jdhuff.c File Reference

#include "jinclude.h"
#include "jpeglib.h"

Include dependency graph for jdhuff.c:

Go to the source code of this file.

Classes
struct	d_derived_tbl
struct	bitread_perm_state
struct	bitread_working_state
struct	savable_state
struct	huff_entropy_decoder

Macros
#define	JPEG_INTERNALS
#define	HUFF_LOOKAHEAD   8 /* # of bits of lookahead */
#define	BIT_BUF_SIZE   32 /* size of buffer in bits */
#define	BITREAD_STATE_VARS
#define	BITREAD_LOAD_STATE(cinfop, permstate)
#define	BITREAD_SAVE_STATE(cinfop, permstate)
#define	CHECK_BIT_BUFFER(state, nbits, action)
#define	GET_BITS(nbits)    (((int) (get_buffer >> (bits_left -= (nbits)))) & BIT_MASK(nbits))
#define	PEEK_BITS(nbits)    (((int) (get_buffer >> (bits_left - (nbits)))) & BIT_MASK(nbits))
#define	DROP_BITS(nbits)    (bits_left -= (nbits))
#define	HUFF_DECODE(result, state, htbl, failaction, slowlabel)
#define	ASSIGN_STATE(dest, src)   ((dest) = (src))
#define	MIN_GET_BITS   (BIT_BUF_SIZE-7)
#define	BIT_MASK(nbits)   bmask[nbits]
#define	HUFF_EXTEND(x, s)   ((x) <= bmask[(s) - 1] ? (x) - bmask[s] : (x))

Typedefs
typedef INT32	bit_buf_type
typedef huff_entropy_decoder *	huff_entropy_ptr

Functions
	jpeg_make_d_derived_tbl (j_decompress_ptr cinfo, boolean isDC, int tblno, d_derived_tbl **pdtbl)
	jpeg_fill_bit_buffer (bitread_working_state *state, register bit_buf_type get_buffer, register int bits_left, int nbits)
	jpeg_huff_decode (bitread_working_state *state, register bit_buf_type get_buffer, register int bits_left, d_derived_tbl *htbl, int min_bits)
	finish_pass_huff (j_decompress_ptr cinfo)
	process_restart (j_decompress_ptr cinfo)
	decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
	decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
	decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
	decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
	decode_mcu_sub (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
	decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
	start_pass_huff_decoder (j_decompress_ptr cinfo)
	jinit_huff_decoder (j_decompress_ptr cinfo)

Variables
static const int	jpeg_zigzag_order [8][8]
static const int	jpeg_zigzag_order7 [7][7]
static const int	jpeg_zigzag_order6 [6][6]
static const int	jpeg_zigzag_order5 [5][5]
static const int	jpeg_zigzag_order4 [4][4]
static const int	jpeg_zigzag_order3 [3][3]
static const int	jpeg_zigzag_order2 [2][2]
static const int	bmask [16]

Macro Definition Documentation

ASSIGN_STATE

#define ASSIGN_STATE	(		dest,
			src
	)		((dest) = (src))

Definition at line 209 of file jdhuff.c.

BIT_BUF_SIZE

#define BIT_BUF_SIZE   32 /* size of buffer in bits */

Definition at line 70 of file jdhuff.c.

BIT_MASK

#define BIT_MASK

(

nbits

)

bmask[nbits]

Definition at line 576 of file jdhuff.c.

BITREAD_LOAD_STATE

#define BITREAD_LOAD_STATE	(		cinfop,
			permstate
	)

Value:

    br_state.cinfo = cinfop; \
    br_state.next_input_byte = cinfop->src->next_input_byte; \
    br_state.bytes_in_buffer = cinfop->src->bytes_in_buffer; \
    get_buffer = permstate.get_buffer; \
    bits_left = permstate.bits_left;

Definition at line 104 of file jdhuff.c.

BITREAD_SAVE_STATE

#define BITREAD_SAVE_STATE	(		cinfop,
			permstate
	)

Value:

    cinfop->src->next_input_byte = br_state.next_input_byte; \
    cinfop->src->bytes_in_buffer = br_state.bytes_in_buffer; \
    permstate.get_buffer = get_buffer; \
    permstate.bits_left = bits_left

Definition at line 111 of file jdhuff.c.

BITREAD_STATE_VARS

#define BITREAD_STATE_VARS

Value:

    register bit_buf_type get_buffer;  \
    register int bits_left;  \
    bitread_working_state br_state

Definition at line 99 of file jdhuff.c.

