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| 1 /* | |
| 2 * jdphuff.c | |
| 3 * | |
| 4 * Copyright (C) 1995-1997, 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 /* Arguably the maximum Al value should be less than 13 for 8-bit precision, | |
| 123 * but the spec doesn't say so, and we try to be liberal about what we | |
| 124 * accept. Note: large Al values could result in out-of-range DC | |
| 125 * coefficients during early scans, leading to bizarre displays due to | |
| 126 * overflows in the IDCT math. But we won't crash. | |
| 127 */ | |
| 128 if (bad) | |
| 129 ERREXIT4(cinfo, JERR_BAD_PROGRESSION, | |
| 130 cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al); | |
| 131 /* Update progression status, and verify that scan order is legal. | |
| 132 * Note that inter-scan inconsistencies are treated as warnings | |
| 133 * not fatal errors ... not clear if this is right way to behave. | |
| 134 */ | |
| 135 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { | |
| 136 int cindex = cinfo->cur_comp_info[ci]->component_index; | |
| 137 coef_bit_ptr = & cinfo->coef_bits[cindex][0]; | |
| 138 if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */ | |
| 139 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0); | |
| 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 coef_bit_ptr[coefi] = cinfo->Al; | |
| 145 } | |
| 146 } | |
| 147 | |
| 148 /* Select MCU decoding routine */ | |
| 149 if (cinfo->Ah == 0) { | |
| 150 if (is_DC_band) | |
| 151 entropy->pub.decode_mcu = decode_mcu_DC_first; | |
| 152 else | |
| 153 entropy->pub.decode_mcu = decode_mcu_AC_first; | |
| 154 } else { | |
| 155 if (is_DC_band) | |
| 156 entropy->pub.decode_mcu = decode_mcu_DC_refine; | |
| 157 else | |
| 158 entropy->pub.decode_mcu = decode_mcu_AC_refine; | |
| 159 } | |
| 160 | |
| 161 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { | |
| 162 compptr = cinfo->cur_comp_info[ci]; | |
| 163 /* Make sure requested tables are present, and compute derived tables. | |
| 164 * We may build same derived table more than once, but it's not expensive. | |
| 165 */ | |
| 166 if (is_DC_band) { | |
| 167 if (cinfo->Ah == 0) { /* DC refinement needs no table */ | |
| 168 tbl = compptr->dc_tbl_no; | |
| 169 jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, | |
| 170 & entropy->derived_tbls[tbl]); | |
| 171 } | |
| 172 } else { | |
| 173 tbl = compptr->ac_tbl_no; | |
| 174 jpeg_make_d_derived_tbl(cinfo, FALSE, 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->pub.insufficient_data = 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 /* Reset out-of-data flag, unless read_restart_marker left us smack up | |
| 252 * against a marker. In that case we will end up treating the next data | |
| 253 * segment as empty, and we can avoid producing bogus output pixels by | |
| 254 * leaving the flag set. | |
| 255 */ | |
| 256 if (cinfo->unread_marker == 0) | |
| 257 entropy->pub.insufficient_data = FALSE; | |
| 258 | |
| 259 return TRUE; | |
| 260 } | |
| 261 | |
| 262 | |
| 263 /* | |
| 264 * Huffman MCU decoding. | |
| 265 * Each of these routines decodes and returns one MCU's worth of | |
| 266 * Huffman-compressed coefficients. | |
| 267 * The coefficients are reordered from zigzag order into natural array order, | |
| 268 * but are not dequantized. | |
| 269 * | |
| 270 * The i'th block of the MCU is stored into the block pointed to by | |
| 271 * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER. | |
| 272 * | |
| 273 * We return FALSE if data source requested suspension. In that case no | |
| 274 * changes have been made to permanent state. (Exception: some output | |
