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