CHECK_BIT_BUFFER

#define CHECK_BIT_BUFFER	(		state,
			nbits,
			action
	)

Value:

    { if (bits_left < (nbits)) {  \
        if (! jpeg_fill_bit_buffer(&(state),get_buffer,bits_left,nbits))  \
          { action; }  \
        get_buffer = (state).get_buffer; bits_left = (state).bits_left; } }

Definition at line 135 of file jdhuff.c.

DROP_BITS

#define DROP_BITS

(

nbits

)

(bits_left -= (nbits))

Definition at line 147 of file jdhuff.c.

GET_BITS

#define GET_BITS

(

nbits

)

(((int) (get_buffer >> (bits_left -= (nbits)))) & BIT_MASK(nbits))

Definition at line 141 of file jdhuff.c.

HUFF_DECODE

#define HUFF_DECODE	(		result,
			state,
			htbl,
			failaction,
			slowlabel
	)

Value:

{ register int nb, look; \
  if (bits_left < HUFF_LOOKAHEAD) { \
    if (! jpeg_fill_bit_buffer(&state,get_buffer,bits_left, 0)) {failaction;} \
    get_buffer = state.get_buffer; bits_left = state.bits_left; \
    if (bits_left < HUFF_LOOKAHEAD) { \
      nb = 1; goto slowlabel; \
    } \
  } \
  look = PEEK_BITS(HUFF_LOOKAHEAD); \
  if ((nb = htbl->look_nbits[look]) != 0) { \
    DROP_BITS(nb); \
    result = htbl->look_sym[look]; \
  } else { \
    nb = HUFF_LOOKAHEAD+1; \
slowlabel: \
    if ((result=jpeg_huff_decode(&state,get_buffer,bits_left,htbl,nb)) < 0) \
    { failaction; } \
    get_buffer = state.get_buffer; bits_left = state.bits_left; \
  } \
}

Definition at line 168 of file jdhuff.c.

HUFF_EXTEND

#define HUFF_EXTEND	(		x,
			s
	)		((x) <= bmask[(s) - 1] ? (x) - bmask[s] : (x))

Definition at line 577 of file jdhuff.c.

HUFF_LOOKAHEAD

#define HUFF_LOOKAHEAD   8 /* # of bits of lookahead */

Definition at line 26 of file jdhuff.c.

JPEG_INTERNALS

#define JPEG_INTERNALS

Definition at line 19 of file jdhuff.c.

MIN_GET_BITS

#define MIN_GET_BITS   (BIT_BUF_SIZE-7)

Definition at line 459 of file jdhuff.c.

PEEK_BITS

#define PEEK_BITS

(

nbits

)

(((int) (get_buffer >> (bits_left - (nbits)))) & BIT_MASK(nbits))

Definition at line 144 of file jdhuff.c.

Typedef Documentation

bit_buf_type

typedef INT32 bit_buf_type

Definition at line 69 of file jdhuff.c.

huff_entropy_ptr

typedef huff_entropy_decoder* huff_entropy_ptr

Definition at line 257 of file jdhuff.c.

Function Documentation

decode_mcu()

decode_mcu	(	j_decompress_ptr	cinfo,
		JBLOCKROW *	MCU_data
	)

Definition at line 1204 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  int blkn;
  BITREAD_STATE_VARS;
  savable_state state;
 
  /* 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->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++) {
      JBLOCKROW block = MCU_data[blkn];
      d_derived_tbl * htbl;
      register int s, k, r;
      int coef_limit, ci;
 
      /* Decode a single block's worth of coefficients */
 
      /* Section F.2.2.1: decode the DC coefficient difference */
      htbl = entropy->dc_cur_tbls[blkn];
      HUFF_DECODE(s, br_state, htbl, return FALSE, label1);
 
      htbl = entropy->ac_cur_tbls[blkn];
      k = 1;
      coef_limit = entropy->coef_limit[blkn];
      if (coef_limit) {
    /* Convert DC difference to actual value, update last_dc_val */
    if (s) {
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
      r = GET_BITS(s);
      s = HUFF_EXTEND(r, s);
    }
    ci = cinfo->MCU_membership[blkn];
    s += state.last_dc_val[ci];
    state.last_dc_val[ci] = s;
    /* Output the DC coefficient */
    (*block)[0] = (JCOEF) s;
 