| 275 * coefficients may already have been assigned. This is harmless for | |
| 276 * spectral selection, since we'll just re-assign them on the next call. | |
| 277 * Successive approximation AC refinement has to be more careful, however.) | |
| 278 */ | |
| 279 | |
| 280 /* | |
| 281 * MCU decoding for DC initial scan (either spectral selection, | |
| 282 * or first pass of successive approximation). | |
| 283 */ | |
| 284 | |
| 285 METHODDEF(boolean) | |
| 286 decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) | |
| 287 { | |
| 288 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 289 int Al = cinfo->Al; | |
| 290 register int s, r; | |
| 291 int blkn, ci; | |
| 292 JBLOCKROW block; | |
| 293 BITREAD_STATE_VARS; | |
| 294 savable_state state; | |
| 295 d_derived_tbl * tbl; | |
| 296 jpeg_component_info * compptr; | |
| 297 | |
| 298 /* Process restart marker if needed; may have to suspend */ | |
| 299 if (cinfo->restart_interval) { | |
| 300 if (entropy->restarts_to_go == 0) | |
| 301 if (! process_restart(cinfo)) | |
| 302 return FALSE; | |
| 303 } | |
| 304 | |
| 305 /* If we've run out of data, just leave the MCU set to zeroes. | |
| 306 * This way, we return uniform gray for the remainder of the segment. | |
| 307 */ | |
| 308 if (! entropy->pub.insufficient_data) { | |
| 309 | |
| 310 /* Load up working state */ | |
| 311 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); | |
| 312 ASSIGN_STATE(state, entropy->saved); | |
| 313 | |
| 314 /* Outer loop handles each block in the MCU */ | |
| 315 | |
| 316 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { | |
| 317 block = MCU_data[blkn]; | |
| 318 ci = cinfo->MCU_membership[blkn]; | |
| 319 compptr = cinfo->cur_comp_info[ci]; | |
| 320 tbl = entropy->derived_tbls[compptr->dc_tbl_no]; | |
| 321 | |
| 322 /* Decode a single block's worth of coefficients */ | |
| 323 | |
| 324 /* Section F.2.2.1: decode the DC coefficient difference */ | |
| 325 HUFF_DECODE(s, br_state, tbl, return FALSE, label1); | |
| 326 if (s) { | |
| 327 CHECK_BIT_BUFFER(br_state, s, return FALSE); | |
| 328 r = GET_BITS(s); | |
| 329 s = HUFF_EXTEND(r, s); | |
| 330 } | |
| 331 | |
| 332 /* Convert DC difference to actual value, update last_dc_val */ | |
| 333 s += state.last_dc_val[ci]; | |
| 334 state.last_dc_val[ci] = s; | |
| 335 /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */ | |
| 336 (*block)[0] = (JCOEF) (s << Al); | |
| 337 } | |
| 338 | |
| 339 /* Completed MCU, so update state */ | |
| 340 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
| 341 ASSIGN_STATE(entropy->saved, state); | |
| 342 } | |
| 343 | |
| 344 /* Account for restart interval (no-op if not using restarts) */ | |
| 345 entropy->restarts_to_go--; | |
| 346 | |
| 347 return TRUE; | |
| 348 } | |
| 349 | |
| 350 | |
| 351 /* | |
| 352 * MCU decoding for AC initial scan (either spectral selection, | |
| 353 * or first pass of successive approximation). | |
| 354 */ | |
| 355 | |
| 356 METHODDEF(boolean) | |
| 357 decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) | |
| 358 { | |
| 359 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 360 int Se = cinfo->Se; | |
| 361 int Al = cinfo->Al; | |
| 362 register int s, k, r; | |
| 363 unsigned int EOBRUN; | |
| 364 JBLOCKROW block; | |
| 365 BITREAD_STATE_VARS; | |
| 366 d_derived_tbl * tbl; | |
| 367 | |
| 368 /* Process restart marker if needed; may have to suspend */ | |
| 369 if (cinfo->restart_interval) { | |
| 370 if (entropy->restarts_to_go == 0) | |
| 371 if (! process_restart(cinfo)) | |
| 372 return FALSE; | |
| 373 } | |
| 374 | |
| 375 /* If we've run out of data, just leave the MCU set to zeroes. | |
| 376 * This way, we return uniform gray for the remainder of the segment. | |
