1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/libs/libjpeg/jcphuff.c	Sun Nov 01 00:36:56 2015 +0200
     1.3 @@ -0,0 +1,833 @@
     1.4 +/*
     1.5 + * jcphuff.c
     1.6 + *
     1.7 + * Copyright (C) 1995-1997, 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 for progressive JPEG.
    1.12 + *
    1.13 + * We do not support output suspension in this module, since the library
    1.14 + * currently does not allow multiple-scan files to be written with output
    1.15 + * suspension.
    1.16 + */
    1.17 +
    1.18 +#define JPEG_INTERNALS
    1.19 +#include "jinclude.h"
    1.20 +#include "jpeglib.h"
    1.21 +#include "jchuff.h"		/* Declarations shared with jchuff.c */
    1.22 +
    1.23 +#ifdef C_PROGRESSIVE_SUPPORTED
    1.24 +
    1.25 +/* Expanded entropy encoder object for progressive Huffman encoding. */
    1.26 +
    1.27 +typedef struct {
    1.28 +  struct jpeg_entropy_encoder pub; /* public fields */
    1.29 +
    1.30 +  /* Mode flag: TRUE for optimization, FALSE for actual data output */
    1.31 +  boolean gather_statistics;
    1.32 +
    1.33 +  /* Bit-level coding status.
    1.34 +   * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
    1.35 +   */
    1.36 +  JOCTET * next_output_byte;	/* => next byte to write in buffer */
    1.37 +  size_t free_in_buffer;	/* # of byte spaces remaining in buffer */
    1.38 +  INT32 put_buffer;		/* current bit-accumulation buffer */
    1.39 +  int put_bits;			/* # of bits now in it */
    1.40 +  j_compress_ptr cinfo;		/* link to cinfo (needed for dump_buffer) */
    1.41 +
    1.42 +  /* Coding status for DC components */
    1.43 +  int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
    1.44 +
    1.45 +  /* Coding status for AC components */
    1.46 +  int ac_tbl_no;		/* the table number of the single component */
    1.47 +  unsigned int EOBRUN;		/* run length of EOBs */
    1.48 +  unsigned int BE;		/* # of buffered correction bits before MCU */
    1.49 +  char * bit_buffer;		/* buffer for correction bits (1 per char) */
    1.50 +  /* packing correction bits tightly would save some space but cost time... */
    1.51 +
    1.52 +  unsigned int restarts_to_go;	/* MCUs left in this restart interval */
    1.53 +  int next_restart_num;		/* next restart number to write (0-7) */
    1.54 +
    1.55 +  /* Pointers to derived tables (these workspaces have image lifespan).
    1.56 +   * Since any one scan codes only DC or only AC, we only need one set
    1.57 +   * of tables, not one for DC and one for AC.
    1.58 +   */
    1.59 +  c_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
    1.60 +
    1.61 +  /* Statistics tables for optimization; again, one set is enough */
    1.62 +  long * count_ptrs[NUM_HUFF_TBLS];
    1.63 +} phuff_entropy_encoder;
    1.64 +
    1.65 +typedef phuff_entropy_encoder * phuff_entropy_ptr;
    1.66 +
    1.67 +/* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
    1.68 + * buffer can hold.  Larger sizes may slightly improve compression, but
    1.69 + * 1000 is already well into the realm of overkill.
    1.70 + * The minimum safe size is 64 bits.
    1.71 + */
    1.72 +
    1.73 +#define MAX_CORR_BITS  1000	/* Max # of correction bits I can buffer */
    1.74 +
    1.75 +/* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
    1.76 + * We assume that int right shift is unsigned if INT32 right shift is,
    1.77 + * which should be safe.
    1.78 + */
    1.79 +
    1.80 +#ifdef RIGHT_SHIFT_IS_UNSIGNED
    1.81 +#define ISHIFT_TEMPS	int ishift_temp;
    1.82 +#define IRIGHT_SHIFT(x,shft)  \
    1.83 +	((ishift_temp = (x)) < 0 ? \
    1.84 +	 (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
    1.85 +	 (ishift_temp >> (shft)))
    1.86 +#else
    1.87 +#define ISHIFT_TEMPS
    1.88 +#define IRIGHT_SHIFT(x,shft)	((x) >> (shft))
    1.89 +#endif
    1.90 +
    1.91 +/* Forward declarations */
    1.92 +METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo,
    1.93 +					    JBLOCKROW *MCU_data));
    1.94 +METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo,
    1.95 +					    JBLOCKROW *MCU_data));
    1.96 +METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo,
    1.97 +					     JBLOCKROW *MCU_data));
    1.98 +METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo,
    1.99 +					     JBLOCKROW *MCU_data));
   1.100 +METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo));
   1.101 +METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo));
   1.102 +
   1.103 +
   1.104 +/*
   1.105 + * Initialize for a Huffman-compressed scan using progressive JPEG.