    /* Section F.2.2.2: decode the AC coefficients */
    /* Since zeroes are skipped, output area must be cleared beforehand */
    for (; k < coef_limit; k++) {
      HUFF_DECODE(s, br_state, htbl, 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);
        /* Output coefficient in natural (dezigzagged) order.
         * Note: the extra entries in jpeg_natural_order[] will save us
         * if k >= DCTSIZE2, which could happen if the data is corrupted.
         */
        (*block)[jpeg_natural_order[k]] = (JCOEF) s;
      } else {
        if (r != 15)
          goto EndOfBlock;
        k += 15;
      }
    }
      } else {
    if (s) {
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
      DROP_BITS(s);
    }
      }
 
      /* Section F.2.2.2: decode the AC coefficients */
      /* In this path we just discard the values */
      for (; k < DCTSIZE2; k++) {
    HUFF_DECODE(s, br_state, htbl, return FALSE, label3);
 
    r = s >> 4;
    s &= 15;
 
    if (s) {
      k += r;
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
      DROP_BITS(s);
    } else {
      if (r != 15)
        break;
      k += 15;
    }
      }
 
      EndOfBlock: ;
    }
 
    /* Completed MCU, so update state */
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
    ASSIGN_STATE(entropy->saved, state);
  }
 
  /* Account for restart interval if using restarts */
  if (cinfo->restart_interval)
    entropy->restarts_to_go--;
 
  return TRUE;
}

Referenced by start_pass_huff_decoder().

decode_mcu_AC_first()

decode_mcu_AC_first	(	j_decompress_ptr	cinfo,
		JBLOCKROW *	MCU_data
	)

Definition at line 779 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  register int s, k, r;
  unsigned int EOBRUN;
  int Se, Al;
  const int * natural_order;
  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->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)         /* if it's a band of zeroes... */
      EOBRUN--;         /* ...process it now (we do nothing) */
    else {
      BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
      Se = cinfo->Se;
      Al = cinfo->Al;
      natural_order = cinfo->natural_order;
      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)[natural_order[k]] = (JCOEF) (s << Al);
    } else {
      if (r != 15) {    /* EOBr, run length is 2^r + appended bits */
        if (r) {        /* EOBr, r > 0 */
          EOBRUN = 1 << r;
          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 */
      }
      k += 15;      /* ZRL: skip 15 zeroes in 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 if using restarts */
  if (cinfo->restart_interval)
    entropy->restarts_to_go--;
 
  return TRUE;
}

Referenced by start_pass_huff_decoder().

decode_mcu_AC_refine()

decode_mcu_AC_refine	(	j_decompress_ptr	cinfo,
		JBLOCKROW *	MCU_data
	)

Definition at line 916 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  register int s, k, r;
  unsigned int EOBRUN;
  int Se;
  JCOEF p1, m1;
  const int * natural_order;
  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->insufficient_data) {
 
    Se = cinfo->Se;
    p1 = 1 << cinfo->Al;    /* 1 in the bit position being coded */
    m1 = -p1;           /* -1 in the bit position being coded */
    natural_order = cinfo->natural_order;
 
    /* 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) {
      do {
    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 + natural_order[k];
      if (*thiscoef) {
        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 = 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;
    }
    k++;
      } while (k <= Se);
    }
 
    if (EOBRUN) {
      /* 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.
       */
      do {
    thiscoef = *block + natural_order[k];
    if (*thiscoef) {
      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;
        }
      }
    }
    k++;
      } while (k <= Se);
      /* 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 if using restarts */
  if (cinfo->restart_interval)
    entropy->restarts_to_go--;
 
  return TRUE;
 
undoit:
  /* Re-zero any output coefficients that we made newly nonzero */
  while (num_newnz)
    (*block)[newnz_pos[--num_newnz]] = 0;
 
  return FALSE;
}

Referenced by start_pass_huff_decoder().

decode_mcu_DC_first()

decode_mcu_DC_first	(	j_decompress_ptr	cinfo,
		JBLOCKROW *	MCU_data
	)

Definition at line 707 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_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->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 if using restarts */
  if (cinfo->restart_interval)
    entropy->restarts_to_go--;
 
  return TRUE;
}

Referenced by start_pass_huff_decoder().

decode_mcu_DC_refine()

decode_mcu_DC_refine	(	j_decompress_ptr	cinfo,
		JBLOCKROW *	MCU_data
	)