| 377 */ | |
| 378 if (! entropy->pub.insufficient_data) { | |
| 379 | |
| 380 /* Load up working state. | |
| 381 * We can avoid loading/saving bitread state if in an EOB run. | |
| 382 */ | |
| 383 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ | |
| 384 | |
| 385 /* There is always only one block per MCU */ | |
| 386 | |
| 387 if (EOBRUN > 0) /* if it's a band of zeroes... */ | |
| 388 EOBRUN--; /* ...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 CHECK_BIT_BUFFER(br_state, s, return FALSE); | |
| 401 r = GET_BITS(s); | |
| 402 s = HUFF_EXTEND(r, s); | |
| 403 /* Scale and output coefficient in natural (dezigzagged) order */ | |
| 404 (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al); | |
| 405 } else { | |
| 406 if (r == 15) { /* ZRL */ | |
| 407 k += 15; /* skip 15 zeroes in band */ | |
| 408 } else { /* EOBr, run length is 2^r + appended bits */ | |
| 409 EOBRUN = 1 << r; | |
| 410 if (r) { /* EOBr, r > 0 */ | |
| 411 CHECK_BIT_BUFFER(br_state, r, return FALSE); | |
| 412 r = GET_BITS(r); | |
| 413 EOBRUN += r; | |
| 414 } | |
| 415 EOBRUN--; /* this band is processed at this moment */ | |
| 416 break; /* force end-of-band */ | |
| 417 } | |
| 418 } | |
| 419 } | |
| 420 | |
| 421 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
| 422 } | |
| 423 | |
| 424 /* Completed MCU, so update state */ | |
| 425 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ | |
| 426 } | |
| 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 { | |
| 444 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 445 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ | |
| 446 int blkn; | |
| 447 JBLOCKROW block; | |
| 448 BITREAD_STATE_VARS; | |
| 449 | |
| 450 /* Process restart marker if needed; may have to suspend */ | |
| 451 if (cinfo->restart_interval) { | |
| 452 if (entropy->restarts_to_go == 0) | |
| 453 if (! process_restart(cinfo)) | |
| 454 return FALSE; | |
| 455 } | |
| 456 | |
| 457 /* Not worth the cycles to check insufficient_data here, | |
| 458 * since we will not change the data anyway if we read zeroes. | |
| 459 */ | |
| 460 | |
| 461 /* Load up working state */ | |
| 462 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); | |
| 463 | |
| 464 /* Outer loop handles each block in the MCU */ | |
| 465 | |
| 466 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { | |
| 467 block = MCU_data[blkn]; | |
| 468 | |
| 469 /* Encoded data is simply the next bit of the two's-complement DC value */ | |
| 470 CHECK_BIT_BUFFER(br_state, 1, return FALSE); | |
| 471 if (GET_BITS(1)) | |
| 472 (*block)[0] |= p1; | |
| 473 /* Note: since we use |=, repeating the assignment later is safe */ | |
| 474 } | |
| 475 | |
| 476 /* Completed MCU, so update state */ | |
| 477 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
| 478 | |
| 479 /* Account for restart interval (no-op if not using restarts) */ | |
| 480 entropy->restarts_to_go--; | |
| 481 | |
| 482 return TRUE; | |
| 483 } | |
| 484 | |
| 485 | |
| 486 /* | |
| 487 * MCU decoding for AC successive approximation refinement scan. | |
| 488 */ | |
| 489 | |
| 490 METHODDEF(boolean) | |
| 491 decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data) | |
| 492 { | |
| 493 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 494 int Se = cinfo->Se; | |
| 495 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */ | |
| 496 int m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */ | |
| 497 register int s, k, r; | |
| 498 unsigned int EOBRUN; | |
| 499 JBLOCKROW block; | |
| 500 JCOEFPTR thiscoef; | |
| 501 BITREAD_STATE_VARS; | |
| 502 d_derived_tbl * tbl; | |
| 503 int num_newnz; | |
| 504 int newnz_pos[DCTSIZE2]; | |
