libjpeg update

git-svn-id: http://svn.miranda-ng.org/main/trunk@5843 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c

1 files changed, 1576 insertions, 1576 deletions

diff --git a/plugins/AdvaImg/src/LibJPEG/jchuff.c b/plugins/AdvaImg/src/LibJPEG/jchuff.c
index 257d7aa1f5..4cbab438d5 100644
--- a/plugins/AdvaImg/src/LibJPEG/jchuff.c
+++ b/plugins/AdvaImg/src/LibJPEG/jchuff.c
@@ -1,1576 +1,1576 @@
-/*
- * jchuff.c
- *
- * Copyright (C) 1991-1997, Thomas G. Lane.
- * Modified 2006-2009 by Guido Vollbeding.
- * 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 encoding routines.
- * Both sequential and progressive modes are supported in this single module.
- *
- * Much of the complexity here has to do with supporting output suspension.
- * If the data destination 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 JPEG objects only upon successful completion of an MCU.
- *
- * We do not support output suspension for the progressive JPEG mode, since
- * the library currently does not allow multiple-scan files to be written
- * with output suspension.
- */
-
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "jpeglib.h"
-
-
-/* The legal range of a DCT coefficient is
- *  -1024 .. +1023  for 8-bit data;
- * -16384 .. +16383 for 12-bit data.
- * Hence the magnitude should always fit in 10 or 14 bits respectively.
- */
-
-#if BITS_IN_JSAMPLE == 8
-#define MAX_COEF_BITS 10
-#else
-#define MAX_COEF_BITS 14
-#endif
-
-/* Derived data constructed for each Huffman table */
-
-typedef struct {
-  unsigned int ehufco[256];	/* code for each symbol */
-  char ehufsi[256];		/* length of code for each symbol */
-  /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */
-} c_derived_tbl;
-
-
-/* Expanded entropy encoder object for Huffman encoding.
- *
- * The savable_state subrecord contains fields that change within an MCU,
- * but must not be updated permanently until we complete the MCU.
- */
-
-typedef struct {
-  INT32 put_buffer;		/* current bit-accumulation buffer */
-  int put_bits;			/* # of bits now in it */
-  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).put_buffer = (src).put_buffer, \
-	 (dest).put_bits = (src).put_bits, \
-	 (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_encoder pub; /* public fields */
-
-  savable_state saved;		/* Bit buffer & DC 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 */
-  int next_restart_num;		/* next restart number to write (0-7) */
-
-  /* Pointers to derived tables (these workspaces have image lifespan) */
-  c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];
-  c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];
-
-  /* Statistics tables for optimization */
-  long * dc_count_ptrs[NUM_HUFF_TBLS];
-  long * ac_count_ptrs[NUM_HUFF_TBLS];
-
-  /* Following fields used only in progressive mode */
-
-  /* Mode flag: TRUE for optimization, FALSE for actual data output */
-  boolean gather_statistics;
-
-  /* next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
-   */
-  JOCTET * next_output_byte;	/* => next byte to write in buffer */
-  size_t free_in_buffer;	/* # of byte spaces remaining in buffer */
-  j_compress_ptr cinfo;		/* link to cinfo (needed for dump_buffer) */
-
-  /* Coding status for AC components */
-  int ac_tbl_no;		/* the table number of the single component */
-  unsigned int EOBRUN;		/* run length of EOBs */
-  unsigned int BE;		/* # of buffered correction bits before MCU */
-  char * bit_buffer;		/* buffer for correction bits (1 per char) */
-  /* packing correction bits tightly would save some space but cost time... */
-} huff_entropy_encoder;
-
-typedef huff_entropy_encoder * huff_entropy_ptr;
-
-/* Working state while writing an MCU (sequential mode).
- * This struct contains all the fields that are needed by subroutines.
- */
-
-typedef struct {
-  JOCTET * next_output_byte;	/* => next byte to write in buffer */
-  size_t free_in_buffer;	/* # of byte spaces remaining in buffer */
-  savable_state cur;		/* Current bit buffer & DC state */
-  j_compress_ptr cinfo;		/* dump_buffer needs access to this */
-} working_state;
-
-/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
- * buffer can hold.  Larger sizes may slightly improve compression, but
- * 1000 is already well into the realm of overkill.
- * The minimum safe size is 64 bits.
- */
-
-#define MAX_CORR_BITS  1000	/* Max # of correction bits I can buffer */
-
-/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
- * We assume that int right shift is unsigned if INT32 right shift is,
- * which should be safe.
- */
-
-#ifdef RIGHT_SHIFT_IS_UNSIGNED
-#define ISHIFT_TEMPS	int ishift_temp;
-#define IRIGHT_SHIFT(x,shft)  \
-	((ishift_temp = (x)) < 0 ? \
-	 (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
-	 (ishift_temp >> (shft)))
-#else
-#define ISHIFT_TEMPS
-#define IRIGHT_SHIFT(x,shft)	((x) >> (shft))
-#endif
-
-
-/*
- * Compute the derived values for a Huffman table.
- * This routine also performs some validation checks on the table.
- */
-
-LOCAL(void)
-jpeg_make_c_derived_tbl (j_compress_ptr cinfo, boolean isDC, int tblno,
-			 c_derived_tbl ** pdtbl)
-{
-  JHUFF_TBL *htbl;
-  c_derived_tbl *dtbl;
-  int p, i, l, lastp, si, maxsymbol;
-  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)
-    ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
-
-  /* Allocate a workspace if we haven't already done so. */
-  if (*pdtbl == NULL)
-    *pdtbl = (c_derived_tbl *)
-      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-				  SIZEOF(c_derived_tbl));
-  dtbl = *pdtbl;
-  
-  /* 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;
-  lastp = 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 C.3: generate encoding tables */
-  /* These are code and size indexed by symbol value */
-
-  /* Set all codeless symbols to have code length 0;
-   * this lets us detect duplicate VAL entries here, and later
-   * allows emit_bits to detect any attempt to emit such symbols.
-   */
-  MEMZERO(dtbl->ehufsi, SIZEOF(dtbl->ehufsi));
-
-  /* This is also a convenient place to check for out-of-range
-   * and duplicated VAL entries.  We allow 0..255 for AC symbols
-   * but only 0..15 for DC.  (We could constrain them further
-   * based on data depth and mode, but this seems enough.)
-   */
-  maxsymbol = isDC ? 15 : 255;
-
-  for (p = 0; p < lastp; p++) {
-    i = htbl->huffval[p];
-    if (i < 0 || i > maxsymbol || dtbl->ehufsi[i])
-      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
-    dtbl->ehufco[i] = huffcode[p];
-    dtbl->ehufsi[i] = huffsize[p];
-  }
-}
-
-
-/* Outputting bytes to the file.
- * NB: these must be called only when actually outputting,
- * that is, entropy->gather_statistics == FALSE.
- */
-
-/* Emit a byte, taking 'action' if must suspend. */
-#define emit_byte_s(state,val,action)  \
-	{ *(state)->next_output_byte++ = (JOCTET) (val);  \
-	  if (--(state)->free_in_buffer == 0)  \
-	    if (! dump_buffer_s(state))  \
-	      { action; } }
-
-/* Emit a byte */
-#define emit_byte_e(entropy,val)  \
-	{ *(entropy)->next_output_byte++ = (JOCTET) (val);  \
-	  if (--(entropy)->free_in_buffer == 0)  \
-	    dump_buffer_e(entropy); }
-
-
-LOCAL(boolean)
-dump_buffer_s (working_state * state)
-/* Empty the output buffer; return TRUE if successful, FALSE if must suspend */
-{
-  struct jpeg_destination_mgr * dest = state->cinfo->dest;
-
-  if (! (*dest->empty_output_buffer) (state->cinfo))
-    return FALSE;
-  /* After a successful buffer dump, must reset buffer pointers */
-  state->next_output_byte = dest->next_output_byte;
-  state->free_in_buffer = dest->free_in_buffer;
-  return TRUE;
-}
-
-
-LOCAL(void)
-dump_buffer_e (huff_entropy_ptr entropy)
-/* Empty the output buffer; we do not support suspension in this case. */
-{
-  struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
-
-  if (! (*dest->empty_output_buffer) (entropy->cinfo))
-    ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
-  /* After a successful buffer dump, must reset buffer pointers */
-  entropy->next_output_byte = dest->next_output_byte;
-  entropy->free_in_buffer = dest->free_in_buffer;
-}
-
-
-/* Outputting bits to the file */
-
-/* Only the right 24 bits of put_buffer are used; the valid bits are
- * left-justified in this part.  At most 16 bits can be passed to emit_bits
- * in one call, and we never retain more than 7 bits in put_buffer
- * between calls, so 24 bits are sufficient.
- */
-
-INLINE
-LOCAL(boolean)
-emit_bits_s (working_state * state, unsigned int code, int size)
-/* Emit some bits; return TRUE if successful, FALSE if must suspend */
-{
-  /* This routine is heavily used, so it's worth coding tightly. */
-  register INT32 put_buffer = (INT32) code;
-  register int put_bits = state->cur.put_bits;
-
-  /* if size is 0, caller used an invalid Huffman table entry */
-  if (size == 0)
-    ERREXIT(state->cinfo, JERR_HUFF_MISSING_CODE);
-
-  put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
-  
-  put_bits += size;		/* new number of bits in buffer */
-  
-  put_buffer <<= 24 - put_bits; /* align incoming bits */
-
-  put_buffer |= state->cur.put_buffer; /* and merge with old buffer contents */
-  
-  while (put_bits >= 8) {
-    int c = (int) ((put_buffer >> 16) & 0xFF);
-    
-    emit_byte_s(state, c, return FALSE);
-    if (c == 0xFF) {		/* need to stuff a zero byte? */
-      emit_byte_s(state, 0, return FALSE);
-    }
-    put_buffer <<= 8;
-    put_bits -= 8;
-  }
-
-  state->cur.put_buffer = put_buffer; /* update state variables */
-  state->cur.put_bits = put_bits;
-
-  return TRUE;
-}
-
-
-INLINE
-LOCAL(void)
-emit_bits_e (huff_entropy_ptr entropy, unsigned int code, int size)
-/* Emit some bits, unless we are in gather mode */
-{
-  /* This routine is heavily used, so it's worth coding tightly. */
-  register INT32 put_buffer = (INT32) code;
-  register int put_bits = entropy->saved.put_bits;
-
-  /* if size is 0, caller used an invalid Huffman table entry */
-  if (size == 0)
-    ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
-
-  if (entropy->gather_statistics)
-    return;			/* do nothing if we're only getting stats */
-
-  put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
-  
-  put_bits += size;		/* new number of bits in buffer */
-
-  put_buffer <<= 24 - put_bits; /* align incoming bits */
-
-  /* and merge with old buffer contents */
-  put_buffer |= entropy->saved.put_buffer;
-
-  while (put_bits >= 8) {
-    int c = (int) ((put_buffer >> 16) & 0xFF);
-
-    emit_byte_e(entropy, c);
-    if (c == 0xFF) {		/* need to stuff a zero byte? */
-      emit_byte_e(entropy, 0);
-    }
-    put_buffer <<= 8;
-    put_bits -= 8;
-  }
-
-  entropy->saved.put_buffer = put_buffer; /* update variables */
-  entropy->saved.put_bits = put_bits;
-}
-
-
-LOCAL(boolean)
-flush_bits_s (working_state * state)
-{
-  if (! emit_bits_s(state, 0x7F, 7)) /* fill any partial byte with ones */
-    return FALSE;
-  state->cur.put_buffer = 0;	     /* and reset bit-buffer to empty */
-  state->cur.put_bits = 0;
-  return TRUE;
-}
-
-
-LOCAL(void)
-flush_bits_e (huff_entropy_ptr entropy)
-{
-  emit_bits_e(entropy, 0x7F, 7); /* fill any partial byte with ones */
-  entropy->saved.put_buffer = 0; /* and reset bit-buffer to empty */
-  entropy->saved.put_bits = 0;
-}
-
-
-/*
- * Emit (or just count) a Huffman symbol.
- */
-
-INLINE
-LOCAL(void)
-emit_dc_symbol (huff_entropy_ptr entropy, int tbl_no, int symbol)
-{
-  if (entropy->gather_statistics)
-    entropy->dc_count_ptrs[tbl_no][symbol]++;
-  else {
-    c_derived_tbl * tbl = entropy->dc_derived_tbls[tbl_no];
-    emit_bits_e(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
-  }
-}
-
-
-INLINE
-LOCAL(void)
-emit_ac_symbol (huff_entropy_ptr entropy, int tbl_no, int symbol)
-{
-  if (entropy->gather_statistics)
-    entropy->ac_count_ptrs[tbl_no][symbol]++;
