1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/libs/libjpeg/jchuff.c	Thu Sep 08 06:28:38 2011 +0300
     1.3 @@ -0,0 +1,909 @@
     1.4 +/*
     1.5 + * jchuff.c
     1.6 + *
     1.7 + * Copyright (C) 1991-1997, Thomas G. Lane.
     1.8 + * This file is part of the Independent JPEG Group's software.
     1.9 + * For conditions of distribution and use, see the accompanying README file.
    1.10 + *
    1.11 + * This file contains Huffman entropy encoding routines.
    1.12 + *
    1.13 + * Much of the complexity here has to do with supporting output suspension.
    1.14 + * If the data destination module demands suspension, we want to be able to
    1.15 + * back up to the start of the current MCU.  To do this, we copy state
    1.16 + * variables into local working storage, and update them back to the
    1.17 + * permanent JPEG objects only upon successful completion of an MCU.
    1.18 + */
    1.19 +
    1.20 +#define JPEG_INTERNALS
    1.21 +#include "jinclude.h"
    1.22 +#include "jpeglib.h"
    1.23 +#include "jchuff.h"		/* Declarations shared with jcphuff.c */
    1.24 +
    1.25 +
    1.26 +/* Expanded entropy encoder object for Huffman encoding.
    1.27 + *
    1.28 + * The savable_state subrecord contains fields that change within an MCU,
    1.29 + * but must not be updated permanently until we complete the MCU.
    1.30 + */
    1.31 +
    1.32 +typedef struct {
    1.33 +  INT32 put_buffer;		/* current bit-accumulation buffer */
    1.34 +  int put_bits;			/* # of bits now in it */
    1.35 +  int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
    1.36 +} savable_state;
    1.37 +
    1.38 +/* This macro is to work around compilers with missing or broken
    1.39 + * structure assignment.  You'll need to fix this code if you have
    1.40 + * such a compiler and you change MAX_COMPS_IN_SCAN.
    1.41 + */
    1.42 +
    1.43 +#ifndef NO_STRUCT_ASSIGN
    1.44 +#define ASSIGN_STATE(dest,src)  ((dest) = (src))
    1.45 +#else
    1.46 +#if MAX_COMPS_IN_SCAN == 4
    1.47 +#define ASSIGN_STATE(dest,src)  \
    1.48 +	((dest).put_buffer = (src).put_buffer, \
    1.49 +	 (dest).put_bits = (src).put_bits, \
    1.50 +	 (dest).last_dc_val[0] = (src).last_dc_val[0], \
    1.51 +	 (dest).last_dc_val[1] = (src).last_dc_val[1], \
    1.52 +	 (dest).last_dc_val[2] = (src).last_dc_val[2], \
    1.53 +	 (dest).last_dc_val[3] = (src).last_dc_val[3])
    1.54 +#endif
    1.55 +#endif
    1.56 +
    1.57 +
    1.58 +typedef struct {
    1.59 +  struct jpeg_entropy_encoder pub; /* public fields */
    1.60 +
    1.61 +  savable_state saved;		/* Bit buffer & DC state at start of MCU */
    1.62 +
    1.63 +  /* These fields are NOT loaded into local working state. */
    1.64 +  unsigned int restarts_to_go;	/* MCUs left in this restart interval */
    1.65 +  int next_restart_num;		/* next restart number to write (0-7) */
    1.66 +
    1.67 +  /* Pointers to derived tables (these workspaces have image lifespan) */
    1.68 +  c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];
    1.69 +  c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];
    1.70 +
    1.71 +#ifdef ENTROPY_OPT_SUPPORTED	/* Statistics tables for optimization */
    1.72 +  long * dc_count_ptrs[NUM_HUFF_TBLS];
    1.73 +  long * ac_count_ptrs[NUM_HUFF_TBLS];
    1.74 +#endif
    1.75 +} huff_entropy_encoder;
    1.76 +
    1.77 +typedef huff_entropy_encoder * huff_entropy_ptr;
    1.78 +
    1.79 +/* Working state while writing an MCU.
    1.80 + * This struct contains all the fields that are needed by subroutines.
    1.81 + */
    1.82 +
    1.83 +typedef struct {
    1.84 +  JOCTET * next_output_byte;	/* => next byte to write in buffer */
    1.85 +  size_t free_in_buffer;	/* # of byte spaces remaining in buffer */
    1.86 +  savable_state cur;		/* Current bit buffer & DC state */
    1.87 +  j_compress_ptr cinfo;		/* dump_buffer needs access to this */
    1.88 +} working_state;
    1.89 +
    1.90 +
    1.91 +/* Forward declarations */
    1.92 +METHODDEF(boolean) encode_mcu_huff JPP((j_compress_ptr cinfo,
    1.93 +					JBLOCKROW *MCU_data));
    1.94 +METHODDEF(void) finish_pass_huff JPP((j_compress_ptr cinfo));
    1.95 +#ifdef ENTROPY_OPT_SUPPORTED
    1.96 +METHODDEF(boolean) encode_mcu_gather JPP((j_compress_ptr cinfo,
    1.97 +					  JBLOCKROW *MCU_data));
    1.98 +METHODDEF(void) finish_pass_gather JPP((j_compress_ptr cinfo));
    1.99 +#endif
   1.100 +
   1.101 +
   1.102 +/*
   1.103 + * Initialize for a Huffman-compressed scan.
   1.104 + * If gather_statistics is TRUE, we do not output anything during the scan,
   1.105 + * just count the Huffman symbols used and generate Huffman code tables.
