J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * reserved comment block |
| 3 | * DO NOT REMOVE OR ALTER! |
| 4 | */ |
| 5 | /* |
| 6 | * jcphuff.c |
| 7 | * |
| 8 | * Copyright (C) 1995-1997, Thomas G. Lane. |
| 9 | * This file is part of the Independent JPEG Group's software. |
| 10 | * For conditions of distribution and use, see the accompanying README file. |
| 11 | * |
| 12 | * This file contains Huffman entropy encoding routines for progressive JPEG. |
| 13 | * |
| 14 | * We do not support output suspension in this module, since the library |
| 15 | * currently does not allow multiple-scan files to be written with output |
| 16 | * suspension. |
| 17 | */ |
| 18 | |
| 19 | #define JPEG_INTERNALS |
| 20 | #include "jinclude.h" |
| 21 | #include "jpeglib.h" |
| 22 | #include "jchuff.h" /* Declarations shared with jchuff.c */ |
| 23 | |
| 24 | #ifdef C_PROGRESSIVE_SUPPORTED |
| 25 | |
| 26 | /* Expanded entropy encoder object for progressive Huffman encoding. */ |
| 27 | |
| 28 | typedef struct { |
| 29 | struct jpeg_entropy_encoder pub; /* public fields */ |
| 30 | |
| 31 | /* Mode flag: TRUE for optimization, FALSE for actual data output */ |
| 32 | boolean gather_statistics; |
| 33 | |
| 34 | /* Bit-level coding status. |
| 35 | * next_output_byte/free_in_buffer are local copies of cinfo->dest fields. |
| 36 | */ |
| 37 | JOCTET * next_output_byte; /* => next byte to write in buffer */ |
| 38 | size_t free_in_buffer; /* # of byte spaces remaining in buffer */ |
| 39 | INT32 put_buffer; /* current bit-accumulation buffer */ |
| 40 | int put_bits; /* # of bits now in it */ |
| 41 | j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */ |
| 42 | |
| 43 | /* Coding status for DC components */ |
| 44 | int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ |
| 45 | |
| 46 | /* Coding status for AC components */ |
| 47 | int ac_tbl_no; /* the table number of the single component */ |
| 48 | unsigned int EOBRUN; /* run length of EOBs */ |
| 49 | unsigned int BE; /* # of buffered correction bits before MCU */ |
| 50 | char * bit_buffer; /* buffer for correction bits (1 per char) */ |
| 51 | /* packing correction bits tightly would save some space but cost time... */ |
| 52 | |
| 53 | unsigned int restarts_to_go; /* MCUs left in this restart interval */ |
| 54 | int next_restart_num; /* next restart number to write (0-7) */ |
| 55 | |
| 56 | /* Pointers to derived tables (these workspaces have image lifespan). |
| 57 | * Since any one scan codes only DC or only AC, we only need one set |
| 58 | * of tables, not one for DC and one for AC. |
| 59 | */ |
| 60 | c_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; |
| 61 | |
| 62 | /* Statistics tables for optimization; again, one set is enough */ |
| 63 | long * count_ptrs[NUM_HUFF_TBLS]; |
| 64 | } phuff_entropy_encoder; |
| 65 | |
| 66 | typedef phuff_entropy_encoder * phuff_entropy_ptr; |
| 67 | |
| 68 | /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit |
| 69 | * buffer can hold. Larger sizes may slightly improve compression, but |
| 70 | * 1000 is already well into the realm of overkill. |
| 71 | * The minimum safe size is 64 bits. |
| 72 | */ |
| 73 | |
| 74 | #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */ |
| 75 | |
| 76 | /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32. |
| 77 | * We assume that int right shift is unsigned if INT32 right shift is, |
| 78 | * which should be safe. |
| 79 | */ |
| 80 | |
| 81 | #ifdef RIGHT_SHIFT_IS_UNSIGNED |
| 82 | #define ISHIFT_TEMPS int ishift_temp; |
| 83 | #define IRIGHT_SHIFT(x,shft) \ |
| 84 | ((ishift_temp = (x)) < 0 ? \ |
| 85 | (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \ |
| 86 | (ishift_temp >> (shft))) |
| 87 | #else |
| 88 | #define ISHIFT_TEMPS |
| 89 | #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) |
| 90 | #endif |
| 91 | |
| 92 | /* Forward declarations */ |
| 93 | METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo, |
| 94 | JBLOCKROW *MCU_data)); |
| 95 | METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo, |
| 96 | JBLOCKROW *MCU_data)); |
| 97 | METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo, |
| 98 | JBLOCKROW *MCU_data)); |
| 99 | METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo, |
| 100 | JBLOCKROW *MCU_data)); |
| 101 | METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo)); |
| 102 | METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo)); |
| 103 | |
| 104 | |
| 105 | /* |
| 106 | * Initialize for a Huffman-compressed scan using progressive JPEG. |
| 107 | */ |
| 108 | |
| 109 | METHODDEF(void) |
| 110 | start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics) |
| 111 | { |
| 112 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 113 | boolean is_DC_band; |
| 114 | int ci, tbl; |
| 115 | jpeg_component_info * compptr; |
| 116 | |
| 117 | entropy->cinfo = cinfo; |
| 118 | entropy->gather_statistics = gather_statistics; |
| 119 | |
| 120 | is_DC_band = (cinfo->Ss == 0); |
| 121 | |
| 122 | /* We assume jcmaster.c already validated the scan parameters. */ |
| 123 | |
| 124 | /* Select execution routines */ |
| 125 | if (cinfo->Ah == 0) { |
| 126 | if (is_DC_band) |
| 127 | entropy->pub.encode_mcu = encode_mcu_DC_first; |
| 128 | else |
| 129 | entropy->pub.encode_mcu = encode_mcu_AC_first; |
| 130 | } else { |
| 131 | if (is_DC_band) |
| 132 | entropy->pub.encode_mcu = encode_mcu_DC_refine; |
| 133 | else { |
| 134 | entropy->pub.encode_mcu = encode_mcu_AC_refine; |
| 135 | /* AC refinement needs a correction bit buffer */ |
| 136 | if (entropy->bit_buffer == NULL) |
| 137 | entropy->bit_buffer = (char *) |
| 138 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 139 | MAX_CORR_BITS * SIZEOF(char)); |
| 140 | } |
| 141 | } |
| 142 | if (gather_statistics) |
| 143 | entropy->pub.finish_pass = finish_pass_gather_phuff; |
| 144 | else |
| 145 | entropy->pub.finish_pass = finish_pass_phuff; |
| 146 | |
| 147 | /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1 |
| 148 | * for AC coefficients. |
| 149 | */ |
| 150 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| 151 | compptr = cinfo->cur_comp_info[ci]; |
| 152 | /* Initialize DC predictions to 0 */ |
| 153 | entropy->last_dc_val[ci] = 0; |
| 154 | /* Get table index */ |
| 155 | if (is_DC_band) { |
| 156 | if (cinfo->Ah != 0) /* DC refinement needs no table */ |
| 157 | continue; |
| 158 | tbl = compptr->dc_tbl_no; |
| 159 | } else { |
| 160 | entropy->ac_tbl_no = tbl = compptr->ac_tbl_no; |
| 161 | } |
| 162 | if (gather_statistics) { |
| 163 | /* Check for invalid table index */ |
| 164 | /* (make_c_derived_tbl does this in the other path) */ |
| 165 | if (tbl < 0 || tbl >= NUM_HUFF_TBLS) |
| 166 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); |
| 167 | /* Allocate and zero the statistics tables */ |
| 168 | /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ |
| 169 | if (entropy->count_ptrs[tbl] == NULL) |
| 170 | entropy->count_ptrs[tbl] = (long *) |
| 171 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 172 | 257 * SIZEOF(long)); |
| 173 | MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long)); |
| 174 | } else { |
| 175 | /* Compute derived values for Huffman table */ |
| 176 | /* We may do this more than once for a table, but it's not expensive */ |
| 177 | jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl, |