-  else {
-    c_derived_tbl * tbl = entropy->ac_derived_tbls[tbl_no];
-    emit_bits_e(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
-  }
-}
-
-
-/*
- * Emit bits from a correction bit buffer.
- */
-
-LOCAL(void)
-emit_buffered_bits (huff_entropy_ptr entropy, char * bufstart,
-		    unsigned int nbits)
-{
-  if (entropy->gather_statistics)
-    return;			/* no real work */
-
-  while (nbits > 0) {
-    emit_bits_e(entropy, (unsigned int) (*bufstart), 1);
-    bufstart++;
-    nbits--;
-  }
-}
-
-
-/*
- * Emit any pending EOBRUN symbol.
- */
-
-LOCAL(void)
-emit_eobrun (huff_entropy_ptr entropy)
-{
-  register int temp, nbits;
-
-  if (entropy->EOBRUN > 0) {	/* if there is any pending EOBRUN */
-    temp = entropy->EOBRUN;
-    nbits = 0;
-    while ((temp >>= 1))
-      nbits++;
-    /* safety check: shouldn't happen given limited correction-bit buffer */
-    if (nbits > 14)
-      ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
-
-    emit_ac_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
-    if (nbits)
-      emit_bits_e(entropy, entropy->EOBRUN, nbits);
-
-    entropy->EOBRUN = 0;
-
-    /* Emit any buffered correction bits */
-    emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
-    entropy->BE = 0;
-  }
-}
-
-
-/*
- * Emit a restart marker & resynchronize predictions.
- */
-
-LOCAL(boolean)
-emit_restart_s (working_state * state, int restart_num)
-{
-  int ci;
-
-  if (! flush_bits_s(state))
-    return FALSE;
-
-  emit_byte_s(state, 0xFF, return FALSE);
-  emit_byte_s(state, JPEG_RST0 + restart_num, return FALSE);
-
-  /* Re-initialize DC predictions to 0 */
-  for (ci = 0; ci < state->cinfo->comps_in_scan; ci++)
-    state->cur.last_dc_val[ci] = 0;
-
-  /* The restart counter is not updated until we successfully write the MCU. */
-
-  return TRUE;
-}
-
-
-LOCAL(void)
-emit_restart_e (huff_entropy_ptr entropy, int restart_num)
-{
-  int ci;
-
-  emit_eobrun(entropy);
-
-  if (! entropy->gather_statistics) {
-    flush_bits_e(entropy);
-    emit_byte_e(entropy, 0xFF);
-    emit_byte_e(entropy, JPEG_RST0 + restart_num);
-  }
-
-  if (entropy->cinfo->Ss == 0) {
-    /* Re-initialize DC predictions to 0 */
-    for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
-      entropy->saved.last_dc_val[ci] = 0;
-  } else {
-    /* Re-initialize all AC-related fields to 0 */
-    entropy->EOBRUN = 0;
-    entropy->BE = 0;
-  }
-}
-
-
-/*
- * MCU encoding for DC initial scan (either spectral selection,
- * or first pass of successive approximation).
- */
-
-METHODDEF(boolean)
-encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  register int temp, temp2;
-  register int nbits;
-  int blkn, ci;
-  int Al = cinfo->Al;
-  JBLOCKROW block;
-  jpeg_component_info * compptr;
-  ISHIFT_TEMPS
-
-  entropy->next_output_byte = cinfo->dest->next_output_byte;
-  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
-
-  /* Emit restart marker if needed */
-  if (cinfo->restart_interval)
-    if (entropy->restarts_to_go == 0)
-      emit_restart_e(entropy, entropy->next_restart_num);
-
-  /* Encode the MCU data blocks */
-  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
-    block = MCU_data[blkn];
-    ci = cinfo->MCU_membership[blkn];
-    compptr = cinfo->cur_comp_info[ci];
-
-    /* Compute the DC value after the required point transform by Al.
-     * This is simply an arithmetic right shift.
-     */
-    temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
-
-    /* DC differences are figured on the point-transformed values. */
-    temp = temp2 - entropy->saved.last_dc_val[ci];
-    entropy->saved.last_dc_val[ci] = temp2;
-
-    /* Encode the DC coefficient difference per section G.1.2.1 */
-    temp2 = temp;
-    if (temp < 0) {
-      temp = -temp;		/* temp is abs value of input */
-      /* For a negative input, want temp2 = bitwise complement of abs(input) */
-      /* This code assumes we are on a two's complement machine */
-      temp2--;
-    }
-    
-    /* Find the number of bits needed for the magnitude of the coefficient */
-    nbits = 0;
-    while (temp) {
-      nbits++;
-      temp >>= 1;
-    }
-    /* Check for out-of-range coefficient values.
-     * Since we're encoding a difference, the range limit is twice as much.
-     */
-    if (nbits > MAX_COEF_BITS+1)
-      ERREXIT(cinfo, JERR_BAD_DCT_COEF);
-    
-    /* Count/emit the Huffman-coded symbol for the number of bits */
-    emit_dc_symbol(entropy, compptr->dc_tbl_no, nbits);
-    
-    /* Emit that number of bits of the value, if positive, */
-    /* or the complement of its magnitude, if negative. */
-    if (nbits)			/* emit_bits rejects calls with size 0 */
-      emit_bits_e(entropy, (unsigned int) temp2, nbits);
-  }
-
-  cinfo->dest->next_output_byte = entropy->next_output_byte;
-  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
-
-  /* Update restart-interval state too */
-  if (cinfo->restart_interval) {
-    if (entropy->restarts_to_go == 0) {
-      entropy->restarts_to_go = cinfo->restart_interval;
-      entropy->next_restart_num++;
-      entropy->next_restart_num &= 7;
-    }
-    entropy->restarts_to_go--;
-  }
-
-  return TRUE;
-}
-
-
-/*
- * MCU encoding for AC initial scan (either spectral selection,
- * or first pass of successive approximation).
- */
-
-METHODDEF(boolean)
-encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  register int temp, temp2;
-  register int nbits;
-  register int r, k;
-  int Se, Al;
-  const int * natural_order;
-  JBLOCKROW block;
-
-  entropy->next_output_byte = cinfo->dest->next_output_byte;
-  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
-
-  /* Emit restart marker if needed */
-  if (cinfo->restart_interval)
-    if (entropy->restarts_to_go == 0)
-      emit_restart_e(entropy, entropy->next_restart_num);
-
-  Se = cinfo->Se;
-  Al = cinfo->Al;
-  natural_order = cinfo->natural_order;
-
-  /* Encode the MCU data block */
-  block = MCU_data[0];
-
-  /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
-  
-  r = 0;			/* r = run length of zeros */
-   
-  for (k = cinfo->Ss; k <= Se; k++) {
-    if ((temp = (*block)[natural_order[k]]) == 0) {
-      r++;
-      continue;
-    }
-    /* We must apply the point transform by Al.  For AC coefficients this
-     * is an integer division with rounding towards 0.  To do this portably
-     * in C, we shift after obtaining the absolute value; so the code is
-     * interwoven with finding the abs value (temp) and output bits (temp2).
-     */
-    if (temp < 0) {
-      temp = -temp;		/* temp is abs value of input */
-      temp >>= Al;		/* apply the point transform */
-      /* For a negative coef, want temp2 = bitwise complement of abs(coef) */
-      temp2 = ~temp;
-    } else {
-      temp >>= Al;		/* apply the point transform */
-      temp2 = temp;
-    }
-    /* Watch out for case that nonzero coef is zero after point transform */
-    if (temp == 0) {
-      r++;
-      continue;
-    }
-
-    /* Emit any pending EOBRUN */
-    if (entropy->EOBRUN > 0)
-      emit_eobrun(entropy);
-    /* if run length > 15, must emit special run-length-16 codes (0xF0) */
-    while (r > 15) {
-      emit_ac_symbol(entropy, entropy->ac_tbl_no, 0xF0);
-      r -= 16;
-    }
-
-    /* Find the number of bits needed for the magnitude of the coefficient */
-    nbits = 1;			/* there must be at least one 1 bit */
-    while ((temp >>= 1))
-      nbits++;
-    /* Check for out-of-range coefficient values */
-    if (nbits > MAX_COEF_BITS)
-      ERREXIT(cinfo, JERR_BAD_DCT_COEF);
-
-    /* Count/emit Huffman symbol for run length / number of bits */
-    emit_ac_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
-
-    /* Emit that number of bits of the value, if positive, */
-    /* or the complement of its magnitude, if negative. */
-    emit_bits_e(entropy, (unsigned int) temp2, nbits);
-
-    r = 0;			/* reset zero run length */
-  }
-
-  if (r > 0) {			/* If there are trailing zeroes, */
-    entropy->EOBRUN++;		/* count an EOB */
-    if (entropy->EOBRUN == 0x7FFF)
-      emit_eobrun(entropy);	/* force it out to avoid overflow */
-  }
-
-  cinfo->dest->next_output_byte = entropy->next_output_byte;
-  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
-
-  /* Update restart-interval state too */
-  if (cinfo->restart_interval) {
-    if (entropy->restarts_to_go == 0) {
-      entropy->restarts_to_go = cinfo->restart_interval;
-      entropy->next_restart_num++;
-      entropy->next_restart_num &= 7;
-    }
-    entropy->restarts_to_go--;
-  }
-
-  return TRUE;
-}
-
-
-/*
- * MCU encoding 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)
-encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  register int temp;
-  int blkn;
-  int Al = cinfo->Al;
-  JBLOCKROW block;
-
-  entropy->next_output_byte = cinfo->dest->next_output_byte;
-  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
-
-  /* Emit restart marker if needed */
-  if (cinfo->restart_interval)
-    if (entropy->restarts_to_go == 0)
-      emit_restart_e(entropy, entropy->next_restart_num);
-
-  /* Encode the MCU data blocks */
-  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
-    block = MCU_data[blkn];
-
-    /* We simply emit the Al'th bit of the DC coefficient value. */
-    temp = (*block)[0];
-    emit_bits_e(entropy, (unsigned int) (temp >> Al), 1);
-  }
-
-  cinfo->dest->next_output_byte = entropy->next_output_byte;
-  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
-
-  /* Update restart-interval state too */
-  if (cinfo->restart_interval) {
-    if (entropy->restarts_to_go == 0) {
-      entropy->restarts_to_go = cinfo->restart_interval;
-      entropy->next_restart_num++;
-      entropy->next_restart_num &= 7;
-    }
-    entropy->restarts_to_go--;
-  }
-
-  return TRUE;
-}
-
-
-/*
- * MCU encoding for AC successive approximation refinement scan.
- */
-
-METHODDEF(boolean)
-encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  register int temp;
-  register int r, k;
-  int EOB;
-  char *BR_buffer;
-  unsigned int BR;
-  int Se, Al;
-  const int * natural_order;
-  JBLOCKROW block;
-  int absvalues[DCTSIZE2];
-
-  entropy->next_output_byte = cinfo->dest->next_output_byte;
-  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
-
-  /* Emit restart marker if needed */
-  if (cinfo->restart_interval)
-    if (entropy->restarts_to_go == 0)
-      emit_restart_e(entropy, entropy->next_restart_num);
-
-  Se = cinfo->Se;
-  Al = cinfo->Al;
-  natural_order = cinfo->natural_order;
-
-  /* Encode the MCU data block */
-  block = MCU_data[0];
-
-  /* It is convenient to make a pre-pass to determine the transformed
-   * coefficients' absolute values and the EOB position.
-   */
-  EOB = 0;
-  for (k = cinfo->Ss; k <= Se; k++) {
-    temp = (*block)[natural_order[k]];
-    /* We must apply the point transform by Al.  For AC coefficients this
-     * is an integer division with rounding towards 0.  To do this portably
-     * in C, we shift after obtaining the absolute value.
-     */
-    if (temp < 0)
-      temp = -temp;		/* temp is abs value of input */
-    temp >>= Al;		/* apply the point transform */
-    absvalues[k] = temp;	/* save abs value for main pass */
-    if (temp == 1)
-      EOB = k;			/* EOB = index of last newly-nonzero coef */
-  }
-
-  /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
-  
-  r = 0;			/* r = run length of zeros */
-  BR = 0;			/* BR = count of buffered bits added now */
-  BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
-
-  for (k = cinfo->Ss; k <= Se; k++) {
-    if ((temp = absvalues[k]) == 0) {
-      r++;
-      continue;
-    }
-
-    /* Emit any required ZRLs, but not if they can be folded into EOB */
-    while (r > 15 && k <= EOB) {
-      /* emit any pending EOBRUN and the BE correction bits */
-      emit_eobrun(entropy);
