jdphuff.cpp (23147B)
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 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 94 boolean is_DC_band, bad; 95 int ci, coefi, tbl; 96 int * coef_bit_ptr; 97 jpeg_component_info * compptr; 98 99 is_DC_band = ( cinfo->Ss == 0 ); 100 101 /* Validate scan parameters */ 102 bad = FALSE; 103 if ( is_DC_band ) { 104 if ( cinfo->Se != 0 ) { 105 bad = TRUE; 106 } 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 } 112 /* AC scans may have only one component */ 113 if ( cinfo->comps_in_scan != 1 ) { 114 bad = TRUE; 115 } 116 } 117 if ( cinfo->Ah != 0 ) { 118 /* Successive approximation refinement scan: must have Al = Ah-1. */ 119 if ( cinfo->Al != cinfo->Ah - 1 ) { 120 bad = TRUE; 121 } 122 } 123 if ( cinfo->Al > 13 ) { /* need not check for < 0 */ 124 bad = TRUE; 125 } 126 if ( bad ) { 127 ERREXIT4( cinfo, JERR_BAD_PROGRESSION, 128 cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al ); 129 } 130 /* Update progression status, and verify that scan order is legal. 131 * Note that inter-scan inconsistencies are treated as warnings 132 * not fatal errors ... not clear if this is right way to behave. 133 */ 134 for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) { 135 int cindex = cinfo->cur_comp_info[ci]->component_index; 136 coef_bit_ptr = &cinfo->coef_bits[cindex][0]; 137 if ( ( !is_DC_band ) && ( coef_bit_ptr[0] < 0 ) ) {/* AC without prior DC scan */ 138 WARNMS2( cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0 ); 139 } 140 for ( coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++ ) { 141 int expected = ( coef_bit_ptr[coefi] < 0 ) ? 0 : coef_bit_ptr[coefi]; 142 if ( cinfo->Ah != expected ) { 143 WARNMS2( cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi ); 144 } 145 coef_bit_ptr[coefi] = cinfo->Al; 146 } 147 } 148 149 /* Select MCU decoding routine */ 150 if ( cinfo->Ah == 0 ) { 151 if ( is_DC_band ) { 152 entropy->pub.decode_mcu = decode_mcu_DC_first; 153 } else { 154 entropy->pub.decode_mcu = decode_mcu_AC_first; 155 } 156 } else { 157 if ( is_DC_band ) { 158 entropy->pub.decode_mcu = decode_mcu_DC_refine; 159 } else { 160 entropy->pub.decode_mcu = decode_mcu_AC_refine; 161 } 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 if ( ( tbl < 0 ) || ( tbl >= NUM_HUFF_TBLS ) || 173 ( cinfo->dc_huff_tbl_ptrs[tbl] == NULL ) ) { 174 ERREXIT1( cinfo, JERR_NO_HUFF_TABLE, tbl ); 175 } 176 jpeg_make_d_derived_tbl( cinfo, cinfo->dc_huff_tbl_ptrs[tbl], 177 &entropy->derived_tbls[tbl] ); 178 } 179 } else { 180 tbl = compptr->ac_tbl_no; 181 if ( ( tbl < 0 ) || ( tbl >= NUM_HUFF_TBLS ) || 182 ( cinfo->ac_huff_tbl_ptrs[tbl] == NULL ) ) { 183 ERREXIT1( cinfo, JERR_NO_HUFF_TABLE, tbl ); 184 } 185 jpeg_make_d_derived_tbl( cinfo, cinfo->ac_huff_tbl_ptrs[tbl], 186 &entropy->derived_tbls[tbl] ); 187 /* remember the single active table */ 188 entropy->ac_derived_tbl = entropy->derived_tbls[tbl]; 189 } 190 /* Initialize DC predictions to 0 */ 191 entropy->saved.last_dc_val[ci] = 0; 192 } 193 194 /* Initialize bitread state variables */ 195 entropy->bitstate.bits_left = 0; 196 entropy->bitstate.get_buffer = 0;/* unnecessary, but keeps Purify quiet */ 197 entropy->bitstate.printed_eod = FALSE; 198 199 /* Initialize private state variables */ 200 entropy->saved.EOBRUN = 0; 201 202 /* Initialize restart counter */ 203 entropy->restarts_to_go = cinfo->restart_interval; 204 } 205 206 207 /* 208 * Figure F.12: extend sign bit. 209 * On some machines, a shift and add will be faster than a table lookup. 