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| 1 /* | |
| 2 * jcphuff.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 encoding routines for progressive JPEG. | |
| 9 * | |
| 10 * We do not support output suspension in this module, since the library | |
| 11 * currently does not allow multiple-scan files to be written with output | |
| 12 * suspension. | |
| 13 */ | |
| 14 | |
| 15 #define JPEG_INTERNALS | |
| 16 #include "jinclude.h" | |
| 17 #include "jpeglib.h" | |
| 18 #include "jchuff.h" /* Declarations shared with jchuff.c */ | |
| 19 | |
| 20 #ifdef C_PROGRESSIVE_SUPPORTED | |
| 21 | |
| 22 /* Expanded entropy encoder object for progressive Huffman encoding. */ | |
| 23 | |
| 24 typedef struct { | |
| 25 struct jpeg_entropy_encoder pub; /* public fields */ | |
| 26 | |
| 27 /* Mode flag: TRUE for optimization, FALSE for actual data output */ | |
| 28 boolean gather_statistics; | |
| 29 | |
| 30 /* Bit-level coding status. | |
| 31 * next_output_byte/free_in_buffer are local copies of cinfo->dest fields. | |
| 32 */ | |
| 33 JOCTET * next_output_byte; /* => next byte to write in buffer */ | |
| 34 size_t free_in_buffer; /* # of byte spaces remaining in buffer */ | |
| 35 INT32 put_buffer; /* current bit-accumulation buffer */ | |
| 36 int put_bits; /* # of bits now in it */ | |
| 37 j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */ | |
| 38 | |
| 39 /* Coding status for DC components */ | |
| 40 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ | |
| 41 | |
| 42 /* Coding status for AC components */ | |
| 43 int ac_tbl_no; /* the table number of the single component */ | |
| 44 unsigned int EOBRUN; /* run length of EOBs */ | |
| 45 unsigned int BE; /* # of buffered correction bits before MCU */ | |
| 46 char * bit_buffer; /* buffer for correction bits (1 per char) */ | |
| 47 /* packing correction bits tightly would save some space but cost time... */ | |
| 48 | |
| 49 unsigned int restarts_to_go; /* MCUs left in this restart interval */ | |
| 50 int next_restart_num; /* next restart number to write (0-7) */ | |
| 51 | |
| 52 /* Pointers to derived tables (these workspaces have image lifespan). | |
| 53 * Since any one scan codes only DC or only AC, we only need one set | |
| 54 * of tables, not one for DC and one for AC. | |
| 55 */ | |
| 56 c_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; | |
| 57 | |
| 58 /* Statistics tables for optimization; again, one set is enough */ | |
| 59 long * count_ptrs[NUM_HUFF_TBLS]; | |
| 60 } phuff_entropy_encoder; | |
| 61 | |
| 62 typedef phuff_entropy_encoder * phuff_entropy_ptr; | |
| 63 | |
| 64 /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit | |
| 65 * buffer can hold. Larger sizes may slightly improve compression, but | |
| 66 * 1000 is already well into the realm of overkill. | |
| 67 * The minimum safe size is 64 bits. | |
| 68 */ | |
| 69 | |
| 70 #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */ | |
| 71 | |
| 72 /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32. | |
| 73 * We assume that int right shift is unsigned if INT32 right shift is, | |
| 74 * which should be safe. | |
| 75 */ | |
| 76 | |
| 77 #ifdef RIGHT_SHIFT_IS_UNSIGNED | |
| 78 #define ISHIFT_TEMPS int ishift_temp; | |
| 79 #define IRIGHT_SHIFT(x,shft) \ | |
| 80 ((ishift_temp = (x)) < 0 ? \ | |
| 81 (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \ | |
| 82 (ishift_temp >> (shft))) | |
| 83 #else | |
| 84 #define ISHIFT_TEMPS | |
| 85 #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) | |
| 86 #endif | |
| 87 | |
| 88 /* Forward declarations */ | |
| 89 METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo, | |
| 90 JBLOCKROW *MCU_data)); | |
| 91 METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo, | |
| 92 JBLOCKROW *MCU_data)); | |
| 93 METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo, | |