-      /* Emit ZRL */
-      emit_ac_symbol(entropy, entropy->ac_tbl_no, 0xF0);
-      r -= 16;
-      /* Emit buffered correction bits that must be associated with ZRL */
-      emit_buffered_bits(entropy, BR_buffer, BR);
-      BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
-      BR = 0;
-    }
-
-    /* If the coef was previously nonzero, it only needs a correction bit.
-     * NOTE: a straight translation of the spec's figure G.7 would suggest
-     * that we also need to test r > 15.  But if r > 15, we can only get here
-     * if k > EOB, which implies that this coefficient is not 1.
-     */
-    if (temp > 1) {
-      /* The correction bit is the next bit of the absolute value. */
-      BR_buffer[BR++] = (char) (temp & 1);
-      continue;
-    }
-
-    /* Emit any pending EOBRUN and the BE correction bits */
-    emit_eobrun(entropy);
-
-    /* Count/emit Huffman symbol for run length / number of bits */
-    emit_ac_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
-
-    /* Emit output bit for newly-nonzero coef */
-    temp = ((*block)[natural_order[k]] < 0) ? 0 : 1;
-    emit_bits_e(entropy, (unsigned int) temp, 1);
-
-    /* Emit buffered correction bits that must be associated with this code */
-    emit_buffered_bits(entropy, BR_buffer, BR);
-    BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
-    BR = 0;
-    r = 0;			/* reset zero run length */
-  }
-
-  if (r > 0 || BR > 0) {	/* If there are trailing zeroes, */
-    entropy->EOBRUN++;		/* count an EOB */
-    entropy->BE += BR;		/* concat my correction bits to older ones */
-    /* We force out the EOB if we risk either:
-     * 1. overflow of the EOB counter;
-     * 2. overflow of the correction bit buffer during the next MCU.
-     */
-    if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
-      emit_eobrun(entropy);
-  }
-
-  cinfo->dest->next_output_byte = entropy->next_output_byte;
-  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
-
-  /* Update restart-interval state too */
-  if (cinfo->restart_interval) {
-    if (entropy->restarts_to_go == 0) {
-      entropy->restarts_to_go = cinfo->restart_interval;
-      entropy->next_restart_num++;
-      entropy->next_restart_num &= 7;
-    }
-    entropy->restarts_to_go--;
-  }
-
-  return TRUE;
-}
-
-
-/* Encode a single block's worth of coefficients */
-
-LOCAL(boolean)
-encode_one_block (working_state * state, JCOEFPTR block, int last_dc_val,
-		  c_derived_tbl *dctbl, c_derived_tbl *actbl)
-{
-  register int temp, temp2;
-  register int nbits;
-  register int k, r, i;
-  int Se = state->cinfo->lim_Se;
-  const int * natural_order = state->cinfo->natural_order;
-
-  /* Encode the DC coefficient difference per section F.1.2.1 */
-
-  temp = temp2 = block[0] - last_dc_val;
-
-  if (temp < 0) {
-    temp = -temp;		/* temp is abs value of input */
-    /* For a negative input, want temp2 = bitwise complement of abs(input) */
-    /* This code assumes we are on a two's complement machine */
-    temp2--;
-  }
-
-  /* Find the number of bits needed for the magnitude of the coefficient */
-  nbits = 0;
-  while (temp) {
-    nbits++;
-    temp >>= 1;
-  }
-  /* Check for out-of-range coefficient values.
-   * Since we're encoding a difference, the range limit is twice as much.
-   */
-  if (nbits > MAX_COEF_BITS+1)
-    ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
-
-  /* Emit the Huffman-coded symbol for the number of bits */
-  if (! emit_bits_s(state, dctbl->ehufco[nbits], dctbl->ehufsi[nbits]))
-    return FALSE;
-
-  /* Emit that number of bits of the value, if positive, */
-  /* or the complement of its magnitude, if negative. */
-  if (nbits)			/* emit_bits rejects calls with size 0 */
-    if (! emit_bits_s(state, (unsigned int) temp2, nbits))
-      return FALSE;
-
-  /* Encode the AC coefficients per section F.1.2.2 */
-
-  r = 0;			/* r = run length of zeros */
-
-  for (k = 1; k <= Se; k++) {
-    if ((temp = block[natural_order[k]]) == 0) {
-      r++;
-    } else {
-      /* if run length > 15, must emit special run-length-16 codes (0xF0) */
-      while (r > 15) {
-	if (! emit_bits_s(state, actbl->ehufco[0xF0], actbl->ehufsi[0xF0]))
-	  return FALSE;
-	r -= 16;
-      }
-
-      temp2 = temp;
-      if (temp < 0) {
-	temp = -temp;		/* temp is abs value of input */
-	/* This code assumes we are on a two's complement machine */
-	temp2--;
-      }
-
-      /* Find the number of bits needed for the magnitude of the coefficient */
-      nbits = 1;		/* there must be at least one 1 bit */
-      while ((temp >>= 1))
-	nbits++;
-      /* Check for out-of-range coefficient values */
-      if (nbits > MAX_COEF_BITS)
-	ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
-
-      /* Emit Huffman symbol for run length / number of bits */
-      i = (r << 4) + nbits;
-      if (! emit_bits_s(state, actbl->ehufco[i], actbl->ehufsi[i]))
-	return FALSE;
-
-      /* Emit that number of bits of the value, if positive, */
-      /* or the complement of its magnitude, if negative. */
-      if (! emit_bits_s(state, (unsigned int) temp2, nbits))
-	return FALSE;
-
-      r = 0;
-    }
-  }
-
-  /* If the last coef(s) were zero, emit an end-of-block code */
-  if (r > 0)
-    if (! emit_bits_s(state, actbl->ehufco[0], actbl->ehufsi[0]))
-      return FALSE;
-
-  return TRUE;
-}
-
-
-/*
- * Encode and output one MCU's worth of Huffman-compressed coefficients.
- */
-
-METHODDEF(boolean)
-encode_mcu_huff (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  working_state state;
-  int blkn, ci;
-  jpeg_component_info * compptr;
-
-  /* Load up working state */
-  state.next_output_byte = cinfo->dest->next_output_byte;
-  state.free_in_buffer = cinfo->dest->free_in_buffer;
-  ASSIGN_STATE(state.cur, entropy->saved);
-  state.cinfo = cinfo;
-
-  /* Emit restart marker if needed */
-  if (cinfo->restart_interval) {
-    if (entropy->restarts_to_go == 0)
-      if (! emit_restart_s(&state, entropy->next_restart_num))
-	return FALSE;
-  }
-
-  /* Encode the MCU data blocks */
-  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
-    ci = cinfo->MCU_membership[blkn];
-    compptr = cinfo->cur_comp_info[ci];
-    if (! encode_one_block(&state,
-			   MCU_data[blkn][0], state.cur.last_dc_val[ci],
-			   entropy->dc_derived_tbls[compptr->dc_tbl_no],
-			   entropy->ac_derived_tbls[compptr->ac_tbl_no]))
-      return FALSE;
-    /* Update last_dc_val */
-    state.cur.last_dc_val[ci] = MCU_data[blkn][0][0];
-  }
-
-  /* Completed MCU, so update state */
-  cinfo->dest->next_output_byte = state.next_output_byte;
-  cinfo->dest->free_in_buffer = state.free_in_buffer;
-  ASSIGN_STATE(entropy->saved, state.cur);
-
-  /* Update restart-interval state too */
-  if (cinfo->restart_interval) {
-    if (entropy->restarts_to_go == 0) {
-      entropy->restarts_to_go = cinfo->restart_interval;
-      entropy->next_restart_num++;
-      entropy->next_restart_num &= 7;
-    }
-    entropy->restarts_to_go--;
-  }
-
-  return TRUE;
-}
-
-
-/*
- * Finish up at the end of a Huffman-compressed scan.
- */
-
-METHODDEF(void)
-finish_pass_huff (j_compress_ptr cinfo)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  working_state state;
-
-  if (cinfo->progressive_mode) {
-    entropy->next_output_byte = cinfo->dest->next_output_byte;
-    entropy->free_in_buffer = cinfo->dest->free_in_buffer;
-
-    /* Flush out any buffered data */
-    emit_eobrun(entropy);
-    flush_bits_e(entropy);
-
-    cinfo->dest->next_output_byte = entropy->next_output_byte;
-    cinfo->dest->free_in_buffer = entropy->free_in_buffer;
-  } else {
-    /* Load up working state ... flush_bits needs it */
-    state.next_output_byte = cinfo->dest->next_output_byte;
-    state.free_in_buffer = cinfo->dest->free_in_buffer;
-    ASSIGN_STATE(state.cur, entropy->saved);
-    state.cinfo = cinfo;
-
-    /* Flush out the last data */
-    if (! flush_bits_s(&state))
-      ERREXIT(cinfo, JERR_CANT_SUSPEND);
-
-    /* Update state */
-    cinfo->dest->next_output_byte = state.next_output_byte;
-    cinfo->dest->free_in_buffer = state.free_in_buffer;
-    ASSIGN_STATE(entropy->saved, state.cur);
-  }
-}
-
-
-/*
- * Huffman coding optimization.
- *
- * We first scan the supplied data and count the number of uses of each symbol
- * that is to be Huffman-coded. (This process MUST agree with the code above.)
- * Then we build a Huffman coding tree for the observed counts.
- * Symbols which are not needed at all for the particular image are not
- * assigned any code, which saves space in the DHT marker as well as in
- * the compressed data.
- */
-
-
-/* Process a single block's worth of coefficients */
-
-LOCAL(void)
-htest_one_block (j_compress_ptr cinfo, JCOEFPTR block, int last_dc_val,
-		 long dc_counts[], long ac_counts[])
-{
-  register int temp;
-  register int nbits;
-  register int k, r;
-  int Se = cinfo->lim_Se;
-  const int * natural_order = cinfo->natural_order;
-  
-  /* Encode the DC coefficient difference per section F.1.2.1 */
-  
-  temp = block[0] - last_dc_val;
-  if (temp < 0)
-    temp = -temp;
-  
-  /* Find the number of bits needed for the magnitude of the coefficient */
-  nbits = 0;
-  while (temp) {
-    nbits++;
-    temp >>= 1;
-  }
-  /* Check for out-of-range coefficient values.
-   * Since we're encoding a difference, the range limit is twice as much.
-   */
-  if (nbits > MAX_COEF_BITS+1)
-    ERREXIT(cinfo, JERR_BAD_DCT_COEF);
-
-  /* Count the Huffman symbol for the number of bits */
-  dc_counts[nbits]++;
-  
-  /* Encode the AC coefficients per section F.1.2.2 */
-  
-  r = 0;			/* r = run length of zeros */
-  
-  for (k = 1; k <= Se; k++) {
-    if ((temp = block[natural_order[k]]) == 0) {
-      r++;
-    } else {
-      /* if run length > 15, must emit special run-length-16 codes (0xF0) */
-      while (r > 15) {
-	ac_counts[0xF0]++;
-	r -= 16;
-      }
-      
-      /* Find the number of bits needed for the magnitude of the coefficient */
-      if (temp < 0)
-	temp = -temp;
-      
-      /* Find the number of bits needed for the magnitude of the coefficient */
-      nbits = 1;		/* there must be at least one 1 bit */
-      while ((temp >>= 1))
-	nbits++;
-      /* Check for out-of-range coefficient values */
-      if (nbits > MAX_COEF_BITS)
-	ERREXIT(cinfo, JERR_BAD_DCT_COEF);
-      
-      /* Count Huffman symbol for run length / number of bits */
-      ac_counts[(r << 4) + nbits]++;
-      
-      r = 0;
-    }
-  }
-
-  /* If the last coef(s) were zero, emit an end-of-block code */
-  if (r > 0)
-    ac_counts[0]++;
-}
-
-
-/*
- * Trial-encode one MCU's worth of Huffman-compressed coefficients.
- * No data is actually output, so no suspension return is possible.
- */
-
-METHODDEF(boolean)
-encode_mcu_gather (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  int blkn, ci;
-  jpeg_component_info * compptr;
-
-  /* Take care of restart intervals if needed */
-  if (cinfo->restart_interval) {
-    if (entropy->restarts_to_go == 0) {
-      /* Re-initialize DC predictions to 0 */
-      for (ci = 0; ci < cinfo->comps_in_scan; ci++)
-	entropy->saved.last_dc_val[ci] = 0;
-      /* Update restart state */
-      entropy->restarts_to_go = cinfo->restart_interval;
-    }
-    entropy->restarts_to_go--;
-  }
-
-  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
-    ci = cinfo->MCU_membership[blkn];
-    compptr = cinfo->cur_comp_info[ci];
-    htest_one_block(cinfo, MCU_data[blkn][0], entropy->saved.last_dc_val[ci],
-		    entropy->dc_count_ptrs[compptr->dc_tbl_no],
-		    entropy->ac_count_ptrs[compptr->ac_tbl_no]);
-    entropy->saved.last_dc_val[ci] = MCU_data[blkn][0][0];
-  }
-
-  return TRUE;
-}
-
-
-/*
- * Generate the best Huffman code table for the given counts, fill htbl.
- *
- * The JPEG standard requires that no symbol be assigned a codeword of all