   1.106 + */
   1.107 +
   1.108 +METHODDEF(void)
   1.109 +start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
   1.110 +{  
   1.111 +  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   1.112 +  boolean is_DC_band;
   1.113 +  int ci, tbl;
   1.114 +  jpeg_component_info * compptr;
   1.115 +
   1.116 +  entropy->cinfo = cinfo;
   1.117 +  entropy->gather_statistics = gather_statistics;
   1.118 +
   1.119 +  is_DC_band = (cinfo->Ss == 0);
   1.120 +
   1.121 +  /* We assume jcmaster.c already validated the scan parameters. */
   1.122 +
   1.123 +  /* Select execution routines */
   1.124 +  if (cinfo->Ah == 0) {
   1.125 +    if (is_DC_band)
   1.126 +      entropy->pub.encode_mcu = encode_mcu_DC_first;
   1.127 +    else
   1.128 +      entropy->pub.encode_mcu = encode_mcu_AC_first;
   1.129 +  } else {
   1.130 +    if (is_DC_band)
   1.131 +      entropy->pub.encode_mcu = encode_mcu_DC_refine;
   1.132 +    else {
   1.133 +      entropy->pub.encode_mcu = encode_mcu_AC_refine;
   1.134 +      /* AC refinement needs a correction bit buffer */
   1.135 +      if (entropy->bit_buffer == NULL)
   1.136 +	entropy->bit_buffer = (char *)
   1.137 +	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.138 +				      MAX_CORR_BITS * SIZEOF(char));
   1.139 +    }
   1.140 +  }
   1.141 +  if (gather_statistics)
   1.142 +    entropy->pub.finish_pass = finish_pass_gather_phuff;
   1.143 +  else
   1.144 +    entropy->pub.finish_pass = finish_pass_phuff;
   1.145 +
   1.146 +  /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
   1.147 +   * for AC coefficients.
   1.148 +   */
   1.149 +  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
   1.150 +    compptr = cinfo->cur_comp_info[ci];
   1.151 +    /* Initialize DC predictions to 0 */
   1.152 +    entropy->last_dc_val[ci] = 0;
   1.153 +    /* Get table index */
   1.154 +    if (is_DC_band) {
   1.155 +      if (cinfo->Ah != 0)	/* DC refinement needs no table */
   1.156 +	continue;
   1.157 +      tbl = compptr->dc_tbl_no;
   1.158 +    } else {
   1.159 +      entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
   1.160 +    }
   1.161 +    if (gather_statistics) {
   1.162 +      /* Check for invalid table index */
   1.163 +      /* (make_c_derived_tbl does this in the other path) */
   1.164 +      if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
   1.165 +        ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
   1.166 +      /* Allocate and zero the statistics tables */
   1.167 +      /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
   1.168 +      if (entropy->count_ptrs[tbl] == NULL)
   1.169 +	entropy->count_ptrs[tbl] = (long *)
   1.170 +	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.171 +				      257 * SIZEOF(long));
   1.172 +      MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long));
   1.173 +    } else {
   1.174 +      /* Compute derived values for Huffman table */
   1.175 +      /* We may do this more than once for a table, but it's not expensive */
   1.176 +      jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl,
   1.177 +			      & entropy->derived_tbls[tbl]);
   1.178 +    }
   1.179 +  }
   1.180 +
   1.181 +  /* Initialize AC stuff */
   1.182 +  entropy->EOBRUN = 0;
   1.183 +  entropy->BE = 0;
   1.184 +
   1.185 +  /* Initialize bit buffer to empty */
   1.186 +  entropy->put_buffer = 0;
   1.187 +  entropy->put_bits = 0;
   1.188 +
   1.189 +  /* Initialize restart stuff */
   1.190 +  entropy->restarts_to_go = cinfo->restart_interval;
   1.191 +  entropy->next_restart_num = 0;
   1.192 +}
   1.193 +
   1.194 +
   1.195 +/* Outputting bytes to the file.
   1.196 + * NB: these must be called only when actually outputting,
   1.197 + * that is, entropy->gather_statistics == FALSE.