Definition at line 867 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  JCOEF p1;
  int blkn;
  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);
 
  p1 = 1 << cinfo->Al;      /* 1 in the bit position being coded */
 
  /* Outer loop handles each block in the MCU */
 
  for (blkn = 0; blkn < cinfo->blocks_in_MCU; 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))
      MCU_data[blkn][0][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 if using restarts */
  if (cinfo->restart_interval)
    entropy->restarts_to_go--;
 
  return TRUE;
}

Referenced by start_pass_huff_decoder().

decode_mcu_sub()

decode_mcu_sub	(	j_decompress_ptr	cinfo,
		JBLOCKROW *	MCU_data
	)

Definition at line 1075 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  const int * natural_order;
  int Se, blkn;
  BITREAD_STATE_VARS;
  savable_state state;
 
  /* 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->insufficient_data) {
 
    natural_order = cinfo->natural_order;
    Se = cinfo->lim_Se;
 
    /* 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++) {
      JBLOCKROW block = MCU_data[blkn];
      d_derived_tbl * htbl;
      register int s, k, r;
      int coef_limit, ci;
 
      /* Decode a single block's worth of coefficients */
 
      /* Section F.2.2.1: decode the DC coefficient difference */
      htbl = entropy->dc_cur_tbls[blkn];
      HUFF_DECODE(s, br_state, htbl, return FALSE, label1);
 
      htbl = entropy->ac_cur_tbls[blkn];
      k = 1;
      coef_limit = entropy->coef_limit[blkn];
      if (coef_limit) {
    /* Convert DC difference to actual value, update last_dc_val */
    if (s) {
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
      r = GET_BITS(s);
      s = HUFF_EXTEND(r, s);
    }
    ci = cinfo->MCU_membership[blkn];
    s += state.last_dc_val[ci];
    state.last_dc_val[ci] = s;
    /* Output the DC coefficient */
    (*block)[0] = (JCOEF) s;
 
    /* Section F.2.2.2: decode the AC coefficients */
    /* Since zeroes are skipped, output area must be cleared beforehand */
    for (; k < coef_limit; k++) {
      HUFF_DECODE(s, br_state, htbl, 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);
        /* Output coefficient in natural (dezigzagged) order.
         * Note: the extra entries in natural_order[] will save us
         * if k > Se, which could happen if the data is corrupted.
         */
        (*block)[natural_order[k]] = (JCOEF) s;
      } else {
        if (r != 15)
          goto EndOfBlock;
        k += 15;
      }
    }
      } else {
    if (s) {
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
      DROP_BITS(s);
    }
      }
 
      /* Section F.2.2.2: decode the AC coefficients */
      /* In this path we just discard the values */
      for (; k <= Se; k++) {
    HUFF_DECODE(s, br_state, htbl, return FALSE, label3);
 
    r = s >> 4;
    s &= 15;
 
    if (s) {
      k += r;
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
      DROP_BITS(s);
    } else {
      if (r != 15)
        break;
      k += 15;
    }
      }
 
      EndOfBlock: ;
    }
 
    /* Completed MCU, so update state */
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
    ASSIGN_STATE(entropy->saved, state);
  }
 
  /* Account for restart interval if using restarts */
  if (cinfo->restart_interval)
    entropy->restarts_to_go--;
 
  return TRUE;
}

Referenced by start_pass_huff_decoder().

finish_pass_huff()

finish_pass_huff

(

j_decompress_ptr

cinfo

)

Definition at line 634 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
 
  /* 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;
}

Referenced by jinit_huff_decoder(), and process_restart().

jinit_huff_decoder()

jinit_huff_decoder

(

j_decompress_ptr

cinfo

)

Definition at line 1527 of file jdhuff.c.

{
  huff_entropy_ptr entropy;
  int i;
 
  entropy = (huff_entropy_ptr) (*cinfo->mem->alloc_small)
    ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(huff_entropy_decoder));
  cinfo->entropy = &entropy->pub;
  entropy->pub.start_pass = start_pass_huff_decoder;
  entropy->pub.finish_pass = finish_pass_huff;
 
  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;
 
    /* Mark derived tables unallocated */
    for (i = 0; i < NUM_HUFF_TBLS; i++) {
      entropy->derived_tbls[i] = NULL;
    }
  } else {
    /* Mark derived tables unallocated */
    for (i = 0; i < NUM_HUFF_TBLS; i++) {
      entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
    }
  }
}

Referenced by master_selection(), and transdecode_master_selection().

jpeg_fill_bit_buffer()

jpeg_fill_bit_buffer	(	bitread_working_state *	state,
		register bit_buf_type	get_buffer,
		register int	bits_left,
		int	nbits
	)

Definition at line 464 of file jdhuff.c.

