1/* 2 * jdphuff.c 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1995-1997, Thomas G. Lane. 6 * libjpeg-turbo Modifications: 7 * Copyright (C) 2015-2016, D. R. Commander. 8 * For conditions of distribution and use, see the accompanying README.ijg 9 * file. 10 * 11 * This file contains Huffman entropy decoding routines for progressive JPEG. 12 * 13 * Much of the complexity here has to do with supporting input suspension. 14 * If the data source module demands suspension, we want to be able to back 15 * up to the start of the current MCU. To do this, we copy state variables 16 * into local working storage, and update them back to the permanent 17 * storage only upon successful completion of an MCU. 18 */ 19 20#define JPEG_INTERNALS 21#include "jinclude.h" 22#include "jpeglib.h" 23#include "jdhuff.h" /* Declarations shared with jdhuff.c */ 24 25 26#ifdef D_PROGRESSIVE_SUPPORTED 27 28/* 29 * Expanded entropy decoder object for progressive Huffman decoding. 30 * 31 * The savable_state subrecord contains fields that change within an MCU, 32 * but must not be updated permanently until we complete the MCU. 33 */ 34 35typedef struct { 36 unsigned int EOBRUN; /* remaining EOBs in EOBRUN */ 37 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ 38} savable_state; 39 40/* This macro is to work around compilers with missing or broken 41 * structure assignment. You'll need to fix this code if you have 42 * such a compiler and you change MAX_COMPS_IN_SCAN. 43 */ 44 45#ifndef NO_STRUCT_ASSIGN 46#define ASSIGN_STATE(dest,src) ((dest) = (src)) 47#else 48#if MAX_COMPS_IN_SCAN == 4 49#define ASSIGN_STATE(dest,src) \ 50 ((dest).EOBRUN = (src).EOBRUN, \ 51 (dest).last_dc_val[0] = (src).last_dc_val[0], \ 52 (dest).last_dc_val[1] = (src).last_dc_val[1], \ 53 (dest).last_dc_val[2] = (src).last_dc_val[2], \ 54 (dest).last_dc_val[3] = (src).last_dc_val[3]) 55#endif 56#endif 57 58 59typedef struct { 60 struct jpeg_entropy_decoder pub; /* public fields */ 61 62 /* These fields are loaded into local variables at start of each MCU. 63 * In case of suspension, we exit WITHOUT updating them. 64 */ 65 bitread_perm_state bitstate; /* Bit buffer at start of MCU */ 66 savable_state saved; /* Other state at start of MCU */ 67 68 /* These fields are NOT loaded into local working state. */ 69 unsigned int restarts_to_go; /* MCUs left in this restart interval */ 70 71 /* Pointers to derived tables (these workspaces have image lifespan) */ 72 d_derived_tbl *derived_tbls[NUM_HUFF_TBLS]; 73 74 d_derived_tbl *ac_derived_tbl; /* active table during an AC scan */ 75} phuff_entropy_decoder; 76 77typedef phuff_entropy_decoder *phuff_entropy_ptr; 78 79/* Forward declarations */ 80METHODDEF(boolean) decode_mcu_DC_first (j_decompress_ptr cinfo, 81 JBLOCKROW *MCU_data); 82METHODDEF(boolean) decode_mcu_AC_first (j_decompress_ptr cinfo, 83 JBLOCKROW *MCU_data); 84METHODDEF(boolean) decode_mcu_DC_refine (j_decompress_ptr cinfo, 85 JBLOCKROW *MCU_data); 86METHODDEF(boolean) decode_mcu_AC_refine (j_decompress_ptr cinfo, 87 JBLOCKROW *MCU_data); 88 89 90/* 91 * Initialize for a Huffman-compressed scan. 92 */ 93 94METHODDEF(void) 95start_pass_phuff_decoder (j_decompress_ptr cinfo) 96{ 97 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 98 boolean is_DC_band, bad; 99 int ci, coefi, tbl; 100 d_derived_tbl **pdtbl; 101 int *coef_bit_ptr; 102 jpeg_component_info *compptr; 103 104 is_DC_band = (cinfo->Ss == 0); 105 106 /* Validate scan parameters */ 107 bad = FALSE; 108 if (is_DC_band) { 109 if (cinfo->Se != 0) 110 bad = TRUE; 111 } else { 112 /* need not check Ss/Se < 0 since they came from unsigned bytes */ 113 if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2) 114 bad = TRUE; 115 /* AC scans may have only one component */ 116 if (cinfo->comps_in_scan != 1) 117 bad = TRUE; 118 } 119 if (cinfo->Ah != 0) { 120 /* Successive approximation refinement scan: must have Al = Ah-1. */ 121 if (cinfo->Al != cinfo->Ah-1) 122 bad = TRUE; 123 } 124 if (cinfo->Al > 13) /* need not check for < 0 */ 125 bad = TRUE; 126 /* Arguably the maximum Al value should be less than 13 for 8-bit precision, 127 * but the spec doesn't say so, and we try to be liberal about what we 128 * accept. Note: large Al values could result in out-of-range DC 129 * coefficients during early scans, leading to bizarre displays due to 130 * overflows in the IDCT math. But we won't crash. 