0; | |
/* initialize coefficient loop counter to start of band */ | |
k = cinfo->Ss; | |
if (EOBRUN == 0) { | |
for (; k <= Se; k++) { | |
HUFF_DECODE(s, br_state, tbl, goto undoit, label3); | |
r = s >> 4; | |
s &= 15; | |
if (s) { | |
if (s != 1) /* size of new coef should always be 1 */ | |
WARNMS(cinfo, JWRN_HUFF_BAD_CODE); | |
CHECK_BIT_BUFFER(br_state, 1, goto undoit); | |
if (GET_BITS(1)) | |
s = p1; /* newly nonzero coef is positive */ | |
else | |
s = m1; /* newly nonzero coef is negative */ | |
} else { | |
if (r != 15) { | |
EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */ | |
if (r) { | |
CHECK_BIT_BUFFER(br_state, r, goto undoit); | |
r = GET_BITS(r); | |
EOBRUN += r; | |
} | |
break; /* rest of block is handled by EOB logic */ | |
} | |
/* note s = 0 for processing ZRL */ | |
} | |
/* Advance over already-nonzero coefs and r still-zero coefs, | |
* appending correction bits to the nonzeroes. A correction bit is 1 | |
* if the absolute value of the coefficient must be increased. | |
*/ | |
do { | |
thiscoef = *block + jpeg_natural_order[k]; | |
if (*thiscoef != 0) { | |
CHECK_BIT_BUFFER(br_state, 1, goto undoit); | |
if (GET_BITS(1)) { | |
if ((*thiscoef & p1) == 0) { /* do nothing if already set it */ | |
if (*thiscoef >= 0) | |
*thiscoef += p1; | |
else | |
*thiscoef += m1; | |
} | |
} | |
} else { | |
if (--r < 0) | |
break; /* reached target zero coefficient */ | |
} | |
k++; | |
} while (k <= Se); | |
if (s) { | |
int pos = jpeg_natural_order[k]; | |
/* Output newly nonzero coefficient */ | |
(*block)[pos] = (JCOEF) s; | |
/* Remember its position in case we have to suspend */ | |
newnz_pos[num_newnz++] = pos; | |
} | |
} | |
} | |
if (EOBRUN > 0) { | |
/* Scan any remaining coefficient positions after the end-of-band | |
* (the last newly nonzero coefficient, if any). Append a correction | |
* bit to each already-nonzero coefficient. A correction bit is 1 | |
* if the absolute value of the coefficient must be increased. | |
*/ | |
for (; k <= Se; k++) { | |
thiscoef = *block + jpeg_natural_order[k]; | |
if (*thiscoef != 0) { | |
CHECK_BIT_BUFFER(br_state, 1, goto undoit); | |
if (GET_BITS(1)) { | |
if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */ | |
if (*thiscoef >= 0) | |
*thiscoef += p1; | |
else | |
*thiscoef += m1; | |
} | |
} | |
} | |
} | |
/* Count one block completed in EOB run */ | |
EOBRUN--; | |
} | |
/* Completed MCU, so update state */ | |
BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ | |
} | |
/* Account for restart interval (no-op if not using restarts) */ | |
entropy->restarts_to_go--; | |
return TRUE; | |
undoit: | |
/* Re-zero any output coefficients that we made newly nonzero */ | |
while (num_newnz > 0) | |
(*block)[newnz_pos[--num_newnz]] = 0; | |
return FALSE; | |
} | |
/* | |
* Module initialization routine for progressive Huffman entropy decoding. | |
*/ | |
GLOBAL(void) | |
jinit_phuff_decoder (j_decompress_ptr cinfo) | |
{ | |
phuff_entropy_ptr entropy; | |
int *coef_bit_ptr; | |
int ci, i; | |
entropy = (phuff_entropy_ptr) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
SIZEOF(phuff_entropy_decoder)); | |
cinfo->entropy = (struct jpeg_entropy_decoder *) entropy; | |
entropy->pub.start_pass = start_pass_phuff_decoder; | |
/* Mark derived tables unallocated */ | |
for (i = 0; i < NUM_HUFF_TBLS; i++) { | |
entropy->derived_tbls[i] = NULL; | |
} | |
/* Create progression status table */ | |
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; | |
} | |
#endif /* D_PROGRESSIVE_SUPPORTED */ | |
#endif //_FX_JPEG_TURBO_ |