dbf-halloween2015

annotate libs/libjpeg/jchuff.c @ 3:c37fe5d8a4ed

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windows port
author John Tsiombikas <nuclear@member.fsf.org>
date Sun, 01 Nov 2015 06:04:28 +0200
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rev   line source
nuclear@1 1 /*
nuclear@1 2 * jchuff.c
nuclear@1 3 *
nuclear@1 4 * Copyright (C) 1991-1997, Thomas G. Lane.
nuclear@1 5 * This file is part of the Independent JPEG Group's software.
nuclear@1 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@1 7 *
nuclear@1 8 * This file contains Huffman entropy encoding routines.
nuclear@1 9 *
nuclear@1 10 * Much of the complexity here has to do with supporting output suspension.
nuclear@1 11 * If the data destination module demands suspension, we want to be able to
nuclear@1 12 * back up to the start of the current MCU. To do this, we copy state
nuclear@1 13 * variables into local working storage, and update them back to the
nuclear@1 14 * permanent JPEG objects only upon successful completion of an MCU.
nuclear@1 15 */
nuclear@1 16
nuclear@1 17 #define JPEG_INTERNALS
nuclear@1 18 #include "jinclude.h"
nuclear@1 19 #include "jpeglib.h"
nuclear@1 20 #include "jchuff.h" /* Declarations shared with jcphuff.c */
nuclear@1 21
nuclear@1 22
nuclear@1 23 /* Expanded entropy encoder object for Huffman encoding.
nuclear@1 24 *
nuclear@1 25 * The savable_state subrecord contains fields that change within an MCU,
nuclear@1 26 * but must not be updated permanently until we complete the MCU.
nuclear@1 27 */
nuclear@1 28
nuclear@1 29 typedef struct {
nuclear@1 30 INT32 put_buffer; /* current bit-accumulation buffer */
nuclear@1 31 int put_bits; /* # of bits now in it */
nuclear@1 32 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
nuclear@1 33 } savable_state;
nuclear@1 34
nuclear@1 35 /* This macro is to work around compilers with missing or broken
nuclear@1 36 * structure assignment. You'll need to fix this code if you have
nuclear@1 37 * such a compiler and you change MAX_COMPS_IN_SCAN.
nuclear@1 38 */
nuclear@1 39
nuclear@1 40 #ifndef NO_STRUCT_ASSIGN
nuclear@1 41 #define ASSIGN_STATE(dest,src) ((dest) = (src))
nuclear@1 42 #else
nuclear@1 43 #if MAX_COMPS_IN_SCAN == 4
nuclear@1 44 #define ASSIGN_STATE(dest,src) \
nuclear@1 45 ((dest).put_buffer = (src).put_buffer, \
nuclear@1 46 (dest).put_bits = (src).put_bits, \
nuclear@1 47 (dest).last_dc_val[0] = (src).last_dc_val[0], \
nuclear@1 48 (dest).last_dc_val[1] = (src).last_dc_val[1], \
nuclear@1 49 (dest).last_dc_val[2] = (src).last_dc_val[2], \
nuclear@1 50 (dest).last_dc_val[3] = (src).last_dc_val[3])
nuclear@1 51 #endif
nuclear@1 52 #endif
nuclear@1 53
nuclear@1 54
nuclear@1 55 typedef struct {
nuclear@1 56 struct jpeg_entropy_encoder pub; /* public fields */
nuclear@1 57
nuclear@1 58 savable_state saved; /* Bit buffer & DC state at start of MCU */
nuclear@1 59
nuclear@1 60 /* These fields are NOT loaded into local working state. */
nuclear@1 61 unsigned int restarts_to_go; /* MCUs left in this restart interval */
nuclear@1 62 int next_restart_num; /* next restart number to write (0-7) */
nuclear@1 63
nuclear@1 64 /* Pointers to derived tables (these workspaces have image lifespan) */
nuclear@1 65 c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];
nuclear@1 66 c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];
nuclear@1 67
nuclear@1 68 #ifdef ENTROPY_OPT_SUPPORTED /* Statistics tables for optimization */
nuclear@1 69 long * dc_count_ptrs[NUM_HUFF_TBLS];
nuclear@1 70 long * ac_count_ptrs[NUM_HUFF_TBLS];
nuclear@1 71 #endif
nuclear@1 72 } huff_entropy_encoder;
nuclear@1 73
nuclear@1 74 typedef huff_entropy_encoder * huff_entropy_ptr;
nuclear@1 75
nuclear@1 76 /* Working state while writing an MCU.
nuclear@1 77 * This struct contains all the fields that are needed by subroutines.
nuclear@1 78 */
nuclear@1 79
nuclear@1 80 typedef struct {
nuclear@1 81 JOCTET * next_output_byte; /* => next byte to write in buffer */
nuclear@1 82 size_t free_in_buffer; /* # of byte spaces remaining in buffer */
nuclear@1 83 savable_state cur; /* Current bit buffer & DC state */
nuclear@1 84 j_compress_ptr cinfo; /* dump_buffer needs access to this */
nuclear@1 85 } working_state;
nuclear@1 86
nuclear@1 87
nuclear@1 88 /* Forward declarations */
nuclear@1 89 METHODDEF(boolean) encode_mcu_huff JPP((j_compress_ptr cinfo,
nuclear@1 90 JBLOCKROW *MCU_data));
nuclear@1 91 METHODDEF(void) finish_pass_huff JPP((j_compress_ptr cinfo));
nuclear@1 92 #ifdef ENTROPY_OPT_SUPPORTED
nuclear@1 93 METHODDEF(boolean) encode_mcu_gather JPP((j_compress_ptr cinfo,
nuclear@1 94 JBLOCKROW *MCU_data));
nuclear@1 95 METHODDEF(void) finish_pass_gather JPP((j_compress_ptr cinfo));
nuclear@1 96 #endif
nuclear@1 97
nuclear@1 98
nuclear@1 99 /*
nuclear@1 100 * Initialize for a Huffman-compressed scan.
nuclear@1 101 * If gather_statistics is TRUE, we do not output anything during the scan,
nuclear@1 102 * just count the Huffman symbols used and generate Huffman code tables.