   1.106 + */
   1.107 +
   1.108 +METHODDEF(void)
   1.109 +start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics)
   1.110 +{
   1.111 +  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
   1.112 +  int ci, dctbl, actbl;
   1.113 +  jpeg_component_info * compptr;
   1.114 +
   1.115 +  if (gather_statistics) {
   1.116 +#ifdef ENTROPY_OPT_SUPPORTED
   1.117 +    entropy->pub.encode_mcu = encode_mcu_gather;
   1.118 +    entropy->pub.finish_pass = finish_pass_gather;
   1.119 +#else
   1.120 +    ERREXIT(cinfo, JERR_NOT_COMPILED);
   1.121 +#endif
   1.122 +  } else {
   1.123 +    entropy->pub.encode_mcu = encode_mcu_huff;
   1.124 +    entropy->pub.finish_pass = finish_pass_huff;
   1.125 +  }
   1.126 +
   1.127 +  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
   1.128 +    compptr = cinfo->cur_comp_info[ci];
   1.129 +    dctbl = compptr->dc_tbl_no;
   1.130 +    actbl = compptr->ac_tbl_no;
   1.131 +    if (gather_statistics) {
   1.132 +#ifdef ENTROPY_OPT_SUPPORTED
   1.133 +      /* Check for invalid table indexes */
   1.134 +      /* (make_c_derived_tbl does this in the other path) */
   1.135 +      if (dctbl < 0 || dctbl >= NUM_HUFF_TBLS)
   1.136 +	ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, dctbl);
   1.137 +      if (actbl < 0 || actbl >= NUM_HUFF_TBLS)
   1.138 +	ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, actbl);
   1.139 +      /* Allocate and zero the statistics tables */
   1.140 +      /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
   1.141 +      if (entropy->dc_count_ptrs[dctbl] == NULL)
   1.142 +	entropy->dc_count_ptrs[dctbl] = (long *)
   1.143 +	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.144 +				      257 * SIZEOF(long));
   1.145 +      MEMZERO(entropy->dc_count_ptrs[dctbl], 257 * SIZEOF(long));
   1.146 +      if (entropy->ac_count_ptrs[actbl] == NULL)
   1.147 +	entropy->ac_count_ptrs[actbl] = (long *)
   1.148 +	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.149 +				      257 * SIZEOF(long));
   1.150 +      MEMZERO(entropy->ac_count_ptrs[actbl], 257 * SIZEOF(long));
   1.151 +#endif
   1.152 +    } else {
   1.153 +      /* Compute derived values for Huffman tables */
   1.154 +      /* We may do this more than once for a table, but it's not expensive */
   1.155 +      jpeg_make_c_derived_tbl(cinfo, TRUE, dctbl,
   1.156 +			      & entropy->dc_derived_tbls[dctbl]);
   1.157 +      jpeg_make_c_derived_tbl(cinfo, FALSE, actbl,
   1.158 +			      & entropy->ac_derived_tbls[actbl]);
   1.159 +    }
   1.160 +    /* Initialize DC predictions to 0 */
   1.161 +    entropy->saved.last_dc_val[ci] = 0;
   1.162 +  }
   1.163 +
   1.164 +  /* Initialize bit buffer to empty */
   1.165 +  entropy->saved.put_buffer = 0;
   1.166 +  entropy->saved.put_bits = 0;
   1.167 +
   1.168 +  /* Initialize restart stuff */
   1.169 +  entropy->restarts_to_go = cinfo->restart_interval;
   1.170 +  entropy->next_restart_num = 0;
   1.171 +}
   1.172 +
   1.173 +
   1.174 +/*
   1.175 + * Compute the derived values for a Huffman table.
   1.176 + * This routine also performs some validation checks on the table.
   1.177 + *
   1.178 + * Note this is also used by jcphuff.c.
   1.179 + */
   1.180 +
   1.181 +GLOBAL(void)
   1.182 +jpeg_make_c_derived_tbl (j_compress_ptr cinfo, boolean isDC, int tblno,
   1.183 +			 c_derived_tbl ** pdtbl)
   1.184 +{
   1.185 +  JHUFF_TBL *htbl;
   1.186 +  c_derived_tbl *dtbl;
   1.187 +  int p, i, l, lastp, si, maxsymbol;
   1.188 +  char huffsize[257];
   1.189 +  unsigned int huffcode[257];
   1.190 +  unsigned int code;
   1.191 +
   1.192 +  /* Note that huffsize[] and huffcode[] are filled in code-length order,
   1.193 +   * paralleling the order of the symbols themselves in htbl->huffval[].
   1.194 +   */
   1.195 +
   1.196 +  /* Find the input Huffman table */
   1.197 +  if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
   1.198 +    ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
   1.199 +  htbl =
   1.200 +    isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno];
   1.201 +  if (htbl == NULL)
   1.202 +    ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
   1.203 +
   1.204 +  /* Allocate a workspace if we haven't already done so. */
   1.205 +  if (*pdtbl == NULL)
   1.206 +    *pdtbl = (c_derived_tbl *)
   1.207 +      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.208 +				  SIZEOF(c_derived_tbl));
   1.209 +  dtbl = *pdtbl;
   1.210 +  
   1.211 +  /* Figure C.1: make table of Huffman code length for each symbol */
   1.212 +
   1.213 +  p = 0;
   1.214 +  for (l = 1; l <= 16; l++) {
   1.215 +    i = (int) htbl->bits[l];
   1.216 +    if (i < 0 || p + i > 256)	/* protect against table overrun */
   1.217 +      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
   1.218 +    while (i--)
   1.219 +      huffsize[p++] = (char) l;
   1.220 +  }
   1.221 +  huffsize[p] = 0;
   1.222 +  lastp = p;
   1.223 +  
   1.224 +  /* Figure C.2: generate the codes themselves */
   1.225 +  /* We also validate that the counts represent a legal Huffman code tree. */
   1.226 +
   1.227 +  code = 0;
   1.228 +  si = huffsize[0];
   1.229 +  p = 0;
   1.230 +  while (huffsize[p]) {
   1.231 +    while (((int) huffsize[p]) == si) {
   1.232 +      huffcode[p++] = code;
   1.233 +      code++;
   1.234 +    }
   1.235 +    /* code is now 1 more than the last code used for codelength si; but
   1.236 +     * it must still fit in si bits, since no code is allowed to be all ones.