- * one bits (so that padding bits added at the end of a compressed segment
- * can't look like a valid code).  Because of the canonical ordering of
- * codewords, this just means that there must be an unused slot in the
- * longest codeword length category.  Section K.2 of the JPEG spec suggests
- * reserving such a slot by pretending that symbol 256 is a valid symbol
- * with count 1.  In theory that's not optimal; giving it count zero but
- * including it in the symbol set anyway should give a better Huffman code.
- * But the theoretically better code actually seems to come out worse in
- * practice, because it produces more all-ones bytes (which incur stuffed
- * zero bytes in the final file).  In any case the difference is tiny.
- *
- * The JPEG standard requires Huffman codes to be no more than 16 bits long.
- * If some symbols have a very small but nonzero probability, the Huffman tree
- * must be adjusted to meet the code length restriction.  We currently use
- * the adjustment method suggested in JPEG section K.2.  This method is *not*
- * optimal; it may not choose the best possible limited-length code.  But
- * typically only very-low-frequency symbols will be given less-than-optimal
- * lengths, so the code is almost optimal.  Experimental comparisons against
- * an optimal limited-length-code algorithm indicate that the difference is
- * microscopic --- usually less than a hundredth of a percent of total size.
- * So the extra complexity of an optimal algorithm doesn't seem worthwhile.
- */
-
-LOCAL(void)
-jpeg_gen_optimal_table (j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[])
-{
-#define MAX_CLEN 32		/* assumed maximum initial code length */
-  UINT8 bits[MAX_CLEN+1];	/* bits[k] = # of symbols with code length k */
-  int codesize[257];		/* codesize[k] = code length of symbol k */
-  int others[257];		/* next symbol in current branch of tree */
-  int c1, c2;
-  int p, i, j;
-  long v;
-
-  /* This algorithm is explained in section K.2 of the JPEG standard */
-
-  MEMZERO(bits, SIZEOF(bits));
-  MEMZERO(codesize, SIZEOF(codesize));
-  for (i = 0; i < 257; i++)
-    others[i] = -1;		/* init links to empty */
-  
-  freq[256] = 1;		/* make sure 256 has a nonzero count */
-  /* Including the pseudo-symbol 256 in the Huffman procedure guarantees
-   * that no real symbol is given code-value of all ones, because 256
-   * will be placed last in the largest codeword category.
-   */
-
-  /* Huffman's basic algorithm to assign optimal code lengths to symbols */
-
-  for (;;) {
-    /* Find the smallest nonzero frequency, set c1 = its symbol */
-    /* In case of ties, take the larger symbol number */
-    c1 = -1;
-    v = 1000000000L;
-    for (i = 0; i <= 256; i++) {
-      if (freq[i] && freq[i] <= v) {
-	v = freq[i];
-	c1 = i;
-      }
-    }
-
-    /* Find the next smallest nonzero frequency, set c2 = its symbol */
-    /* In case of ties, take the larger symbol number */
-    c2 = -1;
-    v = 1000000000L;
-    for (i = 0; i <= 256; i++) {
-      if (freq[i] && freq[i] <= v && i != c1) {
-	v = freq[i];
-	c2 = i;
-      }
-    }
-
-    /* Done if we've merged everything into one frequency */
-    if (c2 < 0)
-      break;
-    
-    /* Else merge the two counts/trees */
-    freq[c1] += freq[c2];
-    freq[c2] = 0;
-
-    /* Increment the codesize of everything in c1's tree branch */
-    codesize[c1]++;
-    while (others[c1] >= 0) {
-      c1 = others[c1];
-      codesize[c1]++;
-    }
-    
-    others[c1] = c2;		/* chain c2 onto c1's tree branch */
-    
-    /* Increment the codesize of everything in c2's tree branch */
-    codesize[c2]++;
-    while (others[c2] >= 0) {
-      c2 = others[c2];
-      codesize[c2]++;
-    }
-  }
-
-  /* Now count the number of symbols of each code length */
-  for (i = 0; i <= 256; i++) {
-    if (codesize[i]) {
-      /* The JPEG standard seems to think that this can't happen, */
-      /* but I'm paranoid... */
-      if (codesize[i] > MAX_CLEN)
-	ERREXIT(cinfo, JERR_HUFF_CLEN_OVERFLOW);
-
-      bits[codesize[i]]++;
-    }
-  }
-
-  /* JPEG doesn't allow symbols with code lengths over 16 bits, so if the pure
-   * Huffman procedure assigned any such lengths, we must adjust the coding.
-   * Here is what the JPEG spec says about how this next bit works:
-   * Since symbols are paired for the longest Huffman code, the symbols are
-   * removed from this length category two at a time.  The prefix for the pair
-   * (which is one bit shorter) is allocated to one of the pair; then,
-   * skipping the BITS entry for that prefix length, a code word from the next
-   * shortest nonzero BITS entry is converted into a prefix for two code words
-   * one bit longer.
-   */
-  
-  for (i = MAX_CLEN; i > 16; i--) {
-    while (bits[i] > 0) {
-      j = i - 2;		/* find length of new prefix to be used */
-      while (bits[j] == 0)
-	j--;
-      
-      bits[i] -= 2;		/* remove two symbols */
-      bits[i-1]++;		/* one goes in this length */
-      bits[j+1] += 2;		/* two new symbols in this length */
-      bits[j]--;		/* symbol of this length is now a prefix */
-    }
-  }
-
-  /* Remove the count for the pseudo-symbol 256 from the largest codelength */
-  while (bits[i] == 0)		/* find largest codelength still in use */
-    i--;
-  bits[i]--;
-  
-  /* Return final symbol counts (only for lengths 0..16) */
-  MEMCOPY(htbl->bits, bits, SIZEOF(htbl->bits));
-  
-  /* Return a list of the symbols sorted by code length */
-  /* It's not real clear to me why we don't need to consider the codelength
-   * changes made above, but the JPEG spec seems to think this works.
-   */
-  p = 0;
-  for (i = 1; i <= MAX_CLEN; i++) {
-    for (j = 0; j <= 255; j++) {
-      if (codesize[j] == i) {
-	htbl->huffval[p] = (UINT8) j;
-	p++;
-      }
-    }
-  }
-
-  /* Set sent_table FALSE so updated table will be written to JPEG file. */
-  htbl->sent_table = FALSE;
-}
-
-
-/*
- * Finish up a statistics-gathering pass and create the new Huffman tables.
- */
-
-METHODDEF(void)
-finish_pass_gather (j_compress_ptr cinfo)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  int ci, tbl;
-  jpeg_component_info * compptr;
-  JHUFF_TBL **htblptr;
-  boolean did_dc[NUM_HUFF_TBLS];
-  boolean did_ac[NUM_HUFF_TBLS];
-
-  /* It's important not to apply jpeg_gen_optimal_table more than once
-   * per table, because it clobbers the input frequency counts!
-   */
-  if (cinfo->progressive_mode)
-    /* Flush out buffered data (all we care about is counting the EOB symbol) */
-    emit_eobrun(entropy);
-
-  MEMZERO(did_dc, SIZEOF(did_dc));
-  MEMZERO(did_ac, SIZEOF(did_ac));
-
-  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
-    compptr = cinfo->cur_comp_info[ci];
-    /* DC needs no table for refinement scan */
-    if (cinfo->Ss == 0 && cinfo->Ah == 0) {
-      tbl = compptr->dc_tbl_no;
-      if (! did_dc[tbl]) {
-	htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
-	if (*htblptr == NULL)
-	  *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
-	jpeg_gen_optimal_table(cinfo, *htblptr, entropy->dc_count_ptrs[tbl]);
-	did_dc[tbl] = TRUE;
-      }
-    }
-    /* AC needs no table when not present */
-    if (cinfo->Se) {
-      tbl = compptr->ac_tbl_no;
-      if (! did_ac[tbl]) {
-	htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
-	if (*htblptr == NULL)
-	  *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
-	jpeg_gen_optimal_table(cinfo, *htblptr, entropy->ac_count_ptrs[tbl]);
-	did_ac[tbl] = TRUE;
-      }
-    }
-  }
-}
-
-
-/*
- * Initialize for a Huffman-compressed scan.
- * If gather_statistics is TRUE, we do not output anything during the scan,
- * just count the Huffman symbols used and generate Huffman code tables.
- */
-
-METHODDEF(void)
-start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics)
-{
-  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
-  int ci, tbl;
-  jpeg_component_info * compptr;
-
-  if (gather_statistics)
-    entropy->pub.finish_pass = finish_pass_gather;
-  else
-    entropy->pub.finish_pass = finish_pass_huff;
-
-  if (cinfo->progressive_mode) {
-    entropy->cinfo = cinfo;
-    entropy->gather_statistics = gather_statistics;
-
-    /* We assume jcmaster.c already validated the scan parameters. */
-
-    /* Select execution routine */
-    if (cinfo->Ah == 0) {
-      if (cinfo->Ss == 0)
-	entropy->pub.encode_mcu = encode_mcu_DC_first;
-      else
-	entropy->pub.encode_mcu = encode_mcu_AC_first;
-    } else {
-      if (cinfo->Ss == 0)
-	entropy->pub.encode_mcu = encode_mcu_DC_refine;
-      else {
-	entropy->pub.encode_mcu = encode_mcu_AC_refine;
-	/* AC refinement needs a correction bit buffer */
-	if (entropy->bit_buffer == NULL)
-	  entropy->bit_buffer = (char *)
-	    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-					MAX_CORR_BITS * SIZEOF(char));
-      }
-    }
-
-    /* Initialize AC stuff */
-    entropy->ac_tbl_no = cinfo->cur_comp_info[0]->ac_tbl_no;
-    entropy->EOBRUN = 0;
-    entropy->BE = 0;
-  } else {
-    if (gather_statistics)
-      entropy->pub.encode_mcu = encode_mcu_gather;
-    else
-      entropy->pub.encode_mcu = encode_mcu_huff;
-  }
-
-  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
-    compptr = cinfo->cur_comp_info[ci];
-    /* DC needs no table for refinement scan */
-    if (cinfo->Ss == 0 && cinfo->Ah == 0) {
-      tbl = compptr->dc_tbl_no;
-      if (gather_statistics) {
-	/* Check for invalid table index */
-	/* (make_c_derived_tbl does this in the other path) */
-	if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
-	  ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
-	/* Allocate and zero the statistics tables */
-	/* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
-	if (entropy->dc_count_ptrs[tbl] == NULL)
-	  entropy->dc_count_ptrs[tbl] = (long *)
-	    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-					257 * SIZEOF(long));
-	MEMZERO(entropy->dc_count_ptrs[tbl], 257 * SIZEOF(long));
-      } else {
-	/* Compute derived values for Huffman tables */
-	/* We may do this more than once for a table, but it's not expensive */
-	jpeg_make_c_derived_tbl(cinfo, TRUE, tbl,
-				& entropy->dc_derived_tbls[tbl]);
-      }
-      /* Initialize DC predictions to 0 */
-      entropy->saved.last_dc_val[ci] = 0;
-    }
-    /* AC needs no table when not present */
-    if (cinfo->Se) {
-      tbl = compptr->ac_tbl_no;
-      if (gather_statistics) {
-	if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
-	  ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
-	if (entropy->ac_count_ptrs[tbl] == NULL)
-	  entropy->ac_count_ptrs[tbl] = (long *)
-	    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-					257 * SIZEOF(long));
-	MEMZERO(entropy->ac_count_ptrs[tbl], 257 * SIZEOF(long));
-      } else {
-	jpeg_make_c_derived_tbl(cinfo, FALSE, tbl,
-				& entropy->ac_derived_tbls[tbl]);
-      }
-    }
-  }
-
-  /* Initialize bit buffer to empty */
-  entropy->saved.put_buffer = 0;
-  entropy->saved.put_bits = 0;
-
-  /* Initialize restart stuff */
-  entropy->restarts_to_go = cinfo->restart_interval;
-  entropy->next_restart_num = 0;
-}
-
-
-/*
- * Module initialization routine for Huffman entropy encoding.
- */
-
-GLOBAL(void)
-jinit_huff_encoder (j_compress_ptr cinfo)
-{
-  huff_entropy_ptr entropy;
-  int i;
-
-  entropy = (huff_entropy_ptr)
-    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-				SIZEOF(huff_entropy_encoder));
-  cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
-  entropy->pub.start_pass = start_pass_huff;
-
-  /* Mark tables unallocated */
-  for (i = 0; i < NUM_HUFF_TBLS; i++) {
-    entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
-    entropy->dc_count_ptrs[i] = entropy->ac_count_ptrs[i] = NULL;
-  }
-
-  if (cinfo->progressive_mode)
-    entropy->bit_buffer = NULL;	/* needed only in AC refinement scan */
-}
+/*