nuclear@1 103 */
nuclear@1 104
nuclear@1 105 METHODDEF(void)
nuclear@1 106 start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics)
nuclear@1 107 {
nuclear@1 108 huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
nuclear@1 109 int ci, dctbl, actbl;
nuclear@1 110 jpeg_component_info * compptr;
nuclear@1 111
nuclear@1 112 if (gather_statistics) {
nuclear@1 113 #ifdef ENTROPY_OPT_SUPPORTED
nuclear@1 114 entropy->pub.encode_mcu = encode_mcu_gather;
nuclear@1 115 entropy->pub.finish_pass = finish_pass_gather;
nuclear@1 116 #else
nuclear@1 117 ERREXIT(cinfo, JERR_NOT_COMPILED);
nuclear@1 118 #endif
nuclear@1 119 } else {
nuclear@1 120 entropy->pub.encode_mcu = encode_mcu_huff;
nuclear@1 121 entropy->pub.finish_pass = finish_pass_huff;
nuclear@1 122 }
nuclear@1 123
nuclear@1 124 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
nuclear@1 125 compptr = cinfo->cur_comp_info[ci];
nuclear@1 126 dctbl = compptr->dc_tbl_no;
nuclear@1 127 actbl = compptr->ac_tbl_no;
nuclear@1 128 if (gather_statistics) {
nuclear@1 129 #ifdef ENTROPY_OPT_SUPPORTED
nuclear@1 130 /* Check for invalid table indexes */
nuclear@1 131 /* (make_c_derived_tbl does this in the other path) */
nuclear@1 132 if (dctbl < 0 || dctbl >= NUM_HUFF_TBLS)
nuclear@1 133 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, dctbl);
nuclear@1 134 if (actbl < 0 || actbl >= NUM_HUFF_TBLS)
nuclear@1 135 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, actbl);
nuclear@1 136 /* Allocate and zero the statistics tables */
nuclear@1 137 /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
nuclear@1 138 if (entropy->dc_count_ptrs[dctbl] == NULL)
nuclear@1 139 entropy->dc_count_ptrs[dctbl] = (long *)
nuclear@1 140 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@1 141 257 * SIZEOF(long));
nuclear@1 142 MEMZERO(entropy->dc_count_ptrs[dctbl], 257 * SIZEOF(long));
nuclear@1 143 if (entropy->ac_count_ptrs[actbl] == NULL)
nuclear@1 144 entropy->ac_count_ptrs[actbl] = (long *)
nuclear@1 145 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@1 146 257 * SIZEOF(long));
nuclear@1 147 MEMZERO(entropy->ac_count_ptrs[actbl], 257 * SIZEOF(long));
nuclear@1 148 #endif
nuclear@1 149 } else {
nuclear@1 150 /* Compute derived values for Huffman tables */
nuclear@1 151 /* We may do this more than once for a table, but it's not expensive */
nuclear@1 152 jpeg_make_c_derived_tbl(cinfo, TRUE, dctbl,
nuclear@1 153 & entropy->dc_derived_tbls[dctbl]);
nuclear@1 154 jpeg_make_c_derived_tbl(cinfo, FALSE, actbl,
nuclear@1 155 & entropy->ac_derived_tbls[actbl]);
nuclear@1 156 }
nuclear@1 157 /* Initialize DC predictions to 0 */
nuclear@1 158 entropy->saved.last_dc_val[ci] = 0;
nuclear@1 159 }
nuclear@1 160
nuclear@1 161 /* Initialize bit buffer to empty */
nuclear@1 162 entropy->saved.put_buffer = 0;
nuclear@1 163 entropy->saved.put_bits = 0;
nuclear@1 164
nuclear@1 165 /* Initialize restart stuff */
nuclear@1 166 entropy->restarts_to_go = cinfo->restart_interval;
nuclear@1 167 entropy->next_restart_num = 0;
nuclear@1 168 }
nuclear@1 169
nuclear@1 170
nuclear@1 171 /*
nuclear@1 172 * Compute the derived values for a Huffman table.
nuclear@1 173 * This routine also performs some validation checks on the table.
nuclear@1 174 *
nuclear@1 175 * Note this is also used by jcphuff.c.
nuclear@1 176 */
nuclear@1 177
nuclear@1 178 GLOBAL(void)
nuclear@1 179 jpeg_make_c_derived_tbl (j_compress_ptr cinfo, boolean isDC, int tblno,
nuclear@1 180 c_derived_tbl ** pdtbl)
nuclear@1 181 {
nuclear@1 182 JHUFF_TBL *htbl;
nuclear@1 183 c_derived_tbl *dtbl;
nuclear@1 184 int p, i, l, lastp, si, maxsymbol;
nuclear@1 185 char huffsize[257];
nuclear@1 186 unsigned int huffcode[257];
nuclear@1 187 unsigned int code;
nuclear@1 188
nuclear@1 189 /* Note that huffsize[] and huffcode[] are filled in code-length order,
nuclear@1 190 * paralleling the order of the symbols themselves in htbl->huffval[].
nuclear@1 191 */
nuclear@1 192
nuclear@1 193 /* Find the input Huffman table */
nuclear@1 194 if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
nuclear@1 195 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
nuclear@1 196 htbl =
nuclear@1 197 isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno];
nuclear@1 198 if (htbl == NULL)
nuclear@1 199 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
nuclear@1 200
nuclear@1 201 /* Allocate a workspace if we haven't already done so. */
nuclear@1 202 if (*pdtbl == NULL)
nuclear@1 203 *pdtbl = (c_derived_tbl *)
nuclear@1 204 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@1 205 SIZEOF(c_derived_tbl));
nuclear@1 206 dtbl = *pdtbl;
nuclear@1 207
nuclear@1 208 /* Figure C.1: make table of Huffman code length for each symbol */
nuclear@1 209
nuclear@1 210 p = 0;
nuclear@1 211 for (l = 1; l <= 16; l++) {
nuclear@1 212 i = (int) htbl->bits[l];
nuclear@1 213 if (i < 0 || p + i > 256) /* protect against table overrun */
nuclear@1 214 ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
nuclear@1 215 while (i--)
nuclear@1 216 huffsize[p++] = (char) l;
nuclear@1 217 }
nuclear@1 218 huffsize[p] = 0;
nuclear@1 219 lastp = p;
nuclear@1 220
nuclear@1 221 /* Figure C.2: generate the codes themselves */
nuclear@1 222 /* We also validate that the counts represent a legal Huffman code tree. */
nuclear@1 223
nuclear@1 224 code = 0;
nuclear@1 225 si = huffsize[0];
nuclear@1 226 p = 0;
nuclear@1 227 while (huffsize[p]) {
nuclear@1 228 while (((int) huffsize[p]) == si) {
nuclear@1 229 huffcode[p++] = code;
nuclear@1 230 code++;
nuclear@1 231 }
nuclear@1 232 /* code is now 1 more than the last code used for codelength si; but
nuclear@1 233 * it must still fit in si bits, since no code is allowed to be all ones.