131 */ 132 if (bad) 133 ERREXIT4(cinfo, JERR_BAD_PROGRESSION, 134 cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); 135 /* Update progression status, and verify that scan order is legal. 136 * Note that inter-scan inconsistencies are treated as warnings 137 * not fatal errors ... not clear if this is right way to behave. 138 */ 139 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 140 int cindex = cinfo->cur_comp_info[ci]->component_index; 141 coef_bit_ptr = & cinfo->coef_bits[cindex][0]; 142 if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */ 143 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0); 144 for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) { 145 int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi]; 146 if (cinfo->Ah != expected) 147 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi); 148 coef_bit_ptr[coefi] = cinfo->Al; 149 } 150 } 151 152 /* Select MCU decoding routine */ 153 if (cinfo->Ah == 0) { 154 if (is_DC_band) 155 entropy->pub.decode_mcu = decode_mcu_DC_first; 156 else 157 entropy->pub.decode_mcu = decode_mcu_AC_first; 158 } else { 159 if (is_DC_band) 160 entropy->pub.decode_mcu = decode_mcu_DC_refine; 161 else 162 entropy->pub.decode_mcu = decode_mcu_AC_refine; 163 } 164 165 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 166 compptr = cinfo->cur_comp_info[ci]; 167 /* Make sure requested tables are present, and compute derived tables. 168 * We may build same derived table more than once, but it's not expensive. 169 */ 170 if (is_DC_band) { 171 if (cinfo->Ah == 0) { /* DC refinement needs no table */ 172 tbl = compptr->dc_tbl_no; 173 pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl; 174 jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, pdtbl); 175 } 176 } else { 177 tbl = compptr->ac_tbl_no; 178 pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl; 179 jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, pdtbl); 180 /* remember the single active table */ 181 entropy->ac_derived_tbl = entropy->derived_tbls[tbl]; 182 } 183 /* Initialize DC predictions to 0 */ 184 entropy->saved.last_dc_val[ci] = 0; 185 } 186 187 /* Initialize bitread state variables */ 188 entropy->bitstate.bits_left = 0; 189 entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */ 190 entropy->pub.insufficient_data = FALSE; 191 192 /* Initialize private state variables */ 193 entropy->saved.EOBRUN = 0; 194 195 /* Initialize restart counter */ 196 entropy->restarts_to_go = cinfo->restart_interval; 197} 198 199 200/* 201 * Figure F.12: extend sign bit. 202 * On some machines, a shift and add will be faster than a table lookup. 203 */ 204 205#define AVOID_TABLES 206#ifdef AVOID_TABLES 207 208#define NEG_1 ((unsigned)-1) 209#define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((NEG_1)<<(s)) + 1) : (x)) 210 211#else 212 213#define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x)) 214 215static const int extend_test[16] = /* entry n is 2**(n-1) */ 216 { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 217 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; 218 219static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ 220 { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1, 221 ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1, 222 ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1, 223 ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 }; 224 225#endif /* AVOID_TABLES */ 226 227 228/* 229 * Check for a restart marker & resynchronize decoder. 230 * Returns FALSE if must suspend. 231 */ 232 233LOCAL(boolean) 234process_restart (j_decompress_ptr cinfo) 235{ 236 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 237 int ci; 238 239 /* Throw away any unused bits remaining in bit buffer; */ 240 /* include any full bytes in next_marker's count of discarded bytes */ 241 cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; 242 entropy->bitstate.bits_left = 0; 243 244 /* Advance past the RSTn marker */ 245 if (! (*cinfo->marker->read_restart_marker) (cinfo)) 246 return FALSE; 247 248 /* Re-initialize DC predictions to 0 */ 249 for (ci = 0; ci < cinfo->comps_in_scan; ci++) 250 entropy->saved.last_dc_val[ci] = 0; 251 /* Re-init EOB run count, too */ 252 entropy->saved.EOBRUN = 0; 253 254 /* Reset restart counter */ 255 entropy->restarts_to_go = cinfo->restart_interval; 256 257 /* Reset out-of-data flag, unless read_restart_marker left us smack up 258 * against a marker. In that case we will end up treating the next data 259 * segment as empty, and we can avoid producing bogus output pixels by 260 * leaving the flag set. 261 */ 262 if (cinfo->unread_marker == 0) 263 entropy->pub.insufficient_data = FALSE; 264 265 return TRUE; 266} 267 268 269/* 270 * Huffman MCU decoding. 