+ * jchuff.c

+ *

+ * Copyright (C) 1991-1997, Thomas G. Lane.

+ * Modified 2006-2009 by Guido Vollbeding.

+ * 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 encoding routines.

+ * Both sequential and progressive modes are supported in this single module.

+ *

+ * Much of the complexity here has to do with supporting output suspension.

+ * If the data destination 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 JPEG objects only upon successful completion of an MCU.

+ *

+ * We do not support output suspension for the progressive JPEG mode, since

+ * the library currently does not allow multiple-scan files to be written

+ * with output suspension.

+ */

+

+#define JPEG_INTERNALS

+#include "jinclude.h"

+#include "jpeglib.h"

+

+

+/* The legal range of a DCT coefficient is

+ *  -1024 .. +1023  for 8-bit data;

+ * -16384 .. +16383 for 12-bit data.

+ * Hence the magnitude should always fit in 10 or 14 bits respectively.

+ */

+

+#if BITS_IN_JSAMPLE == 8

+#define MAX_COEF_BITS 10

+#else

+#define MAX_COEF_BITS 14

+#endif

+

+/* Derived data constructed for each Huffman table */

+

+typedef struct {

+  unsigned int ehufco[256];	/* code for each symbol */

+  char ehufsi[256];		/* length of code for each symbol */

+  /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */

+} c_derived_tbl;

+

+

+/* Expanded entropy encoder object for Huffman encoding.

+ *

+ * The savable_state subrecord contains fields that change within an MCU,

+ * but must not be updated permanently until we complete the MCU.

+ */

+

+typedef struct {

+  INT32 put_buffer;		/* current bit-accumulation buffer */

+  int put_bits;			/* # of bits now in it */

+  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).put_buffer = (src).put_buffer, \

+	 (dest).put_bits = (src).put_bits, \

+	 (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_encoder pub; /* public fields */

+

+  savable_state saved;		/* Bit buffer & DC 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 */

+  int next_restart_num;		/* next restart number to write (0-7) */

+

+  /* Pointers to derived tables (these workspaces have image lifespan) */

+  c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];

+  c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];

+

+  /* Statistics tables for optimization */

+  long * dc_count_ptrs[NUM_HUFF_TBLS];

+  long * ac_count_ptrs[NUM_HUFF_TBLS];

+

+  /* Following fields used only in progressive mode */

+

+  /* Mode flag: TRUE for optimization, FALSE for actual data output */

+  boolean gather_statistics;

+

+  /* next_output_byte/free_in_buffer are local copies of cinfo->dest fields.

+   */

+  JOCTET * next_output_byte;	/* => next byte to write in buffer */

+  size_t free_in_buffer;	/* # of byte spaces remaining in buffer */

+  j_compress_ptr cinfo;		/* link to cinfo (needed for dump_buffer) */

+

+  /* Coding status for AC components */

+  int ac_tbl_no;		/* the table number of the single component */

+  unsigned int EOBRUN;		/* run length of EOBs */

+  unsigned int BE;		/* # of buffered correction bits before MCU */

+  char * bit_buffer;		/* buffer for correction bits (1 per char) */

+  /* packing correction bits tightly would save some space but cost time... */

+} huff_entropy_encoder;

+

+typedef huff_entropy_encoder * huff_entropy_ptr;

+

+/* Working state while writing an MCU (sequential mode).

+ * This struct contains all the fields that are needed by subroutines.

+ */

+

+typedef struct {

+  JOCTET * next_output_byte;	/* => next byte to write in buffer */

+  size_t free_in_buffer;	/* # of byte spaces remaining in buffer */

+  savable_state cur;		/* Current bit buffer & DC state */

+  j_compress_ptr cinfo;		/* dump_buffer needs access to this */

+} working_state;

+

+/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit

+ * buffer can hold.  Larger sizes may slightly improve compression, but

+ * 1000 is already well into the realm of overkill.

+ * The minimum safe size is 64 bits.

+ */

+

+#define MAX_CORR_BITS  1000	/* Max # of correction bits I can buffer */

+

+/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.

+ * We assume that int right shift is unsigned if INT32 right shift is,

+ * which should be safe.

+ */

+

+#ifdef RIGHT_SHIFT_IS_UNSIGNED

+#define ISHIFT_TEMPS	int ishift_temp;

+#define IRIGHT_SHIFT(x,shft)  \

+	((ishift_temp = (x)) < 0 ? \

+	 (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \

+	 (ishift_temp >> (shft)))

+#else

+#define ISHIFT_TEMPS

+#define IRIGHT_SHIFT(x,shft)	((x) >> (shft))

+#endif

+

+

+/*

+ * Compute the derived values for a Huffman table.

+ * This routine also performs some validation checks on the table.

+ */

+

+LOCAL(void)

+jpeg_make_c_derived_tbl (j_compress_ptr cinfo, boolean isDC, int tblno,

+			 c_derived_tbl ** pdtbl)

+{

+  JHUFF_TBL *htbl;

+  c_derived_tbl *dtbl;

+  int p, i, l, lastp, si, maxsymbol;

+  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)

+    ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);

+

+  /* Allocate a workspace if we haven't already done so. */

+  if (*pdtbl == NULL)

+    *pdtbl = (c_derived_tbl *)

+      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

+				  SIZEOF(c_derived_tbl));

+  dtbl = *pdtbl;

+  

+  /* 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;

+  lastp = 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 C.3: generate encoding tables */

+  /* These are code and size indexed by symbol value */

+

+  /* Set all codeless symbols to have code length 0;

+   * this lets us detect duplicate VAL entries here, and later

+   * allows emit_bits to detect any attempt to emit such symbols.

+   */

+  MEMZERO(dtbl->ehufsi, SIZEOF(dtbl->ehufsi));

+

+  /* This is also a convenient place to check for out-of-range

+   * and duplicated VAL entries.  We allow 0..255 for AC symbols

+   * but only 0..15 for DC.  (We could constrain them further

+   * based on data depth and mode, but this seems enough.)

+   */

+  maxsymbol = isDC ? 15 : 255;

+

+  for (p = 0; p < lastp; p++) {

+    i = htbl->huffval[p];

+    if (i < 0 || i > maxsymbol || dtbl->ehufsi[i])

+      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);

+    dtbl->ehufco[i] = huffcode[p];

+    dtbl->ehufsi[i] = huffsize[p];

+  }

+}

+

+

+/* Outputting bytes to the file.

+ * NB: these must be called only when actually outputting,

+ * that is, entropy->gather_statistics == FALSE.

+ */

+

+/* Emit a byte, taking 'action' if must suspend. */

+#define emit_byte_s(state,val,action)  \

+	{ *(state)->next_output_byte++ = (JOCTET) (val);  \

+	  if (--(state)->free_in_buffer == 0)  \

+	    if (! dump_buffer_s(state))  \

+	      { action; } }

+

+/* Emit a byte */

+#define emit_byte_e(entropy,val)  \

+	{ *(entropy)->next_output_byte++ = (JOCTET) (val);  \

+	  if (--(entropy)->free_in_buffer == 0)  \

+	    dump_buffer_e(entropy); }

+

+

+LOCAL(boolean)

+dump_buffer_s (working_state * state)

+/* Empty the output buffer; return TRUE if successful, FALSE if must suspend */

+{

+  struct jpeg_destination_mgr * dest = state->cinfo->dest;

+

+  if (! (*dest->empty_output_buffer) (state->cinfo))

+    return FALSE;

+  /* After a successful buffer dump, must reset buffer pointers */

+  state->next_output_byte = dest->next_output_byte;

+  state->free_in_buffer = dest->free_in_buffer;

+  return TRUE;

+}

+

+

+LOCAL(void)

+dump_buffer_e (huff_entropy_ptr entropy)

+/* Empty the output buffer; we do not support suspension in this case. */

+{

+  struct jpeg_destination_mgr * dest = entropy->cinfo->dest;

+

+  if (! (*dest->empty_output_buffer) (entropy->cinfo))

+    ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);

+  /* After a successful buffer dump, must reset buffer pointers */

+  entropy->next_output_byte = dest->next_output_byte;

+  entropy->free_in_buffer = dest->free_in_buffer;

+}

+

+

+/* Outputting bits to the file */

+

+/* Only the right 24 bits of put_buffer are used; the valid bits are

+ * left-justified in this part.  At most 16 bits can be passed to emit_bits

+ * in one call, and we never retain more than 7 bits in put_buffer

+ * between calls, so 24 bits are sufficient.

+ */

+

+INLINE

+LOCAL(boolean)

+emit_bits_s (working_state * state, unsigned int code, int size)

+/* Emit some bits; return TRUE if successful, FALSE if must suspend */

+{

+  /* This routine is heavily used, so it's worth coding tightly. */

+  register INT32 put_buffer = (INT32) code;

+  register int put_bits = state->cur.put_bits;

+

+  /* if size is 0, caller used an invalid Huffman table entry */

+  if (size == 0)

+    ERREXIT(state->cinfo, JERR_HUFF_MISSING_CODE);

+

+  put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */

+  

+  put_bits += size;		/* new number of bits in buffer */

+  

+  put_buffer <<= 24 - put_bits; /* align incoming bits */

+

+  put_buffer |= state->cur.put_buffer; /* and merge with old buffer contents */

+  

+  while (put_bits >= 8) {

+    int c = (int) ((put_buffer >> 16) & 0xFF);

+    

+    emit_byte_s(state, c, return FALSE);

+    if (c == 0xFF) {		/* need to stuff a zero byte? */

+      emit_byte_s(state, 0, return FALSE);

+    }

+    put_buffer <<= 8;

+    put_bits -= 8;

+  }

+

+  state->cur.put_buffer = put_buffer; /* update state variables */

+  state->cur.put_bits = put_bits;

+

+  return TRUE;

+}

+

+

+INLINE

+LOCAL(void)

+emit_bits_e (huff_entropy_ptr entropy, unsigned int code, int size)

+/* Emit some bits, unless we are in gather mode */

+{

+  /* This routine is heavily used, so it's worth coding tightly. */

+  register INT32 put_buffer = (INT32) code;

+  register int put_bits = entropy->saved.put_bits;

+

+  /* if size is 0, caller used an invalid Huffman table entry */

+  if (size == 0)

+    ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);

+

+  if (entropy->gather_statistics)

+    return;			/* do nothing if we're only getting stats */

+

+  put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */

+  

+  put_bits += size;		/* new number of bits in buffer */

+

+  put_buffer <<= 24 - put_bits; /* align incoming bits */

+

+  /* and merge with old buffer contents */

+  put_buffer |= entropy->saved.put_buffer;

+

+  while (put_bits >= 8) {

+    int c = (int) ((put_buffer >> 16) & 0xFF);

+

+    emit_byte_e(entropy, c);

+    if (c == 0xFF) {		/* need to stuff a zero byte? */

+      emit_byte_e(entropy, 0);

+    }

+    put_buffer <<= 8;

+    put_bits -= 8;

+  }

+

+  entropy->saved.put_buffer = put_buffer; /* update variables */

+  entropy->saved.put_bits = put_bits;

+}

+

+

+LOCAL(boolean)

+flush_bits_s (working_state * state)

+{

+  if (! emit_bits_s(state, 0x7F, 7)) /* fill any partial byte with ones */

+    return FALSE;

+  state->cur.put_buffer = 0;	     /* and reset bit-buffer to empty */

+  state->cur.put_bits = 0;

+  return TRUE;

+}

+

+

+LOCAL(void)

+flush_bits_e (huff_entropy_ptr entropy)

+{

+  emit_bits_e(entropy, 0x7F, 7); /* fill any partial byte with ones */

+  entropy->saved.put_buffer = 0; /* and reset bit-buffer to empty */

+  entropy->saved.put_bits = 0;

+}

+

+

+/*

+ * Emit (or just count) a Huffman symbol.

+ */

+

+INLINE

+LOCAL(void)

+emit_dc_symbol (huff_entropy_ptr entropy, int tbl_no, int symbol)

+{

+  if (entropy->gather_statistics)

+    entropy->dc_count_ptrs[tbl_no][symbol]++;

+  else {

+    c_derived_tbl * tbl = entropy->dc_derived_tbls[tbl_no];

+    emit_bits_e(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);

+  }

+}

+

+

+INLINE

+LOCAL(void)

+emit_ac_symbol (huff_entropy_ptr entropy, int tbl_no, int symbol)

+{

+  if (entropy->gather_statistics)

+    entropy->ac_count_ptrs[tbl_no][symbol]++;

+  else {

+    c_derived_tbl * tbl = entropy->ac_derived_tbls[tbl_no];

+    emit_bits_e(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);

+  }

+}

+

+

+/*

+ * Emit bits from a correction bit buffer.

+ */

+

+LOCAL(void)

+emit_buffered_bits (huff_entropy_ptr entropy, char * bufstart,

+		    unsigned int nbits)

+{

+  if (entropy->gather_statistics)

+    return;			/* no real work */

+

+  while (nbits > 0) {

+    emit_bits_e(entropy, (unsigned int) (*bufstart), 1);

+    bufstart++;

+    nbits--;

+  }

+}

+

+

+/*

+ * Emit any pending EOBRUN symbol.