| 94 JBLOCKROW *MCU_data)); | |
| 95 METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo, | |
| 96 JBLOCKROW *MCU_data)); | |
| 97 METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo)); | |
| 98 METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo)); | |
| 99 | |
| 100 | |
| 101 /* | |
| 102 * Initialize for a Huffman-compressed scan using progressive JPEG. | |
| 103 */ | |
| 104 | |
| 105 METHODDEF(void) | |
| 106 start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics) | |
| 107 { | |
| 108 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 109 boolean is_DC_band; | |
| 110 int ci, tbl; | |
| 111 jpeg_component_info * compptr; | |
| 112 | |
| 113 entropy->cinfo = cinfo; | |
| 114 entropy->gather_statistics = gather_statistics; | |
| 115 | |
| 116 is_DC_band = (cinfo->Ss == 0); | |
| 117 | |
| 118 /* We assume jcmaster.c already validated the scan parameters. */ | |
| 119 | |
| 120 /* Select execution routines */ | |
| 121 if (cinfo->Ah == 0) { | |
| 122 if (is_DC_band) | |
| 123 entropy->pub.encode_mcu = encode_mcu_DC_first; | |
| 124 else | |
| 125 entropy->pub.encode_mcu = encode_mcu_AC_first; | |
| 126 } else { | |
| 127 if (is_DC_band) | |
| 128 entropy->pub.encode_mcu = encode_mcu_DC_refine; | |
| 129 else { | |
| 130 entropy->pub.encode_mcu = encode_mcu_AC_refine; | |
| 131 /* AC refinement needs a correction bit buffer */ | |
| 132 if (entropy->bit_buffer == NULL) | |
| 133 entropy->bit_buffer = (char *) | |
| 134 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 135 MAX_CORR_BITS * SIZEOF(char)); | |
| 136 } | |
| 137 } | |
| 138 if (gather_statistics) | |
| 139 entropy->pub.finish_pass = finish_pass_gather_phuff; | |
| 140 else | |
| 141 entropy->pub.finish_pass = finish_pass_phuff; | |
| 142 | |
| 143 /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1 | |
| 144 * for AC coefficients. | |
| 145 */ | |
| 146 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { | |
| 147 compptr = cinfo->cur_comp_info[ci]; | |
| 148 /* Initialize DC predictions to 0 */ | |
| 149 entropy->last_dc_val[ci] = 0; | |
| 150 /* Get table index */ | |
| 151 if (is_DC_band) { | |
| 152 if (cinfo->Ah != 0) /* DC refinement needs no table */ | |
| 153 continue; | |
| 154 tbl = compptr->dc_tbl_no; | |
| 155 } else { | |
| 156 entropy->ac_tbl_no = tbl = compptr->ac_tbl_no; | |
| 157 } | |
| 158 if (gather_statistics) { | |
| 159 /* Check for invalid table index */ | |
| 160 /* (make_c_derived_tbl does this in the other path) */ | |
| 161 if (tbl < 0 || tbl >= NUM_HUFF_TBLS) | |
| 162 ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); | |
| 163 /* Allocate and zero the statistics tables */ | |
| 164 /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ | |
| 165 if (entropy->count_ptrs[tbl] == NULL) | |
| 166 entropy->count_ptrs[tbl] = (long *) | |
| 167 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 168 257 * SIZEOF(long)); | |
| 169 MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long)); | |
| 170 } else { | |
| 171 /* Compute derived values for Huffman table */ | |
| 172 /* We may do this more than once for a table, but it's not expensive */ | |
| 173 jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl, | |
| 174 & entropy->derived_tbls[tbl]); | |
| 175 } | |
| 176 } | |
| 177 | |
| 178 /* Initialize AC stuff */ | |
| 179 entropy->EOBRUN = 0; | |
| 180 entropy->BE = 0; | |
| 181 | |
| 182 /* Initialize bit buffer to empty */ | |
| 183 entropy->put_buffer = 0; | |
| 184 entropy->put_bits = 0; | |
| 185 | |
| 186 /* Initialize restart stuff */ | |
| 187 entropy->restarts_to_go = cinfo->restart_interval; | |
| 188 entropy->next_restart_num = 0; | |
| 189 } | |
| 190 | |
| 191 | |
| 192 /* Outputting bytes to the file. | |
| 193 * NB: these must be called only when actually outputting, | |
| 194 * that is, entropy->gather_statistics == FALSE. | |