nuclear@1 234 */
nuclear@1 235 if (((INT32) code) >= (((INT32) 1) << si))
nuclear@1 236 ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
nuclear@1 237 code <<= 1;
nuclear@1 238 si++;
nuclear@1 239 }
nuclear@1 240
nuclear@1 241 /* Figure C.3: generate encoding tables */
nuclear@1 242 /* These are code and size indexed by symbol value */
nuclear@1 243
nuclear@1 244 /* Set all codeless symbols to have code length 0;
nuclear@1 245 * this lets us detect duplicate VAL entries here, and later
nuclear@1 246 * allows emit_bits to detect any attempt to emit such symbols.
nuclear@1 247 */
nuclear@1 248 MEMZERO(dtbl->ehufsi, SIZEOF(dtbl->ehufsi));
nuclear@1 249
nuclear@1 250 /* This is also a convenient place to check for out-of-range
nuclear@1 251 * and duplicated VAL entries. We allow 0..255 for AC symbols
nuclear@1 252 * but only 0..15 for DC. (We could constrain them further
nuclear@1 253 * based on data depth and mode, but this seems enough.)
nuclear@1 254 */
nuclear@1 255 maxsymbol = isDC ? 15 : 255;
nuclear@1 256
nuclear@1 257 for (p = 0; p < lastp; p++) {
nuclear@1 258 i = htbl->huffval[p];
nuclear@1 259 if (i < 0 || i > maxsymbol || dtbl->ehufsi[i])
nuclear@1 260 ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
nuclear@1 261 dtbl->ehufco[i] = huffcode[p];
nuclear@1 262 dtbl->ehufsi[i] = huffsize[p];
nuclear@1 263 }
nuclear@1 264 }
nuclear@1 265
nuclear@1 266
nuclear@1 267 /* Outputting bytes to the file */
nuclear@1 268
nuclear@1 269 /* Emit a byte, taking 'action' if must suspend. */
nuclear@1 270 #define emit_byte(state,val,action) \
nuclear@1 271 { *(state)->next_output_byte++ = (JOCTET) (val); \
nuclear@1 272 if (--(state)->free_in_buffer == 0) \
nuclear@1 273 if (! dump_buffer(state)) \
nuclear@1 274 { action; } }
nuclear@1 275
nuclear@1 276
nuclear@1 277 LOCAL(boolean)
nuclear@1 278 dump_buffer (working_state * state)
nuclear@1 279 /* Empty the output buffer; return TRUE if successful, FALSE if must suspend */
nuclear@1 280 {
nuclear@1 281 struct jpeg_destination_mgr * dest = state->cinfo->dest;
nuclear@1 282
nuclear@1 283 if (! (*dest->empty_output_buffer) (state->cinfo))
nuclear@1 284 return FALSE;
nuclear@1 285 /* After a successful buffer dump, must reset buffer pointers */
nuclear@1 286 state->next_output_byte = dest->next_output_byte;
nuclear@1 287 state->free_in_buffer = dest->free_in_buffer;
nuclear@1 288 return TRUE;
nuclear@1 289 }
nuclear@1 290
nuclear@1 291
nuclear@1 292 /* Outputting bits to the file */
nuclear@1 293
nuclear@1 294 /* Only the right 24 bits of put_buffer are used; the valid bits are
nuclear@1 295 * left-justified in this part. At most 16 bits can be passed to emit_bits
nuclear@1 296 * in one call, and we never retain more than 7 bits in put_buffer
nuclear@1 297 * between calls, so 24 bits are sufficient.
