jdphuff.c (19671B)
1 /* 2 * jdphuff.c 3 * 4 * Copyright (C) 1995, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README file. 7 * 8 * This file contains Huffman entropy decoding routines for progressive JPEG. 9 * 10 * Much of the complexity here has to do with supporting input suspension. 11 * If the data source module demands suspension, we want to be able to back 12 * up to the start of the current MCU. To do this, we copy state variables 13 * into local working storage, and update them back to the permanent 14 * storage only upon successful completion of an MCU. 15 */ 16 17 #define JPEG_INTERNALS 18 #include "jinclude.h" 19 #include "jpeglib.h" 20 #include "jdhuff.h" /* Declarations shared with jdhuff.c */ 21 22 23 #ifdef D_PROGRESSIVE_SUPPORTED 24 25 /* 26 * Expanded entropy decoder object for progressive Huffman decoding. 27 * 28 * The savable_state subrecord contains fields that change within an MCU, 29 * but must not be updated permanently until we complete the MCU. 30 */ 31 32 typedef struct { 33 unsigned int EOBRUN; /* remaining EOBs in EOBRUN */ 34 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ 35 } savable_state; 36 37 /* This macro is to work around compilers with missing or broken 38 * structure assignment. You'll need to fix this code if you have 39 * such a compiler and you change MAX_COMPS_IN_SCAN. 40 */ 41 42 #ifndef NO_STRUCT_ASSIGN 43 #define ASSIGN_STATE(dest,src) ((dest) = (src)) 44 #else 45 #if MAX_COMPS_IN_SCAN == 4 46 #define ASSIGN_STATE(dest,src) \ 47 ((dest).EOBRUN = (src).EOBRUN, \ 48 (dest).last_dc_val[0] = (src).last_dc_val[0], \ 49 (dest).last_dc_val[1] = (src).last_dc_val[1], \ 50 (dest).last_dc_val[2] = (src).last_dc_val[2], \ 51 (dest).last_dc_val[3] = (src).last_dc_val[3]) 52 #endif 53 #endif 54 55 56 typedef struct { 57 struct jpeg_entropy_decoder pub; /* public fields */ 58 59 /* These fields are loaded into local variables at start of each MCU. 60 * In case of suspension, we exit WITHOUT updating them. 61 */ 62 bitread_perm_state bitstate; /* Bit buffer at start of MCU */ 63 savable_state saved; /* Other state at start of MCU */ 64 65 /* These fields are NOT loaded into local working state. */ 66 unsigned int restarts_to_go; /* MCUs left in this restart interval */ 67 68 /* Pointers to derived tables (these workspaces have image lifespan) */ 69 d_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; 70 71 d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */ 72 } phuff_entropy_decoder; 73 74 typedef phuff_entropy_decoder * phuff_entropy_ptr; 75 76 /* Forward declarations */ 77 METHODDEF boolean decode_mcu_DC_first JPP((j_decompress_ptr cinfo, 78 JBLOCKROW *MCU_data)); 79 METHODDEF boolean decode_mcu_AC_first JPP((j_decompress_ptr cinfo, 80 JBLOCKROW *MCU_data)); 81 METHODDEF boolean decode_mcu_DC_refine JPP((j_decompress_ptr cinfo, 82 JBLOCKROW *MCU_data)); 83 METHODDEF boolean decode_mcu_AC_refine JPP((j_decompress_ptr cinfo, 84 JBLOCKROW *MCU_data)); 85 86 87 /* 88 * Initialize for a Huffman-compressed scan. 89 */ 90 91 METHODDEF void 92 start_pass_phuff_decoder (j_decompress_ptr cinfo) 93 { 94 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 95 boolean is_DC_band, bad; 96 int ci, coefi, tbl; 97 int *coef_bit_ptr; 98 jpeg_component_info * compptr; 99 100 is_DC_band = (cinfo->Ss == 0); 101 102 /* Validate scan parameters */ 103 bad = FALSE; 104 if (is_DC_band) { 105 if (cinfo->Se != 0) 106 bad = TRUE; 107 } else { 108 /* need not check Ss/Se < 0 since they came from unsigned bytes */ 109 if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2) 110 bad = TRUE; 111 /* AC scans may have only one component */ 112 if (cinfo->comps_in_scan != 1) 113 bad = TRUE; 114 } 115 if (cinfo->Ah != 0) { 116 /* Successive approximation refinement scan: must have Al = Ah-1. */ 117 if (cinfo->Al != cinfo->Ah-1) 118 bad = TRUE; 119 } 120 if (cinfo->Al > 13) /* need not check for < 0 */ 121 bad = TRUE; 122 if (bad) 123 ERREXIT4(cinfo, JERR_BAD_PROGRESSION, 124 cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); 125 /* Update progression status, and verify that scan order is legal. 