| 195 */ | |
| 196 | |
| 197 /* Emit a byte */ | |
| 198 #define emit_byte(entropy,val) \ | |
| 199 { *(entropy)->next_output_byte++ = (JOCTET) (val); \ | |
| 200 if (--(entropy)->free_in_buffer == 0) \ | |
| 201 dump_buffer(entropy); } | |
| 202 | |
| 203 | |
| 204 LOCAL(void) | |
| 205 dump_buffer (phuff_entropy_ptr entropy) | |
| 206 /* Empty the output buffer; we do not support suspension in this module. */ | |
| 207 { | |
| 208 struct jpeg_destination_mgr * dest = entropy->cinfo->dest; | |
| 209 | |
| 210 if (! (*dest->empty_output_buffer) (entropy->cinfo)) | |
| 211 ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND); | |
| 212 /* After a successful buffer dump, must reset buffer pointers */ | |
| 213 entropy->next_output_byte = dest->next_output_byte; | |
| 214 entropy->free_in_buffer = dest->free_in_buffer; | |
| 215 } | |
| 216 | |
| 217 | |
| 218 /* Outputting bits to the file */ | |
| 219 | |
| 220 /* Only the right 24 bits of put_buffer are used; the valid bits are | |
| 221 * left-justified in this part. At most 16 bits can be passed to emit_bits | |
| 222 * in one call, and we never retain more than 7 bits in put_buffer | |
| 223 * between calls, so 24 bits are sufficient. | |
| 224 */ | |
| 225 | |
| 226 INLINE | |
| 227 LOCAL(void) | |
| 228 emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size) | |
| 229 /* Emit some bits, unless we are in gather mode */ | |
| 230 { | |
| 231 /* This routine is heavily used, so it's worth coding tightly. */ | |
| 232 register INT32 put_buffer = (INT32) code; | |
| 233 register int put_bits = entropy->put_bits; | |
| 234 | |
| 235 /* if size is 0, caller used an invalid Huffman table entry */ | |
| 236 if (size == 0) | |
| 237 ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); | |
| 238 | |
| 239 if (entropy->gather_statistics) | |
| 240 return; /* do nothing if we're only getting stats */ | |
| 241 | |
| 242 put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */ | |
| 243 | |
| 244 put_bits += size; /* new number of bits in buffer */ | |
| 245 | |
| 246 put_buffer <<= 24 - put_bits; /* align incoming bits */ | |
| 247 | |
| 248 put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */ | |
| 249 | |
| 250 while (put_bits >= 8) { | |
| 251 int c = (int) ((put_buffer >> 16) & 0xFF); | |
| 252 | |
| 253 emit_byte(entropy, c); | |
| 254 if (c == 0xFF) { /* need to stuff a zero byte? */ | |
| 255 emit_byte(entropy, 0); | |
| 256 } | |
| 257 put_buffer <<= 8; | |
| 258 put_bits -= 8; | |
| 259 } | |
| 260 | |
| 261 entropy->put_buffer = put_buffer; /* update variables */ | |
| 262 entropy->put_bits = put_bits; | |
| 263 } | |
| 264 | |
| 265 | |
| 266 LOCAL(void) | |
| 267 flush_bits (phuff_entropy_ptr entropy) | |
| 268 { | |
| 269 emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */ | |
| 270 entropy->put_buffer = 0; /* and reset bit-buffer to empty */ | |
| 271 entropy->put_bits = 0; | |
| 272 } | |
| 273 | |
| 274 | |
| 275 /* | |
| 276 * Emit (or just count) a Huffman symbol. | |
| 277 */ | |
| 278 | |
| 279 INLINE | |
| 280 LOCAL(void) | |
| 281 emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol) | |
| 282 { | |
| 283 if (entropy->gather_statistics) | |
| 284 entropy->count_ptrs[tbl_no][symbol]++; | |
| 285 else { | |
| 286 c_derived_tbl * tbl = entropy->derived_tbls[tbl_no]; | |
| 287 emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]); | |
| 288 } | |
| 289 } | |
| 290 | |
| 291 | |
| 292 /* | |
| 293 * Emit bits from a correction bit buffer. | |
| 294 */ | |
| 295 | |
| 296 LOCAL(void) | |
| 297 emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart, | |
| 298 unsigned int nbits) | |
| 299 { | |
| 300 if (entropy->gather_statistics) | |
| 301 return; /* no real work */ | |
| 302 | |
| 303 while (nbits > 0) { | |
| 304 emit_bits(entropy, (unsigned int) (*bufstart), 1); | |