nuclear@1 298 */
nuclear@1 299
nuclear@1 300 INLINE
nuclear@1 301 LOCAL(boolean)
nuclear@1 302 emit_bits (working_state * state, unsigned int code, int size)
nuclear@1 303 /* Emit some bits; return TRUE if successful, FALSE if must suspend */
nuclear@1 304 {
nuclear@1 305 /* This routine is heavily used, so it's worth coding tightly. */
nuclear@1 306 register INT32 put_buffer = (INT32) code;
nuclear@1 307 register int put_bits = state->cur.put_bits;
nuclear@1 308
nuclear@1 309 /* if size is 0, caller used an invalid Huffman table entry */
nuclear@1 310 if (size == 0)
nuclear@1 311 ERREXIT(state->cinfo, JERR_HUFF_MISSING_CODE);
nuclear@1 312
nuclear@1 313 put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
nuclear@1 314
nuclear@1 315 put_bits += size; /* new number of bits in buffer */
nuclear@1 316
nuclear@1 317 put_buffer <<= 24 - put_bits; /* align incoming bits */
nuclear@1 318
nuclear@1 319 put_buffer |= state->cur.put_buffer; /* and merge with old buffer contents */
nuclear@1 320
nuclear@1 321 while (put_bits >= 8) {
nuclear@1 322 int c = (int) ((put_buffer >> 16) & 0xFF);
nuclear@1 323
nuclear@1 324 emit_byte(state, c, return FALSE);
nuclear@1 325 if (c == 0xFF) { /* need to stuff a zero byte? */
nuclear@1 326 emit_byte(state, 0, return FALSE);
nuclear@1 327 }
nuclear@1 328 put_buffer <<= 8;
nuclear@1 329 put_bits -= 8;
nuclear@1 330 }
nuclear@1 331
nuclear@1 332 state->cur.put_buffer = put_buffer; /* update state variables */
nuclear@1 333 state->cur.put_bits = put_bits;
nuclear@1 334
nuclear@1 335 return TRUE;
nuclear@1 336 }
nuclear@1 337
nuclear@1 338
nuclear@1 339 LOCAL(boolean)
nuclear@1 340 flush_bits (working_state * state)
nuclear@1 341 {
nuclear@1 342 if (! emit_bits(state, 0x7F, 7)) /* fill any partial byte with ones */
nuclear@1 343 return FALSE;
nuclear@1 344 state->cur.put_buffer = 0; /* and reset bit-buffer to empty */
nuclear@1 345 state->cur.put_bits = 0;
nuclear@1 346 return TRUE;
nuclear@1 347 }
nuclear@1 348
nuclear@1 349
nuclear@1 350 /* Encode a single block's worth of coefficients */
nuclear@1 351
nuclear@1 352 LOCAL(boolean)
nuclear@1 353 encode_one_block (working_state * state, JCOEFPTR block, int last_dc_val,
nuclear@1 354 c_derived_tbl *dctbl, c_derived_tbl *actbl)
nuclear@1 355 {
nuclear@1 356 register int temp, temp2;
nuclear@1 357 register int nbits;
nuclear@1 358 register int k, r, i;
nuclear@1 359
nuclear@1 360 /* Encode the DC coefficient difference per section F.1.2.1 */
nuclear@1 361
nuclear@1 362 temp = temp2 = block[0] - last_dc_val;
nuclear@1 363
nuclear@1 364 if (temp < 0) {
nuclear@1 365 temp = -temp; /* temp is abs value of input */
nuclear@1 366 /* For a negative input, want temp2 = bitwise complement of abs(input) */
nuclear@1 367 /* This code assumes we are on a two's complement machine */
nuclear@1 368 temp2--;
nuclear@1 369 }
nuclear@1 370
nuclear@1 371 /* Find the number of bits needed for the magnitude of the coefficient */
nuclear@1 372 nbits = 0;
nuclear@1 373 while (temp) {
nuclear@1 374 nbits++;
nuclear@1 375 temp >>= 1;
nuclear@1 376 }
nuclear@1 377 /* Check for out-of-range coefficient values.
nuclear@1 378 * Since we're encoding a difference, the range limit is twice as much.
nuclear@1 379 */
nuclear@1 380 if (nbits > MAX_COEF_BITS+1)
nuclear@1 381 ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
nuclear@1 382
nuclear@1 383 /* Emit the Huffman-coded symbol for the number of bits */
nuclear@1 384 if (! emit_bits(state, dctbl->ehufco[nbits], dctbl->ehufsi[nbits]))
nuclear@1 385 return FALSE;
nuclear@1 386
nuclear@1 387 /* Emit that number of bits of the value, if positive, */
nuclear@1 388 /* or the complement of its magnitude, if negative. */
nuclear@1 389 if (nbits) /* emit_bits rejects calls with size 0 */
nuclear@1 390 if (! emit_bits(state, (unsigned int) temp2, nbits))
nuclear@1 391 return FALSE;
nuclear@1 392
nuclear@1 393 /* Encode the AC coefficients per section F.1.2.2 */
nuclear@1 394
nuclear@1 395 r = 0; /* r = run length of zeros */
nuclear@1 396
nuclear@1 397 for (k = 1; k < DCTSIZE2; k++) {
nuclear@1 398 if ((temp = block[jpeg_natural_order[k]]) == 0) {
nuclear@1 399 r++;
nuclear@1 400 } else {
nuclear@1 401 /* if run length > 15, must emit special run-length-16 codes (0xF0) */
nuclear@1 402 while (r > 15) {
nuclear@1 403 if (! emit_bits(state, actbl->ehufco[0xF0], actbl->ehufsi[0xF0]))
nuclear@1 404 return FALSE;
nuclear@1 405 r -= 16;
nuclear@1 406 }
nuclear@1 407
nuclear@1 408 temp2 = temp;
nuclear@1 409 if (temp < 0) {
nuclear@1 410 temp = -temp; /* temp is abs value of input */
nuclear@1 411 /* This code assumes we are on a two's complement machine */
nuclear@1 412 temp2--;
nuclear@1 413 }
nuclear@1 414
nuclear@1 415 /* Find the number of bits needed for the magnitude of the coefficient */
nuclear@1 416 nbits = 1; /* there must be at least one 1 bit */
nuclear@1 417 while ((temp >>= 1))
nuclear@1 418 nbits++;
nuclear@1 419 /* Check for out-of-range coefficient values */
nuclear@1 420 if (nbits > MAX_COEF_BITS)
nuclear@1 421 ERREXIT(state->cinfo, JERR_BAD_DCT_COEF);
nuclear@1 422
nuclear@1 423 /* Emit Huffman symbol for run length / number of bits */
nuclear@1 424 i = (r << 4) + nbits;
nuclear@1 425 if (! emit_bits(state, actbl->ehufco[i], actbl->ehufsi[i]))
nuclear@1 426 return FALSE;
nuclear@1 427
nuclear@1 428 /* Emit that number of bits of the value, if positive, */
nuclear@1 429 /* or the complement of its magnitude, if negative. */
nuclear@1 430 if (! emit_bits(state, (unsigned int) temp2, nbits))
nuclear@1 431 return FALSE;
nuclear@1 432
nuclear@1 433 r = 0;
nuclear@1 434 }
nuclear@1 435 }
nuclear@1 436
nuclear@1 437 /* If the last coef(s) were zero, emit an end-of-block code */
nuclear@1 438 if (r > 0)
nuclear@1 439 if (! emit_bits(state, actbl->ehufco[0], actbl->ehufsi[0]))
nuclear@1 440 return FALSE;
nuclear@1 441
nuclear@1 442 return TRUE;
nuclear@1 443 }
nuclear@1 444
nuclear@1 445
nuclear@1 446 /*
nuclear@1 447 * Emit a restart marker & resynchronize predictions.