{
  /* Copy heavily used state fields into locals (hopefully registers) */
  register const JOCTET * next_input_byte = state->next_input_byte;
  register size_t bytes_in_buffer = state->bytes_in_buffer;
  j_decompress_ptr cinfo = state->cinfo;
 
  /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */
  /* (It is assumed that no request will be for more than that many bits.) */
  /* We fail to do so only if we hit a marker or are forced to suspend. */
 
  if (cinfo->unread_marker == 0) {  /* cannot advance past a marker */
    while (bits_left < MIN_GET_BITS) {
      register int c;
 
      /* Attempt to read a byte */
      if (bytes_in_buffer == 0) {
    if (! (*cinfo->src->fill_input_buffer) (cinfo))
      return FALSE;
    next_input_byte = cinfo->src->next_input_byte;
    bytes_in_buffer = cinfo->src->bytes_in_buffer;
      }
      bytes_in_buffer--;
      c = GETJOCTET(*next_input_byte++);
 
      /* If it's 0xFF, check and discard stuffed zero byte */
      if (c == 0xFF) {
    /* Loop here to discard any padding FF's on terminating marker,
     * so that we can save a valid unread_marker value.  NOTE: we will
     * accept multiple FF's followed by a 0 as meaning a single FF data
     * byte.  This data pattern is not valid according to the standard.
     */
    do {
      if (bytes_in_buffer == 0) {
        if (! (*cinfo->src->fill_input_buffer) (cinfo))
          return FALSE;
        next_input_byte = cinfo->src->next_input_byte;
        bytes_in_buffer = cinfo->src->bytes_in_buffer;
      }
      bytes_in_buffer--;
      c = GETJOCTET(*next_input_byte++);
    } while (c == 0xFF);
 
    if (c == 0) {
      /* Found FF/00, which represents an FF data byte */
      c = 0xFF;
    } else {
      /* Oops, it's actually a marker indicating end of compressed data.
       * Save the marker code for later use.
       * Fine point: it might appear that we should save the marker into
       * bitread working state, not straight into permanent state.  But
       * once we have hit a marker, we cannot need to suspend within the
       * current MCU, because we will read no more bytes from the data
       * source.  So it is OK to update permanent state right away.
       */
      cinfo->unread_marker = c;
      /* See if we need to insert some fake zero bits. */
      goto no_more_bytes;
    }
      }
 
      /* OK, load c into get_buffer */
      get_buffer = (get_buffer << 8) | c;
      bits_left += 8;
    } /* end while */
  } else {
  no_more_bytes:
    /* We get here if we've read the marker that terminates the compressed
     * data segment.  There should be enough bits in the buffer register
     * to satisfy the request; if so, no problem.
     */
    if (nbits > bits_left) {
      /* Uh-oh.  Report corrupted data to user and stuff zeroes into
       * the data stream, so that we can produce some kind of image.
       * We use a nonvolatile flag to ensure that only one warning message
       * appears per data segment.
       */
      if (! ((huff_entropy_ptr) cinfo->entropy)->insufficient_data) {
    WARNMS(cinfo, JWRN_HIT_MARKER);
    ((huff_entropy_ptr) cinfo->entropy)->insufficient_data = TRUE;
      }
      /* Fill the buffer with zero bits */
      get_buffer <<= MIN_GET_BITS - bits_left;
      bits_left = MIN_GET_BITS;
    }
  }
 
  /* Unload the local registers */
  state->next_input_byte = next_input_byte;
  state->bytes_in_buffer = bytes_in_buffer;
  state->get_buffer = get_buffer;
  state->bits_left = bits_left;
 
  return TRUE;
}

jpeg_huff_decode()

jpeg_huff_decode	(	bitread_working_state *	state,
		register bit_buf_type	get_buffer,
		register int	bits_left,
		d_derived_tbl *	htbl,
		int	min_bits
	)

Definition at line 591 of file jdhuff.c.