| 305 bufstart++; | |
| 306 nbits--; | |
| 307 } | |
| 308 } | |
| 309 | |
| 310 | |
| 311 /* | |
| 312 * Emit any pending EOBRUN symbol. | |
| 313 */ | |
| 314 | |
| 315 LOCAL(void) | |
| 316 emit_eobrun (phuff_entropy_ptr entropy) | |
| 317 { | |
| 318 register int temp, nbits; | |
| 319 | |
| 320 if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */ | |
| 321 temp = entropy->EOBRUN; | |
| 322 nbits = 0; | |
| 323 while ((temp >>= 1)) | |
| 324 nbits++; | |
| 325 /* safety check: shouldn't happen given limited correction-bit buffer */ | |
| 326 if (nbits > 14) | |
| 327 ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); | |
| 328 | |
| 329 emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4); | |
| 330 if (nbits) | |
| 331 emit_bits(entropy, entropy->EOBRUN, nbits); | |
| 332 | |
| 333 entropy->EOBRUN = 0; | |
| 334 | |
| 335 /* Emit any buffered correction bits */ | |
| 336 emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE); | |
| 337 entropy->BE = 0; | |
| 338 } | |
| 339 } | |
| 340 | |
| 341 | |
| 342 /* | |
| 343 * Emit a restart marker & resynchronize predictions. | |
| 344 */ | |
| 345 | |
| 346 LOCAL(void) | |
| 347 emit_restart (phuff_entropy_ptr entropy, int restart_num) | |
| 348 { | |
| 349 int ci; | |
| 350 | |
| 351 emit_eobrun(entropy); | |
| 352 | |
| 353 if (! entropy->gather_statistics) { | |
| 354 flush_bits(entropy); | |
| 355 emit_byte(entropy, 0xFF); | |
| 356 emit_byte(entropy, JPEG_RST0 + restart_num); | |
| 357 } | |
| 358 | |
| 359 if (entropy->cinfo->Ss == 0) { | |
| 360 /* Re-initialize DC predictions to 0 */ | |
| 361 for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++) | |
| 362 entropy->last_dc_val[ci] = 0; | |
| 363 } else { | |
| 364 /* Re-initialize all AC-related fields to 0 */ | |
| 365 entropy->EOBRUN = 0; | |
| 366 entropy->BE = 0; | |
| 367 } | |
| 368 } | |
| 369 | |
| 370 | |
| 371 /* | |
| 372 * MCU encoding for DC initial scan (either spectral selection, | |
| 373 * or first pass of successive approximation). | |
| 374 */ | |
| 375 | |
| 376 METHODDEF(boolean) | |
| 377 encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
| 378 { | |
| 379 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 380 register int temp, temp2; | |
| 381 register int nbits; | |
| 382 int blkn, ci; | |
| 383 int Al = cinfo->Al; | |
| 384 JBLOCKROW block; | |
| 385 jpeg_component_info * compptr; | |
| 386 ISHIFT_TEMPS | |
| 387 | |
| 388 entropy->next_output_byte = cinfo->dest->next_output_byte; | |
| 389 entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
| 390 | |
| 391 /* Emit restart marker if needed */ | |
| 392 if (cinfo->restart_interval) | |
| 393 if (entropy->restarts_to_go == 0) | |
| 394 emit_restart(entropy, entropy->next_restart_num); | |
| 395 | |
| 396 /* Encode the MCU data blocks */ | |
| 397 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { | |
| 398 block = MCU_data[blkn]; | |
| 399 ci = cinfo->MCU_membership[blkn]; | |
| 400 compptr = cinfo->cur_comp_info[ci]; | |
| 401 | |
| 402 /* Compute the DC value after the required point transform by Al. | |
| 403 * This is simply an arithmetic right shift. | |
| 404 */ | |
| 405 temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al); | |
| 406 | |
| 407 /* DC differences are figured on the point-transformed values. */ | |
| 408 temp = temp2 - entropy->last_dc_val[ci]; | |
| 409 entropy->last_dc_val[ci] = temp2; | |
| 410 | |
| 411 /* Encode the DC coefficient difference per section G.1.2.1 */ | |
| 412 temp2 = temp; | |
| 413 if (temp < 0) { | |
| 414 temp = -temp; /* temp is abs value of input */ | |
| 415 /* For a negative input, want temp2 = bitwise complement of abs(input) */ | |
| 416 /* This code assumes we are on a two's complement machine */ | |
| 417 temp2--; | |
| 418 } | |
| 419 | |
| 420 /* Find the number of bits needed for the magnitude of the coefficient */ | |