nuclear@1 448 */
nuclear@1 449
nuclear@1 450 LOCAL(boolean)
nuclear@1 451 emit_restart (working_state * state, int restart_num)
nuclear@1 452 {
nuclear@1 453 int ci;
nuclear@1 454
nuclear@1 455 if (! flush_bits(state))
nuclear@1 456 return FALSE;
nuclear@1 457
nuclear@1 458 emit_byte(state, 0xFF, return FALSE);
nuclear@1 459 emit_byte(state, JPEG_RST0 + restart_num, return FALSE);
nuclear@1 460
nuclear@1 461 /* Re-initialize DC predictions to 0 */
nuclear@1 462 for (ci = 0; ci < state->cinfo->comps_in_scan; ci++)
nuclear@1 463 state->cur.last_dc_val[ci] = 0;
nuclear@1 464
nuclear@1 465 /* The restart counter is not updated until we successfully write the MCU. */
nuclear@1 466
nuclear@1 467 return TRUE;
nuclear@1 468 }
nuclear@1 469
nuclear@1 470
nuclear@1 471 /*
nuclear@1 472 * Encode and output one MCU's worth of Huffman-compressed coefficients.
nuclear@1 473 */
nuclear@1 474
nuclear@1 475 METHODDEF(boolean)
nuclear@1 476 encode_mcu_huff (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
nuclear@1 477 {
nuclear@1 478 huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
nuclear@1 479 working_state state;
nuclear@1 480 int blkn, ci;
nuclear@1 481 jpeg_component_info * compptr;
nuclear@1 482
nuclear@1 483 /* Load up working state */
nuclear@1 484 state.next_output_byte = cinfo->dest->next_output_byte;
nuclear@1 485 state.free_in_buffer = cinfo->dest->free_in_buffer;
nuclear@1 486 ASSIGN_STATE(state.cur, entropy->saved);
nuclear@1 487 state.cinfo = cinfo;
nuclear@1 488
nuclear@1 489 /* Emit restart marker if needed */
nuclear@1 490 if (cinfo->restart_interval) {
nuclear@1 491 if (entropy->restarts_to_go == 0)
nuclear@1 492 if (! emit_restart(&state, entropy->next_restart_num))
nuclear@1 493 return FALSE;
nuclear@1 494 }
nuclear@1 495
nuclear@1 496 /* Encode the MCU data blocks */
nuclear@1 497 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
nuclear@1 498 ci = cinfo->MCU_membership[blkn];
nuclear@1 499 compptr = cinfo->cur_comp_info[ci];
nuclear@1 500 if (! encode_one_block(&state,
nuclear@1 501 MCU_data[blkn][0], state.cur.last_dc_val[ci],
nuclear@1 502 entropy->dc_derived_tbls[compptr->dc_tbl_no],
nuclear@1 503 entropy->ac_derived_tbls[compptr->ac_tbl_no]))
nuclear@1 504 return FALSE;
nuclear@1 505 /* Update last_dc_val */
nuclear@1 506 state.cur.last_dc_val[ci] = MCU_data[blkn][0][0];
nuclear@1 507 }
nuclear@1 508
nuclear@1 509 /* Completed MCU, so update state */
nuclear@1 510 cinfo->dest->next_output_byte = state.next_output_byte;
nuclear@1 511 cinfo->dest->free_in_buffer = state.free_in_buffer;
nuclear@1 512 ASSIGN_STATE(entropy->saved, state.cur);
nuclear@1 513
nuclear@1 514 /* Update restart-interval state too */
nuclear@1 515 if (cinfo->restart_interval) {
nuclear@1 516 if (entropy->restarts_to_go == 0) {
nuclear@1 517 entropy->restarts_to_go = cinfo->restart_interval;
nuclear@1 518 entropy->next_restart_num++;
nuclear@1 519 entropy->next_restart_num &= 7;
nuclear@1 520 }
nuclear@1 521 entropy->restarts_to_go--;
nuclear@1 522 }
nuclear@1 523
nuclear@1 524 return TRUE;
nuclear@1 525 }
nuclear@1 526
nuclear@1 527
nuclear@1 528 /*
nuclear@1 529 * Finish up at the end of a Huffman-compressed scan.
nuclear@1 530 */
nuclear@1 531
nuclear@1 532 METHODDEF(void)
nuclear@1 533 finish_pass_huff (j_compress_ptr cinfo)
nuclear@1 534 {
nuclear@1 535 huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
nuclear@1 536 working_state state;
nuclear@1 537
nuclear@1 538 /* Load up working state ... flush_bits needs it */
nuclear@1 539 state.next_output_byte = cinfo->dest->next_output_byte;
nuclear@1 540 state.free_in_buffer = cinfo->dest->free_in_buffer;
nuclear@1 541 ASSIGN_STATE(state.cur, entropy->saved);
nuclear@1 542 state.cinfo = cinfo;
nuclear@1 543
nuclear@1 544 /* Flush out the last data */
nuclear@1 545 if (! flush_bits(&state))
nuclear@1 546 ERREXIT(cinfo, JERR_CANT_SUSPEND);
nuclear@1 547
nuclear@1 548 /* Update state */
nuclear@1 549 cinfo->dest->next_output_byte = state.next_output_byte;
nuclear@1 550 cinfo->dest->free_in_buffer = state.free_in_buffer;
nuclear@1 551 ASSIGN_STATE(entropy->saved, state.cur);
nuclear@1 552 }
nuclear@1 553
nuclear@1 554
nuclear@1 555 /*
nuclear@1 556 * Huffman coding optimization.
nuclear@1 557 *
nuclear@1 558 * We first scan the supplied data and count the number of uses of each symbol
nuclear@1 559 * that is to be Huffman-coded. (This process MUST agree with the code above.)
nuclear@1 560 * Then we build a Huffman coding tree for the observed counts.
nuclear@1 561 * Symbols which are not needed at all for the particular image are not
nuclear@1 562 * assigned any code, which saves space in the DHT marker as well as in
nuclear@1 563 * the compressed data.