+ */

+

+LOCAL(void)

+emit_eobrun (huff_entropy_ptr entropy)

+{

+  register int temp, nbits;

+

+  if (entropy->EOBRUN > 0) {	/* if there is any pending EOBRUN */

+    temp = entropy->EOBRUN;

+    nbits = 0;

+    while ((temp >>= 1))

+      nbits++;

+    /* safety check: shouldn't happen given limited correction-bit buffer */

+    if (nbits > 14)

+      ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);

+

+    emit_ac_symbol(entropy, entropy->ac_tbl_no, nbits << 4);

+    if (nbits)

+      emit_bits_e(entropy, entropy->EOBRUN, nbits);

+

+    entropy->EOBRUN = 0;

+

+    /* Emit any buffered correction bits */

+    emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);

+    entropy->BE = 0;

+  }

+}

+

+

+/*

+ * Emit a restart marker & resynchronize predictions.

+ */

+

+LOCAL(boolean)

+emit_restart_s (working_state * state, int restart_num)

+{

+  int ci;

+

+  if (! flush_bits_s(state))

+    return FALSE;

+

+  emit_byte_s(state, 0xFF, return FALSE);

+  emit_byte_s(state, JPEG_RST0 + restart_num, return FALSE);

+

+  /* Re-initialize DC predictions to 0 */

+  for (ci = 0; ci < state->cinfo->comps_in_scan; ci++)

+    state->cur.last_dc_val[ci] = 0;

+

+  /* The restart counter is not updated until we successfully write the MCU. */

+

+  return TRUE;

+}

+

+

+LOCAL(void)

+emit_restart_e (huff_entropy_ptr entropy, int restart_num)

+{

+  int ci;

+

+  emit_eobrun(entropy);

+

+  if (! entropy->gather_statistics) {

+    flush_bits_e(entropy);

+    emit_byte_e(entropy, 0xFF);

+    emit_byte_e(entropy, JPEG_RST0 + restart_num);

+  }

+

+  if (entropy->cinfo->Ss == 0) {

+    /* Re-initialize DC predictions to 0 */

+    for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)

+      entropy->saved.last_dc_val[ci] = 0;

+  } else {

+    /* Re-initialize all AC-related fields to 0 */

+    entropy->EOBRUN = 0;

+    entropy->BE = 0;

+  }

+}

+

+

+/*

+ * MCU encoding for DC initial scan (either spectral selection,

+ * or first pass of successive approximation).

+ */

+

+METHODDEF(boolean)

+encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  register int temp, temp2;

+  register int nbits;

+  int blkn, ci;

+  int Al = cinfo->Al;

+  JBLOCKROW block;

+  jpeg_component_info * compptr;

+  ISHIFT_TEMPS

+

+  entropy->next_output_byte = cinfo->dest->next_output_byte;

+  entropy->free_in_buffer = cinfo->dest->free_in_buffer;

+

+  /* Emit restart marker if needed */

+  if (cinfo->restart_interval)

+    if (entropy->restarts_to_go == 0)

+      emit_restart_e(entropy, entropy->next_restart_num);

+

+  /* Encode the MCU data blocks */

+  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {

+    block = MCU_data[blkn];

+    ci = cinfo->MCU_membership[blkn];

+    compptr = cinfo->cur_comp_info[ci];

+

+    /* Compute the DC value after the required point transform by Al.

+     * This is simply an arithmetic right shift.

+     */

+    temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);

+

+    /* DC differences are figured on the point-transformed values. */

+    temp = temp2 - entropy->saved.last_dc_val[ci];

+    entropy->saved.last_dc_val[ci] = temp2;

+

+    /* Encode the DC coefficient difference per section G.1.2.1 */

+    temp2 = temp;

+    if (temp < 0) {

+      temp = -temp;		/* temp is abs value of input */

+      /* For a negative input, want temp2 = bitwise complement of abs(input) */

+      /* This code assumes we are on a two's complement machine */

+      temp2--;

+    }

+    

+    /* Find the number of bits needed for the magnitude of the coefficient */

+    nbits = 0;

+    while (temp) {

+      nbits++;

+      temp >>= 1;

+    }

+    /* Check for out-of-range coefficient values.

+     * Since we're encoding a difference, the range limit is twice as much.

+     */

+    if (nbits > MAX_COEF_BITS+1)

+      ERREXIT(cinfo, JERR_BAD_DCT_COEF);

+    

+    /* Count/emit the Huffman-coded symbol for the number of bits */

+    emit_dc_symbol(entropy, compptr->dc_tbl_no, nbits);

+    

+    /* Emit that number of bits of the value, if positive, */

+    /* or the complement of its magnitude, if negative. */

+    if (nbits)			/* emit_bits rejects calls with size 0 */

+      emit_bits_e(entropy, (unsigned int) temp2, nbits);

+  }

+

+  cinfo->dest->next_output_byte = entropy->next_output_byte;

+  cinfo->dest->free_in_buffer = entropy->free_in_buffer;

+

+  /* Update restart-interval state too */

+  if (cinfo->restart_interval) {

+    if (entropy->restarts_to_go == 0) {

+      entropy->restarts_to_go = cinfo->restart_interval;

+      entropy->next_restart_num++;

+      entropy->next_restart_num &= 7;

+    }

+    entropy->restarts_to_go--;

+  }

+

+  return TRUE;

+}

+

+

+/*

+ * MCU encoding for AC initial scan (either spectral selection,

+ * or first pass of successive approximation).

+ */

+

+METHODDEF(boolean)

+encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  register int temp, temp2;

+  register int nbits;

+  register int r, k;

+  int Se, Al;

+  const int * natural_order;

+  JBLOCKROW block;

+

+  entropy->next_output_byte = cinfo->dest->next_output_byte;

+  entropy->free_in_buffer = cinfo->dest->free_in_buffer;

+

+  /* Emit restart marker if needed */

+  if (cinfo->restart_interval)

+    if (entropy->restarts_to_go == 0)

+      emit_restart_e(entropy, entropy->next_restart_num);

+

+  Se = cinfo->Se;

+  Al = cinfo->Al;

+  natural_order = cinfo->natural_order;

+

+  /* Encode the MCU data block */

+  block = MCU_data[0];

+

+  /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */

+  

+  r = 0;			/* r = run length of zeros */

+   

+  for (k = cinfo->Ss; k <= Se; k++) {

+    if ((temp = (*block)[natural_order[k]]) == 0) {

+      r++;

+      continue;

+    }

+    /* We must apply the point transform by Al.  For AC coefficients this

+     * is an integer division with rounding towards 0.  To do this portably

+     * in C, we shift after obtaining the absolute value; so the code is

+     * interwoven with finding the abs value (temp) and output bits (temp2).

+     */

+    if (temp < 0) {

+      temp = -temp;		/* temp is abs value of input */

+      temp >>= Al;		/* apply the point transform */

+      /* For a negative coef, want temp2 = bitwise complement of abs(coef) */

+      temp2 = ~temp;

+    } else {

+      temp >>= Al;		/* apply the point transform */

+      temp2 = temp;

+    }

+    /* Watch out for case that nonzero coef is zero after point transform */

+    if (temp == 0) {

+      r++;

+      continue;

+    }

+

+    /* Emit any pending EOBRUN */

+    if (entropy->EOBRUN > 0)

+      emit_eobrun(entropy);

+    /* if run length > 15, must emit special run-length-16 codes (0xF0) */

+    while (r > 15) {

+      emit_ac_symbol(entropy, entropy->ac_tbl_no, 0xF0);

+      r -= 16;

+    }

+

+    /* Find the number of bits needed for the magnitude of the coefficient */

+    nbits = 1;			/* there must be at least one 1 bit */

+    while ((temp >>= 1))

+      nbits++;

+    /* Check for out-of-range coefficient values */

+    if (nbits > MAX_COEF_BITS)

+      ERREXIT(cinfo, JERR_BAD_DCT_COEF);

+

+    /* Count/emit Huffman symbol for run length / number of bits */

+    emit_ac_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);

+

+    /* Emit that number of bits of the value, if positive, */

+    /* or the complement of its magnitude, if negative. */

+    emit_bits_e(entropy, (unsigned int) temp2, nbits);

+

+    r = 0;			/* reset zero run length */

+  }

+

+  if (r > 0) {			/* If there are trailing zeroes, */

+    entropy->EOBRUN++;		/* count an EOB */

+    if (entropy->EOBRUN == 0x7FFF)

+      emit_eobrun(entropy);	/* force it out to avoid overflow */

+  }

+

+  cinfo->dest->next_output_byte = entropy->next_output_byte;

+  cinfo->dest->free_in_buffer = entropy->free_in_buffer;

+

+  /* Update restart-interval state too */

+  if (cinfo->restart_interval) {

+    if (entropy->restarts_to_go == 0) {

+      entropy->restarts_to_go = cinfo->restart_interval;

+      entropy->next_restart_num++;

+      entropy->next_restart_num &= 7;

+    }

+    entropy->restarts_to_go--;

+  }

+

+  return TRUE;

+}

+

+

+/*

+ * MCU encoding 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)

+encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  register int temp;

+  int blkn;

+  int Al = cinfo->Al;

+  JBLOCKROW block;

+

+  entropy->next_output_byte = cinfo->dest->next_output_byte;

+  entropy->free_in_buffer = cinfo->dest->free_in_buffer;

+

+  /* Emit restart marker if needed */

+  if (cinfo->restart_interval)

+    if (entropy->restarts_to_go == 0)

+      emit_restart_e(entropy, entropy->next_restart_num);

+

+  /* Encode the MCU data blocks */

+  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {

+    block = MCU_data[blkn];

+

+    /* We simply emit the Al'th bit of the DC coefficient value. */

+    temp = (*block)[0];

+    emit_bits_e(entropy, (unsigned int) (temp >> Al), 1);

+  }

+

+  cinfo->dest->next_output_byte = entropy->next_output_byte;

+  cinfo->dest->free_in_buffer = entropy->free_in_buffer;

+

+  /* Update restart-interval state too */

+  if (cinfo->restart_interval) {

+    if (entropy->restarts_to_go == 0) {

+      entropy->restarts_to_go = cinfo->restart_interval;

+      entropy->next_restart_num++;

+      entropy->next_restart_num &= 7;

+    }

+    entropy->restarts_to_go--;

+  }

+

+  return TRUE;

+}

+

+

+/*

+ * MCU encoding for AC successive approximation refinement scan.

+ */

+

+METHODDEF(boolean)

+encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  register int temp;

+  register int r, k;

+  int EOB;

+  char *BR_buffer;

+  unsigned int BR;

+  int Se, Al;

+  const int * natural_order;

+  JBLOCKROW block;

+  int absvalues[DCTSIZE2];

+

+  entropy->next_output_byte = cinfo->dest->next_output_byte;

+  entropy->free_in_buffer = cinfo->dest->free_in_buffer;

+

+  /* Emit restart marker if needed */

+  if (cinfo->restart_interval)

+    if (entropy->restarts_to_go == 0)

+      emit_restart_e(entropy, entropy->next_restart_num);

+

+  Se = cinfo->Se;

+  Al = cinfo->Al;

+  natural_order = cinfo->natural_order;

+

+  /* Encode the MCU data block */

+  block = MCU_data[0];

+

+  /* It is convenient to make a pre-pass to determine the transformed

+   * coefficients' absolute values and the EOB position.

+   */

+  EOB = 0;

+  for (k = cinfo->Ss; k <= Se; k++) {

+    temp = (*block)[natural_order[k]];

+    /* We must apply the point transform by Al.  For AC coefficients this

+     * is an integer division with rounding towards 0.  To do this portably

+     * in C, we shift after obtaining the absolute value.

+     */

+    if (temp < 0)

+      temp = -temp;		/* temp is abs value of input */

+    temp >>= Al;		/* apply the point transform */

+    absvalues[k] = temp;	/* save abs value for main pass */

+    if (temp == 1)

+      EOB = k;			/* EOB = index of last newly-nonzero coef */

+  }

+

+  /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */

+  

+  r = 0;			/* r = run length of zeros */

+  BR = 0;			/* BR = count of buffered bits added now */

+  BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */

+

+  for (k = cinfo->Ss; k <= Se; k++) {

+    if ((temp = absvalues[k]) == 0) {

+      r++;

+      continue;

+    }

+

+    /* Emit any required ZRLs, but not if they can be folded into EOB */

+    while (r > 15 && k <= EOB) {

+      /* emit any pending EOBRUN and the BE correction bits */

+      emit_eobrun(entropy);

+      /* Emit ZRL */

+      emit_ac_symbol(entropy, entropy->ac_tbl_no, 0xF0);

+      r -= 16;

+      /* Emit buffered correction bits that must be associated with ZRL */

+      emit_buffered_bits(entropy, BR_buffer, BR);

+      BR_buffer = entropy->bit_buffer; /* BE bits are gone now */

+      BR = 0;

+    }

+

+    /* If the coef was previously nonzero, it only needs a correction bit.

+     * NOTE: a straight translation of the spec's figure G.7 would suggest

+     * that we also need to test r > 15.  But if r > 15, we can only get here

+     * if k > EOB, which implies that this coefficient is not 1.