   1.198 + */
   1.199 +
   1.200 +/* Emit a byte */
   1.201 +#define emit_byte(entropy,val)  \
   1.202 +	{ *(entropy)->next_output_byte++ = (JOCTET) (val);  \
   1.203 +	  if (--(entropy)->free_in_buffer == 0)  \
   1.204 +	    dump_buffer(entropy); }
   1.205 +
   1.206 +
   1.207 +LOCAL(void)
   1.208 +dump_buffer (phuff_entropy_ptr entropy)
   1.209 +/* Empty the output buffer; we do not support suspension in this module. */
   1.210 +{
   1.211 +  struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
   1.212 +
   1.213 +  if (! (*dest->empty_output_buffer) (entropy->cinfo))
   1.214 +    ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
   1.215 +  /* After a successful buffer dump, must reset buffer pointers */
   1.216 +  entropy->next_output_byte = dest->next_output_byte;
   1.217 +  entropy->free_in_buffer = dest->free_in_buffer;
   1.218 +}
   1.219 +
   1.220 +
   1.221 +/* Outputting bits to the file */
   1.222 +
   1.223 +/* Only the right 24 bits of put_buffer are used; the valid bits are
   1.224 + * left-justified in this part.  At most 16 bits can be passed to emit_bits
   1.225 + * in one call, and we never retain more than 7 bits in put_buffer
   1.226 + * between calls, so 24 bits are sufficient.
   1.227 + */
   1.228 +
   1.229 +INLINE
   1.230 +LOCAL(void)
   1.231 +emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
   1.232 +/* Emit some bits, unless we are in gather mode */
   1.233 +{
   1.234 +  /* This routine is heavily used, so it's worth coding tightly. */
   1.235 +  register INT32 put_buffer = (INT32) code;
   1.236 +  register int put_bits = entropy->put_bits;
   1.237 +
   1.238 +  /* if size is 0, caller used an invalid Huffman table entry */
   1.239 +  if (size == 0)
   1.240 +    ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
   1.241 +
   1.242 +  if (entropy->gather_statistics)
   1.243 +    return;			/* do nothing if we're only getting stats */
   1.244 +
   1.245 +  put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
   1.246 +  
   1.247 +  put_bits += size;		/* new number of bits in buffer */
   1.248 +  
   1.249 +  put_buffer <<= 24 - put_bits; /* align incoming bits */
   1.250 +
   1.251 +  put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */
   1.252 +
   1.253 +  while (put_bits >= 8) {
   1.254 +    int c = (int) ((put_buffer >> 16) & 0xFF);
   1.255 +    
   1.256 +    emit_byte(entropy, c);
   1.257 +    if (c == 0xFF) {		/* need to stuff a zero byte? */
   1.258 +      emit_byte(entropy, 0);
   1.259 +    }
   1.260 +    put_buffer <<= 8;
   1.261 +    put_bits -= 8;
   1.262 +  }
   1.263 +
   1.264 +  entropy->put_buffer = put_buffer; /* update variables */
   1.265 +  entropy->put_bits = put_bits;
   1.266 +}
   1.267 +
   1.268 +
   1.269 +LOCAL(void)
   1.270 +flush_bits (phuff_entropy_ptr entropy)
   1.271 +{
   1.272 +  emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
   1.273 +  entropy->put_buffer = 0;     /* and reset bit-buffer to empty */
   1.274 +  entropy->put_bits = 0;
   1.275 +}
   1.276 +
   1.277 +
   1.278 +/*
   1.279 + * Emit (or just count) a Huffman symbol.
   1.280 + */
   1.281 +
   1.282 +INLINE
   1.283 +LOCAL(void)
   1.284 +emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol)
   1.285 +{
   1.286 +  if (entropy->gather_statistics)
   1.287 +    entropy->count_ptrs[tbl_no][symbol]++;
   1.288 +  else {
   1.289 +    c_derived_tbl * tbl = entropy->derived_tbls[tbl_no];
   1.290 +    emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
   1.291 +  }
   1.292 +}
   1.293 +
   1.294 +
   1.295 +/*
   1.296 + * Emit bits from a correction bit buffer.
   1.297 + */
   1.298 +
   1.299 +LOCAL(void)
   1.300 +emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart,
   1.301 +		    unsigned int nbits)
   1.302 +{
   1.303 +  if (entropy->gather_statistics)
   1.304 +    return;			/* no real work */
   1.305 +
   1.306 +  while (nbits > 0) {
   1.307 +    emit_bits(entropy, (unsigned int) (*bufstart), 1);
   1.308 +    bufstart++;
   1.309 +    nbits--;
   1.310 +  }
   1.311 +}
   1.312 +
   1.313 +
   1.314 +/*
   1.315 + * Emit any pending EOBRUN symbol.