nuclear@1 564 */
nuclear@1 565
nuclear@1 566 #ifdef ENTROPY_OPT_SUPPORTED
nuclear@1 567
nuclear@1 568
nuclear@1 569 /* Process a single block's worth of coefficients */
nuclear@1 570
nuclear@1 571 LOCAL(void)
nuclear@1 572 htest_one_block (j_compress_ptr cinfo, JCOEFPTR block, int last_dc_val,
nuclear@1 573 long dc_counts[], long ac_counts[])
nuclear@1 574 {
nuclear@1 575 register int temp;
nuclear@1 576 register int nbits;
nuclear@1 577 register int k, r;
nuclear@1 578
nuclear@1 579 /* Encode the DC coefficient difference per section F.1.2.1 */
nuclear@1 580
nuclear@1 581 temp = block[0] - last_dc_val;
nuclear@1 582 if (temp < 0)
nuclear@1 583 temp = -temp;
nuclear@1 584
nuclear@1 585 /* Find the number of bits needed for the magnitude of the coefficient */
nuclear@1 586 nbits = 0;
nuclear@1 587 while (temp) {
nuclear@1 588 nbits++;
nuclear@1 589 temp >>= 1;
nuclear@1 590 }
nuclear@1 591 /* Check for out-of-range coefficient values.
nuclear@1 592 * Since we're encoding a difference, the range limit is twice as much.
nuclear@1 593 */
nuclear@1 594 if (nbits > MAX_COEF_BITS+1)
nuclear@1 595 ERREXIT(cinfo, JERR_BAD_DCT_COEF);
nuclear@1 596
nuclear@1 597 /* Count the Huffman symbol for the number of bits */
nuclear@1 598 dc_counts[nbits]++;
nuclear@1 599
nuclear@1 600 /* Encode the AC coefficients per section F.1.2.2 */
nuclear@1 601
nuclear@1 602 r = 0; /* r = run length of zeros */
nuclear@1 603
nuclear@1 604 for (k = 1; k < DCTSIZE2; k++) {
nuclear@1 605 if ((temp = block[jpeg_natural_order[k]]) == 0) {
nuclear@1 606 r++;
nuclear@1 607 } else {
nuclear@1 608 /* if run length > 15, must emit special run-length-16 codes (0xF0) */
nuclear@1 609 while (r > 15) {
nuclear@1 610 ac_counts[0xF0]++;
nuclear@1 611 r -= 16;
nuclear@1 612 }
nuclear@1 613
nuclear@1 614 /* Find the number of bits needed for the magnitude of the coefficient */
nuclear@1 615 if (temp < 0)
nuclear@1 616 temp = -temp;
nuclear@1 617
nuclear@1 618 /* Find the number of bits needed for the magnitude of the coefficient */
nuclear@1 619 nbits = 1; /* there must be at least one 1 bit */
nuclear@1 620 while ((temp >>= 1))
nuclear@1 621 nbits++;
nuclear@1 622 /* Check for out-of-range coefficient values */
nuclear@1 623 if (nbits > MAX_COEF_BITS)
nuclear@1 624 ERREXIT(cinfo, JERR_BAD_DCT_COEF);
nuclear@1 625
nuclear@1 626 /* Count Huffman symbol for run length / number of bits */
nuclear@1 627 ac_counts[(r << 4) + nbits]++;
nuclear@1 628
nuclear@1 629 r = 0;
nuclear@1 630 }
nuclear@1 631 }
nuclear@1 632
nuclear@1 633 /* If the last coef(s) were zero, emit an end-of-block code */
nuclear@1 634 if (r > 0)
nuclear@1 635 ac_counts[0]++;
nuclear@1 636 }
nuclear@1 637
nuclear@1 638
nuclear@1 639 /*
nuclear@1 640 * Trial-encode one MCU's worth of Huffman-compressed coefficients.
nuclear@1 641 * No data is actually output, so no suspension return is possible.
nuclear@1 642 */
nuclear@1 643
nuclear@1 644 METHODDEF(boolean)
nuclear@1 645 encode_mcu_gather (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
nuclear@1 646 {
nuclear@1 647 huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
nuclear@1 648 int blkn, ci;
nuclear@1 649 jpeg_component_info * compptr;
nuclear@1 650
nuclear@1 651 /* Take care of restart intervals if needed */
nuclear@1 652 if (cinfo->restart_interval) {
nuclear@1 653 if (entropy->restarts_to_go == 0) {
nuclear@1 654 /* Re-initialize DC predictions to 0 */
nuclear@1 655 for (ci = 0; ci < cinfo->comps_in_scan; ci++)
nuclear@1 656 entropy->saved.last_dc_val[ci] = 0;
nuclear@1 657 /* Update restart state */
nuclear@1 658 entropy->restarts_to_go = cinfo->restart_interval;
nuclear@1 659 }
nuclear@1 660 entropy->restarts_to_go--;
nuclear@1 661 }
nuclear@1 662
nuclear@1 663 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
nuclear@1 664 ci = cinfo->MCU_membership[blkn];
nuclear@1 665 compptr = cinfo->cur_comp_info[ci];
nuclear@1 666 htest_one_block(cinfo, MCU_data[blkn][0], entropy->saved.last_dc_val[ci],
nuclear@1 667 entropy->dc_count_ptrs[compptr->dc_tbl_no],
nuclear@1 668 entropy->ac_count_ptrs[compptr->ac_tbl_no]);
nuclear@1 669 entropy->saved.last_dc_val[ci] = MCU_data[blkn][0][0];
nuclear@1 670 }
nuclear@1 671
nuclear@1 672 return TRUE;
nuclear@1 673 }
nuclear@1 674
nuclear@1 675
nuclear@1 676 /*
nuclear@1 677 * Generate the best Huffman code table for the given counts, fill htbl.
nuclear@1 678 * Note this is also used by jcphuff.c.
nuclear@1 679 *
nuclear@1 680 * The JPEG standard requires that no symbol be assigned a codeword of all
nuclear@1 681 * one bits (so that padding bits added at the end of a compressed segment
nuclear@1 682 * can't look like a valid code). Because of the canonical ordering of
nuclear@1 683 * codewords, this just means that there must be an unused slot in the
nuclear@1 684 * longest codeword length category. Section K.2 of the JPEG spec suggests
nuclear@1 685 * reserving such a slot by pretending that symbol 256 is a valid symbol
nuclear@1 686 * with count 1. In theory that's not optimal; giving it count zero but
nuclear@1 687 * including it in the symbol set anyway should give a better Huffman code.