126 * Note that inter-scan inconsistencies are treated as warnings 127 * not fatal errors ... not clear if this is right way to behave. 128 */ 129 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 130 int cindex = cinfo->cur_comp_info[ci]->component_index; 131 coef_bit_ptr = & cinfo->coef_bits[cindex][0]; 132 if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */ 133 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0); 134 for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) { 135 int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi]; 136 if (cinfo->Ah != expected) 137 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi); 138 coef_bit_ptr[coefi] = cinfo->Al; 139 } 140 } 141 142 /* Select MCU decoding routine */ 143 if (cinfo->Ah == 0) { 144 if (is_DC_band) 145 entropy->pub.decode_mcu = decode_mcu_DC_first; 146 else 147 entropy->pub.decode_mcu = decode_mcu_AC_first; 148 } else { 149 if (is_DC_band) 150 entropy->pub.decode_mcu = decode_mcu_DC_refine; 151 else 152 entropy->pub.decode_mcu = decode_mcu_AC_refine; 153 } 154 155 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 156 compptr = cinfo->cur_comp_info[ci]; 157 /* Make sure requested tables are present, and compute derived tables. 158 * We may build same derived table more than once, but it's not expensive. 159 */ 160 if (is_DC_band) { 161 if (cinfo->Ah == 0) { /* DC refinement needs no table */ 162 tbl = compptr->dc_tbl_no; 163 if (tbl < 0 || tbl >= NUM_HUFF_TBLS || 164 cinfo->dc_huff_tbl_ptrs[tbl] == NULL) 165 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); 166 jpeg_make_d_derived_tbl(cinfo, cinfo->dc_huff_tbl_ptrs[tbl], 167 & entropy->derived_tbls[tbl]); 168 } 169 } else { 170 tbl = compptr->ac_tbl_no; 171 if (tbl < 0 || tbl >= NUM_HUFF_TBLS || 172 cinfo->ac_huff_tbl_ptrs[tbl] == NULL) 173 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); 174 jpeg_make_d_derived_tbl(cinfo, cinfo->ac_huff_tbl_ptrs[tbl], 175 & entropy->derived_tbls[tbl]); 176 /* remember the single active table */ 177 entropy->ac_derived_tbl = entropy->derived_tbls[tbl]; 178 } 179 /* Initialize DC predictions to 0 */ 180 entropy->saved.last_dc_val[ci] = 0; 181 } 182 183 /* Initialize bitread state variables */ 184 entropy->bitstate.bits_left = 0; 185 entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */ 186 entropy->bitstate.printed_eod = FALSE; 187 188 /* Initialize private state variables */ 189 entropy->saved.EOBRUN = 0; 190 191 /* Initialize restart counter */ 192 entropy->restarts_to_go = cinfo->restart_interval; 193 } 194 195 196 /* 197 * Figure F.12: extend sign bit. 198 * On some machines, a shift and add will be faster than a table lookup. 199 */ 200 201 #ifdef AVOID_TABLES 202 203 #define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x)) 204 205 #else 206 207 #define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x)) 208 209 static const int extend_test[16] = /* entry n is 2**(n-1) */ 210 { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 211 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; 212 213 static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ 214 { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1, 215 ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1, 216 ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1, 217 ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 }; 218 219 #endif /* AVOID_TABLES */ 220 221 222 /* 223 * Check for a restart marker & resynchronize decoder. 224 * Returns FALSE if must suspend. 225 */ 226 227 LOCAL boolean 228 process_restart (j_decompress_ptr cinfo) 229 { 230 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 231 int ci; 232 233 /* Throw away any unused bits remaining in bit buffer; */ 234 /* include any full bytes in next_marker's count of discarded bytes */ 235 cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; 236 entropy->bitstate.bits_left = 0; 237 238 /* Advance past the RSTn marker */ 239 if (! (*cinfo->marker->read_restart_marker) (cinfo)) 240 return FALSE; 241 242 /* Re-initialize DC predictions to 0 */ 243 for (ci = 0; ci < cinfo->comps_in_scan; ci++) 244 entropy->saved.last_dc_val[ci] = 0; 245 /* Re-init EOB run count, too */ 246 entropy->saved.EOBRUN = 0; 247 248 /* Reset restart counter */ 249 entropy->restarts_to_go = cinfo->restart_interval; 250 251 /* Next segment can get another out-of-data warning */ 252 entropy->bitstate.printed_eod = FALSE; 253 254 return TRUE; 255 } 256 257 258 /* 259 * Huffman MCU decoding. 