   1.316 + */
   1.317 +
   1.318 +LOCAL(void)
   1.319 +emit_eobrun (phuff_entropy_ptr entropy)
   1.320 +{
   1.321 +  register int temp, nbits;
   1.322 +
   1.323 +  if (entropy->EOBRUN > 0) {	/* if there is any pending EOBRUN */
   1.324 +    temp = entropy->EOBRUN;
   1.325 +    nbits = 0;
   1.326 +    while ((temp >>= 1))
   1.327 +      nbits++;
   1.328 +    /* safety check: shouldn't happen given limited correction-bit buffer */
   1.329 +    if (nbits > 14)
   1.330 +      ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
   1.331 +
   1.332 +    emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
   1.333 +    if (nbits)
   1.334 +      emit_bits(entropy, entropy->EOBRUN, nbits);
   1.335 +
   1.336 +    entropy->EOBRUN = 0;
   1.337 +
   1.338 +    /* Emit any buffered correction bits */
   1.339 +    emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
   1.340 +    entropy->BE = 0;
   1.341 +  }
   1.342 +}
   1.343 +
   1.344 +
   1.345 +/*
   1.346 + * Emit a restart marker & resynchronize predictions.
   1.347 + */
   1.348 +
   1.349 +LOCAL(void)
   1.350 +emit_restart (phuff_entropy_ptr entropy, int restart_num)
   1.351 +{
   1.352 +  int ci;
   1.353 +
   1.354 +  emit_eobrun(entropy);
   1.355 +
   1.356 +  if (! entropy->gather_statistics) {
   1.357 +    flush_bits(entropy);
   1.358 +    emit_byte(entropy, 0xFF);
   1.359 +    emit_byte(entropy, JPEG_RST0 + restart_num);
   1.360 +  }
   1.361 +
   1.362 +  if (entropy->cinfo->Ss == 0) {
   1.363 +    /* Re-initialize DC predictions to 0 */
   1.364 +    for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
   1.365 +      entropy->last_dc_val[ci] = 0;
   1.366 +  } else {
   1.367 +    /* Re-initialize all AC-related fields to 0 */
   1.368 +    entropy->EOBRUN = 0;
   1.369 +    entropy->BE = 0;
   1.370 +  }
   1.371 +}
   1.372 +
   1.373 +
   1.374 +/*
   1.375 + * MCU encoding for DC initial scan (either spectral selection,
   1.376 + * or first pass of successive approximation).
   1.377 + */
   1.378 +
   1.379 +METHODDEF(boolean)
   1.380 +encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
   1.381 +{
   1.382 +  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   1.383 +  register int temp, temp2;
   1.384 +  register int nbits;
   1.385 +  int blkn, ci;
   1.386 +  int Al = cinfo->Al;
   1.387 +  JBLOCKROW block;
   1.388 +  jpeg_component_info * compptr;
   1.389 +  ISHIFT_TEMPS
   1.390 +
   1.391 +  entropy->next_output_byte = cinfo->dest->next_output_byte;
   1.392 +  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
   1.393 +
   1.394 +  /* Emit restart marker if needed */
   1.395 +  if (cinfo->restart_interval)
   1.396 +    if (entropy->restarts_to_go == 0)
   1.397 +      emit_restart(entropy, entropy->next_restart_num);
   1.398 +
   1.399 +  /* Encode the MCU data blocks */
   1.400 +  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
   1.401 +    block = MCU_data[blkn];
   1.402 +    ci = cinfo->MCU_membership[blkn];
   1.403 +    compptr = cinfo->cur_comp_info[ci];
   1.404 +
   1.405 +    /* Compute the DC value after the required point transform by Al.
   1.406 +     * This is simply an arithmetic right shift.
   1.407 +     */
   1.408 +    temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
   1.409 +
   1.410 +    /* DC differences are figured on the point-transformed values. */
   1.411 +    temp = temp2 - entropy->last_dc_val[ci];
   1.412 +    entropy->last_dc_val[ci] = temp2;
   1.413 +
   1.414 +    /* Encode the DC coefficient difference per section G.1.2.1 */
   1.415 +    temp2 = temp;
   1.416 +    if (temp < 0) {
   1.417 +      temp = -temp;		/* temp is abs value of input */
   1.418 +      /* For a negative input, want temp2 = bitwise complement of abs(input) */
   1.419 +      /* This code assumes we are on a two's complement machine */
   1.420 +      temp2--;
   1.421 +    }
   1.422 +    
   1.423 +    /* Find the number of bits needed for the magnitude of the coefficient */
   1.424 +    nbits = 0;
   1.425 +    while (temp) {
   1.426 +      nbits++;
   1.427 +      temp >>= 1;
   1.428 +    }
   1.429 +    /* Check for out-of-range coefficient values.