nuclear@1 688 * But the theoretically better code actually seems to come out worse in
nuclear@1 689 * practice, because it produces more all-ones bytes (which incur stuffed
nuclear@1 690 * zero bytes in the final file). In any case the difference is tiny.
nuclear@1 691 *
nuclear@1 692 * The JPEG standard requires Huffman codes to be no more than 16 bits long.
nuclear@1 693 * If some symbols have a very small but nonzero probability, the Huffman tree
nuclear@1 694 * must be adjusted to meet the code length restriction. We currently use
nuclear@1 695 * the adjustment method suggested in JPEG section K.2. This method is *not*
nuclear@1 696 * optimal; it may not choose the best possible limited-length code. But
nuclear@1 697 * typically only very-low-frequency symbols will be given less-than-optimal
nuclear@1 698 * lengths, so the code is almost optimal. Experimental comparisons against
nuclear@1 699 * an optimal limited-length-code algorithm indicate that the difference is
nuclear@1 700 * microscopic --- usually less than a hundredth of a percent of total size.
nuclear@1 701 * So the extra complexity of an optimal algorithm doesn't seem worthwhile.
nuclear@1 702 */
nuclear@1 703
nuclear@1 704 GLOBAL(void)
nuclear@1 705 jpeg_gen_optimal_table (j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[])
nuclear@1 706 {
nuclear@1 707 #define MAX_CLEN 32 /* assumed maximum initial code length */
nuclear@1 708 UINT8 bits[MAX_CLEN+1]; /* bits[k] = # of symbols with code length k */
nuclear@1 709 int codesize[257]; /* codesize[k] = code length of symbol k */
nuclear@1 710 int others[257]; /* next symbol in current branch of tree */
nuclear@1 711 int c1, c2;
nuclear@1 712 int p, i, j;
nuclear@1 713 long v;
nuclear@1 714
nuclear@1 715 /* This algorithm is explained in section K.2 of the JPEG standard */
nuclear@1 716
nuclear@1 717 MEMZERO(bits, SIZEOF(bits));
nuclear@1 718 MEMZERO(codesize, SIZEOF(codesize));
nuclear@1 719 for (i = 0; i < 257; i++)
nuclear@1 720 others[i] = -1; /* init links to empty */
nuclear@1 721
nuclear@1 722 freq[256] = 1; /* make sure 256 has a nonzero count */
nuclear@1 723 /* Including the pseudo-symbol 256 in the Huffman procedure guarantees
nuclear@1 724 * that no real symbol is given code-value of all ones, because 256
nuclear@1 725 * will be placed last in the largest codeword category.
nuclear@1 726 */
nuclear@1 727
nuclear@1 728 /* Huffman's basic algorithm to assign optimal code lengths to symbols */
nuclear@1 729
nuclear@1 730 for (;;) {
nuclear@1 731 /* Find the smallest nonzero frequency, set c1 = its symbol */
nuclear@1 732 /* In case of ties, take the larger symbol number */
nuclear@1 733 c1 = -1;
nuclear@1 734 v = 1000000000L;
nuclear@1 735 for (i = 0; i <= 256; i++) {
nuclear@1 736 if (freq[i] && freq[i] <= v) {
nuclear@1 737 v = freq[i];
nuclear@1 738 c1 = i;
nuclear@1 739 }
nuclear@1 740 }
nuclear@1 741
nuclear@1 742 /* Find the next smallest nonzero frequency, set c2 = its symbol */
nuclear@1 743 /* In case of ties, take the larger symbol number */
nuclear@1 744 c2 = -1;
nuclear@1 745 v = 1000000000L;
nuclear@1 746 for (i = 0; i <= 256; i++) {
nuclear@1 747 if (freq[i] && freq[i] <= v && i != c1) {
nuclear@1 748 v = freq[i];
nuclear@1 749 c2 = i;
nuclear@1 750 }
nuclear@1 751 }
nuclear@1 752
nuclear@1 753 /* Done if we've merged everything into one frequency */
nuclear@1 754 if (c2 < 0)
nuclear@1 755 break;
nuclear@1 756
nuclear@1 757 /* Else merge the two counts/trees */
nuclear@1 758 freq[c1] += freq[c2];
nuclear@1 759 freq[c2] = 0;
nuclear@1 760
nuclear@1 761 /* Increment the codesize of everything in c1's tree branch */
nuclear@1 762 codesize[c1]++;
nuclear@1 763 while (others[c1] >= 0) {
nuclear@1 764 c1 = others[c1];
nuclear@1 765 codesize[c1]++;
nuclear@1 766 }
nuclear@1 767
nuclear@1 768 others[c1] = c2; /* chain c2 onto c1's tree branch */
nuclear@1 769
nuclear@1 770 /* Increment the codesize of everything in c2's tree branch */
nuclear@1 771 codesize[c2]++;
nuclear@1 772 while (others[c2] >= 0) {
nuclear@1 773 c2 = others[c2];
nuclear@1 774 codesize[c2]++;
nuclear@1 775 }
nuclear@1 776 }
nuclear@1 777
nuclear@1 778 /* Now count the number of symbols of each code length */
nuclear@1 779 for (i = 0; i <= 256; i++) {
nuclear@1 780 if (codesize[i]) {
nuclear@1 781 /* The JPEG standard seems to think that this can't happen, */
nuclear@1 782 /* but I'm paranoid... */
nuclear@1 783 if (codesize[i] > MAX_CLEN)
nuclear@1 784 ERREXIT(cinfo, JERR_HUFF_CLEN_OVERFLOW);
nuclear@1 785
nuclear@1 786 bits[codesize[i]]++;
nuclear@1 787 }
nuclear@1 788 }
nuclear@1 789
nuclear@1 790 /* JPEG doesn't allow symbols with code lengths over 16 bits, so if the pure
nuclear@1 791 * Huffman procedure assigned any such lengths, we must adjust the coding.