   1.237 +     */
   1.238 +    if (((INT32) code) >= (((INT32) 1) << si))
   1.239 +      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
   1.240 +    code <<= 1;
   1.241 +    si++;
   1.242 +  }
   1.243 +  
   1.244 +  /* Figure C.3: generate encoding tables */
   1.245 +  /* These are code and size indexed by symbol value */
   1.246 +
   1.247 +  /* Set all codeless symbols to have code length 0;
   1.248 +   * this lets us detect duplicate VAL entries here, and later
   1.249 +   * allows emit_bits to detect any attempt to emit such symbols.
   1.250 +   */
   1.251 +  MEMZERO(dtbl->ehufsi, SIZEOF(dtbl->ehufsi));
   1.252 +
   1.253 +  /* This is also a convenient place to check for out-of-range
   1.254 +   * and duplicated VAL entries.  We allow 0..255 for AC symbols
   1.255 +   * but only 0..15 for DC.  (We could constrain them further
   1.256 +   * based on data depth and mode, but this seems enough.)
   1.257 +   */
   1.258 +  maxsymbol = isDC ? 15 : 255;
   1.259 +
   1.260 +  for (p = 0; p < lastp; p++) {
   1.261 +    i = htbl->huffval[p];
   1.262 +    if (i < 0 || i > maxsymbol || dtbl->ehufsi[i])
   1.263 +      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
   1.264 +    dtbl->ehufco[i] = huffcode[p];
   1.265 +    dtbl->ehufsi[i] = huffsize[p];
   1.266 +  }
   1.267 +}
   1.268 +
   1.269 +
   1.270 +/* Outputting bytes to the file */
   1.271 +
   1.272 +/* Emit a byte, taking 'action' if must suspend. */
   1.273 +#define emit_byte(state,val,action)  \
   1.274 +	{ *(state)->next_output_byte++ = (JOCTET) (val);  \
   1.275 +	  if (--(state)->free_in_buffer == 0)  \
   1.276 +	    if (! dump_buffer(state))  \
   1.277 +	      { action; } }
   1.278 +
   1.279 +
   1.280 +LOCAL(boolean)
   1.281 +dump_buffer (working_state * state)
   1.282 +/* Empty the output buffer; return TRUE if successful, FALSE if must suspend */
   1.283 +{
   1.284 +  struct jpeg_destination_mgr * dest = state->cinfo->dest;
   1.285 +
   1.286 +  if (! (*dest->empty_output_buffer) (state->cinfo))
   1.287 +    return FALSE;
   1.288 +  /* After a successful buffer dump, must reset buffer pointers */
   1.289 +  state->next_output_byte = dest->next_output_byte;
   1.290 +  state->free_in_buffer = dest->free_in_buffer;
   1.291 +  return TRUE;
   1.292 +}
   1.293 +
   1.294 +
   1.295 +/* Outputting bits to the file */
   1.296 +
   1.297 +/* Only the right 24 bits of put_buffer are used; the valid bits are
   1.298 + * left-justified in this part.  At most 16 bits can be passed to emit_bits
   1.299 + * in one call, and we never retain more than 7 bits in put_buffer
   1.300 + * between calls, so 24 bits are sufficient.