   1.430 +     * Since we're encoding a difference, the range limit is twice as much.
   1.431 +     */
   1.432 +    if (nbits > MAX_COEF_BITS+1)
   1.433 +      ERREXIT(cinfo, JERR_BAD_DCT_COEF);
   1.434 +    
   1.435 +    /* Count/emit the Huffman-coded symbol for the number of bits */
   1.436 +    emit_symbol(entropy, compptr->dc_tbl_no, nbits);
   1.437 +    
   1.438 +    /* Emit that number of bits of the value, if positive, */
   1.439 +    /* or the complement of its magnitude, if negative. */
   1.440 +    if (nbits)			/* emit_bits rejects calls with size 0 */
   1.441 +      emit_bits(entropy, (unsigned int) temp2, nbits);
   1.442 +  }
   1.443 +
   1.444 +  cinfo->dest->next_output_byte = entropy->next_output_byte;
   1.445 +  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
   1.446 +
   1.447 +  /* Update restart-interval state too */
   1.448 +  if (cinfo->restart_interval) {
   1.449 +    if (entropy->restarts_to_go == 0) {
   1.450 +      entropy->restarts_to_go = cinfo->restart_interval;
   1.451 +      entropy->next_restart_num++;
   1.452 +      entropy->next_restart_num &= 7;
   1.453 +    }
   1.454 +    entropy->restarts_to_go--;
   1.455 +  }
   1.456 +
   1.457 +  return TRUE;
   1.458 +}
   1.459 +
   1.460 +
   1.461 +/*
   1.462 + * MCU encoding for AC initial scan (either spectral selection,
   1.463 + * or first pass of successive approximation).
   1.464 + */
   1.465 +
   1.466 +METHODDEF(boolean)
   1.467 +encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
   1.468 +{
   1.469 +  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   1.470 +  register int temp, temp2;
   1.471 +  register int nbits;
   1.472 +  register int r, k;
   1.473 +  int Se = cinfo->Se;
   1.474 +  int Al = cinfo->Al;
   1.475 +  JBLOCKROW block;
   1.476 +
   1.477 +  entropy->next_output_byte = cinfo->dest->next_output_byte;
   1.478 +  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
   1.479 +
   1.480 +  /* Emit restart marker if needed */
   1.481 +  if (cinfo->restart_interval)
   1.482 +    if (entropy->restarts_to_go == 0)
   1.483 +      emit_restart(entropy, entropy->next_restart_num);
   1.484 +
   1.485 +  /* Encode the MCU data block */
   1.486 +  block = MCU_data[0];
   1.487 +
   1.488 +  /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
   1.489 +  
   1.490 +  r = 0;			/* r = run length of zeros */
   1.491 +   
   1.492 +  for (k = cinfo->Ss; k <= Se; k++) {
   1.493 +    if ((temp = (*block)[jpeg_natural_order[k]]) == 0) {
   1.494 +      r++;
   1.495 +      continue;
   1.496 +    }
   1.497 +    /* We must apply the point transform by Al.  For AC coefficients this
   1.498 +     * is an integer division with rounding towards 0.  To do this portably
   1.499 +     * in C, we shift after obtaining the absolute value; so the code is
   1.500 +     * interwoven with finding the abs value (temp) and output bits (temp2).