{
  register int l = min_bits;
  register INT32 code;
 
  /* HUFF_DECODE has determined that the code is at least min_bits */
  /* bits long, so fetch that many bits in one swoop. */
 
  CHECK_BIT_BUFFER(*state, l, return -1);
  code = GET_BITS(l);
 
  /* Collect the rest of the Huffman code one bit at a time. */
  /* This is per Figure F.16 in the JPEG spec. */
 
  while (code > htbl->maxcode[l]) {
    code <<= 1;
    CHECK_BIT_BUFFER(*state, 1, return -1);
    code |= GET_BITS(1);
    l++;
  }
 
  /* Unload the local registers */
  state->get_buffer = get_buffer;
  state->bits_left = bits_left;
 
  /* With garbage input we may reach the sentinel value l = 17. */
 
  if (l > 16) {
    WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE);
    return 0;           /* fake a zero as the safest result */
  }
 
  return htbl->pub->huffval[ (int) (code + htbl->valoffset[l]) ];
}

jpeg_make_d_derived_tbl()

jpeg_make_d_derived_tbl	(	j_decompress_ptr	cinfo,
		boolean	isDC,
		int	tblno,
		d_derived_tbl **	pdtbl
	)

Definition at line 323 of file jdhuff.c.

{
  JHUFF_TBL *htbl;
  d_derived_tbl *dtbl;
  int p, i, l, si, numsymbols;
  int lookbits, ctr;
  char huffsize[257];
  unsigned int huffcode[257];
  unsigned int code;
 
  /* Note that huffsize[] and huffcode[] are filled in code-length order,
   * paralleling the order of the symbols themselves in htbl->huffval[].
   */
 
  /* Find the input Huffman table */
  if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
    ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
  htbl =
    isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno];
  if (htbl == NULL)
    htbl = jpeg_std_huff_table((j_common_ptr) cinfo, isDC, tblno);
 
  /* Allocate a workspace if we haven't already done so. */
  if (*pdtbl == NULL)
    *pdtbl = (d_derived_tbl *) (*cinfo->mem->alloc_small)
      ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(d_derived_tbl));
  dtbl = *pdtbl;
  dtbl->pub = htbl;     /* fill in back link */
  
  /* Figure C.1: make table of Huffman code length for each symbol */
 
  p = 0;
  for (l = 1; l <= 16; l++) {
    i = (int) htbl->bits[l];
    if (i < 0 || p + i > 256)   /* protect against table overrun */
      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
    while (i--)
      huffsize[p++] = (char) l;
  }
  huffsize[p] = 0;
  numsymbols = p;
  
  /* Figure C.2: generate the codes themselves */
  /* We also validate that the counts represent a legal Huffman code tree. */
  
  code = 0;
  si = huffsize[0];
  p = 0;
  while (huffsize[p]) {
    while (((int) huffsize[p]) == si) {
      huffcode[p++] = code;
      code++;
    }
    /* code is now 1 more than the last code used for codelength si; but
     * it must still fit in si bits, since no code is allowed to be all ones.
     */
    if (((INT32) code) >= (((INT32) 1) << si))
      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
    code <<= 1;
    si++;
  }
 
  /* Figure F.15: generate decoding tables for bit-sequential decoding */
 
  p = 0;
  for (l = 1; l <= 16; l++) {
    if (htbl->bits[l]) {
      /* valoffset[l] = huffval[] index of 1st symbol of code length l,
       * minus the minimum code of length l
       */
      dtbl->valoffset[l] = (INT32) p - (INT32) huffcode[p];
      p += htbl->bits[l];
      dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
    } else {
      dtbl->maxcode[l] = -1;    /* -1 if no codes of this length */
    }
  }
  dtbl->maxcode[17] = 0xFFFFFL; /* ensures jpeg_huff_decode terminates */
 
  /* Compute lookahead tables to speed up decoding.
   * First we set all the table entries to 0, indicating "too long";
   * then we iterate through the Huffman codes that are short enough and
   * fill in all the entries that correspond to bit sequences starting
   * with that code.
   */
 
  MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits));
 
  p = 0;
  for (l = 1; l <= HUFF_LOOKAHEAD; l++) {
    for (i = 1; i <= (int) htbl->bits[l]; i++, p++) {
      /* l = current code's length, p = its index in huffcode[] & huffval[]. */
      /* Generate left-justified code followed by all possible bit sequences */
      lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
      for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) {
    dtbl->look_nbits[lookbits] = l;
    dtbl->look_sym[lookbits] = htbl->huffval[p];
    lookbits++;
      }
    }
  }
 