+     */

+    if (temp > 1) {

+      /* The correction bit is the next bit of the absolute value. */

+      BR_buffer[BR++] = (char) (temp & 1);

+      continue;

+    }

+

+    /* Emit any pending EOBRUN and the BE correction bits */

+    emit_eobrun(entropy);

+

+    /* Count/emit Huffman symbol for run length / number of bits */

+    emit_ac_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);

+

+    /* Emit output bit for newly-nonzero coef */

+    temp = ((*block)[natural_order[k]] < 0) ? 0 : 1;

+    emit_bits_e(entropy, (unsigned int) temp, 1);

+

+    /* Emit buffered correction bits that must be associated with this code */

+    emit_buffered_bits(entropy, BR_buffer, BR);

+    BR_buffer = entropy->bit_buffer; /* BE bits are gone now */

+    BR = 0;

+    r = 0;			/* reset zero run length */

+  }

+

+  if (r > 0 || BR > 0) {	/* If there are trailing zeroes, */

+    entropy->EOBRUN++;		/* count an EOB */

+    entropy->BE += BR;		/* concat my correction bits to older ones */

+    /* We force out the EOB if we risk either:

+     * 1. overflow of the EOB counter;

+     * 2. overflow of the correction bit buffer during the next MCU.

+     */

+    if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))

+      emit_eobrun(entropy);

+  }

+

+  cinfo->dest->next_output_byte = entropy->next_output_byte;

+  cinfo->dest->free_in_buffer = entropy->free_in_buffer;

+

+  /* Update restart-interval state too */

+  if (cinfo->restart_interval) {

+    if (entropy->restarts_to_go == 0) {

+      entropy->restarts_to_go = cinfo->restart_interval;

+      entropy->next_restart_num++;

+      entropy->next_restart_num &= 7;

+    }

+    entropy->restarts_to_go--;

+  }

+

+  return TRUE;

+}

+

+

+/* Encode a single block's worth of coefficients */

+

+LOCAL(boolean)

+encode_one_block (working_state * state, JCOEFPTR block, int last_dc_val,

+		  c_derived_tbl *dctbl, c_derived_tbl *actbl)

+{

+  register int temp, temp2;

+  register int nbits;

+  register int k, r, i;

+  int Se = state->cinfo->lim_Se;

+  const int * natural_order = state->cinfo->natural_order;

+

+  /* Encode the DC coefficient difference per section F.1.2.1 */

+

+  temp = temp2 = block[0] - last_dc_val;

+

+  if (temp < 0) {

+    temp = -temp;		/* temp is abs value of input */

+    /* For a negative input, want temp2 = bitwise complement of abs(input) */

+    /* This code assumes we are on a two's complement machine */

+    temp2--;

+  }

+

+  /* Find the number of bits needed for the magnitude of the coefficient */

+  nbits = 0;

+  while (temp) {

+    nbits++;

+    temp >>= 1;

+  }

+  /* Check for out-of-range coefficient values.

+   * Since we're encoding a difference, the range limit is twice as much.

+   */

+  if (nbits > MAX_COEF_BITS+1)

+    ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);

+

+  /* Emit the Huffman-coded symbol for the number of bits */

+  if (! emit_bits_s(state, dctbl->ehufco[nbits], dctbl->ehufsi[nbits]))

+    return FALSE;

+

+  /* Emit that number of bits of the value, if positive, */

+  /* or the complement of its magnitude, if negative. */

+  if (nbits)			/* emit_bits rejects calls with size 0 */

+    if (! emit_bits_s(state, (unsigned int) temp2, nbits))

+      return FALSE;

+

+  /* Encode the AC coefficients per section F.1.2.2 */

+

+  r = 0;			/* r = run length of zeros */

+

+  for (k = 1; k <= Se; k++) {

+    if ((temp = block[natural_order[k]]) == 0) {

+      r++;

+    } else {

+      /* if run length > 15, must emit special run-length-16 codes (0xF0) */

+      while (r > 15) {

+	if (! emit_bits_s(state, actbl->ehufco[0xF0], actbl->ehufsi[0xF0]))

+	  return FALSE;

+	r -= 16;

+      }

+

+      temp2 = temp;

+      if (temp < 0) {

+	temp = -temp;		/* temp is abs value of input */

+	/* This code assumes we are on a two's complement machine */

+	temp2--;

+      }

+

+      /* Find the number of bits needed for the magnitude of the coefficient */

+      nbits = 1;		/* there must be at least one 1 bit */

+      while ((temp >>= 1))

+	nbits++;

+      /* Check for out-of-range coefficient values */

+      if (nbits > MAX_COEF_BITS)

+	ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);

+

+      /* Emit Huffman symbol for run length / number of bits */

+      i = (r << 4) + nbits;

+      if (! emit_bits_s(state, actbl->ehufco[i], actbl->ehufsi[i]))

+	return FALSE;

+

+      /* Emit that number of bits of the value, if positive, */

+      /* or the complement of its magnitude, if negative. */

+      if (! emit_bits_s(state, (unsigned int) temp2, nbits))

+	return FALSE;

+

+      r = 0;

+    }

+  }

+

+  /* If the last coef(s) were zero, emit an end-of-block code */

+  if (r > 0)

+    if (! emit_bits_s(state, actbl->ehufco[0], actbl->ehufsi[0]))

+      return FALSE;

+

+  return TRUE;

+}

+

+

+/*

+ * Encode and output one MCU's worth of Huffman-compressed coefficients.

+ */

+

+METHODDEF(boolean)

+encode_mcu_huff (j_compress_ptr cinfo, JBLOCKROW *MCU_data)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  working_state state;

+  int blkn, ci;

+  jpeg_component_info * compptr;

+

+  /* Load up working state */

+  state.next_output_byte = cinfo->dest->next_output_byte;

+  state.free_in_buffer = cinfo->dest->free_in_buffer;

+  ASSIGN_STATE(state.cur, entropy->saved);

+  state.cinfo = cinfo;

+

+  /* Emit restart marker if needed */

+  if (cinfo->restart_interval) {

+    if (entropy->restarts_to_go == 0)

+      if (! emit_restart_s(&state, entropy->next_restart_num))

+	return FALSE;

+  }

+

+  /* Encode the MCU data blocks */

+  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {

+    ci = cinfo->MCU_membership[blkn];

+    compptr = cinfo->cur_comp_info[ci];

+    if (! encode_one_block(&state,

+			   MCU_data[blkn][0], state.cur.last_dc_val[ci],

+			   entropy->dc_derived_tbls[compptr->dc_tbl_no],

+			   entropy->ac_derived_tbls[compptr->ac_tbl_no]))

+      return FALSE;

+    /* Update last_dc_val */

+    state.cur.last_dc_val[ci] = MCU_data[blkn][0][0];

+  }

+

+  /* Completed MCU, so update state */

+  cinfo->dest->next_output_byte = state.next_output_byte;

+  cinfo->dest->free_in_buffer = state.free_in_buffer;

+  ASSIGN_STATE(entropy->saved, state.cur);

+

+  /* Update restart-interval state too */

+  if (cinfo->restart_interval) {

+    if (entropy->restarts_to_go == 0) {

+      entropy->restarts_to_go = cinfo->restart_interval;

+      entropy->next_restart_num++;

+      entropy->next_restart_num &= 7;

+    }

+    entropy->restarts_to_go--;

+  }

+

+  return TRUE;

+}

+

+

+/*

+ * Finish up at the end of a Huffman-compressed scan.

+ */

+

+METHODDEF(void)

+finish_pass_huff (j_compress_ptr cinfo)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  working_state state;

+

+  if (cinfo->progressive_mode) {

+    entropy->next_output_byte = cinfo->dest->next_output_byte;

+    entropy->free_in_buffer = cinfo->dest->free_in_buffer;

+

+    /* Flush out any buffered data */

+    emit_eobrun(entropy);

+    flush_bits_e(entropy);

+

+    cinfo->dest->next_output_byte = entropy->next_output_byte;

+    cinfo->dest->free_in_buffer = entropy->free_in_buffer;

+  } else {

+    /* Load up working state ... flush_bits needs it */

+    state.next_output_byte = cinfo->dest->next_output_byte;

+    state.free_in_buffer = cinfo->dest->free_in_buffer;

+    ASSIGN_STATE(state.cur, entropy->saved);

+    state.cinfo = cinfo;

+

+    /* Flush out the last data */

+    if (! flush_bits_s(&state))

+      ERREXIT(cinfo, JERR_CANT_SUSPEND);

+

+    /* Update state */

+    cinfo->dest->next_output_byte = state.next_output_byte;

+    cinfo->dest->free_in_buffer = state.free_in_buffer;

+    ASSIGN_STATE(entropy->saved, state.cur);

+  }

+}

+

+

+/*

+ * Huffman coding optimization.

+ *

+ * We first scan the supplied data and count the number of uses of each symbol

+ * that is to be Huffman-coded. (This process MUST agree with the code above.)

+ * Then we build a Huffman coding tree for the observed counts.

+ * Symbols which are not needed at all for the particular image are not

+ * assigned any code, which saves space in the DHT marker as well as in

+ * the compressed data.

+ */

+

+

+/* Process a single block's worth of coefficients */

+

+LOCAL(void)

+htest_one_block (j_compress_ptr cinfo, JCOEFPTR block, int last_dc_val,

+		 long dc_counts[], long ac_counts[])

+{

+  register int temp;

+  register int nbits;

+  register int k, r;

+  int Se = cinfo->lim_Se;

+  const int * natural_order = cinfo->natural_order;

+  

+  /* Encode the DC coefficient difference per section F.1.2.1 */

+  

+  temp = block[0] - last_dc_val;

+  if (temp < 0)

+    temp = -temp;

+  

+  /* Find the number of bits needed for the magnitude of the coefficient */

+  nbits = 0;

+  while (temp) {

+    nbits++;

+    temp >>= 1;

+  }

+  /* Check for out-of-range coefficient values.

+   * Since we're encoding a difference, the range limit is twice as much.

+   */

+  if (nbits > MAX_COEF_BITS+1)

+    ERREXIT(cinfo, JERR_BAD_DCT_COEF);

+

+  /* Count the Huffman symbol for the number of bits */

+  dc_counts[nbits]++;

+  

+  /* Encode the AC coefficients per section F.1.2.2 */

+  

+  r = 0;			/* r = run length of zeros */

+  

+  for (k = 1; k <= Se; k++) {

+    if ((temp = block[natural_order[k]]) == 0) {

+      r++;

+    } else {

+      /* if run length > 15, must emit special run-length-16 codes (0xF0) */

+      while (r > 15) {

+	ac_counts[0xF0]++;

+	r -= 16;

+      }

+      

+      /* Find the number of bits needed for the magnitude of the coefficient */

+      if (temp < 0)

+	temp = -temp;

+      

+      /* Find the number of bits needed for the magnitude of the coefficient */

+      nbits = 1;		/* there must be at least one 1 bit */

+      while ((temp >>= 1))

+	nbits++;

+      /* Check for out-of-range coefficient values */

+      if (nbits > MAX_COEF_BITS)

+	ERREXIT(cinfo, JERR_BAD_DCT_COEF);

+      

+      /* Count Huffman symbol for run length / number of bits */

+      ac_counts[(r << 4) + nbits]++;

+      

+      r = 0;

+    }

+  }

+

+  /* If the last coef(s) were zero, emit an end-of-block code */

+  if (r > 0)

+    ac_counts[0]++;

+}

+

+

+/*

+ * Trial-encode one MCU's worth of Huffman-compressed coefficients.

+ * No data is actually output, so no suspension return is possible.

+ */

+

+METHODDEF(boolean)

+encode_mcu_gather (j_compress_ptr cinfo, JBLOCKROW *MCU_data)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  int blkn, ci;

+  jpeg_component_info * compptr;

+

+  /* Take care of restart intervals if needed */

+  if (cinfo->restart_interval) {

+    if (entropy->restarts_to_go == 0) {

+      /* Re-initialize DC predictions to 0 */

+      for (ci = 0; ci < cinfo->comps_in_scan; ci++)

+	entropy->saved.last_dc_val[ci] = 0;

+      /* Update restart state */

+      entropy->restarts_to_go = cinfo->restart_interval;

+    }

+    entropy->restarts_to_go--;

+  }

+

+  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {

+    ci = cinfo->MCU_membership[blkn];

+    compptr = cinfo->cur_comp_info[ci];

+    htest_one_block(cinfo, MCU_data[blkn][0], entropy->saved.last_dc_val[ci],

+		    entropy->dc_count_ptrs[compptr->dc_tbl_no],

+		    entropy->ac_count_ptrs[compptr->ac_tbl_no]);

+    entropy->saved.last_dc_val[ci] = MCU_data[blkn][0][0];

+  }

+

+  return TRUE;

+}

+

+

+/*

+ * Generate the best Huffman code table for the given counts, fill htbl.