   1.301 + */
   1.302 +
   1.303 +INLINE
   1.304 +LOCAL(boolean)
   1.305 +emit_bits (working_state * state, unsigned int code, int size)
   1.306 +/* Emit some bits; return TRUE if successful, FALSE if must suspend */
   1.307 +{
   1.308 +  /* This routine is heavily used, so it's worth coding tightly. */
   1.309 +  register INT32 put_buffer = (INT32) code;
   1.310 +  register int put_bits = state->cur.put_bits;
   1.311 +
   1.312 +  /* if size is 0, caller used an invalid Huffman table entry */
   1.313 +  if (size == 0)
   1.314 +    ERREXIT(state->cinfo, JERR_HUFF_MISSING_CODE);
   1.315 +
   1.316 +  put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
   1.317 +  
   1.318 +  put_bits += size;		/* new number of bits in buffer */
   1.319 +  
   1.320 +  put_buffer <<= 24 - put_bits; /* align incoming bits */
   1.321 +
   1.322 +  put_buffer |= state->cur.put_buffer; /* and merge with old buffer contents */
   1.323 +  
   1.324 +  while (put_bits >= 8) {
   1.325 +    int c = (int) ((put_buffer >> 16) & 0xFF);
   1.326 +    
   1.327 +    emit_byte(state, c, return FALSE);
   1.328 +    if (c == 0xFF) {		/* need to stuff a zero byte? */
   1.329 +      emit_byte(state, 0, return FALSE);
   1.330 +    }
   1.331 +    put_buffer <<= 8;
   1.332 +    put_bits -= 8;
   1.333 +  }
   1.334 +
   1.335 +  state->cur.put_buffer = put_buffer; /* update state variables */
   1.336 +  state->cur.put_bits = put_bits;
   1.337 +
   1.338 +  return TRUE;
   1.339 +}
   1.340 +
   1.341 +
   1.342 +LOCAL(boolean)
   1.343 +flush_bits (working_state * state)
   1.344 +{
   1.345 +  if (! emit_bits(state, 0x7F, 7)) /* fill any partial byte with ones */
   1.346 +    return FALSE;
   1.347 +  state->cur.put_buffer = 0;	/* and reset bit-buffer to empty */
   1.348 +  state->cur.put_bits = 0;
   1.349 +  return TRUE;
   1.350 +}
   1.351 +
   1.352 +
   1.353 +/* Encode a single block's worth of coefficients */
   1.354 +
   1.355 +LOCAL(boolean)
   1.356 +encode_one_block (working_state * state, JCOEFPTR block, int last_dc_val,
   1.357 +		  c_derived_tbl *dctbl, c_derived_tbl *actbl)
   1.358 +{
   1.359 +  register int temp, temp2;
   1.360 +  register int nbits;
   1.361 +  register int k, r, i;
   1.362 +  
   1.363 +  /* Encode the DC coefficient difference per section F.1.2.1 */
   1.364 +  
   1.365 +  temp = temp2 = block[0] - last_dc_val;
   1.366 +
   1.367 +  if (temp < 0) {
   1.368 +    temp = -temp;		/* temp is abs value of input */
   1.369 +    /* For a negative input, want temp2 = bitwise complement of abs(input) */
   1.370 +    /* This code assumes we are on a two's complement machine */
   1.371 +    temp2--;
   1.372 +  }
   1.373 +  
   1.374 +  /* Find the number of bits needed for the magnitude of the coefficient */
   1.375 +  nbits = 0;
   1.376 +  while (temp) {
   1.377 +    nbits++;
   1.378 +    temp >>= 1;
   1.379 +  }
   1.380 +  /* Check for out-of-range coefficient values.
   1.381 +   * Since we're encoding a difference, the range limit is twice as much.
   1.382 +   */
   1.383 +  if (nbits > MAX_COEF_BITS+1)
   1.384 +    ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
   1.385 +  
   1.386 +  /* Emit the Huffman-coded symbol for the number of bits */
   1.387 +  if (! emit_bits(state, dctbl->ehufco[nbits], dctbl->ehufsi[nbits]))
   1.388 +    return FALSE;
   1.389 +
   1.390 +  /* Emit that number of bits of the value, if positive, */
   1.391 +  /* or the complement of its magnitude, if negative. */
   1.392 +  if (nbits)			/* emit_bits rejects calls with size 0 */
   1.393 +    if (! emit_bits(state, (unsigned int) temp2, nbits))
   1.394 +      return FALSE;
   1.395 +
   1.396 +  /* Encode the AC coefficients per section F.1.2.2 */
   1.397 +  
   1.398 +  r = 0;			/* r = run length of zeros */
   1.399 +  
   1.400 +  for (k = 1; k < DCTSIZE2; k++) {
   1.401 +    if ((temp = block[jpeg_natural_order[k]]) == 0) {
   1.402 +      r++;
   1.403 +    } else {
   1.404 +      /* if run length > 15, must emit special run-length-16 codes (0xF0) */
   1.405 +      while (r > 15) {
   1.406 +	if (! emit_bits(state, actbl->ehufco[0xF0], actbl->ehufsi[0xF0]))
   1.407 +	  return FALSE;
   1.408 +	r -= 16;
   1.409 +      }
   1.410 +
   1.411 +      temp2 = temp;
   1.412 +      if (temp < 0) {
   1.413 +	temp = -temp;		/* temp is abs value of input */
   1.414 +	/* This code assumes we are on a two's complement machine */
   1.415 +	temp2--;
   1.416 +      }
   1.417 +      
   1.418 +      /* Find the number of bits needed for the magnitude of the coefficient */
   1.419 +      nbits = 1;		/* there must be at least one 1 bit */
   1.420 +      while ((temp >>= 1))
   1.421 +	nbits++;
   1.422 +      /* Check for out-of-range coefficient values */
   1.423 +      if (nbits > MAX_COEF_BITS)
   1.424 +	ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
   1.425 +      
   1.426 +      /* Emit Huffman symbol for run length / number of bits */
   1.427 +      i = (r << 4) + nbits;
   1.428 +      if (! emit_bits(state, actbl->ehufco[i], actbl->ehufsi[i]))
   1.429 +	return FALSE;
   1.430 +
   1.431 +      /* Emit that number of bits of the value, if positive, */
   1.432 +      /* or the complement of its magnitude, if negative. */
   1.433 +      if (! emit_bits(state, (unsigned int) temp2, nbits))
   1.434 +	return FALSE;
   1.435 +      
   1.436 +      r = 0;
   1.437 +    }
   1.438 +  }
   1.439 +
   1.440 +  /* If the last coef(s) were zero, emit an end-of-block code */
   1.441 +  if (r > 0)
   1.442 +    if (! emit_bits(state, actbl->ehufco[0], actbl->ehufsi[0]))
   1.443 +      return FALSE;
   1.444 +
   1.445 +  return TRUE;
   1.446 +}
   1.447 +
   1.448 +
   1.449 +/*
   1.450 + * Emit a restart marker & resynchronize predictions.