| 178 | & entropy->derived_tbls[tbl]); |
| 179 | } |
| 180 | } |
| 181 | |
| 182 | /* Initialize AC stuff */ |
| 183 | entropy->EOBRUN = 0; |
| 184 | entropy->BE = 0; |
| 185 | |
| 186 | /* Initialize bit buffer to empty */ |
| 187 | entropy->put_buffer = 0; |
| 188 | entropy->put_bits = 0; |
| 189 | |
| 190 | /* Initialize restart stuff */ |
| 191 | entropy->restarts_to_go = cinfo->restart_interval; |
| 192 | entropy->next_restart_num = 0; |
| 193 | } |
| 194 | |
| 195 | |
| 196 | /* Outputting bytes to the file. |
| 197 | * NB: these must be called only when actually outputting, |
| 198 | * that is, entropy->gather_statistics == FALSE. |
| 199 | */ |
| 200 | |
| 201 | /* Emit a byte */ |
| 202 | #define emit_byte(entropy,val) \ |
| 203 | { *(entropy)->next_output_byte++ = (JOCTET) (val); \ |
| 204 | if (--(entropy)->free_in_buffer == 0) \ |
| 205 | dump_buffer(entropy); } |
| 206 | |
| 207 | |
| 208 | LOCAL(void) |
| 209 | dump_buffer (phuff_entropy_ptr entropy) |
| 210 | /* Empty the output buffer; we do not support suspension in this module. */ |
| 211 | { |
| 212 | struct jpeg_destination_mgr * dest = entropy->cinfo->dest; |
| 213 | |
| 214 | if (! (*dest->empty_output_buffer) (entropy->cinfo)) |
| 215 | ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND); |
| 216 | /* After a successful buffer dump, must reset buffer pointers */ |
| 217 | entropy->next_output_byte = dest->next_output_byte; |
| 218 | entropy->free_in_buffer = dest->free_in_buffer; |
| 219 | } |
| 220 | |
| 221 | |
| 222 | /* Outputting bits to the file */ |
| 223 | |
| 224 | /* Only the right 24 bits of put_buffer are used; the valid bits are |
| 225 | * left-justified in this part. At most 16 bits can be passed to emit_bits |
| 226 | * in one call, and we never retain more than 7 bits in put_buffer |
| 227 | * between calls, so 24 bits are sufficient. |
| 228 | */ |
| 229 | |
| 230 | INLINE |
| 231 | LOCAL(void) |
| 232 | emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size) |
| 233 | /* Emit some bits, unless we are in gather mode */ |
| 234 | { |
| 235 | /* This routine is heavily used, so it's worth coding tightly. */ |
| 236 | register INT32 put_buffer = (INT32) code; |
| 237 | register int put_bits = entropy->put_bits; |
| 238 | |
| 239 | /* if size is 0, caller used an invalid Huffman table entry */ |
| 240 | if (size == 0) |
| 241 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); |
| 242 | |
| 243 | if (entropy->gather_statistics) |
| 244 | return; /* do nothing if we're only getting stats */ |
| 245 | |
| 246 | put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */ |
| 247 | |
| 248 | put_bits += size; /* new number of bits in buffer */ |
| 249 | |
| 250 | put_buffer <<= 24 - put_bits; /* align incoming bits */ |
| 251 | |
| 252 | put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */ |
| 253 | |
| 254 | while (put_bits >= 8) { |
| 255 | int c = (int) ((put_buffer >> 16) & 0xFF); |
| 256 | |
| 257 | emit_byte(entropy, c); |
| 258 | if (c == 0xFF) { /* need to stuff a zero byte? */ |
| 259 | emit_byte(entropy, 0); |
| 260 | } |
| 261 | put_buffer <<= 8; |
| 262 | put_bits -= 8; |
| 263 | } |
| 264 | |
| 265 | entropy->put_buffer = put_buffer; /* update variables */ |
| 266 | entropy->put_bits = put_bits; |
| 267 | } |
| 268 | |
| 269 | |
| 270 | LOCAL(void) |
| 271 | flush_bits (phuff_entropy_ptr entropy) |
| 272 | { |
| 273 | emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */ |
| 274 | entropy->put_buffer = 0; /* and reset bit-buffer to empty */ |
| 275 | entropy->put_bits = 0; |
| 276 | } |
| 277 | |
| 278 | |
| 279 | /* |
| 280 | * Emit (or just count) a Huffman symbol. |
| 281 | */ |
| 282 | |
| 283 | INLINE |