260 * Each of these routines decodes and returns one MCU's worth of 261 * Huffman-compressed coefficients. 262 * The coefficients are reordered from zigzag order into natural array order, 263 * but are not dequantized. 264 * 265 * The i'th block of the MCU is stored into the block pointed to by 266 * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. 267 * 268 * We return FALSE if data source requested suspension. In that case no 269 * changes have been made to permanent state. (Exception: some output 270 * coefficients may already have been assigned. This is harmless for 271 * spectral selection, since we'll just re-assign them on the next call. 272 * Successive approximation AC refinement has to be more careful, however.) 273 */ 274 275 /* 276 * MCU decoding for DC initial scan (either spectral selection, 277 * or first pass of successive approximation). 278 */ 279 280 METHODDEF boolean 281 decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 282 { 283 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 284 int Al = cinfo->Al; 285 register int s, r; 286 int blkn, ci; 287 JBLOCKROW block; 288 BITREAD_STATE_VARS; 289 savable_state state; 290 d_derived_tbl * tbl; 291 jpeg_component_info * compptr; 292 293 /* Process restart marker if needed; may have to suspend */ 294 if (cinfo->restart_interval) { 295 if (entropy->restarts_to_go == 0) 296 if (! process_restart(cinfo)) 297 return FALSE; 298 } 299 300 /* Load up working state */ 301 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 302 ASSIGN_STATE(state, entropy->saved); 303 304 /* Outer loop handles each block in the MCU */ 305 306 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { 307 block = MCU_data[blkn]; 308 ci = cinfo->MCU_membership[blkn]; 309 compptr = cinfo->cur_comp_info[ci]; 310 tbl = entropy->derived_tbls[compptr->dc_tbl_no]; 311 312 /* Decode a single block's worth of coefficients */ 313 314 /* Section F.2.2.1: decode the DC coefficient difference */ 315 HUFF_DECODE(s, br_state, tbl, return FALSE, label1); 316 if (s) { 317 CHECK_BIT_BUFFER(br_state, s, return FALSE); 318 r = GET_BITS(s); 319 s = HUFF_EXTEND(r, s); 320 } 321 322 /* Convert DC difference to actual value, update last_dc_val */ 323 s += state.last_dc_val[ci]; 324 state.last_dc_val[ci] = s; 325 /* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */ 326 (*block)[0] = (JCOEF) (s << Al); 327 } 328 329 /* Completed MCU, so update state */ 330 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 331 ASSIGN_STATE(entropy->saved, state); 332 333 /* Account for restart interval (no-op if not using restarts) */ 334 entropy->restarts_to_go--; 335 336 return TRUE; 337 } 338 339 340 /* 341 * MCU decoding for AC initial scan (either spectral selection, 342 * or first pass of successive approximation). 343 */ 344 345 METHODDEF boolean 346 decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 347 { 348 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 349 int Se = cinfo->Se; 350 int Al = cinfo->Al; 351 register int s, k, r; 352 unsigned int EOBRUN; 353 JBLOCKROW block; 354 BITREAD_STATE_VARS; 355 d_derived_tbl * tbl; 356 357 /* Process restart marker if needed; may have to suspend */ 358 if (cinfo->restart_interval) { 359 if (entropy->restarts_to_go == 0) 360 if (! process_restart(cinfo)) 361 return FALSE; 362 } 363 364 /* Load up working state. 