   1.451 + */
   1.452 +
   1.453 +LOCAL(boolean)
   1.454 +emit_restart (working_state * state, int restart_num)
   1.455 +{
   1.456 +  int ci;
   1.457 +
   1.458 +  if (! flush_bits(state))
   1.459 +    return FALSE;
   1.460 +
   1.461 +  emit_byte(state, 0xFF, return FALSE);
   1.462 +  emit_byte(state, JPEG_RST0 + restart_num, return FALSE);
   1.463 +
   1.464 +  /* Re-initialize DC predictions to 0 */
   1.465 +  for (ci = 0; ci < state->cinfo->comps_in_scan; ci++)
   1.466 +    state->cur.last_dc_val[ci] = 0;
   1.467 +
   1.468 +  /* The restart counter is not updated until we successfully write the MCU. */
   1.469 +
   1.470 +  return TRUE;
   1.471 +}
   1.472 +
   1.473 +
   1.474 +/*
   1.475 + * Encode and output one MCU's worth of Huffman-compressed coefficients.
   1.476 + */
   1.477 +
   1.478 +METHODDEF(boolean)
   1.479 +encode_mcu_huff (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
   1.480 +{
   1.481 +  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
   1.482 +  working_state state;
   1.483 +  int blkn, ci;
   1.484 +  jpeg_component_info * compptr;
   1.485 +
   1.486 +  /* Load up working state */
   1.487 +  state.next_output_byte = cinfo->dest->next_output_byte;
   1.488 +  state.free_in_buffer = cinfo->dest->free_in_buffer;
   1.489 +  ASSIGN_STATE(state.cur, entropy->saved);
   1.490 +  state.cinfo = cinfo;
   1.491 +
   1.492 +  /* Emit restart marker if needed */
   1.493 +  if (cinfo->restart_interval) {
   1.494 +    if (entropy->restarts_to_go == 0)
   1.495 +      if (! emit_restart(&state, entropy->next_restart_num))
   1.496 +	return FALSE;
   1.497 +  }
   1.498 +
   1.499 +  /* Encode the MCU data blocks */
   1.500 +  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
   1.501 +    ci = cinfo->MCU_membership[blkn];
   1.502 +    compptr = cinfo->cur_comp_info[ci];
   1.503 +    if (! encode_one_block(&state,
   1.504 +			   MCU_data[blkn][0], state.cur.last_dc_val[ci],
   1.505 +			   entropy->dc_derived_tbls[compptr->dc_tbl_no],
   1.506 +			   entropy->ac_derived_tbls[compptr->ac_tbl_no]))
   1.507 +      return FALSE;
   1.508 +    /* Update last_dc_val */
   1.509 +    state.cur.last_dc_val[ci] = MCU_data[blkn][0][0];
   1.510 +  }
   1.511 +
   1.512 +  /* Completed MCU, so update state */
   1.513 +  cinfo->dest->next_output_byte = state.next_output_byte;
   1.514 +  cinfo->dest->free_in_buffer = state.free_in_buffer;
   1.515 +  ASSIGN_STATE(entropy->saved, state.cur);
   1.516 +
   1.517 +  /* Update restart-interval state too */
   1.518 +  if (cinfo->restart_interval) {
   1.519 +    if (entropy->restarts_to_go == 0) {
   1.520 +      entropy->restarts_to_go = cinfo->restart_interval;
   1.521 +      entropy->next_restart_num++;
   1.522 +      entropy->next_restart_num &= 7;
   1.523 +    }
   1.524 +    entropy->restarts_to_go--;
   1.525 +  }
   1.526 +
   1.527 +  return TRUE;
   1.528 +}
   1.529 +
   1.530 +
   1.531 +/*
   1.532 + * Finish up at the end of a Huffman-compressed scan.
   1.533 + */
   1.534 +
   1.535 +METHODDEF(void)
   1.536 +finish_pass_huff (j_compress_ptr cinfo)
   1.537 +{
   1.538 +  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
   1.539 +  working_state state;
   1.540 +
   1.541 +  /* Load up working state ... flush_bits needs it */
   1.542 +  state.next_output_byte = cinfo->dest->next_output_byte;
   1.543 +  state.free_in_buffer = cinfo->dest->free_in_buffer;
   1.544 +  ASSIGN_STATE(state.cur, entropy->saved);
   1.545 +  state.cinfo = cinfo;
   1.546 +
   1.547 +  /* Flush out the last data */
   1.548 +  if (! flush_bits(&state))
   1.549 +    ERREXIT(cinfo, JERR_CANT_SUSPEND);
   1.550 +
   1.551 +  /* Update state */
   1.552 +  cinfo->dest->next_output_byte = state.next_output_byte;
   1.553 +  cinfo->dest->free_in_buffer = state.free_in_buffer;
   1.554 +  ASSIGN_STATE(entropy->saved, state.cur);
   1.555 +}
   1.556 +
   1.557 +
   1.558 +/*
   1.559 + * Huffman coding optimization.
   1.560 + *
   1.561 + * We first scan the supplied data and count the number of uses of each symbol
   1.562 + * that is to be Huffman-coded. (This process MUST agree with the code above.)
   1.563 + * Then we build a Huffman coding tree for the observed counts.
   1.564 + * Symbols which are not needed at all for the particular image are not
   1.565 + * assigned any code, which saves space in the DHT marker as well as in
   1.566 + * the compressed data.