| 284 | LOCAL(void) |
| 285 | emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol) |
| 286 | { |
| 287 | if (entropy->gather_statistics) |
| 288 | entropy->count_ptrs[tbl_no][symbol]++; |
| 289 | else { |
| 290 | c_derived_tbl * tbl = entropy->derived_tbls[tbl_no]; |
| 291 | emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]); |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | |
| 296 | /* |
| 297 | * Emit bits from a correction bit buffer. |
| 298 | */ |
| 299 | |
| 300 | LOCAL(void) |
| 301 | emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart, |
| 302 | unsigned int nbits) |
| 303 | { |
| 304 | if (entropy->gather_statistics) |
| 305 | return; /* no real work */ |
| 306 | |
| 307 | while (nbits > 0) { |
| 308 | emit_bits(entropy, (unsigned int) (*bufstart), 1); |
| 309 | bufstart++; |
| 310 | nbits--; |
| 311 | } |
| 312 | } |
| 313 | |
| 314 | |
| 315 | /* |
| 316 | * Emit any pending EOBRUN symbol. |
| 317 | */ |
| 318 | |
| 319 | LOCAL(void) |
| 320 | emit_eobrun (phuff_entropy_ptr entropy) |
| 321 | { |
| 322 | register int temp, nbits; |
| 323 | |
| 324 | if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */ |
| 325 | temp = entropy->EOBRUN; |
| 326 | nbits = 0; |
| 327 | while ((temp >>= 1)) |
| 328 | nbits++; |
| 329 | /* safety check: shouldn't happen given limited correction-bit buffer */ |
| 330 | if (nbits > 14) |
| 331 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); |
| 332 | |
| 333 | emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4); |
| 334 | if (nbits) |
| 335 | emit_bits(entropy, entropy->EOBRUN, nbits); |
| 336 | |
| 337 | entropy->EOBRUN = 0; |
| 338 | |
| 339 | /* Emit any buffered correction bits */ |
| 340 | emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE); |
| 341 | entropy->BE = 0; |
| 342 | } |
| 343 | } |
| 344 | |
| 345 | |
| 346 | /* |
| 347 | * Emit a restart marker & resynchronize predictions. |
| 348 | */ |
| 349 | |
| 350 | LOCAL(void) |
| 351 | emit_restart (phuff_entropy_ptr entropy, int restart_num) |
| 352 | { |
| 353 | int ci; |
| 354 | |
| 355 | emit_eobrun(entropy); |
| 356 | |
| 357 | if (! entropy->gather_statistics) { |
| 358 | flush_bits(entropy); |
| 359 | emit_byte(entropy, 0xFF); |
| 360 | emit_byte(entropy, JPEG_RST0 + restart_num); |
| 361 | } |
| 362 | |
| 363 | if (entropy->cinfo->Ss == 0) { |
| 364 | /* Re-initialize DC predictions to 0 */ |
| 365 | for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++) |
| 366 | entropy->last_dc_val[ci] = 0; |
| 367 | } else { |
| 368 | /* Re-initialize all AC-related fields to 0 */ |
| 369 | entropy->EOBRUN = 0; |
| 370 | entropy->BE = 0; |
| 371 | } |
| 372 | } |
| 373 | |
| 374 | |
| 375 | /* |
| 376 | * MCU encoding for DC initial scan (either spectral selection, |
| 377 | * or first pass of successive approximation). |
| 378 | */ |
| 379 | |
| 380 | METHODDEF(boolean) |
| 381 | encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
| 382 | { |
| 383 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 384 | register int temp, temp2; |
| 385 | register int nbits; |
| 386 | int blkn, ci; |
| 387 | int Al = cinfo->Al; |
| 388 | JBLOCKROW block; |
| 389 | jpeg_component_info * compptr; |
| 390 | ISHIFT_TEMPS |
| 391 | |
| 392 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
| 393 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
| 394 | |
| 395 | /* Emit restart marker if needed */ |
| 396 | if (cinfo->restart_interval) |
| 397 | if (entropy->restarts_to_go == 0) |
| 398 | emit_restart(entropy, entropy->next_restart_num); |
| 399 | |
| 400 | /* Encode the MCU data blocks */ |
| 401 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 402 | block = MCU_data[blkn]; |