271 * Each of these routines decodes and returns one MCU's worth of 272 * Huffman-compressed coefficients. 273 * The coefficients are reordered from zigzag order into natural array order, 274 * but are not dequantized. 275 * 276 * The i'th block of the MCU is stored into the block pointed to by 277 * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. 278 * 279 * We return FALSE if data source requested suspension. In that case no 280 * changes have been made to permanent state. (Exception: some output 281 * coefficients may already have been assigned. This is harmless for 282 * spectral selection, since we'll just re-assign them on the next call. 283 * Successive approximation AC refinement has to be more careful, however.) 284 */ 285 286/* 287 * MCU decoding for DC initial scan (either spectral selection, 288 * or first pass of successive approximation). 289 */ 290 291METHODDEF(boolean) 292decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 293{ 294 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 295 int Al = cinfo->Al; 296 register int s, r; 297 int blkn, ci; 298 JBLOCKROW block; 299 BITREAD_STATE_VARS; 300 savable_state state; 301 d_derived_tbl *tbl; 302 jpeg_component_info *compptr; 303 304 /* Process restart marker if needed; may have to suspend */ 305 if (cinfo->restart_interval) { 306 if (entropy->restarts_to_go == 0) 307 if (! process_restart(cinfo)) 308 return FALSE; 309 } 310 311 /* If we've run out of data, just leave the MCU set to zeroes. 312 * This way, we return uniform gray for the remainder of the segment. 313 */ 314 if (! entropy->pub.insufficient_data) { 315 316 /* Load up working state */ 317 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 318 ASSIGN_STATE(state, entropy->saved); 319 320 /* Outer loop handles each block in the MCU */ 321 322 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { 323 block = MCU_data[blkn]; 324 ci = cinfo->MCU_membership[blkn]; 325 compptr = cinfo->cur_comp_info[ci]; 326 tbl = entropy->derived_tbls[compptr->dc_tbl_no]; 327 328 /* Decode a single block's worth of coefficients */ 329 330 /* Section F.2.2.1: decode the DC coefficient difference */ 331 HUFF_DECODE(s, br_state, tbl, return FALSE, label1); 332 if (s) { 333 CHECK_BIT_BUFFER(br_state, s, return FALSE); 334 r = GET_BITS(s); 335 s = HUFF_EXTEND(r, s); 336 } 337 338 /* Convert DC difference to actual value, update last_dc_val */ 339 s += state.last_dc_val[ci]; 340 state.last_dc_val[ci] = s; 341 /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */ 342 (*block)[0] = (JCOEF) LEFT_SHIFT(s, Al); 343 } 344 345 /* Completed MCU, so update state */ 346 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 347 ASSIGN_STATE(entropy->saved, state); 348 } 349 350 /* Account for restart interval (no-op if not using restarts) */ 351 entropy->restarts_to_go--; 352 353 return TRUE; 354} 355 356 357/* 358 * MCU decoding for AC initial scan (either spectral selection, 359 * or first pass of successive approximation). 360 */ 361 362METHODDEF(boolean) 363decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 364{ 365 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 366 int Se = cinfo->Se; 367 int Al = cinfo->Al; 368 register int s, k, r; 369 unsigned int EOBRUN; 370 JBLOCKROW block; 371 BITREAD_STATE_VARS; 372 d_derived_tbl *tbl; 373 374 /* Process restart marker if needed; may have to suspend */ 375 if (cinfo->restart_interval) { 376 if (entropy->restarts_to_go == 0) 377 if (! process_restart(cinfo)) 378 return FALSE; 379 } 380 381 /* If we've run out of data, just leave the MCU set to zeroes. 382 * This way, we return uniform gray for the remainder of the segment. 383 */ 384 if (! entropy->pub.insufficient_data) { 385 386 /* Load up working state. 