365 * We can avoid loading/saving bitread state if in an EOB run. 366 */ 367 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we care about */ 368 369 /* There is always only one block per MCU */ 370 371 if (EOBRUN > 0) /* if it's a band of zeroes... */ 372 EOBRUN--; /* ...process it now (we do nothing) */ 373 else { 374 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 375 block = MCU_data[0]; 376 tbl = entropy->ac_derived_tbl; 377 378 for (k = cinfo->Ss; k <= Se; k++) { 379 HUFF_DECODE(s, br_state, tbl, return FALSE, label2); 380 r = s >> 4; 381 s &= 15; 382 if (s) { 383 k += r; 384 CHECK_BIT_BUFFER(br_state, s, return FALSE); 385 r = GET_BITS(s); 386 s = HUFF_EXTEND(r, s); 387 /* Scale and output coefficient in natural (dezigzagged) order */ 388 (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al); 389 } else { 390 if (r == 15) { /* ZRL */ 391 k += 15; /* skip 15 zeroes in band */ 392 } else { /* EOBr, run length is 2^r + appended bits */ 393 EOBRUN = 1 << r; 394 if (r) { /* EOBr, r > 0 */ 395 CHECK_BIT_BUFFER(br_state, r, return FALSE); 396 r = GET_BITS(r); 397 EOBRUN += r; 398 } 399 EOBRUN--; /* this band is processed at this moment */ 400 break; /* force end-of-band */ 401 } 402 } 403 } 404 405 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 406 } 407 408 /* Completed MCU, so update state */ 409 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we care about */ 410 411 /* Account for restart interval (no-op if not using restarts) */ 412 entropy->restarts_to_go--; 413 414 return TRUE; 415 } 416 417 418 /* 419 * MCU decoding for DC successive approximation refinement scan. 420 * Note: we assume such scans can be multi-component, although the spec 421 * is not very clear on the point. 422 */ 423 424 METHODDEF boolean 425 decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 426 { 427 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 428 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ 429 int blkn; 430 JBLOCKROW block; 431 BITREAD_STATE_VARS; 432 433 /* Process restart marker if needed; may have to suspend */ 434 if (cinfo->restart_interval) { 435 if (entropy->restarts_to_go == 0) 436 if (! process_restart(cinfo)) 437 return FALSE; 438 } 439 440 /* Load up working state */ 441 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 442 443 /* Outer loop handles each block in the MCU */ 444 445 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { 446 block = MCU_data[blkn]; 447 448 /* Encoded data is simply the next bit of the two's-complement DC value */ 449 CHECK_BIT_BUFFER(br_state, 1, return FALSE); 450 if (GET_BITS(1)) 451 (*block)[0] |= p1; 452 /* Note: since we use |=, repeating the assignment later is safe */ 453 } 454 455 /* Completed MCU, so update state */ 456 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 457 458 /* Account for restart interval (no-op if not using restarts) */ 459 entropy->restarts_to_go--; 460 461 return TRUE; 462 } 463 464 465 /* 466 * MCU decoding for AC successive approximation refinement scan. 467 */ 468 469 METHODDEF boolean 470 decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 471 { 472 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 473 int Se = cinfo->Se; 474 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ 475 int m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */ 476 register int s, k, r; 477 unsigned int EOBRUN; 478 JBLOCKROW block; 479 JCOEFPTR thiscoef; 480 BITREAD_STATE_VARS; 481 d_derived_tbl * tbl; 482 int num_newnz; 483 int newnz_pos[DCTSIZE2]; 484 485 /* Process restart marker if needed; may have to suspend */ 486 if (cinfo->restart_interval) { 487 if (entropy->restarts_to_go == 0) 488 if (! process_restart(cinfo)) 489 return FALSE; 490 } 491 492 /* Load up working state */ 493 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 494 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we care about */ 495 496 /* There is always only one block per MCU */ 497 block = MCU_data[0]; 498 tbl = entropy->ac_derived_tbl; 499 500 /* If we are forced to suspend, we must undo the assignments to any newly 501 * nonzero coefficients in the block, because otherwise we'd get confused 502 * next time about which coefficients were already nonzero. 