| 403 | ci = cinfo->MCU_membership[blkn]; |
| 404 | compptr = cinfo->cur_comp_info[ci]; |
| 405 | |
| 406 | /* Compute the DC value after the required point transform by Al. |
| 407 | * This is simply an arithmetic right shift. |
| 408 | */ |
| 409 | temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al); |
| 410 | |
| 411 | /* DC differences are figured on the point-transformed values. */ |
| 412 | temp = temp2 - entropy->last_dc_val[ci]; |
| 413 | entropy->last_dc_val[ci] = temp2; |
| 414 | |
| 415 | /* Encode the DC coefficient difference per section G.1.2.1 */ |
| 416 | temp2 = temp; |
| 417 | if (temp < 0) { |
| 418 | temp = -temp; /* temp is abs value of input */ |
| 419 | /* For a negative input, want temp2 = bitwise complement of abs(input) */ |
| 420 | /* This code assumes we are on a two's complement machine */ |
| 421 | temp2--; |
| 422 | } |
| 423 | |
| 424 | /* Find the number of bits needed for the magnitude of the coefficient */ |
| 425 | nbits = 0; |
| 426 | while (temp) { |
| 427 | nbits++; |
| 428 | temp >>= 1; |
| 429 | } |
| 430 | /* Check for out-of-range coefficient values. |
| 431 | * Since we're encoding a difference, the range limit is twice as much. |
| 432 | */ |
| 433 | if (nbits > MAX_COEF_BITS+1) |
| 434 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
| 435 | |
| 436 | /* Count/emit the Huffman-coded symbol for the number of bits */ |
| 437 | emit_symbol(entropy, compptr->dc_tbl_no, nbits); |
| 438 | |
| 439 | /* Emit that number of bits of the value, if positive, */ |
| 440 | /* or the complement of its magnitude, if negative. */ |
| 441 | if (nbits) /* emit_bits rejects calls with size 0 */ |
| 442 | emit_bits(entropy, (unsigned int) temp2, nbits); |
| 443 | } |
| 444 | |
| 445 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
| 446 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
| 447 | |
| 448 | /* Update restart-interval state too */ |
| 449 | if (cinfo->restart_interval) { |
| 450 | if (entropy->restarts_to_go == 0) { |
| 451 | entropy->restarts_to_go = cinfo->restart_interval; |
| 452 | entropy->next_restart_num++; |
| 453 | entropy->next_restart_num &= 7; |
| 454 | } |
| 455 | entropy->restarts_to_go--; |
| 456 | } |
| 457 | |
| 458 | return TRUE; |
| 459 | } |
| 460 | |
| 461 | |
| 462 | /* |
| 463 | * MCU encoding for AC initial scan (either spectral selection, |
| 464 | * or first pass of successive approximation). |
| 465 | */ |
| 466 | |
| 467 | METHODDEF(boolean) |
| 468 | encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
| 469 | { |
| 470 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 471 | register int temp, temp2; |
| 472 | register int nbits; |
| 473 | register int r, k; |
| 474 | int Se = cinfo->Se; |
| 475 | int Al = cinfo->Al; |
| 476 | JBLOCKROW block; |
| 477 | |
| 478 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
| 479 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
| 480 | |
| 481 | /* Emit restart marker if needed */ |
| 482 | if (cinfo->restart_interval) |
| 483 | if (entropy->restarts_to_go == 0) |
| 484 | emit_restart(entropy, entropy->next_restart_num); |
| 485 | |
| 486 | /* Encode the MCU data block */ |
| 487 | block = MCU_data[0]; |
| 488 | |
| 489 | /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */ |
| 490 | |
| 491 | r = 0; /* r = run length of zeros */ |
| 492 | |
| 493 | for (k = cinfo->Ss; k <= Se; k++) { |
| 494 | if ((temp = (*block)[jpeg_natural_order[k]]) == 0) { |
| 495 | r++; |
| 496 | continue; |
| 497 | } |
| 498 | /* We must apply the point transform by Al. For AC coefficients this |
| 499 | * is an integer division with rounding towards 0. To do this portably |
