www.pudn.com > imgport.rar > jdphuff.c, change:2008-11-05,size:21227b


/* 
 * 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 */