503 * But we need not undo addition of bits to already-nonzero coefficients; 504 * instead, we can test the current bit position to see if we already did it. 505 */ 506 num_newnz = 0; 507 508 /* initialize coefficient loop counter to start of band */ 509 k = cinfo->Ss; 510 511 if (EOBRUN == 0) { 512 for (; k <= Se; k++) { 513 HUFF_DECODE(s, br_state, tbl, goto undoit, label3); 514 r = s >> 4; 515 s &= 15; 516 if (s) { 517 if (s != 1) /* size of new coef should always be 1 */ 518 WARNMS(cinfo, JWRN_HUFF_BAD_CODE); 519 CHECK_BIT_BUFFER(br_state, 1, goto undoit); 520 if (GET_BITS(1)) 521 s = p1; /* newly nonzero coef is positive */ 522 else 523 s = m1; /* newly nonzero coef is negative */ 524 } else { 525 if (r != 15) { 526 EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */ 527 if (r) { 528 CHECK_BIT_BUFFER(br_state, r, goto undoit); 529 r = GET_BITS(r); 530 EOBRUN += r; 531 } 532 break; /* rest of block is handled by EOB logic */ 533 } 534 /* note s = 0 for processing ZRL */ 535 } 536 /* Advance over already-nonzero coefs and r still-zero coefs, 537 * appending correction bits to the nonzeroes. A correction bit is 1 538 * if the absolute value of the coefficient must be increased. 539 */ 540 do { 541 thiscoef = *block + jpeg_natural_order[k]; 542 if (*thiscoef != 0) { 543 CHECK_BIT_BUFFER(br_state, 1, goto undoit); 544 if (GET_BITS(1)) { 545 if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */ 546 if (*thiscoef >= 0) 547 *thiscoef += p1; 548 else 549 *thiscoef += m1; 550 } 551 } 552 } else { 553 if (--r < 0) 554 break; /* reached target zero coefficient */ 555 } 556 k++; 557 } while (k <= Se); 558 if (s) { 559 int pos = jpeg_natural_order[k]; 560 /* Output newly nonzero coefficient */ 561 (*block)[pos] = (JCOEF) s; 562 /* Remember its position in case we have to suspend */ 563 newnz_pos[num_newnz++] = pos; 564 } 565 } 566 } 567 568 if (EOBRUN > 0) { 569 /* Scan any remaining coefficient positions after the end-of-band 570 * (the last newly nonzero coefficient, if any). Append a correction 571 * bit to each already-nonzero coefficient. A correction bit is 1 572 * if the absolute value of the coefficient must be increased. 573 */ 574 for (; k <= Se; k++) { 575 thiscoef = *block + jpeg_natural_order[k]; 576 if (*thiscoef != 0) { 577 CHECK_BIT_BUFFER(br_state, 1, goto undoit); 578 if (GET_BITS(1)) { 579 if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */ 580 if (*thiscoef >= 0) 581 *thiscoef += p1; 582 else 583 *thiscoef += m1; 584 } 585 } 586 } 587 } 588 /* Count one block completed in EOB run */ 589 EOBRUN--; 590 } 591 592 /* Completed MCU, so update state */ 593 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 594 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we care about */ 595 596 /* Account for restart interval (no-op if not using restarts) */ 597 entropy->restarts_to_go--; 598 599 return TRUE; 600 601 undoit: 602 /* Re-zero any output coefficients that we made newly nonzero */ 603 while (num_newnz > 0) 604 (*block)[newnz_pos[--num_newnz]] = 0; 605 606 return FALSE; 607 } 608 609 610 /* 611 * Module initialization routine for progressive Huffman entropy decoding. 612 */ 613 614 GLOBAL void 615 jinit_phuff_decoder (j_decompress_ptr cinfo) 616 { 617 phuff_entropy_ptr entropy; 618 int *coef_bit_ptr; 619 int ci, i; 620 621 entropy = (phuff_entropy_ptr) 622 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 623 SIZEOF(phuff_entropy_decoder)); 624 cinfo->entropy = (struct jpeg_entropy_decoder *) entropy; 625 entropy->pub.start_pass = start_pass_phuff_decoder; 626 627 /* Mark derived tables unallocated */ 628 for (i = 0; i < NUM_HUFF_TBLS; i++) { 629 entropy->derived_tbls[i] = NULL; 630 } 631 632 /* Create progression status table */ 633 cinfo->coef_bits = (int (*)[DCTSIZE2]) 634 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 635 cinfo->num_components*DCTSIZE2*SIZEOF(int)); 636 coef_bit_ptr = & cinfo->coef_bits[0][0]; 637 for (ci = 0; ci < cinfo->num_components; ci++) 638 for (i = 0; i < DCTSIZE2; i++) 639 *coef_bit_ptr++ = -1; 640 } 641 642 #endif /* D_PROGRESSIVE_SUPPORTED */