   1.567 + */
   1.568 +
   1.569 +#ifdef ENTROPY_OPT_SUPPORTED
   1.570 +
   1.571 +
   1.572 +/* Process a single block's worth of coefficients */
   1.573 +
   1.574 +LOCAL(void)
   1.575 +htest_one_block (j_compress_ptr cinfo, JCOEFPTR block, int last_dc_val,
   1.576 +		 long dc_counts[], long ac_counts[])
   1.577 +{
   1.578 +  register int temp;
   1.579 +  register int nbits;
   1.580 +  register int k, r;
   1.581 +  
   1.582 +  /* Encode the DC coefficient difference per section F.1.2.1 */
   1.583 +  
   1.584 +  temp = block[0] - last_dc_val;
   1.585 +  if (temp < 0)
   1.586 +    temp = -temp;
   1.587 +  
   1.588 +  /* Find the number of bits needed for the magnitude of the coefficient */
   1.589 +  nbits = 0;
   1.590 +  while (temp) {
   1.591 +    nbits++;
   1.592 +    temp >>= 1;
   1.593 +  }
   1.594 +  /* Check for out-of-range coefficient values.
   1.595 +   * Since we're encoding a difference, the range limit is twice as much.
   1.596 +   */
   1.597 +  if (nbits > MAX_COEF_BITS+1)
   1.598 +    ERREXIT(cinfo, JERR_BAD_DCT_COEF);
   1.599 +
   1.600 +  /* Count the Huffman symbol for the number of bits */
   1.601 +  dc_counts[nbits]++;
   1.602 +  
   1.603 +  /* Encode the AC coefficients per section F.1.2.2 */
   1.604 +  
   1.605 +  r = 0;			/* r = run length of zeros */
   1.606 +  
   1.607 +  for (k = 1; k < DCTSIZE2; k++) {
   1.608 +    if ((temp = block[jpeg_natural_order[k]]) == 0) {
   1.609 +      r++;
   1.610 +    } else {
   1.611 +      /* if run length > 15, must emit special run-length-16 codes (0xF0) */
   1.612 +      while (r > 15) {
   1.613 +	ac_counts[0xF0]++;
   1.614 +	r -= 16;
   1.615 +      }
   1.616 +      
   1.617 +      /* Find the number of bits needed for the magnitude of the coefficient */
   1.618 +      if (temp < 0)
   1.619 +	temp = -temp;
   1.620 +      
   1.621 +      /* Find the number of bits needed for the magnitude of the coefficient */
   1.622 +      nbits = 1;		/* there must be at least one 1 bit */
   1.623 +      while ((temp >>= 1))
   1.624 +	nbits++;
   1.625 +      /* Check for out-of-range coefficient values */
   1.626 +      if (nbits > MAX_COEF_BITS)
   1.627 +	ERREXIT(cinfo, JERR_BAD_DCT_COEF);
   1.628 +      
   1.629 +      /* Count Huffman symbol for run length / number of bits */
   1.630 +      ac_counts[(r << 4) + nbits]++;
   1.631 +      
   1.632 +      r = 0;
   1.633 +    }
   1.634 +  }
   1.635 +
   1.636 +  /* If the last coef(s) were zero, emit an end-of-block code */
   1.637 +  if (r > 0)
   1.638 +    ac_counts[0]++;
   1.639 +}
   1.640 +
   1.641 +
   1.642 +/*
   1.643 + * Trial-encode one MCU's worth of Huffman-compressed coefficients.
   1.644 + * No data is actually output, so no suspension return is possible.
   1.645 + */
   1.646 +
   1.647 +METHODDEF(boolean)
   1.648 +encode_mcu_gather (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
   1.649 +{
   1.650 +  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
   1.651 +  int blkn, ci;
   1.652 +  jpeg_component_info * compptr;
   1.653 +
   1.654 +  /* Take care of restart intervals if needed */
   1.655 +  if (cinfo->restart_interval) {
   1.656 +    if (entropy->restarts_to_go == 0) {
   1.657 +      /* Re-initialize DC predictions to 0 */
   1.658 +      for (ci = 0; ci < cinfo->comps_in_scan; ci++)
   1.659 +	entropy->saved.last_dc_val[ci] = 0;
   1.660 +      /* Update restart state */
   1.661 +      entropy->restarts_to_go = cinfo->restart_interval;
   1.662 +    }
   1.663 +    entropy->restarts_to_go--;
   1.664 +  }
   1.665 +
   1.666 +  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
   1.667 +    ci = cinfo->MCU_membership[blkn];
   1.668 +    compptr = cinfo->cur_comp_info[ci];
   1.669 +    htest_one_block(cinfo, MCU_data[blkn][0], entropy->saved.last_dc_val[ci],
   1.670 +		    entropy->dc_count_ptrs[compptr->dc_tbl_no],
   1.671 +		    entropy->ac_count_ptrs[compptr->ac_tbl_no]);
   1.672 +    entropy->saved.last_dc_val[ci] = MCU_data[blkn][0][0];
   1.673 +  }
   1.674 +
   1.675 +  return TRUE;
   1.676 +}
   1.677 +
   1.678 +
   1.679 +/*
   1.680 + * Generate the best Huffman code table for the given counts, fill htbl.
   1.681 + * Note this is also used by jcphuff.c.
   1.682 + *
   1.683 + * The JPEG standard requires that no symbol be assigned a codeword of all
   1.684 + * one bits (so that padding bits added at the end of a compressed segment
   1.685 + * can't look like a valid code).  Because of the canonical ordering of
   1.686 + * codewords, this just means that there must be an unused slot in the
   1.687 + * longest codeword length category.  Section K.2 of the JPEG spec suggests
   1.688 + * reserving such a slot by pretending that symbol 256 is a valid symbol
   1.689 + * with count 1.  In theory that's not optimal; giving it count zero but
   1.690 + * including it in the symbol set anyway should give a better Huffman code.