210 */ 211 212 #ifdef AVOID_TABLES 213 214 #define HUFF_EXTEND( x, s ) ( ( x ) < ( 1 << ( ( s ) - 1 ) ) ? ( x ) + ( ( ( -1 ) << ( s ) ) + 1 ) : ( x ) ) 215 216 #else 217 218 #define HUFF_EXTEND( x, s ) ( ( x ) < extend_test[s] ? ( x ) + extend_offset[s] : ( x ) ) 219 220 static const int extend_test[16] = /* entry n is 2**(n-1) */ 221 { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 222 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; 223 224 static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */ 225 { 0, ( ( -1 ) << 1 ) + 1, ( ( -1 ) << 2 ) + 1, ( ( -1 ) << 3 ) + 1, ( ( -1 ) << 4 ) + 1, 226 ( ( -1 ) << 5 ) + 1, ( ( -1 ) << 6 ) + 1, ( ( -1 ) << 7 ) + 1, ( ( -1 ) << 8 ) + 1, 227 ( ( -1 ) << 9 ) + 1, ( ( -1 ) << 10 ) + 1, ( ( -1 ) << 11 ) + 1, ( ( -1 ) << 12 ) + 1, 228 ( ( -1 ) << 13 ) + 1, ( ( -1 ) << 14 ) + 1, ( ( -1 ) << 15 ) + 1 }; 229 230 #endif /* AVOID_TABLES */ 231 232 233 /* 234 * Check for a restart marker & resynchronize decoder. 235 * Returns FALSE if must suspend. 236 */ 237 238 LOCAL boolean 239 process_restart( j_decompress_ptr cinfo ) { 240 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 241 int ci; 242 243 /* Throw away any unused bits remaining in bit buffer; */ 244 /* include any full bytes in next_marker's count of discarded bytes */ 245 cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8; 246 entropy->bitstate.bits_left = 0; 247 248 /* Advance past the RSTn marker */ 249 if ( !( *cinfo->marker->read_restart_marker )( cinfo ) ) { 250 return FALSE; 251 } 252 253 /* Re-initialize DC predictions to 0 */ 254 for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) { 255 entropy->saved.last_dc_val[ci] = 0; 256 } 257 /* Re-init EOB run count, too */ 258 entropy->saved.EOBRUN = 0; 259 260 /* Reset restart counter */ 261 entropy->restarts_to_go = cinfo->restart_interval; 262 263 /* Next segment can get another out-of-data warning */ 264 entropy->bitstate.printed_eod = FALSE; 265 266 return TRUE; 267 } 268 269 270 /* 271 * Huffman MCU decoding. 272 * Each of these routines decodes and returns one MCU's worth of 273 * Huffman-compressed coefficients. 274 * The coefficients are reordered from zigzag order into natural array order, 275 * but are not dequantized. 276 * 277 * The i'th block of the MCU is stored into the block pointed to by 278 * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. 279 * 280 * We return FALSE if data source requested suspension. In that case no 281 * changes have been made to permanent state. (Exception: some output 282 * coefficients may already have been assigned. This is harmless for 283 * spectral selection, since we'll just re-assign them on the next call. 284 * Successive approximation AC refinement has to be more careful, however.) 285 */ 286 287 /* 288 * MCU decoding for DC initial scan (either spectral selection, 289 * or first pass of successive approximation). 