| 505 | |
| 506 /* Process restart marker if needed; may have to suspend */ | |
| 507 if (cinfo->restart_interval) { | |
| 508 if (entropy->restarts_to_go == 0) | |
| 509 if (! process_restart(cinfo)) | |
| 510 return FALSE; | |
| 511 } | |
| 512 | |
| 513 /* If we've run out of data, don't modify the MCU. | |
| 514 */ | |
| 515 if (! entropy->pub.insufficient_data) { | |
| 516 | |
| 517 /* Load up working state */ | |
| 518 BITREAD_LOAD_STATE(cinfo,entropy->bitstate); | |
| 519 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */ | |
| 520 | |
| 521 /* There is always only one block per MCU */ | |
| 522 block = MCU_data[0]; | |
| 523 tbl = entropy->ac_derived_tbl; | |
| 524 | |
| 525 /* If we are forced to suspend, we must undo the assignments to any newly | |
| 526 * nonzero coefficients in the block, because otherwise we'd get confused | |
| 527 * next time about which coefficients were already nonzero. | |
| 528 * But we need not undo addition of bits to already-nonzero coefficients; | |
| 529 * instead, we can test the current bit to see if we already did it. | |
| 530 */ | |
| 531 num_newnz = 0; | |
| 532 | |
| 533 /* initialize coefficient loop counter to start of band */ | |
| 534 k = cinfo->Ss; | |
| 535 | |
| 536 if (EOBRUN == 0) { | |
| 537 for (; k <= Se; k++) { | |
| 538 HUFF_DECODE(s, br_state, tbl, goto undoit, label3); | |
| 539 r = s >> 4; | |
| 540 s &= 15; | |
| 541 if (s) { | |
| 542 if (s != 1) /* size of new coef should always be 1 */ | |
| 543 WARNMS(cinfo, JWRN_HUFF_BAD_CODE); | |
| 544 CHECK_BIT_BUFFER(br_state, 1, goto undoit); | |
| 545 if (GET_BITS(1)) | |
| 546 s = p1; /* newly nonzero coef is positive */ | |
| 547 else | |
| 548 s = m1; /* newly nonzero coef is negative */ | |
| 549 } else { | |
| 550 if (r != 15) { | |
| 551 EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */ | |
| 552 if (r) { | |
| 553 CHECK_BIT_BUFFER(br_state, r, goto undoit); | |
| 554 r = GET_BITS(r); | |
| 555 EOBRUN += r; | |
| 556 } | |
| 557 break; /* rest of block is handled by EOB logic */ | |
| 558 } | |
| 559 /* note s = 0 for processing ZRL */ | |
| 560 } | |
| 561 /* Advance over already-nonzero coefs and r still-zero coefs, | |
| 562 * appending correction bits to the nonzeroes. A correction bit is 1 | |
| 563 * if the absolute value of the coefficient must be increased. | |
| 564 */ | |
| 565 do { | |
| 566 thiscoef = *block + jpeg_natural_order[k]; | |
| 567 if (*thiscoef != 0) { | |
| 568 CHECK_BIT_BUFFER(br_state, 1, goto undoit); | |
| 569 if (GET_BITS(1)) { | |
| 570 if ((*thiscoef & p1) == 0) { /* do nothing if already set it */ | |
| 571 if (*thiscoef >= 0) | |
| 572 *thiscoef += p1; | |
| 573 else | |
| 574 *thiscoef += m1; | |
| 575 } | |
| 576 } | |
| 577 } else { | |
| 578 if (--r < 0) | |
| 579 break; /* 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 /* Count one block completed in EOB run */ | |
| 614 EOBRUN--; | |
| 615 } | |
| 616 | |
| 617 /* Completed MCU, so update state */ | |
| 618 BITREAD_SAVE_STATE(cinfo,entropy->bitstate); | |
| 619 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */ | |
| 620 } | |
| 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 return FALSE; | |
| 633 } | |
| 634 | |
| 635 | |
| 636 /* | |
| 637 * Module initialization routine for progressive Huffman entropy decoding. | |
| 638 */ | |
| 639 | |
| 640 GLOBAL(void) | |
| 641 jinit_phuff_decoder (j_decompress_ptr cinfo) | |
| 642 { | |
| 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 #endif /* D_PROGRESSIVE_SUPPORTED */ | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1705523002:
Remove libjpeg and libjpeg_turbo. (Closed)
Base URL: https://github.com/domokit/mojo.git@master