  /* Validate symbols as being reasonable.
   * For AC tables, we make no check, but accept all byte values 0..255.
   * For DC tables, we require the symbols to be in range 0..15.
   * (Tighter bounds could be applied depending on the data depth and mode,
   * but this is sufficient to ensure safe decoding.)
   */
  if (isDC) {
    for (i = 0; i < numsymbols; i++) {
      int sym = htbl->huffval[i];
      if (sym < 0 || sym > 15)
    ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
    }
  }
}

Referenced by start_pass_huff_decoder().

process_restart()

process_restart

(

j_decompress_ptr

cinfo

)

Definition at line 651 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  int ci;
 
  finish_pass_huff(cinfo);
 
  /* 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->insufficient_data = FALSE;
 
  return TRUE;
}

Referenced by decode_mcu(), decode_mcu_AC_first(), decode_mcu_AC_refine(), decode_mcu_DC_first(), decode_mcu_DC_refine(), and decode_mcu_sub().

start_pass_huff_decoder()

start_pass_huff_decoder

(

j_decompress_ptr

cinfo

)

Definition at line 1328 of file jdhuff.c.

{
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
  int ci, blkn, tbl, i;
  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 */
      /* 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.
       */
      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;
    }
 
    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 (cinfo->Ss == 0) {
    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 private state variables */
    entropy->saved.EOBRUN = 0;
  } 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 because
     * there are some baseline files out there with all zeroes in these bytes.
     */
    if (cinfo->Ss != 0 || cinfo->Ah != 0 || cinfo->Al != 0 ||
    ((cinfo->is_baseline || cinfo->Se < DCTSIZE2) &&
    cinfo->Se != cinfo->lim_Se))
      WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
 
    /* Select MCU decoding routine */
    /* We retain the hard-coded case for full-size blocks.
     * This is not necessary, but it appears that this version is slightly
     * more performant in the given implementation.
     * With an improved implementation we would prefer a single optimized
     * function.
     */
    if (cinfo->lim_Se != DCTSIZE2-1)
      entropy->pub.decode_mcu = decode_mcu_sub;
    else
      entropy->pub.decode_mcu = decode_mcu;
 
    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
      compptr = cinfo->cur_comp_info[ci];
      /* Compute derived values for Huffman tables */
      /* We may do this more than once for a table, but it's not expensive */
      tbl = compptr->dc_tbl_no;
      jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
                  & entropy->dc_derived_tbls[tbl]);
      if (cinfo->lim_Se) {  /* AC needs no table when not present */
    tbl = compptr->ac_tbl_no;
    jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
                & entropy->ac_derived_tbls[tbl]);
      }
      /* Initialize DC predictions to 0 */
      entropy->saved.last_dc_val[ci] = 0;
    }
 
    /* Precalculate decoding info for each block in an MCU of this scan */
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
      ci = cinfo->MCU_membership[blkn];
      compptr = cinfo->cur_comp_info[ci];
      /* Precalculate which table to use for each block */
      entropy->dc_cur_tbls[blkn] = entropy->dc_derived_tbls[compptr->dc_tbl_no];
      entropy->ac_cur_tbls[blkn] =  /* AC needs no table when not present */
    cinfo->lim_Se ? entropy->ac_derived_tbls[compptr->ac_tbl_no] : NULL;
      /* Decide whether we really care about the coefficient values */
      if (compptr->component_needed) {
    ci = compptr->DCT_v_scaled_size;
    i = compptr->DCT_h_scaled_size;
    switch (cinfo->lim_Se) {
    case (1*1-1):
      entropy->coef_limit[blkn] = 1;
      break;
    case (2*2-1):
      if (ci <= 0 || ci > 2) ci = 2;
      if (i <= 0 || i > 2) i = 2;
      entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order2[ci - 1][i - 1];
      break;
    case (3*3-1):
      if (ci <= 0 || ci > 3) ci = 3;
      if (i <= 0 || i > 3) i = 3;
      entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order3[ci - 1][i - 1];
      break;
    case (4*4-1):
      if (ci <= 0 || ci > 4) ci = 4;
      if (i <= 0 || i > 4) i = 4;
      entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order4[ci - 1][i - 1];
      break;
    case (5*5-1):
      if (ci <= 0 || ci > 5) ci = 5;
      if (i <= 0 || i > 5) i = 5;
      entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order5[ci - 1][i - 1];
      break;
    case (6*6-1):
      if (ci <= 0 || ci > 6) ci = 6;
      if (i <= 0 || i > 6) i = 6;
      entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order6[ci - 1][i - 1];
      break;
    case (7*7-1):
      if (ci <= 0 || ci > 7) ci = 7;
      if (i <= 0 || i > 7) i = 7;
      entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order7[ci - 1][i - 1];
      break;
    default:
      if (ci <= 0 || ci > 8) ci = 8;
      if (i <= 0 || i > 8) i = 8;
      entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order[ci - 1][i - 1];
    }
      } else {
    entropy->coef_limit[blkn] = 0;
      }
    }
  }
 
