/* | |

* 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. | |

*/ | |

#define AVOID_TABLES | |

#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 */ |