   1.501 +     */
   1.502 +    if (temp < 0) {
   1.503 +      temp = -temp;		/* temp is abs value of input */
   1.504 +      temp >>= Al;		/* apply the point transform */
   1.505 +      /* For a negative coef, want temp2 = bitwise complement of abs(coef) */
   1.506 +      temp2 = ~temp;
   1.507 +    } else {
   1.508 +      temp >>= Al;		/* apply the point transform */
   1.509 +      temp2 = temp;
   1.510 +    }
   1.511 +    /* Watch out for case that nonzero coef is zero after point transform */
   1.512 +    if (temp == 0) {
   1.513 +      r++;
   1.514 +      continue;
   1.515 +    }
   1.516 +
   1.517 +    /* Emit any pending EOBRUN */
   1.518 +    if (entropy->EOBRUN > 0)
   1.519 +      emit_eobrun(entropy);
   1.520 +    /* if run length > 15, must emit special run-length-16 codes (0xF0) */
   1.521 +    while (r > 15) {
   1.522 +      emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
   1.523 +      r -= 16;
   1.524 +    }
   1.525 +
   1.526 +    /* Find the number of bits needed for the magnitude of the coefficient */
   1.527 +    nbits = 1;			/* there must be at least one 1 bit */
   1.528 +    while ((temp >>= 1))
   1.529 +      nbits++;
   1.530 +    /* Check for out-of-range coefficient values */
   1.531 +    if (nbits > MAX_COEF_BITS)
   1.532 +      ERREXIT(cinfo, JERR_BAD_DCT_COEF);
   1.533 +
   1.534 +    /* Count/emit Huffman symbol for run length / number of bits */
   1.535 +    emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
   1.536 +
   1.537 +    /* Emit that number of bits of the value, if positive, */
   1.538 +    /* or the complement of its magnitude, if negative. */
   1.539 +    emit_bits(entropy, (unsigned int) temp2, nbits);
   1.540 +
   1.541 +    r = 0;			/* reset zero run length */
   1.542 +  }
   1.543 +
   1.544 +  if (r > 0) {			/* If there are trailing zeroes, */
   1.545 +    entropy->EOBRUN++;		/* count an EOB */
   1.546 +    if (entropy->EOBRUN == 0x7FFF)
   1.547 +      emit_eobrun(entropy);	/* force it out to avoid overflow */
   1.548 +  }
   1.549 +
   1.550 +  cinfo->dest->next_output_byte = entropy->next_output_byte;
   1.551 +  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
   1.552 +
   1.553 +  /* Update restart-interval state too */
   1.554 +  if (cinfo->restart_interval) {
   1.555 +    if (entropy->restarts_to_go == 0) {
   1.556 +      entropy->restarts_to_go = cinfo->restart_interval;
   1.557 +      entropy->next_restart_num++;
   1.558 +      entropy->next_restart_num &= 7;
   1.559 +    }
   1.560 +    entropy->restarts_to_go--;
   1.561 +  }
   1.562 +
   1.563 +  return TRUE;
   1.564 +}
   1.565 +
   1.566 +
   1.567 +/*
   1.568 + * MCU encoding for DC successive approximation refinement scan.
   1.569 + * Note: we assume such scans can be multi-component, although the spec
   1.570 + * is not very clear on the point.
   1.571 + */
   1.572 +
   1.573 +METHODDEF(boolean)
   1.574 +encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
   1.575 +{
   1.576 +  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   1.577 +  register int temp;
   1.578 +  int blkn;
   1.579 +  int Al = cinfo->Al;
   1.580 +  JBLOCKROW block;
   1.581 +
   1.582 +  entropy->next_output_byte = cinfo->dest->next_output_byte;
   1.583 +  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
   1.584 +
   1.585 +  /* Emit restart marker if needed */
   1.586 +  if (cinfo->restart_interval)
   1.587 +    if (entropy->restarts_to_go == 0)
   1.588 +      emit_restart(entropy, entropy->next_restart_num);
   1.589 +
   1.590 +  /* Encode the MCU data blocks */
   1.591 +  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
   1.592 +    block = MCU_data[blkn];
   1.593 +
   1.594 +    /* We simply emit the Al'th bit of the DC coefficient value. */
   1.595 +    temp = (*block)[0];
   1.596 +    emit_bits(entropy, (unsigned int) (temp >> Al), 1);
   1.597 +  }
   1.598 +
   1.599 +  cinfo->dest->next_output_byte = entropy->next_output_byte;
   1.600 +  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
   1.601 +
   1.602 +  /* Update restart-interval state too */
   1.603 +  if (cinfo->restart_interval) {
   1.604 +    if (entropy->restarts_to_go == 0) {
   1.605 +      entropy->restarts_to_go = cinfo->restart_interval;
   1.606 +      entropy->next_restart_num++;
   1.607 +      entropy->next_restart_num &= 7;
   1.608 +    }
   1.609 +    entropy->restarts_to_go--;
   1.610 +  }
   1.611 +
   1.612 +  return TRUE;
   1.613 +}
   1.614 +
   1.615 +
   1.616 +/*
   1.617 + * MCU encoding for AC successive approximation refinement scan.
   1.618 + */
   1.619 +
   1.620 +METHODDEF(boolean)
   1.621 +encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
   1.622 +{
   1.623 +  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   1.624 +  register int temp;
   1.625 +  register int r, k;
   1.626 +  int EOB;
   1.627 +  char *BR_buffer;
   1.628 +  unsigned int BR;
   1.629 +  int Se = cinfo->Se;
   1.630 +  int Al = cinfo->Al;
   1.631 +  JBLOCKROW block;
   1.632 +  int absvalues[DCTSIZE2];
   1.633 +
   1.634 +  entropy->next_output_byte = cinfo->dest->next_output_byte;
   1.635 +  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
   1.636 +
   1.637 +  /* Emit restart marker if needed */
   1.638 +  if (cinfo->restart_interval)
   1.639 +    if (entropy->restarts_to_go == 0)
   1.640 +      emit_restart(entropy, entropy->next_restart_num);
   1.641 +
   1.642 +  /* Encode the MCU data block */
   1.643 +  block = MCU_data[0];
   1.644 +
   1.645 +  /* It is convenient to make a pre-pass to determine the transformed
   1.646 +   * coefficients' absolute values and the EOB position.