| 421 nbits = 0; | |
| 422 while (temp) { | |
| 423 nbits++; | |
| 424 temp >>= 1; | |
| 425 } | |
| 426 /* Check for out-of-range coefficient values. | |
| 427 * Since we're encoding a difference, the range limit is twice as much. | |
| 428 */ | |
| 429 if (nbits > MAX_COEF_BITS+1) | |
| 430 ERREXIT(cinfo, JERR_BAD_DCT_COEF); | |
| 431 | |
| 432 /* Count/emit the Huffman-coded symbol for the number of bits */ | |
| 433 emit_symbol(entropy, compptr->dc_tbl_no, nbits); | |
| 434 | |
| 435 /* Emit that number of bits of the value, if positive, */ | |
| 436 /* or the complement of its magnitude, if negative. */ | |
| 437 if (nbits) /* emit_bits rejects calls with size 0 */ | |
| 438 emit_bits(entropy, (unsigned int) temp2, nbits); | |
| 439 } | |
| 440 | |
| 441 cinfo->dest->next_output_byte = entropy->next_output_byte; | |
| 442 cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
| 443 | |
| 444 /* Update restart-interval state too */ | |
| 445 if (cinfo->restart_interval) { | |
| 446 if (entropy->restarts_to_go == 0) { | |
| 447 entropy->restarts_to_go = cinfo->restart_interval; | |
| 448 entropy->next_restart_num++; | |
| 449 entropy->next_restart_num &= 7; | |
| 450 } | |
| 451 entropy->restarts_to_go--; | |
| 452 } | |
| 453 | |
| 454 return TRUE; | |
| 455 } | |
| 456 | |
| 457 | |
| 458 /* | |
| 459 * MCU encoding for AC initial scan (either spectral selection, | |
| 460 * or first pass of successive approximation). | |
| 461 */ | |
| 462 | |
| 463 METHODDEF(boolean) | |
| 464 encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
| 465 { | |
| 466 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 467 register int temp, temp2; | |
| 468 register int nbits; | |
| 469 register int r, k; | |
| 470 int Se = cinfo->Se; | |
| 471 int Al = cinfo->Al; | |
| 472 JBLOCKROW block; | |
| 473 | |
| 474 entropy->next_output_byte = cinfo->dest->next_output_byte; | |
| 475 entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
| 476 | |
| 477 /* Emit restart marker if needed */ | |
| 478 if (cinfo->restart_interval) | |
| 479 if (entropy->restarts_to_go == 0) | |
| 480 emit_restart(entropy, entropy->next_restart_num); | |
| 481 | |
| 482 /* Encode the MCU data block */ | |
| 483 block = MCU_data[0]; | |
| 484 | |
| 485 /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */ | |
| 486 | |
| 487 r = 0; /* r = run length of zeros */ | |
| 488 | |
| 489 for (k = cinfo->Ss; k <= Se; k++) { | |
| 490 if ((temp = (*block)[jpeg_natural_order[k]]) == 0) { | |
| 491 r++; | |
| 492 continue; | |
| 493 } | |
| 494 /* We must apply the point transform by Al. For AC coefficients this | |
| 495 * is an integer division with rounding towards 0. To do this portably | |
| 496 * in C, we shift after obtaining the absolute value; so the code is | |
| 497 * interwoven with finding the abs value (temp) and output bits (temp2). | |
| 498 */ | |
| 499 if (temp < 0) { | |
| 500 temp = -temp; /* temp is abs value of input */ | |
| 501 temp >>= Al; /* apply the point transform */ | |
| 502 /* For a negative coef, want temp2 = bitwise complement of abs(coef) */ | |
| 503 temp2 = ~temp; | |
| 504 } else { | |
| 505 temp >>= Al; /* apply the point transform */ | |
| 506 temp2 = temp; | |
| 507 } | |
| 508 /* Watch out for case that nonzero coef is zero after point transform */ | |
| 509 if (temp == 0) { | |
| 510 r++; | |
| 511 continue; | |
| 512 } | |
| 513 | |
| 514 /* Emit any pending EOBRUN */ | |
| 515 if (entropy->EOBRUN > 0) | |
| 516 emit_eobrun(entropy); | |
| 517 /* if run length > 15, must emit special run-length-16 codes (0xF0) */ | |
| 518 while (r > 15) { | |
| 519 emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); | |
| 520 r -= 16; | |
| 521 } | |
| 522 | |
| 523 /* Find the number of bits needed for the magnitude of the coefficient */ | |