nuclear@1 792 * Here is what the JPEG spec says about how this next bit works:
nuclear@1 793 * Since symbols are paired for the longest Huffman code, the symbols are
nuclear@1 794 * removed from this length category two at a time. The prefix for the pair
nuclear@1 795 * (which is one bit shorter) is allocated to one of the pair; then,
nuclear@1 796 * skipping the BITS entry for that prefix length, a code word from the next
nuclear@1 797 * shortest nonzero BITS entry is converted into a prefix for two code words
nuclear@1 798 * one bit longer.
nuclear@1 799 */
nuclear@1 800
nuclear@1 801 for (i = MAX_CLEN; i > 16; i--) {
nuclear@1 802 while (bits[i] > 0) {
nuclear@1 803 j = i - 2; /* find length of new prefix to be used */
nuclear@1 804 while (bits[j] == 0)
nuclear@1 805 j--;
nuclear@1 806
nuclear@1 807 bits[i] -= 2; /* remove two symbols */
nuclear@1 808 bits[i-1]++; /* one goes in this length */
nuclear@1 809 bits[j+1] += 2; /* two new symbols in this length */
nuclear@1 810 bits[j]--; /* symbol of this length is now a prefix */
nuclear@1 811 }
nuclear@1 812 }
nuclear@1 813
nuclear@1 814 /* Remove the count for the pseudo-symbol 256 from the largest codelength */
nuclear@1 815 while (bits[i] == 0) /* find largest codelength still in use */
nuclear@1 816 i--;
nuclear@1 817 bits[i]--;
nuclear@1 818
nuclear@1 819 /* Return final symbol counts (only for lengths 0..16) */
nuclear@1 820 MEMCOPY(htbl->bits, bits, SIZEOF(htbl->bits));
nuclear@1 821
nuclear@1 822 /* Return a list of the symbols sorted by code length */
nuclear@1 823 /* It's not real clear to me why we don't need to consider the codelength
nuclear@1 824 * changes made above, but the JPEG spec seems to think this works.
nuclear@1 825 */
nuclear@1 826 p = 0;
nuclear@1 827 for (i = 1; i <= MAX_CLEN; i++) {
nuclear@1 828 for (j = 0; j <= 255; j++) {
nuclear@1 829 if (codesize[j] == i) {
nuclear@1 830 htbl->huffval[p] = (UINT8) j;
nuclear@1 831 p++;
nuclear@1 832 }
nuclear@1 833 }
nuclear@1 834 }
nuclear@1 835
nuclear@1 836 /* Set sent_table FALSE so updated table will be written to JPEG file. */
nuclear@1 837 htbl->sent_table = FALSE;
nuclear@1 838 }
nuclear@1 839
nuclear@1 840
nuclear@1 841 /*
nuclear@1 842 * Finish up a statistics-gathering pass and create the new Huffman tables.
nuclear@1 843 */
nuclear@1 844
nuclear@1 845 METHODDEF(void)
nuclear@1 846 finish_pass_gather (j_compress_ptr cinfo)
nuclear@1 847 {
nuclear@1 848 huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
nuclear@1 849 int ci, dctbl, actbl;
nuclear@1 850 jpeg_component_info * compptr;
nuclear@1 851 JHUFF_TBL **htblptr;
nuclear@1 852 boolean did_dc[NUM_HUFF_TBLS];
nuclear@1 853 boolean did_ac[NUM_HUFF_TBLS];
nuclear@1 854
nuclear@1 855 /* It's important not to apply jpeg_gen_optimal_table more than once
nuclear@1 856 * per table, because it clobbers the input frequency counts!
nuclear@1 857 */
nuclear@1 858 MEMZERO(did_dc, SIZEOF(did_dc));
nuclear@1 859 MEMZERO(did_ac, SIZEOF(did_ac));
nuclear@1 860
nuclear@1 861 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
nuclear@1 862 compptr = cinfo->cur_comp_info[ci];
nuclear@1 863 dctbl = compptr->dc_tbl_no;
nuclear@1 864 actbl = compptr->ac_tbl_no;
nuclear@1 865 if (! did_dc[dctbl]) {
nuclear@1 866 htblptr = & cinfo->dc_huff_tbl_ptrs[dctbl];
nuclear@1 867 if (*htblptr == NULL)
nuclear@1 868 *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
nuclear@1 869 jpeg_gen_optimal_table(cinfo, *htblptr, entropy->dc_count_ptrs[dctbl]);
nuclear@1 870 did_dc[dctbl] = TRUE;
nuclear@1 871 }
nuclear@1 872 if (! did_ac[actbl]) {
nuclear@1 873 htblptr = & cinfo->ac_huff_tbl_ptrs[actbl];
nuclear@1 874 if (*htblptr == NULL)
nuclear@1 875 *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
nuclear@1 876 jpeg_gen_optimal_table(cinfo, *htblptr, entropy->ac_count_ptrs[actbl]);
nuclear@1 877 did_ac[actbl] = TRUE;
nuclear@1 878 }
nuclear@1 879 }
nuclear@1 880 }
nuclear@1 881
nuclear@1 882
nuclear@1 883 #endif /* ENTROPY_OPT_SUPPORTED */
nuclear@1 884
nuclear@1 885
nuclear@1 886 /*
nuclear@1 887 * Module initialization routine for Huffman entropy encoding.
nuclear@1 888 */
nuclear@1 889
nuclear@1 890 GLOBAL(void)
nuclear@1 891 jinit_huff_encoder (j_compress_ptr cinfo)
nuclear@1 892 {
nuclear@1 893 huff_entropy_ptr entropy;
nuclear@1 894 int i;
nuclear@1 895
nuclear@1 896 entropy = (huff_entropy_ptr)
nuclear@1 897 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@1 898 SIZEOF(huff_entropy_encoder));
nuclear@1 899 cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
nuclear@1 900 entropy->pub.start_pass = start_pass_huff;
nuclear@1 901
nuclear@1 902 /* Mark tables unallocated */
nuclear@1 903 for (i = 0; i < NUM_HUFF_TBLS; i++) {
nuclear@1 904 entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
nuclear@1 905 #ifdef ENTROPY_OPT_SUPPORTED
nuclear@1 906 entropy->dc_count_ptrs[i] = entropy->ac_count_ptrs[i] = NULL;
nuclear@1 907 #endif
nuclear@1 908 }
nuclear@1 909 }