   1.647 +   */
   1.648 +  EOB = 0;
   1.649 +  for (k = cinfo->Ss; k <= Se; k++) {
   1.650 +    temp = (*block)[jpeg_natural_order[k]];
   1.651 +    /* We must apply the point transform by Al.  For AC coefficients this
   1.652 +     * is an integer division with rounding towards 0.  To do this portably
   1.653 +     * in C, we shift after obtaining the absolute value.
   1.654 +     */
   1.655 +    if (temp < 0)
   1.656 +      temp = -temp;		/* temp is abs value of input */
   1.657 +    temp >>= Al;		/* apply the point transform */
   1.658 +    absvalues[k] = temp;	/* save abs value for main pass */
   1.659 +    if (temp == 1)
   1.660 +      EOB = k;			/* EOB = index of last newly-nonzero coef */
   1.661 +  }
   1.662 +
   1.663 +  /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
   1.664 +  
   1.665 +  r = 0;			/* r = run length of zeros */
   1.666 +  BR = 0;			/* BR = count of buffered bits added now */
   1.667 +  BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
   1.668 +
   1.669 +  for (k = cinfo->Ss; k <= Se; k++) {
   1.670 +    if ((temp = absvalues[k]) == 0) {
   1.671 +      r++;
   1.672 +      continue;
   1.673 +    }
   1.674 +
   1.675 +    /* Emit any required ZRLs, but not if they can be folded into EOB */
   1.676 +    while (r > 15 && k <= EOB) {
   1.677 +      /* emit any pending EOBRUN and the BE correction bits */
   1.678 +      emit_eobrun(entropy);
   1.679 +      /* Emit ZRL */
   1.680 +      emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
   1.681 +      r -= 16;
   1.682 +      /* Emit buffered correction bits that must be associated with ZRL */
   1.683 +      emit_buffered_bits(entropy, BR_buffer, BR);
   1.684 +      BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
   1.685 +      BR = 0;
   1.686 +    }
   1.687 +
   1.688 +    /* If the coef was previously nonzero, it only needs a correction bit.
   1.689 +     * NOTE: a straight translation of the spec's figure G.7 would suggest
   1.690 +     * that we also need to test r > 15.  But if r > 15, we can only get here
   1.691 +     * if k > EOB, which implies that this coefficient is not 1.
   1.692 +     */
   1.693 +    if (temp > 1) {
   1.694 +      /* The correction bit is the next bit of the absolute value. */
   1.695 +      BR_buffer[BR++] = (char) (temp & 1);
   1.696 +      continue;
   1.697 +    }
   1.698 +
   1.699 +    /* Emit any pending EOBRUN and the BE correction bits */
   1.700 +    emit_eobrun(entropy);
   1.701 +
   1.702 +    /* Count/emit Huffman symbol for run length / number of bits */
   1.703 +    emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
   1.704 +
   1.705 +    /* Emit output bit for newly-nonzero coef */
   1.706 +    temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
   1.707 +    emit_bits(entropy, (unsigned int) temp, 1);
   1.708 +
   1.709 +    /* Emit buffered correction bits that must be associated with this code */
   1.710 +    emit_buffered_bits(entropy, BR_buffer, BR);
   1.711 +    BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
   1.712 +    BR = 0;
   1.713 +    r = 0;			/* reset zero run length */
   1.714 +  }
   1.715 +
   1.716 +  if (r > 0 || BR > 0) {	/* If there are trailing zeroes, */
   1.717 +    entropy->EOBRUN++;		/* count an EOB */
   1.718 +    entropy->BE += BR;		/* concat my correction bits to older ones */
   1.719 +    /* We force out the EOB if we risk either:
   1.720 +     * 1. overflow of the EOB counter;
   1.721 +     * 2. overflow of the correction bit buffer during the next MCU.