| 524 nbits = 1; /* there must be at least one 1 bit */ | |
| 525 while ((temp >>= 1)) | |
| 526 nbits++; | |
| 527 /* Check for out-of-range coefficient values */ | |
| 528 if (nbits > MAX_COEF_BITS) | |
| 529 ERREXIT(cinfo, JERR_BAD_DCT_COEF); | |
| 530 | |
| 531 /* Count/emit Huffman symbol for run length / number of bits */ | |
| 532 emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits); | |
| 533 | |
| 534 /* Emit that number of bits of the value, if positive, */ | |
| 535 /* or the complement of its magnitude, if negative. */ | |
| 536 emit_bits(entropy, (unsigned int) temp2, nbits); | |
| 537 | |
| 538 r = 0; /* reset zero run length */ | |
| 539 } | |
| 540 | |
| 541 if (r > 0) { /* If there are trailing zeroes, */ | |
| 542 entropy->EOBRUN++; /* count an EOB */ | |
| 543 if (entropy->EOBRUN == 0x7FFF) | |
| 544 emit_eobrun(entropy); /* force it out to avoid overflow */ | |
| 545 } | |
| 546 | |
| 547 cinfo->dest->next_output_byte = entropy->next_output_byte; | |
| 548 cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
| 549 | |
| 550 /* Update restart-interval state too */ | |
| 551 if (cinfo->restart_interval) { | |
| 552 if (entropy->restarts_to_go == 0) { | |
| 553 entropy->restarts_to_go = cinfo->restart_interval; | |
| 554 entropy->next_restart_num++; | |
| 555 entropy->next_restart_num &= 7; | |
| 556 } | |
| 557 entropy->restarts_to_go--; | |
| 558 } | |
| 559 | |
| 560 return TRUE; | |
| 561 } | |
| 562 | |
| 563 | |
| 564 /* | |
| 565 * MCU encoding for DC successive approximation refinement scan. | |
| 566 * Note: we assume such scans can be multi-component, although the spec | |
| 567 * is not very clear on the point. | |
| 568 */ | |
| 569 | |
| 570 METHODDEF(boolean) | |
| 571 encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
| 572 { | |
| 573 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 574 register int temp; | |
| 575 int blkn; | |
| 576 int Al = cinfo->Al; | |
| 577 JBLOCKROW block; | |
| 578 | |
| 579 entropy->next_output_byte = cinfo->dest->next_output_byte; | |
| 580 entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
| 581 | |
| 582 /* Emit restart marker if needed */ | |
| 583 if (cinfo->restart_interval) | |
| 584 if (entropy->restarts_to_go == 0) | |
| 585 emit_restart(entropy, entropy->next_restart_num); | |
| 586 | |
| 587 /* Encode the MCU data blocks */ | |
| 588 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { | |
| 589 block = MCU_data[blkn]; | |
| 590 | |
| 591 /* We simply emit the Al'th bit of the DC coefficient value. */ | |
| 592 temp = (*block)[0]; | |
| 593 emit_bits(entropy, (unsigned int) (temp >> Al), 1); | |
| 594 } | |
| 595 | |
| 596 cinfo->dest->next_output_byte = entropy->next_output_byte; | |
| 597 cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
| 598 | |
| 599 /* Update restart-interval state too */ | |
| 600 if (cinfo->restart_interval) { | |
| 601 if (entropy->restarts_to_go == 0) { | |
| 602 entropy->restarts_to_go = cinfo->restart_interval; | |
| 603 entropy->next_restart_num++; | |
| 604 entropy->next_restart_num &= 7; | |
| 605 } | |
| 606 entropy->restarts_to_go--; | |
| 607 } | |
| 608 | |
| 609 return TRUE; | |
| 610 } | |
| 611 | |
| 612 | |
| 613 /* | |
| 614 * MCU encoding for AC successive approximation refinement scan. | |
| 615 */ | |
| 616 | |
| 617 METHODDEF(boolean) | |
| 618 encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
| 619 { | |
| 620 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 621 register int temp; | |
| 622 register int r, k; | |
| 623 int EOB; | |
| 624 char *BR_buffer; | |
| 625 unsigned int BR; | |
| 626 int Se = cinfo->Se; | |
| 627 int Al = cinfo->Al; | |
| 628 JBLOCKROW block; | |
| 629 int absvalues[DCTSIZE2]; | |
| 630 | |
| 631 entropy->next_output_byte = cinfo->dest->next_output_byte; | |
| 632 entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