| 500 | * in C, we shift after obtaining the absolute value; so the code is |
| 501 | * interwoven with finding the abs value (temp) and output bits (temp2). |
| 502 | */ |
| 503 | if (temp < 0) { |
| 504 | temp = -temp; /* temp is abs value of input */ |
| 505 | temp >>= Al; /* apply the point transform */ |
| 506 | /* For a negative coef, want temp2 = bitwise complement of abs(coef) */ |
| 507 | temp2 = ~temp; |
| 508 | } else { |
| 509 | temp >>= Al; /* apply the point transform */ |
| 510 | temp2 = temp; |
| 511 | } |
| 512 | /* Watch out for case that nonzero coef is zero after point transform */ |
| 513 | if (temp == 0) { |
| 514 | r++; |
| 515 | continue; |
| 516 | } |
| 517 | |
| 518 | /* Emit any pending EOBRUN */ |
| 519 | if (entropy->EOBRUN > 0) |
| 520 | emit_eobrun(entropy); |
| 521 | /* if run length > 15, must emit special run-length-16 codes (0xF0) */ |
| 522 | while (r > 15) { |
| 523 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); |
| 524 | r -= 16; |
| 525 | } |
| 526 | |
| 527 | /* Find the number of bits needed for the magnitude of the coefficient */ |
| 528 | nbits = 1; /* there must be at least one 1 bit */ |
| 529 | while ((temp >>= 1)) |
| 530 | nbits++; |
| 531 | /* Check for out-of-range coefficient values */ |
| 532 | if (nbits > MAX_COEF_BITS) |
| 533 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
| 534 | |
| 535 | /* Count/emit Huffman symbol for run length / number of bits */ |
| 536 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits); |
| 537 | |
| 538 | /* Emit that number of bits of the value, if positive, */ |
| 539 | /* or the complement of its magnitude, if negative. */ |
| 540 | emit_bits(entropy, (unsigned int) temp2, nbits); |
| 541 | |
| 542 | r = 0; /* reset zero run length */ |
| 543 | } |
| 544 | |
| 545 | if (r > 0) { /* If there are trailing zeroes, */ |
| 546 | entropy->EOBRUN++; /* count an EOB */ |
| 547 | if (entropy->EOBRUN == 0x7FFF) |
| 548 | emit_eobrun(entropy); /* force it out to avoid overflow */ |
| 549 | } |
| 550 | |
| 551 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
| 552 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
| 553 | |
| 554 | /* Update restart-interval state too */ |
| 555 | if (cinfo->restart_interval) { |
| 556 | if (entropy->restarts_to_go == 0) { |
| 557 | entropy->restarts_to_go = cinfo->restart_interval; |
| 558 | entropy->next_restart_num++; |
| 559 | entropy->next_restart_num &= 7; |
| 560 | } |
| 561 | entropy->restarts_to_go--; |
| 562 | } |
| 563 | |
| 564 | return TRUE; |
| 565 | } |
| 566 | |
| 567 | |
| 568 | /* |
| 569 | * MCU encoding for DC successive approximation refinement scan. |
| 570 | * Note: we assume such scans can be multi-component, although the spec |
| 571 | * is not very clear on the point. |
| 572 | */ |
| 573 | |
| 574 | METHODDEF(boolean) |
| 575 | encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
| 576 | { |
| 577 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 578 | register int temp; |
| 579 | int blkn; |
| 580 | int Al = cinfo->Al; |
| 581 | JBLOCKROW block; |
| 582 | |
| 583 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
| 584 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
| 585 | |
| 586 | /* Emit restart marker if needed */ |
| 587 | if (cinfo->restart_interval) |
| 588 | if (entropy->restarts_to_go == 0) |
| 589 | emit_restart(entropy, entropy->next_restart_num); |
| 590 | |
| 591 | /* Encode the MCU data blocks */ |
| 592 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| 593 | block = MCU_data[blkn]; |
| 594 | |
| 595 | /* We simply emit the Al'th bit of the DC coefficient value. */ |
| 596 | temp = (*block)[0]; |
| 597 | emit_bits(entropy, (unsigned int) (temp >> Al), 1); |