387 * We can avoid loading/saving bitread state if in an EOB run. 388 */ 389 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ 390 391 /* There is always only one block per MCU */ 392 393 if (EOBRUN > 0) /* if it's a band of zeroes... */ 394 EOBRUN--; /* ...process it now (we do nothing) */ 395 else { 396 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 397 block = MCU_data[0]; 398 tbl = entropy->ac_derived_tbl; 399 400 for (k = cinfo->Ss; k <= Se; k++) { 401 HUFF_DECODE(s, br_state, tbl, return FALSE, label2); 402 r = s >> 4; 403 s &= 15; 404 if (s) { 405 k += r; 406 CHECK_BIT_BUFFER(br_state, s, return FALSE); 407 r = GET_BITS(s); 408 s = HUFF_EXTEND(r, s); 409 /* Scale and output coefficient in natural (dezigzagged) order */ 410 (*block)[jpeg_natural_order[k]] = (JCOEF) LEFT_SHIFT(s, Al); 411 } else { 412 if (r == 15) { /* ZRL */ 413 k += 15; /* skip 15 zeroes in band */ 414 } else { /* EOBr, run length is 2^r + appended bits */ 415 EOBRUN = 1 << r; 416 if (r) { /* EOBr, r > 0 */ 417 CHECK_BIT_BUFFER(br_state, r, return FALSE); 418 r = GET_BITS(r); 419 EOBRUN += r; 420 } 421 EOBRUN--; /* this band is processed at this moment */ 422 break; /* force end-of-band */ 423 } 424 } 425 } 426 427 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 428 } 429 430 /* Completed MCU, so update state */ 431 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ 432 } 433 434 /* Account for restart interval (no-op if not using restarts) */ 435 entropy->restarts_to_go--; 436 437 return TRUE; 438} 439 440 441/* 442 * MCU decoding for DC successive approximation refinement scan. 443 * Note: we assume such scans can be multi-component, although the spec 444 * is not very clear on the point. 445 */ 446 447METHODDEF(boolean) 448decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 449{ 450 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 451 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ 452 int blkn; 453 JBLOCKROW block; 454 BITREAD_STATE_VARS; 455 456 /* Process restart marker if needed; may have to suspend */ 457 if (cinfo->restart_interval) { 458 if (entropy->restarts_to_go == 0) 459 if (! process_restart(cinfo)) 460 return FALSE; 461 } 462 463 /* Not worth the cycles to check insufficient_data here, 464 * since we will not change the data anyway if we read zeroes. 465 */ 466 467 /* Load up working state */ 468 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 469 470 /* Outer loop handles each block in the MCU */ 471 472 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { 473 block = MCU_data[blkn]; 474 475 /* Encoded data is simply the next bit of the two's-complement DC value */ 476 CHECK_BIT_BUFFER(br_state, 1, return FALSE); 477 if (GET_BITS(1)) 478 (*block)[0] |= p1; 479 /* Note: since we use |=, repeating the assignment later is safe */ 480 } 481 482 /* Completed MCU, so update state */ 483 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 484 485 /* Account for restart interval (no-op if not using restarts) */ 486 entropy->restarts_to_go--; 487 488 return TRUE; 489} 490 491 492/* 493 * MCU decoding for AC successive approximation refinement scan. 494 */ 495 496METHODDEF(boolean) 497decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) 498{ 499 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 500 int Se = cinfo->Se; 501 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ 502 int m1 = (NEG_1) << cinfo->Al; /* -1 in the bit position being coded */ 503 register int s, k, r; 504 unsigned int EOBRUN; 505 JBLOCKROW block; 506 JCOEFPTR thiscoef; 507 BITREAD_STATE_VARS; 508 d_derived_tbl *tbl; 509 int num_newnz; 510 int newnz_pos[DCTSIZE2]; 511 512 /* Process restart marker if needed; may have to suspend */ 513 if (cinfo->restart_interval) { 514 if (entropy->restarts_to_go == 0) 515 if (! process_restart(cinfo)) 516 return FALSE; 517 } 518 519 /* If we've run out of data, don't modify the MCU. 520 */ 521 if (! entropy->pub.insufficient_data) { 522 523 /* Load up working state */ 524 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); 525 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ 526 527 /* There is always only one block per MCU */ 528 block = MCU_data[0]; 529 tbl = entropy->ac_derived_tbl; 530 531 /* If we are forced to suspend, we must undo the assignments to any newly 532 * nonzero coefficients in the block, because otherwise we'd get confused 533 * next time about which coefficients were already nonzero. 