| 633 | |
| 634 /* Emit restart marker if needed */ | |
| 635 if (cinfo->restart_interval) | |
| 636 if (entropy->restarts_to_go == 0) | |
| 637 emit_restart(entropy, entropy->next_restart_num); | |
| 638 | |
| 639 /* Encode the MCU data block */ | |
| 640 block = MCU_data[0]; | |
| 641 | |
| 642 /* It is convenient to make a pre-pass to determine the transformed | |
| 643 * coefficients' absolute values and the EOB position. | |
| 644 */ | |
| 645 EOB = 0; | |
| 646 for (k = cinfo->Ss; k <= Se; k++) { | |
| 647 temp = (*block)[jpeg_natural_order[k]]; | |
| 648 /* We must apply the point transform by Al. For AC coefficients this | |
| 649 * is an integer division with rounding towards 0. To do this portably | |
| 650 * in C, we shift after obtaining the absolute value. | |
| 651 */ | |
| 652 if (temp < 0) | |
| 653 temp = -temp; /* temp is abs value of input */ | |
| 654 temp >>= Al; /* apply the point transform */ | |
| 655 absvalues[k] = temp; /* save abs value for main pass */ | |
| 656 if (temp == 1) | |
| 657 EOB = k; /* EOB = index of last newly-nonzero coef */ | |
| 658 } | |
| 659 | |
| 660 /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */ | |
| 661 | |
| 662 r = 0; /* r = run length of zeros */ | |
| 663 BR = 0; /* BR = count of buffered bits added now */ | |
| 664 BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */ | |
| 665 | |
| 666 for (k = cinfo->Ss; k <= Se; k++) { | |
| 667 if ((temp = absvalues[k]) == 0) { | |
| 668 r++; | |
| 669 continue; | |
| 670 } | |
| 671 | |
| 672 /* Emit any required ZRLs, but not if they can be folded into EOB */ | |
| 673 while (r > 15 && k <= EOB) { | |
| 674 /* emit any pending EOBRUN and the BE correction bits */ | |
| 675 emit_eobrun(entropy); | |
| 676 /* Emit ZRL */ | |
| 677 emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); | |
| 678 r -= 16; | |
| 679 /* Emit buffered correction bits that must be associated with ZRL */ | |
| 680 emit_buffered_bits(entropy, BR_buffer, BR); | |
| 681 BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ | |
| 682 BR = 0; | |
| 683 } | |
| 684 | |
| 685 /* If the coef was previously nonzero, it only needs a correction bit. | |
| 686 * NOTE: a straight translation of the spec's figure G.7 would suggest | |
| 687 * that we also need to test r > 15. But if r > 15, we can only get here | |
| 688 * if k > EOB, which implies that this coefficient is not 1. | |
| 689 */ | |
| 690 if (temp > 1) { | |
| 691 /* The correction bit is the next bit of the absolute value. */ | |
| 692 BR_buffer[BR++] = (char) (temp & 1); | |
| 693 continue; | |
| 694 } | |
| 695 | |
| 696 /* Emit any pending EOBRUN and the BE correction bits */ | |
| 697 emit_eobrun(entropy); | |
| 698 | |
| 699 /* Count/emit Huffman symbol for run length / number of bits */ | |
| 700 emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1); | |
| 701 | |
| 702 /* Emit output bit for newly-nonzero coef */ | |
| 703 temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1; | |
| 704 emit_bits(entropy, (unsigned int) temp, 1); | |
| 705 | |
| 706 /* Emit buffered correction bits that must be associated with this code */ | |
| 707 emit_buffered_bits(entropy, BR_buffer, BR); | |
| 708 BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ | |
| 709 BR = 0; | |
| 710 r = 0; /* reset zero run length */ | |
| 711 } | |
| 712 | |
| 713 if (r > 0 || BR > 0) { /* If there are trailing zeroes, */ | |
| 714 entropy->EOBRUN++; /* count an EOB */ | |
| 715 entropy->BE += BR; /* concat my correction bits to older ones */ | |
| 716 /* We force out the EOB if we risk either: | |
| 717 * 1. overflow of the EOB counter; | |
| 718 * 2. overflow of the correction bit buffer during the next MCU. | |
| 719 */ | |
| 720 if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1)) | |
| 721 emit_eobrun(entropy); | |
| 722 } | |
| 723 | |