+ *

+ * The JPEG standard requires that no symbol be assigned a codeword of all

+ * one bits (so that padding bits added at the end of a compressed segment

+ * can't look like a valid code).  Because of the canonical ordering of

+ * codewords, this just means that there must be an unused slot in the

+ * longest codeword length category.  Section K.2 of the JPEG spec suggests

+ * reserving such a slot by pretending that symbol 256 is a valid symbol

+ * with count 1.  In theory that's not optimal; giving it count zero but

+ * including it in the symbol set anyway should give a better Huffman code.

+ * But the theoretically better code actually seems to come out worse in

+ * practice, because it produces more all-ones bytes (which incur stuffed

+ * zero bytes in the final file).  In any case the difference is tiny.

+ *

+ * The JPEG standard requires Huffman codes to be no more than 16 bits long.

+ * If some symbols have a very small but nonzero probability, the Huffman tree

+ * must be adjusted to meet the code length restriction.  We currently use

+ * the adjustment method suggested in JPEG section K.2.  This method is *not*

+ * optimal; it may not choose the best possible limited-length code.  But

+ * typically only very-low-frequency symbols will be given less-than-optimal

+ * lengths, so the code is almost optimal.  Experimental comparisons against

+ * an optimal limited-length-code algorithm indicate that the difference is

+ * microscopic --- usually less than a hundredth of a percent of total size.

+ * So the extra complexity of an optimal algorithm doesn't seem worthwhile.

+ */

+

+LOCAL(void)

+jpeg_gen_optimal_table (j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[])

+{

+#define MAX_CLEN 32		/* assumed maximum initial code length */

+  UINT8 bits[MAX_CLEN+1];	/* bits[k] = # of symbols with code length k */

+  int codesize[257];		/* codesize[k] = code length of symbol k */

+  int others[257];		/* next symbol in current branch of tree */

+  int c1, c2;

+  int p, i, j;

+  long v;

+

+  /* This algorithm is explained in section K.2 of the JPEG standard */

+

+  MEMZERO(bits, SIZEOF(bits));

+  MEMZERO(codesize, SIZEOF(codesize));

+  for (i = 0; i < 257; i++)

+    others[i] = -1;		/* init links to empty */

+  

+  freq[256] = 1;		/* make sure 256 has a nonzero count */

+  /* Including the pseudo-symbol 256 in the Huffman procedure guarantees

+   * that no real symbol is given code-value of all ones, because 256

+   * will be placed last in the largest codeword category.

+   */

+

+  /* Huffman's basic algorithm to assign optimal code lengths to symbols */

+

+  for (;;) {

+    /* Find the smallest nonzero frequency, set c1 = its symbol */

+    /* In case of ties, take the larger symbol number */

+    c1 = -1;

+    v = 1000000000L;

+    for (i = 0; i <= 256; i++) {

+      if (freq[i] && freq[i] <= v) {

+	v = freq[i];

+	c1 = i;

+      }

+    }

+

+    /* Find the next smallest nonzero frequency, set c2 = its symbol */

+    /* In case of ties, take the larger symbol number */

+    c2 = -1;

+    v = 1000000000L;

+    for (i = 0; i <= 256; i++) {

+      if (freq[i] && freq[i] <= v && i != c1) {

+	v = freq[i];

+	c2 = i;

+      }

+    }

+

+    /* Done if we've merged everything into one frequency */

+    if (c2 < 0)

+      break;

+    

+    /* Else merge the two counts/trees */

+    freq[c1] += freq[c2];

+    freq[c2] = 0;

+

+    /* Increment the codesize of everything in c1's tree branch */

+    codesize[c1]++;

+    while (others[c1] >= 0) {

+      c1 = others[c1];

+      codesize[c1]++;

+    }

+    

+    others[c1] = c2;		/* chain c2 onto c1's tree branch */

+    

+    /* Increment the codesize of everything in c2's tree branch */

+    codesize[c2]++;

+    while (others[c2] >= 0) {

+      c2 = others[c2];

+      codesize[c2]++;

+    }

+  }

+

+  /* Now count the number of symbols of each code length */

+  for (i = 0; i <= 256; i++) {

+    if (codesize[i]) {

+      /* The JPEG standard seems to think that this can't happen, */

+      /* but I'm paranoid... */

+      if (codesize[i] > MAX_CLEN)

+	ERREXIT(cinfo, JERR_HUFF_CLEN_OVERFLOW);

+

+      bits[codesize[i]]++;

+    }

+  }

+

+  /* JPEG doesn't allow symbols with code lengths over 16 bits, so if the pure

+   * Huffman procedure assigned any such lengths, we must adjust the coding.

+   * Here is what the JPEG spec says about how this next bit works:

+   * Since symbols are paired for the longest Huffman code, the symbols are

+   * removed from this length category two at a time.  The prefix for the pair

+   * (which is one bit shorter) is allocated to one of the pair; then,

+   * skipping the BITS entry for that prefix length, a code word from the next

+   * shortest nonzero BITS entry is converted into a prefix for two code words

+   * one bit longer.

+   */

+  

+  for (i = MAX_CLEN; i > 16; i--) {

+    while (bits[i] > 0) {

+      j = i - 2;		/* find length of new prefix to be used */

+      while (bits[j] == 0)

+	j--;

+      

+      bits[i] -= 2;		/* remove two symbols */

+      bits[i-1]++;		/* one goes in this length */

+      bits[j+1] += 2;		/* two new symbols in this length */

+      bits[j]--;		/* symbol of this length is now a prefix */

+    }

+  }

+

+  /* Remove the count for the pseudo-symbol 256 from the largest codelength */

+  while (bits[i] == 0)		/* find largest codelength still in use */

+    i--;

+  bits[i]--;

+  

+  /* Return final symbol counts (only for lengths 0..16) */

+  MEMCOPY(htbl->bits, bits, SIZEOF(htbl->bits));

+  

+  /* Return a list of the symbols sorted by code length */

+  /* It's not real clear to me why we don't need to consider the codelength

+   * changes made above, but the JPEG spec seems to think this works.

+   */

+  p = 0;

+  for (i = 1; i <= MAX_CLEN; i++) {

+    for (j = 0; j <= 255; j++) {

+      if (codesize[j] == i) {

+	htbl->huffval[p] = (UINT8) j;

+	p++;

+      }

+    }

+  }

+

+  /* Set sent_table FALSE so updated table will be written to JPEG file. */

+  htbl->sent_table = FALSE;

+}

+

+

+/*

+ * Finish up a statistics-gathering pass and create the new Huffman tables.

+ */

+

+METHODDEF(void)

+finish_pass_gather (j_compress_ptr cinfo)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  int ci, tbl;

+  jpeg_component_info * compptr;

+  JHUFF_TBL **htblptr;

+  boolean did_dc[NUM_HUFF_TBLS];

+  boolean did_ac[NUM_HUFF_TBLS];

+

+  /* It's important not to apply jpeg_gen_optimal_table more than once

+   * per table, because it clobbers the input frequency counts!

+   */

+  if (cinfo->progressive_mode)

+    /* Flush out buffered data (all we care about is counting the EOB symbol) */

+    emit_eobrun(entropy);

+

+  MEMZERO(did_dc, SIZEOF(did_dc));

+  MEMZERO(did_ac, SIZEOF(did_ac));

+

+  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

+    compptr = cinfo->cur_comp_info[ci];

+    /* DC needs no table for refinement scan */

+    if (cinfo->Ss == 0 && cinfo->Ah == 0) {

+      tbl = compptr->dc_tbl_no;

+      if (! did_dc[tbl]) {

+	htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];

+	if (*htblptr == NULL)

+	  *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);

+	jpeg_gen_optimal_table(cinfo, *htblptr, entropy->dc_count_ptrs[tbl]);

+	did_dc[tbl] = TRUE;

+      }

+    }

+    /* AC needs no table when not present */

+    if (cinfo->Se) {

+      tbl = compptr->ac_tbl_no;

+      if (! did_ac[tbl]) {

+	htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];

+	if (*htblptr == NULL)

+	  *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);

+	jpeg_gen_optimal_table(cinfo, *htblptr, entropy->ac_count_ptrs[tbl]);

+	did_ac[tbl] = TRUE;

+      }

+    }

+  }

+}

+

+

+/*

+ * Initialize for a Huffman-compressed scan.

+ * If gather_statistics is TRUE, we do not output anything during the scan,

+ * just count the Huffman symbols used and generate Huffman code tables.

+ */

+

+METHODDEF(void)

+start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics)

+{

+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;

+  int ci, tbl;

+  jpeg_component_info * compptr;

+

+  if (gather_statistics)

+    entropy->pub.finish_pass = finish_pass_gather;

+  else

+    entropy->pub.finish_pass = finish_pass_huff;

+

+  if (cinfo->progressive_mode) {

+    entropy->cinfo = cinfo;

+    entropy->gather_statistics = gather_statistics;

+

+    /* We assume jcmaster.c already validated the scan parameters. */

+

+    /* Select execution routine */

+    if (cinfo->Ah == 0) {

+      if (cinfo->Ss == 0)

+	entropy->pub.encode_mcu = encode_mcu_DC_first;

+      else

+	entropy->pub.encode_mcu = encode_mcu_AC_first;

+    } else {

+      if (cinfo->Ss == 0)

+	entropy->pub.encode_mcu = encode_mcu_DC_refine;

+      else {

+	entropy->pub.encode_mcu = encode_mcu_AC_refine;

+	/* AC refinement needs a correction bit buffer */

+	if (entropy->bit_buffer == NULL)

+	  entropy->bit_buffer = (char *)

+	    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

+					MAX_CORR_BITS * SIZEOF(char));

+      }

+    }

+

+    /* Initialize AC stuff */

+    entropy->ac_tbl_no = cinfo->cur_comp_info[0]->ac_tbl_no;

+    entropy->EOBRUN = 0;

+    entropy->BE = 0;

+  } else {

+    if (gather_statistics)

+      entropy->pub.encode_mcu = encode_mcu_gather;

+    else

+      entropy->pub.encode_mcu = encode_mcu_huff;

+  }

+

+  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

+    compptr = cinfo->cur_comp_info[ci];

+    /* DC needs no table for refinement scan */

+    if (cinfo->Ss == 0 && cinfo->Ah == 0) {

+      tbl = compptr->dc_tbl_no;

+      if (gather_statistics) {

+	/* Check for invalid table index */

+	/* (make_c_derived_tbl does this in the other path) */

+	if (tbl < 0 || tbl >= NUM_HUFF_TBLS)

+	  ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);

+	/* Allocate and zero the statistics tables */

+	/* Note that jpeg_gen_optimal_table expects 257 entries in each table! */

+	if (entropy->dc_count_ptrs[tbl] == NULL)

+	  entropy->dc_count_ptrs[tbl] = (long *)

+	    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

+					257 * SIZEOF(long));

+	MEMZERO(entropy->dc_count_ptrs[tbl], 257 * SIZEOF(long));

+      } else {

+	/* Compute derived values for Huffman tables */

+	/* We may do this more than once for a table, but it's not expensive */

+	jpeg_make_c_derived_tbl(cinfo, TRUE, tbl,

+				& entropy->dc_derived_tbls[tbl]);

+      }

+      /* Initialize DC predictions to 0 */

+      entropy->saved.last_dc_val[ci] = 0;

+    }

+    /* AC needs no table when not present */

+    if (cinfo->Se) {

+      tbl = compptr->ac_tbl_no;

+      if (gather_statistics) {

+	if (tbl < 0 || tbl >= NUM_HUFF_TBLS)

+	  ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);

+	if (entropy->ac_count_ptrs[tbl] == NULL)

+	  entropy->ac_count_ptrs[tbl] = (long *)

+	    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

+					257 * SIZEOF(long));

+	MEMZERO(entropy->ac_count_ptrs[tbl], 257 * SIZEOF(long));

+      } else {

+	jpeg_make_c_derived_tbl(cinfo, FALSE, tbl,

+				& entropy->ac_derived_tbls[tbl]);

+      }

+    }

+  }

+

+  /* Initialize bit buffer to empty */

+  entropy->saved.put_buffer = 0;

+  entropy->saved.put_bits = 0;

+

+  /* Initialize restart stuff */

+  entropy->restarts_to_go = cinfo->restart_interval;

+  entropy->next_restart_num = 0;

+}

+

+

+/*

+ * Module initialization routine for Huffman entropy encoding.

+ */

+

+GLOBAL(void)

+jinit_huff_encoder (j_compress_ptr cinfo)

+{

+  huff_entropy_ptr entropy;

+  int i;

+

+  entropy = (huff_entropy_ptr)

+    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

+				SIZEOF(huff_entropy_encoder));

+  cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;

+  entropy->pub.start_pass = start_pass_huff;

+

+  /* Mark tables unallocated */

+  for (i = 0; i < NUM_HUFF_TBLS; i++) {

+    entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;

+    entropy->dc_count_ptrs[i] = entropy->ac_count_ptrs[i] = NULL;

+  }

+

+  if (cinfo->progressive_mode)

+    entropy->bit_buffer = NULL;	/* needed only in AC refinement scan */

+}