   1.722 +     */
   1.723 +    if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
   1.724 +      emit_eobrun(entropy);
   1.725 +  }
   1.726 +
   1.727 +  cinfo->dest->next_output_byte = entropy->next_output_byte;
   1.728 +  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
   1.729 +
   1.730 +  /* Update restart-interval state too */
   1.731 +  if (cinfo->restart_interval) {
   1.732 +    if (entropy->restarts_to_go == 0) {
   1.733 +      entropy->restarts_to_go = cinfo->restart_interval;
   1.734 +      entropy->next_restart_num++;
   1.735 +      entropy->next_restart_num &= 7;
   1.736 +    }
   1.737 +    entropy->restarts_to_go--;
   1.738 +  }
   1.739 +
   1.740 +  return TRUE;
   1.741 +}
   1.742 +
   1.743 +
   1.744 +/*
   1.745 + * Finish up at the end of a Huffman-compressed progressive scan.
   1.746 + */
   1.747 +
   1.748 +METHODDEF(void)
   1.749 +finish_pass_phuff (j_compress_ptr cinfo)
   1.750 +{   
   1.751 +  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   1.752 +
   1.753 +  entropy->next_output_byte = cinfo->dest->next_output_byte;
   1.754 +  entropy->free_in_buffer = cinfo->dest->free_in_buffer;
   1.755 +
   1.756 +  /* Flush out any buffered data */
   1.757 +  emit_eobrun(entropy);
   1.758 +  flush_bits(entropy);
   1.759 +
   1.760 +  cinfo->dest->next_output_byte = entropy->next_output_byte;
   1.761 +  cinfo->dest->free_in_buffer = entropy->free_in_buffer;
   1.762 +}
   1.763 +
   1.764 +
   1.765 +/*
   1.766 + * Finish up a statistics-gathering pass and create the new Huffman tables.
   1.767 + */
   1.768 +
   1.769 +METHODDEF(void)
   1.770 +finish_pass_gather_phuff (j_compress_ptr cinfo)
   1.771 +{
   1.772 +  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
   1.773 +  boolean is_DC_band;
   1.774 +  int ci, tbl;
   1.775 +  jpeg_component_info * compptr;
   1.776 +  JHUFF_TBL **htblptr;
   1.777 +  boolean did[NUM_HUFF_TBLS];
   1.778 +
   1.779 +  /* Flush out buffered data (all we care about is counting the EOB symbol) */
   1.780 +  emit_eobrun(entropy);
   1.781 +
   1.782 +  is_DC_band = (cinfo->Ss == 0);
   1.783 +
   1.784 +  /* It's important not to apply jpeg_gen_optimal_table more than once
   1.785 +   * per table, because it clobbers the input frequency counts!
   1.786 +   */
   1.787 +  MEMZERO(did, SIZEOF(did));
   1.788 +
   1.789 +  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
   1.790 +    compptr = cinfo->cur_comp_info[ci];
   1.791 +    if (is_DC_band) {
   1.792 +      if (cinfo->Ah != 0)	/* DC refinement needs no table */
   1.793 +	continue;
   1.794 +      tbl = compptr->dc_tbl_no;
   1.795 +    } else {
   1.796 +      tbl = compptr->ac_tbl_no;
   1.797 +    }
   1.798 +    if (! did[tbl]) {
   1.799 +      if (is_DC_band)
   1.800 +        htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
   1.801 +      else
   1.802 +        htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
   1.803 +      if (*htblptr == NULL)
   1.804 +        *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
   1.805 +      jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
   1.806 +      did[tbl] = TRUE;
   1.807 +    }
   1.808 +  }
   1.809 +}
   1.810 +
   1.811 +
   1.812 +/*
   1.813 + * Module initialization routine for progressive Huffman entropy encoding.
   1.814 + */
   1.815 +
   1.816 +GLOBAL(void)
   1.817 +jinit_phuff_encoder (j_compress_ptr cinfo)
   1.818 +{
   1.819 +  phuff_entropy_ptr entropy;
   1.820 +  int i;
   1.821 +
   1.822 +  entropy = (phuff_entropy_ptr)
   1.823 +    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
   1.824 +				SIZEOF(phuff_entropy_encoder));
   1.825 +  cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
   1.826 +  entropy->pub.start_pass = start_pass_phuff;
   1.827 +
   1.828 +  /* Mark tables unallocated */
   1.829 +  for (i = 0; i < NUM_HUFF_TBLS; i++) {
   1.830 +    entropy->derived_tbls[i] = NULL;
   1.831 +    entropy->count_ptrs[i] = NULL;
   1.832 +  }
   1.833 +  entropy->bit_buffer = NULL;	/* needed only in AC refinement scan */
   1.834 +}
   1.835 +
   1.836 +#endif /* C_PROGRESSIVE_SUPPORTED */