  /* Initialize bitread state variables */
  entropy->bitstate.bits_left = 0;
  entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
  entropy->insufficient_data = FALSE;
 
  /* Initialize restart counter */
  entropy->restarts_to_go = cinfo->restart_interval;
}

Referenced by jinit_huff_decoder().

Variable Documentation

bmask

const int bmask[16]

static

Initial value:

=   
  { 0, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF,
    0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF }

Definition at line 579 of file jdhuff.c.

Referenced by check_dds_pixel_format_().

jpeg_zigzag_order

const int jpeg_zigzag_order[8][8]

static

Initial value:

= {
  {  0,  1,  5,  6, 14, 15, 27, 28 },
  {  2,  4,  7, 13, 16, 26, 29, 42 },
  {  3,  8, 12, 17, 25, 30, 41, 43 },
  {  9, 11, 18, 24, 31, 40, 44, 53 },
  { 10, 19, 23, 32, 39, 45, 52, 54 },
  { 20, 22, 33, 38, 46, 51, 55, 60 },
  { 21, 34, 37, 47, 50, 56, 59, 61 },
  { 35, 36, 48, 49, 57, 58, 62, 63 }
}

Definition at line 260 of file jdhuff.c.

Referenced by start_pass_huff_decoder().

jpeg_zigzag_order2

const int jpeg_zigzag_order2[2][2]

static

Initial value:

= {
  { 0, 1 },
  { 2, 3 }
}

Definition at line 311 of file jdhuff.c.

Referenced by start_pass_huff_decoder().

jpeg_zigzag_order3

const int jpeg_zigzag_order3[3][3]

static

Initial value:

= {
  { 0, 1, 5 },
  { 2, 4, 6 },
  { 3, 7, 8 }
}

Definition at line 305 of file jdhuff.c.

Referenced by start_pass_huff_decoder().

jpeg_zigzag_order4

const int jpeg_zigzag_order4[4][4]

static

Initial value:

= {
  { 0,  1,  5,  6 },
  { 2,  4,  7, 12 },
  { 3,  8, 11, 13 },
  { 9, 10, 14, 15 }
}

Definition at line 298 of file jdhuff.c.

Referenced by start_pass_huff_decoder().

jpeg_zigzag_order5

const int jpeg_zigzag_order5[5][5]

static

Initial value:

= {
  {  0,  1,  5,  6, 14 },
  {  2,  4,  7, 13, 15 },
  {  3,  8, 12, 16, 21 },
  {  9, 11, 17, 20, 22 },
  { 10, 18, 19, 23, 24 }
}

Definition at line 290 of file jdhuff.c.

Referenced by start_pass_huff_decoder().

jpeg_zigzag_order6

const int jpeg_zigzag_order6[6][6]

static

Initial value:

= {
  {  0,  1,  5,  6, 14, 15 },
  {  2,  4,  7, 13, 16, 25 },
  {  3,  8, 12, 17, 24, 26 },
  {  9, 11, 18, 23, 27, 32 },
  { 10, 19, 22, 28, 31, 33 },
  { 20, 21, 29, 30, 34, 35 }
}

Definition at line 281 of file jdhuff.c.

Referenced by start_pass_huff_decoder().

jpeg_zigzag_order7

const int jpeg_zigzag_order7[7][7]

static

Initial value:

= {
  {  0,  1,  5,  6, 14, 15, 27 },
  {  2,  4,  7, 13, 16, 26, 28 },
  {  3,  8, 12, 17, 25, 29, 38 },
  {  9, 11, 18, 24, 30, 37, 39 },
  { 10, 19, 23, 31, 36, 40, 45 },
  { 20, 22, 32, 35, 41, 44, 46 },
  { 21, 33, 34, 42, 43, 47, 48 }
}

Definition at line 271 of file jdhuff.c.

Referenced by start_pass_huff_decoder().