| 724 cinfo->dest->next_output_byte = entropy->next_output_byte; | |
| 725 cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
| 726 | |
| 727 /* Update restart-interval state too */ | |
| 728 if (cinfo->restart_interval) { | |
| 729 if (entropy->restarts_to_go == 0) { | |
| 730 entropy->restarts_to_go = cinfo->restart_interval; | |
| 731 entropy->next_restart_num++; | |
| 732 entropy->next_restart_num &= 7; | |
| 733 } | |
| 734 entropy->restarts_to_go--; | |
| 735 } | |
| 736 | |
| 737 return TRUE; | |
| 738 } | |
| 739 | |
| 740 | |
| 741 /* | |
| 742 * Finish up at the end of a Huffman-compressed progressive scan. | |
| 743 */ | |
| 744 | |
| 745 METHODDEF(void) | |
| 746 finish_pass_phuff (j_compress_ptr cinfo) | |
| 747 { | |
| 748 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 749 | |
| 750 entropy->next_output_byte = cinfo->dest->next_output_byte; | |
| 751 entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
| 752 | |
| 753 /* Flush out any buffered data */ | |
| 754 emit_eobrun(entropy); | |
| 755 flush_bits(entropy); | |
| 756 | |
| 757 cinfo->dest->next_output_byte = entropy->next_output_byte; | |
| 758 cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
| 759 } | |
| 760 | |
| 761 | |
| 762 /* | |
| 763 * Finish up a statistics-gathering pass and create the new Huffman tables. | |
| 764 */ | |
| 765 | |
| 766 METHODDEF(void) | |
| 767 finish_pass_gather_phuff (j_compress_ptr cinfo) | |
| 768 { | |
| 769 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
| 770 boolean is_DC_band; | |
| 771 int ci, tbl; | |
| 772 jpeg_component_info * compptr; | |
| 773 JHUFF_TBL **htblptr; | |
| 774 boolean did[NUM_HUFF_TBLS]; | |
| 775 | |
| 776 /* Flush out buffered data (all we care about is counting the EOB symbol) */ | |
| 777 emit_eobrun(entropy); | |
| 778 | |
| 779 is_DC_band = (cinfo->Ss == 0); | |
| 780 | |
| 781 /* It's important not to apply jpeg_gen_optimal_table more than once | |
| 782 * per table, because it clobbers the input frequency counts! | |
| 783 */ | |
| 784 MEMZERO(did, SIZEOF(did)); | |
| 785 | |
| 786 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { | |
| 787 compptr = cinfo->cur_comp_info[ci]; | |
| 788 if (is_DC_band) { | |
| 789 if (cinfo->Ah != 0) /* DC refinement needs no table */ | |
| 790 continue; | |
| 791 tbl = compptr->dc_tbl_no; | |
| 792 } else { | |
| 793 tbl = compptr->ac_tbl_no; | |
| 794 } | |
| 795 if (! did[tbl]) { | |
| 796 if (is_DC_band) | |
| 797 htblptr = & cinfo->dc_huff_tbl_ptrs[tbl]; | |
| 798 else | |
| 799 htblptr = & cinfo->ac_huff_tbl_ptrs[tbl]; | |
| 800 if (*htblptr == NULL) | |
| 801 *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); | |
| 802 jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]); | |
| 803 did[tbl] = TRUE; | |
| 804 } | |
| 805 } | |
| 806 } | |
| 807 | |
| 808 | |
| 809 /* | |
| 810 * Module initialization routine for progressive Huffman entropy encoding. | |
| 811 */ | |
| 812 | |
| 813 GLOBAL(void) | |
| 814 jinit_phuff_encoder (j_compress_ptr cinfo) | |
| 815 { | |
| 816 phuff_entropy_ptr entropy; | |
| 817 int i; | |
| 818 | |
| 819 entropy = (phuff_entropy_ptr) | |
| 820 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 821 SIZEOF(phuff_entropy_encoder)); | |
| 822 cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; | |
| 823 entropy->pub.start_pass = start_pass_phuff; | |
| 824 | |
| 825 /* Mark tables unallocated */ | |
| 826 for (i = 0; i < NUM_HUFF_TBLS; i++) { | |
| 827 entropy->derived_tbls[i] = NULL; | |
| 828 entropy->count_ptrs[i] = NULL; | |
| 829 } | |
| 830 entropy->bit_buffer = NULL; /* needed only in AC refinement scan */ | |
| 831 } | |
| 832 | |
| 833 #endif /* C_PROGRESSIVE_SUPPORTED */ | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1705523002:
Remove libjpeg and libjpeg_turbo. (Closed)
Base URL: https://github.com/domokit/mojo.git@master