290 */ 291 292 METHODDEF boolean 293 decode_mcu_DC_first( j_decompress_ptr cinfo, JBLOCKROW * MCU_data ) { 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 } 312 313 /* Load up working state */ 314 BITREAD_LOAD_STATE( cinfo, entropy->bitstate ); 315 ASSIGN_STATE( state, entropy->saved ); 316 317 /* Outer loop handles each block in the MCU */ 318 319 for ( blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++ ) { 320 block = MCU_data[blkn]; 321 ci = cinfo->MCU_membership[blkn]; 322 compptr = cinfo->cur_comp_info[ci]; 323 tbl = entropy->derived_tbls[compptr->dc_tbl_no]; 324 325 /* Decode a single block's worth of coefficients */ 326 327 /* Section F.2.2.1: decode the DC coefficient difference */ 328 HUFF_DECODE( s, br_state, tbl, return FALSE, label1 ); 329 if ( s ) { 330 CHECK_BIT_BUFFER( br_state, s, return FALSE ); 331 332 r = GET_BITS( s ); 333 s = HUFF_EXTEND( r, s ); 334 } 335 336 /* Convert DC difference to actual value, update last_dc_val */ 337 s += state.last_dc_val[ci]; 338 state.last_dc_val[ci] = s; 339 /* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */ 340 ( *block )[0] = (JCOEF) ( s << Al ); 341 } 342 343 /* Completed MCU, so update state */ 344 BITREAD_SAVE_STATE( cinfo, entropy->bitstate ); 345 ASSIGN_STATE( entropy->saved, state ); 346 347 /* Account for restart interval (no-op if not using restarts) */ 348 entropy->restarts_to_go--; 349 350 return TRUE; 351 } 352 353 354 /* 355 * MCU decoding for AC initial scan (either spectral selection, 356 * or first pass of successive approximation). 357 */ 358 359 METHODDEF boolean 360 decode_mcu_AC_first( j_decompress_ptr cinfo, JBLOCKROW * MCU_data ) { 361 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 362 int Se = cinfo->Se; 363 int Al = cinfo->Al; 364 register int s, k, r; 365 unsigned int EOBRUN; 366 JBLOCKROW block; 367 BITREAD_STATE_VARS; 368 d_derived_tbl * tbl; 369 370 /* Process restart marker if needed; may have to suspend */ 371 if ( cinfo->restart_interval ) { 372 if ( entropy->restarts_to_go == 0 ) { 373 if ( !process_restart( cinfo ) ) { 374 return FALSE; 375 } 376 } 377 } 378 379 /* Load up working state. 380 * We can avoid loading/saving bitread state if in an EOB run. 381 */ 382 EOBRUN = entropy->saved.EOBRUN;/* only part of saved state we care about */ 383 384 /* There is always only one block per MCU */ 385 386 if ( EOBRUN > 0 ) { /* if it's a band of zeroes... */ 387 EOBRUN--; 388 } /* ...process it now (we do nothing) */ 389 else { 390 BITREAD_LOAD_STATE( cinfo, entropy->bitstate ); 391 block = MCU_data[0]; 392 tbl = entropy->ac_derived_tbl; 393 394 for ( k = cinfo->Ss; k <= Se; k++ ) { 395 HUFF_DECODE( s, br_state, tbl, return FALSE, label2 ); 396 r = s >> 4; 397 s &= 15; 398 if ( s ) { 399 k += r; 400 401 CHECK_BIT_BUFFER( br_state, s, return FALSE ); 402 r = GET_BITS( s ); 403 s = HUFF_EXTEND( r, s ); 404 /* Scale and output coefficient in natural (dezigzagged) order */ 405 ( *block )[jpeg_natural_order[k]] = (JCOEF) ( s << Al ); 406 } else { 407 if ( r == 15 ) {/* ZRL */ 408 k += 15;/* skip 15 zeroes in band */ 409 } else {/* EOBr, run length is 2^r + appended bits */ 410 EOBRUN = 1 << r; 411 if ( r ) {/* EOBr, r > 0 */ 412 CHECK_BIT_BUFFER( br_state, r, return FALSE ); 413 r = GET_BITS( r ); 414 EOBRUN += r; 415 } 416 EOBRUN--; /* this band is processed at this moment */ 417 break; /* force end-of-band */ 418 } 419 } 420 } 421 422 BITREAD_SAVE_STATE( cinfo, entropy->bitstate ); 423 } 424 425 /* Completed MCU, so update state */ 426 entropy->saved.EOBRUN = EOBRUN;/* only part of saved state we care about */ 427 428 /* Account for restart interval (no-op if not using restarts) */ 429 entropy->restarts_to_go--; 430 431 return TRUE; 432 } 433 434 435 /* 436 * MCU decoding for DC successive approximation refinement scan. 437 * Note: we assume such scans can be multi-component, although the spec 438 * is not very clear on the point. 