   1.691 + * But the theoretically better code actually seems to come out worse in
   1.692 + * practice, because it produces more all-ones bytes (which incur stuffed
   1.693 + * zero bytes in the final file).  In any case the difference is tiny.
   1.694 + *
   1.695 + * The JPEG standard requires Huffman codes to be no more than 16 bits long.
   1.696 + * If some symbols have a very small but nonzero probability, the Huffman tree
   1.697 + * must be adjusted to meet the code length restriction.  We currently use
   1.698 + * the adjustment method suggested in JPEG section K.2.  This method is *not*
   1.699 + * optimal; it may not choose the best possible limited-length code.  But
   1.700 + * typically only very-low-frequency symbols will be given less-than-optimal
   1.701 + * lengths, so the code is almost optimal.  Experimental comparisons against
   1.702 + * an optimal limited-length-code algorithm indicate that the difference is
   1.703 + * microscopic --- usually less than a hundredth of a percent of total size.
   1.704 + * So the extra complexity of an optimal algorithm doesn't seem worthwhile.
   1.705 + */
   1.706 +
   1.707 +GLOBAL(void)
   1.708 +jpeg_gen_optimal_table (j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[])
   1.709 +{
   1.710 +#define MAX_CLEN 32		/* assumed maximum initial code length */
   1.711 +  UINT8 bits[MAX_CLEN+1];	/* bits[k] = # of symbols with code length k */
   1.712 +  int codesize[257];		/* codesize[k] = code length of symbol k */
   1.713 +  int others[257];		/* next symbol in current branch of tree */
   1.714 +  int c1, c2;
   1.715 +  int p, i, j;
   1.716 +  long v;
   1.717 +
   1.718 +  /* This algorithm is explained in section K.2 of the JPEG standard */
   1.719 +
   1.720 +  MEMZERO(bits, SIZEOF(bits));
   1.721 +  MEMZERO(codesize, SIZEOF(codesize));
   1.722 +  for (i = 0; i < 257; i++)
   1.723 +    others[i] = -1;		/* init links to empty */
   1.724 +  
   1.725 +  freq[256] = 1;		/* make sure 256 has a nonzero count */
   1.726 +  /* Including the pseudo-symbol 256 in the Huffman procedure guarantees
   1.727 +   * that no real symbol is given code-value of all ones, because 256
   1.728 +   * will be placed last in the largest codeword category.
   1.729 +   */
   1.730 +
   1.731 +  /* Huffman's basic algorithm to assign optimal code lengths to symbols */
   1.732 +
   1.733 +  for (;;) {
   1.734 +    /* Find the smallest nonzero frequency, set c1 = its symbol */
   1.735 +    /* In case of ties, take the larger symbol number */
   1.736 +    c1 = -1;
   1.737 +    v = 1000000000L;
   1.738 +    for (i = 0; i <= 256; i++) {
   1.739 +      if (freq[i] && freq[i] <= v) {
   1.740 +	v = freq[i];
   1.741 +	c1 = i;
   1.742 +      }
   1.743 +    }
   1.744 +
   1.745 +    /* Find the next smallest nonzero frequency, set c2 = its symbol */
   1.746 +    /* In case of ties, take the larger symbol number */
   1.747 +    c2 = -1;
   1.748 +    v = 1000000000L;
   1.749 +    for (i = 0; i <= 256; i++) {
   1.750 +      if (freq[i] && freq[i] <= v && i != c1) {
   1.751 +	v = freq[i];
   1.752 +	c2 = i;
   1.753 +      }
   1.754 +    }
   1.755 +
   1.756 +    /* Done if we've merged everything into one frequency */
   1.757 +    if (c2 < 0)
   1.758 +      break;
   1.759 +    
   1.760 +    /* Else merge the two counts/trees */
   1.761 +    freq[c1] += freq[c2];
   1.762 +    freq[c2] = 0;
   1.763 +
   1.764 +    /* Increment the codesize of everything in c1's tree branch */
   1.765 +    codesize[c1]++;
   1.766 +    while (others[c1] >= 0) {
   1.767 +      c1 = others[c1];
   1.768 +      codesize[c1]++;
   1.769 +    }
   1.770 +    
   1.771 +    others[c1] = c2;		/* chain c2 onto c1's tree branch */
   1.772 +    
   1.773 +    /* Increment the codesize of everything in c2's tree branch */
   1.774 +    codesize[c2]++;
   1.775 +    while (others[c2] >= 0) {
   1.776 +      c2 = others[c2];
   1.777 +      codesize[c2]++;
   1.778 +    }
   1.779 +  }
   1.780 +
   1.781 +  /* Now count the number of symbols of each code length */
   1.782 +  for (i = 0; i <= 256; i++) {
   1.783 +    if (codesize[i]) {
   1.784 +      /* The JPEG standard seems to think that this can't happen, */
   1.785 +      /* but I'm paranoid... */
   1.786 +      if (codesize[i] > MAX_CLEN)
   1.787 +	ERREXIT(cinfo, JERR_HUFF_CLEN_OVERFLOW);
   1.788 +
   1.789 +      bits[codesize[i]]++;
   1.790 +    }
   1.791 +  }
   1.792 +
   1.793 +  /* JPEG doesn't allow symbols with code lengths over 16 bits, so if the pure
   1.794 +   * Huffman procedure assigned any such lengths, we must adjust the coding.