| 598 | } |
| 599 | |
| 600 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
| 601 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
| 602 | |
| 603 | /* Update restart-interval state too */ |
| 604 | if (cinfo->restart_interval) { |
| 605 | if (entropy->restarts_to_go == 0) { |
| 606 | entropy->restarts_to_go = cinfo->restart_interval; |
| 607 | entropy->next_restart_num++; |
| 608 | entropy->next_restart_num &= 7; |
| 609 | } |
| 610 | entropy->restarts_to_go--; |
| 611 | } |
| 612 | |
| 613 | return TRUE; |
| 614 | } |
| 615 | |
| 616 | |
| 617 | /* |
| 618 | * MCU encoding for AC successive approximation refinement scan. |
| 619 | */ |
| 620 | |
| 621 | METHODDEF(boolean) |
| 622 | encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
| 623 | { |
| 624 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 625 | register int temp; |
| 626 | register int r, k; |
| 627 | int EOB; |
| 628 | char *BR_buffer; |
| 629 | unsigned int BR; |
| 630 | int Se = cinfo->Se; |
| 631 | int Al = cinfo->Al; |
| 632 | JBLOCKROW block; |
| 633 | int absvalues[DCTSIZE2]; |
| 634 | |
| 635 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
| 636 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
| 637 | |
| 638 | /* Emit restart marker if needed */ |
| 639 | if (cinfo->restart_interval) |
| 640 | if (entropy->restarts_to_go == 0) |
| 641 | emit_restart(entropy, entropy->next_restart_num); |
| 642 | |
| 643 | /* Encode the MCU data block */ |
| 644 | block = MCU_data[0]; |
| 645 | |
| 646 | /* It is convenient to make a pre-pass to determine the transformed |
| 647 | * coefficients' absolute values and the EOB position. |
| 648 | */ |
| 649 | EOB = 0; |
| 650 | for (k = cinfo->Ss; k <= Se; k++) { |
| 651 | temp = (*block)[jpeg_natural_order[k]]; |
| 652 | /* We must apply the point transform by Al. For AC coefficients this |
| 653 | * is an integer division with rounding towards 0. To do this portably |
| 654 | * in C, we shift after obtaining the absolute value. |
| 655 | */ |
| 656 | if (temp < 0) |
| 657 | temp = -temp; /* temp is abs value of input */ |
| 658 | temp >>= Al; /* apply the point transform */ |
| 659 | absvalues[k] = temp; /* save abs value for main pass */ |
| 660 | if (temp == 1) |
| 661 | EOB = k; /* EOB = index of last newly-nonzero coef */ |
| 662 | } |
| 663 | |
| 664 | /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */ |
| 665 | |
| 666 | r = 0; /* r = run length of zeros */ |
| 667 | BR = 0; /* BR = count of buffered bits added now */ |
| 668 | BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */ |
| 669 | |
| 670 | for (k = cinfo->Ss; k <= Se; k++) { |
| 671 | if ((temp = absvalues[k]) == 0) { |
| 672 | r++; |
| 673 | continue; |
| 674 | } |
| 675 | |
| 676 | /* Emit any required ZRLs, but not if they can be folded into EOB */ |
| 677 | while (r > 15 && k <= EOB) { |
| 678 | /* emit any pending EOBRUN and the BE correction bits */ |
| 679 | emit_eobrun(entropy); |
| 680 | /* Emit ZRL */ |
| 681 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); |
| 682 | r -= 16; |
| 683 | /* Emit buffered correction bits that must be associated with ZRL */ |
| 684 | emit_buffered_bits(entropy, BR_buffer, BR); |
| 685 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ |
| 686 | BR = 0; |
| 687 | } |
| 688 | |
| 689 | /* If the coef was previously nonzero, it only needs a correction bit. |
| 690 | * NOTE: a straight translation of the spec's figure G.7 would suggest |
| 691 | * that we also need to test r > 15. But if r > 15, we can only get here |
| 692 | * if k > EOB, which implies that this coefficient is not 1. |
| 693 | */ |
| 694 | if (temp > 1) { |
| 695 | /* The correction bit is the next bit of the absolute value. */ |