534 * But we need not undo addition of bits to already-nonzero coefficients; 535 * instead, we can test the current bit to see if we already did it. 536 */ 537 num_newnz = 0; 538 539 /* initialize coefficient loop counter to start of band */ 540 k = cinfo->Ss; 541 542 if (EOBRUN == 0) { 543 for (; k <= Se; k++) { 544 HUFF_DECODE(s, br_state, tbl, goto undoit, label3); 545 r = s >> 4; 546 s &= 15; 547 if (s) { 548 if (s != 1) /* size of new coef should always be 1 */ 549 WARNMS(cinfo, JWRN_HUFF_BAD_CODE); 550 CHECK_BIT_BUFFER(br_state, 1, goto undoit); 551 if (GET_BITS(1)) 552 s = p1; /* newly nonzero coef is positive */ 553 else 554 s = m1; /* newly nonzero coef is negative */ 555 } else { 556 if (r != 15) { 557 EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */ 558 if (r) { 559 CHECK_BIT_BUFFER(br_state, r, goto undoit); 560 r = GET_BITS(r); 561 EOBRUN += r; 562 } 563 break; /* rest of block is handled by EOB logic */ 564 } 565 /* note s = 0 for processing ZRL */ 566 } 567 /* Advance over already-nonzero coefs and r still-zero coefs, 568 * appending correction bits to the nonzeroes. A correction bit is 1 569 * if the absolute value of the coefficient must be increased. 570 */ 571 do { 572 thiscoef = *block + jpeg_natural_order[k]; 573 if (*thiscoef != 0) { 574 CHECK_BIT_BUFFER(br_state, 1, goto undoit); 575 if (GET_BITS(1)) { 576 if ((*thiscoef & p1) == 0) { /* do nothing if already set it */ 577 if (*thiscoef >= 0) 578 *thiscoef += p1; 579 else 580 *thiscoef += m1; 581 } 582 } 583 } else { 584 if (--r < 0) 585 break; /* reached target zero coefficient */ 586 } 587 k++; 588 } while (k <= Se); 589 if (s) { 590 int pos = jpeg_natural_order[k]; 591 /* Output newly nonzero coefficient */ 592 (*block)[pos] = (JCOEF) s; 593 /* Remember its position in case we have to suspend */ 594 newnz_pos[num_newnz++] = pos; 595 } 596 } 597 } 598 599 if (EOBRUN > 0) { 600 /* Scan any remaining coefficient positions after the end-of-band 601 * (the last newly nonzero coefficient, if any). Append a correction 602 * bit to each already-nonzero coefficient. A correction bit is 1 603 * if the absolute value of the coefficient must be increased. 604 */ 605 for (; k <= Se; k++) { 606 thiscoef = *block + jpeg_natural_order[k]; 607 if (*thiscoef != 0) { 608 CHECK_BIT_BUFFER(br_state, 1, goto undoit); 609 if (GET_BITS(1)) { 610 if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */ 611 if (*thiscoef >= 0) 612 *thiscoef += p1; 613 else 614 *thiscoef += m1; 615 } 616 } 617 } 618 } 619 /* Count one block completed in EOB run */ 620 EOBRUN--; 621 } 622 623 /* Completed MCU, so update state */ 624 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); 625 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ 626 } 627 628 /* Account for restart interval (no-op if not using restarts) */ 629 entropy->restarts_to_go--; 630 631 return TRUE; 632 633undoit: 634 /* Re-zero any output coefficients that we made newly nonzero */ 635 while (num_newnz > 0) 636 (*block)[newnz_pos[--num_newnz]] = 0; 637 638 return FALSE; 639} 640 641 642/* 643 * Module initialization routine for progressive Huffman entropy decoding. 644 */ 645 646GLOBAL(void) 647jinit_phuff_decoder (j_decompress_ptr cinfo) 648{ 649 phuff_entropy_ptr entropy; 650 int *coef_bit_ptr; 651 int ci, i; 652 653 entropy = (phuff_entropy_ptr) 654 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 655 sizeof(phuff_entropy_decoder)); 656 cinfo->entropy = (struct jpeg_entropy_decoder *) entropy; 657 entropy->pub.start_pass = start_pass_phuff_decoder; 658 659 /* Mark derived tables unallocated */ 660 for (i = 0; i < NUM_HUFF_TBLS; i++) { 661 entropy->derived_tbls[i] = NULL; 662 } 663 664 /* Create progression status table */ 665 cinfo->coef_bits = (int (*)[DCTSIZE2]) 666 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 667 cinfo->num_components*DCTSIZE2*sizeof(int)); 668 coef_bit_ptr = & cinfo->coef_bits[0][0]; 669 for (ci = 0; ci < cinfo->num_components; ci++) 670 for (i = 0; i < DCTSIZE2; i++) 671 *coef_bit_ptr++ = -1; 672} 673 674#endif /* D_PROGRESSIVE_SUPPORTED */ 675