   1.795 +   * Here is what the JPEG spec says about how this next bit works:
   1.796 +   * Since symbols are paired for the longest Huffman code, the symbols are
   1.797 +   * removed from this length category two at a time.  The prefix for the pair
   1.798 +   * (which is one bit shorter) is allocated to one of the pair; then,
   1.799 +   * skipping the BITS entry for that prefix length, a code word from the next
   1.800 +   * shortest nonzero BITS entry is converted into a prefix for two code words
   1.801 +   * one bit longer.
   1.802 +   */
   1.803 +  
   1.804 +  for (i = MAX_CLEN; i > 16; i--) {
   1.805 +    while (bits[i] > 0) {
   1.806 +      j = i - 2;		/* find length of new prefix to be used */
   1.807 +      while (bits[j] == 0)
   1.808 +	j--;
   1.809 +      
   1.810 +      bits[i] -= 2;		/* remove two symbols */
   1.811 +      bits[i-1]++;		/* one goes in this length */
   1.812 +      bits[j+1] += 2;		/* two new symbols in this length */
   1.813 +      bits[j]--;		/* symbol of this length is now a prefix */
   1.814 +    }
   1.815 +  }
   1.816 +
   1.817 +  /* Remove the count for the pseudo-symbol 256 from the largest codelength */
   1.818 +  while (bits[i] == 0)		/* find largest codelength still in use */
   1.819 +    i--;
   1.820 +  bits[i]--;
   1.821 +  
   1.822 +  /* Return final symbol counts (only for lengths 0..16) */
   1.823 +  MEMCOPY(htbl->bits, bits, SIZEOF(htbl->bits));
   1.824 +  
   1.825 +  /* Return a list of the symbols sorted by code length */
   1.826 +  /* It's not real clear to me why we don't need to consider the codelength
   1.827 +   * changes made above, but the JPEG spec seems to think this works.
   1.828 +   */
   1.829 +  p = 0;
   1.830 +  for (i = 1; i <= MAX_CLEN; i++) {
   1.831 +    for (j = 0; j <= 255; j++) {
   1.832 +      if (codesize[j] == i) {
   1.833 +	htbl->huffval[p] = (UINT8) j;
   1.834 +	p++;
   1.835 +      }
   1.836 +    }
   1.837 +  }
   1.838 +
   1.839 +  /* Set sent_table FALSE so updated table will be written to JPEG file. */
   1.840 +  htbl->sent_table = FALSE;
   1.841 +}
   1.842 +
   1.843 +
   1.844 +/*
   1.845 + * Finish up a statistics-gathering pass and create the new Huffman tables.
   1.846 + */
   1.847 +
   1.848 +METHODDEF(void)
   1.849 +finish_pass_gather (j_compress_ptr cinfo)
   1.850 +{
   1.851 +  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
   1.852 +  int ci, dctbl, actbl;
   1.853 +  jpeg_component_info * compptr;
   1.854 +  JHUFF_TBL **htblptr;
   1.855 +  boolean did_dc[NUM_HUFF_TBLS];
   1.856 +  boolean did_ac[NUM_HUFF_TBLS];
   1.857 +
   1.858 +  /* It's important not to apply jpeg_gen_optimal_table more than once
   1.859 +   * per table, because it clobbers the input frequency counts!
   1.860 +   */
   1.861 +  MEMZERO(did_dc, SIZEOF(did_dc));
   1.862 +  MEMZERO(did_ac, SIZEOF(did_ac));
   1.863 +
   1.864 +  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
   1.865 +    compptr = cinfo->cur_comp_info[ci];
   1.866 +    dctbl = compptr->dc_tbl_no;
   1.867 +    actbl = compptr->ac_tbl_no;
   1.868 +    if (! did_dc[dctbl]) {
   1.869 +      htblptr = & cinfo->dc_huff_tbl_ptrs[dctbl];
   1.870 +      if (*htblptr == NULL)
   1.871 +	*htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
   1.872 +      jpeg_gen_optimal_table(cinfo, *htblptr, entropy->dc_count_ptrs[dctbl]);
   1.873 +      did_dc[dctbl] = TRUE;
   1.874 +    }
   1.875 +    if (! did_ac[actbl]) {
   1.876 +      htblptr = & cinfo->ac_huff_tbl_ptrs[actbl];
   1.877 +      if (*htblptr == NULL)
   1.878 +	*htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
   1.879 +      jpeg_gen_optimal_table(cinfo, *htblptr, entropy->ac_count_ptrs[actbl]);
   1.880 +      did_ac[actbl] = TRUE;
   1.881 +    }
   1.882 +  }
   1.883 +}
   1.884 +
   1.885 +
   1.886 +#endif /* ENTROPY_OPT_SUPPORTED */
   1.887 +
   1.888 +
   1.889 +/*
   1.890 + * Module initialization routine for Huffman entropy encoding.
   1.891 + */
   1.892 +
   1.893 +GLOBAL(void)
   1.894 +jinit_huff_encoder (j_compress_ptr cinfo)
   1.895 +{
   1.896 +  huff_entropy_ptr entropy;
   1.897 +  int i;
   1.898 +
   1.899 +  entropy = (huff_entropy_ptr)
   1.900 +    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.901 +				SIZEOF(huff_entropy_encoder));
   1.902 +  cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
   1.903 +  entropy->pub.start_pass = start_pass_huff;
   1.904 +
   1.905 +  /* Mark tables unallocated */
   1.906 +  for (i = 0; i < NUM_HUFF_TBLS; i++) {
   1.907 +    entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
   1.908 +#ifdef ENTROPY_OPT_SUPPORTED
   1.909 +    entropy->dc_count_ptrs[i] = entropy->ac_count_ptrs[i] = NULL;
   1.910 +#endif
   1.911 +  }
   1.912 +}