439 */ 440 441 METHODDEF boolean 442 decode_mcu_DC_refine( j_decompress_ptr cinfo, JBLOCKROW * MCU_data ) { 443 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 444 int p1 = 1 << cinfo->Al;/* 1 in the bit position being coded */ 445 int blkn; 446 JBLOCKROW block; 447 BITREAD_STATE_VARS; 448 449 /* Process restart marker if needed; may have to suspend */ 450 if ( cinfo->restart_interval ) { 451 if ( entropy->restarts_to_go == 0 ) { 452 if ( !process_restart( cinfo ) ) { 453 return FALSE; 454 } 455 } 456 } 457 458 /* Load up working state */ 459 BITREAD_LOAD_STATE( cinfo, entropy->bitstate ); 460 461 /* Outer loop handles each block in the MCU */ 462 463 for ( blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++ ) { 464 block = MCU_data[blkn]; 465 466 /* Encoded data is simply the next bit of the two's-complement DC value */ 467 CHECK_BIT_BUFFER( br_state, 1, return FALSE ); 468 if ( GET_BITS( 1 ) ) { 469 ( *block )[0] |= p1; 470 } 471 /* Note: since we use |=, repeating the assignment later is safe */ 472 } 473 474 /* Completed MCU, so update state */ 475 BITREAD_SAVE_STATE( cinfo, entropy->bitstate ); 476 477 /* Account for restart interval (no-op if not using restarts) */ 478 entropy->restarts_to_go--; 479 480 return TRUE; 481 } 482 483 484 /* 485 * MCU decoding for AC successive approximation refinement scan. 486 */ 487 488 METHODDEF boolean 489 decode_mcu_AC_refine( j_decompress_ptr cinfo, JBLOCKROW * MCU_data ) { 490 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; 491 int Se = cinfo->Se; 492 int p1 = 1 << cinfo->Al;/* 1 in the bit position being coded */ 493 int m1 = ( -1 ) << cinfo->Al;/* -1 in the bit position being coded */ 494 register int s, k, r; 495 unsigned int EOBRUN; 496 JBLOCKROW block; 497 JCOEFPTR thiscoef; 498 BITREAD_STATE_VARS; 499 d_derived_tbl * tbl; 500 int num_newnz; 501 int newnz_pos[DCTSIZE2]; 502 503 /* Process restart marker if needed; may have to suspend */ 504 if ( cinfo->restart_interval ) { 505 if ( entropy->restarts_to_go == 0 ) { 506 if ( !process_restart( cinfo ) ) { 507 return FALSE; 508 } 509 } 510 } 511 512 /* Load up working state */ 513 BITREAD_LOAD_STATE( cinfo, entropy->bitstate ); 514 EOBRUN = entropy->saved.EOBRUN;/* only part of saved state we care about */ 515 516 /* There is always only one block per MCU */ 517 block = MCU_data[0]; 518 tbl = entropy->ac_derived_tbl; 519 520 /* If we are forced to suspend, we must undo the assignments to any newly 521 * nonzero coefficients in the block, because otherwise we'd get confused 522 * next time about which coefficients were already nonzero. 523 * But we need not undo addition of bits to already-nonzero coefficients; 524 * instead, we can test the current bit position to see if we already did it. 525 */ 526 num_newnz = 0; 527 528 /* initialize coefficient loop counter to start of band */ 529 k = cinfo->Ss; 530 531 if ( EOBRUN == 0 ) { 532 for (; k <= Se; k++ ) { 533 HUFF_DECODE( s, br_state, tbl, goto undoit, label3 ); 534 r = s >> 4; 535 s &= 15; 536 if ( s ) { 537 if ( s != 1 ) {/* size of new coef should always be 1 */ 538 WARNMS( cinfo, JWRN_HUFF_BAD_CODE ); 539 } 540 CHECK_BIT_BUFFER( br_state, 1, goto undoit ); 541 if ( GET_BITS( 1 ) ) { 542 s = p1; 543 } /* newly nonzero coef is positive */ 544 else { 545 s = m1; 546 } /* newly nonzero coef is negative */ 547 } else { 548 if ( r != 15 ) { 549 EOBRUN = 1 << r;/* EOBr, run length is 2^r + appended bits */ 550 if ( r ) { 551 CHECK_BIT_BUFFER( br_state, r, goto undoit ); 552 r = GET_BITS( r ); 553 EOBRUN += r; 554 } 555 break; /* rest of block is handled by EOB logic */ 556 } 557 /* note s = 0 for processing ZRL */ 558 } 559 /* Advance over already-nonzero coefs and r still-zero coefs, 560 * appending correction bits to the nonzeroes. A correction bit is 1 561 * if the absolute value of the coefficient must be increased. 562 */ 563 do { 564 thiscoef = *block + jpeg_natural_order[k]; 565 if ( *thiscoef != 0 ) { 566 CHECK_BIT_BUFFER( br_state, 1, goto undoit ); 567 if ( GET_BITS( 1 ) ) { 568 if ( ( *thiscoef & p1 ) == 0 ) {/* do nothing if already changed it */ 569 if ( *thiscoef >= 0 ) { 570 *thiscoef += p1; 571 } else { 572 *thiscoef += m1; 573 } 574 } 575 } 576 } else { 577 if ( --r < 0 ) { 578 break; 579 } /* reached target zero coefficient */ 580 } 581 k++; 582 } while ( k <= Se ); 583 if ( s ) { 584 int pos = jpeg_natural_order[k]; 585 /* Output newly nonzero coefficient */ 586 ( *block )[pos] = (JCOEF) s; 587 /* Remember its position in case we have to suspend */ 588 newnz_pos[num_newnz++] = pos; 589 } 590 } 591 } 592 593 if ( EOBRUN > 0 ) { 594 /* Scan any remaining coefficient positions after the end-of-band 595 * (the last newly nonzero coefficient, if any). Append a correction 596 * bit to each already-nonzero coefficient. A correction bit is 1 597 * if the absolute value of the coefficient must be increased. 598 */ 599 for (; k <= Se; k++ ) { 600 thiscoef = *block + jpeg_natural_order[k]; 601 if ( *thiscoef != 0 ) { 602 CHECK_BIT_BUFFER( br_state, 1, goto undoit ); 603 if ( GET_BITS( 1 ) ) { 604 if ( ( *thiscoef & p1 ) == 0 ) {/* do nothing if already changed it */ 605 if ( *thiscoef >= 0 ) { 606 *thiscoef += p1; 607 } else { 608 *thiscoef += m1; 609 } 610 } 611 } 612 } 613 } 614 /* Count one block completed in EOB run */ 615 EOBRUN--; 616 } 617 618 /* Completed MCU, so update state */ 619 BITREAD_SAVE_STATE( cinfo, entropy->bitstate ); 620 entropy->saved.EOBRUN = EOBRUN;/* only part of saved state we care about */ 621 622 /* Account for restart interval (no-op if not using restarts) */ 623 entropy->restarts_to_go--; 624 625 return TRUE; 626 627 undoit: 628 /* Re-zero any output coefficients that we made newly nonzero */ 629 while ( num_newnz > 0 ) { 630 ( *block )[newnz_pos[--num_newnz]] = 0; 631 } 632 633 return FALSE; 634 } 635 636 637 /* 638 * Module initialization routine for progressive Huffman entropy decoding. 639 */ 640 641 GLOBAL void 642 jinit_phuff_decoder( j_decompress_ptr cinfo ) { 643 phuff_entropy_ptr entropy; 644 int * coef_bit_ptr; 645 int ci, i; 646 647 entropy = (phuff_entropy_ptr) 648 ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE, 649 SIZEOF( phuff_entropy_decoder ) ); 650 cinfo->entropy = (struct jpeg_entropy_decoder *) entropy; 651 entropy->pub.start_pass = start_pass_phuff_decoder; 652 653 /* Mark derived tables unallocated */ 654 for ( i = 0; i < NUM_HUFF_TBLS; i++ ) { 655 entropy->derived_tbls[i] = NULL; 656 } 657 658 /* Create progression status table */ 659 cinfo->coef_bits = ( int ( * )[DCTSIZE2] ) 660 ( *cinfo->mem->alloc_small ) ( (j_common_ptr) cinfo, JPOOL_IMAGE, 661 cinfo->num_components * DCTSIZE2 * SIZEOF( int ) ); 662 coef_bit_ptr = &cinfo->coef_bits[0][0]; 663 for ( ci = 0; ci < cinfo->num_components; ci++ ) { 664 for ( i = 0; i < DCTSIZE2; i++ ) { 665 *coef_bit_ptr++ = -1; 666 } 667 } 668 } 669 670 #endif /* D_PROGRESSIVE_SUPPORTED */