| 696 | BR_buffer[BR++] = (char) (temp & 1); |
| 697 | continue; |
| 698 | } |
| 699 | |
| 700 | /* Emit any pending EOBRUN and the BE correction bits */ |
| 701 | emit_eobrun(entropy); |
| 702 | |
| 703 | /* Count/emit Huffman symbol for run length / number of bits */ |
| 704 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1); |
| 705 | |
| 706 | /* Emit output bit for newly-nonzero coef */ |
| 707 | temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1; |
| 708 | emit_bits(entropy, (unsigned int) temp, 1); |
| 709 | |
| 710 | /* Emit buffered correction bits that must be associated with this code */ |
| 711 | emit_buffered_bits(entropy, BR_buffer, BR); |
| 712 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ |
| 713 | BR = 0; |
| 714 | r = 0; /* reset zero run length */ |
| 715 | } |
| 716 | |
| 717 | if (r > 0 || BR > 0) { /* If there are trailing zeroes, */ |
| 718 | entropy->EOBRUN++; /* count an EOB */ |
| 719 | entropy->BE += BR; /* concat my correction bits to older ones */ |
| 720 | /* We force out the EOB if we risk either: |
| 721 | * 1. overflow of the EOB counter; |
| 722 | * 2. overflow of the correction bit buffer during the next MCU. |
| 723 | */ |
| 724 | if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1)) |
| 725 | emit_eobrun(entropy); |
| 726 | } |
| 727 | |
| 728 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
| 729 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
| 730 | |
| 731 | /* Update restart-interval state too */ |
| 732 | if (cinfo->restart_interval) { |
| 733 | if (entropy->restarts_to_go == 0) { |
| 734 | entropy->restarts_to_go = cinfo->restart_interval; |
| 735 | entropy->next_restart_num++; |
| 736 | entropy->next_restart_num &= 7; |
| 737 | } |
| 738 | entropy->restarts_to_go--; |
| 739 | } |
| 740 | |
| 741 | return TRUE; |
| 742 | } |
| 743 | |
| 744 | |
| 745 | /* |
| 746 | * Finish up at the end of a Huffman-compressed progressive scan. |
| 747 | */ |
| 748 | |
| 749 | METHODDEF(void) |
| 750 | finish_pass_phuff (j_compress_ptr cinfo) |
| 751 | { |
| 752 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 753 | |
| 754 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
| 755 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
| 756 | |
| 757 | /* Flush out any buffered data */ |
| 758 | emit_eobrun(entropy); |
| 759 | flush_bits(entropy); |
| 760 | |
| 761 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
| 762 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
| 763 | } |
| 764 | |
| 765 | |
| 766 | /* |
| 767 | * Finish up a statistics-gathering pass and create the new Huffman tables. |
| 768 | */ |
| 769 | |
| 770 | METHODDEF(void) |
| 771 | finish_pass_gather_phuff (j_compress_ptr cinfo) |
| 772 | { |
| 773 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |
| 774 | boolean is_DC_band; |
| 775 | int ci, tbl; |
| 776 | jpeg_component_info * compptr; |
| 777 | JHUFF_TBL **htblptr; |
| 778 | boolean did[NUM_HUFF_TBLS]; |
| 779 | |
| 780 | /* Flush out buffered data (all we care about is counting the EOB symbol) */ |
| 781 | emit_eobrun(entropy); |
| 782 | |
| 783 | is_DC_band = (cinfo->Ss == 0); |
| 784 | |
| 785 | /* It's important not to apply jpeg_gen_optimal_table more than once |
| 786 | * per table, because it clobbers the input frequency counts! |
| 787 | */ |
| 788 | MEMZERO(did, SIZEOF(did)); |
| 789 | |
| 790 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
| 791 | compptr = cinfo->cur_comp_info[ci]; |
| 792 | if (is_DC_band) { |
| 793 | if (cinfo->Ah != 0) /* DC refinement needs no table */ |
| 794 | continue; |
| 795 | tbl = compptr->dc_tbl_no; |
| 796 | } else { |
| 797 | tbl = compptr->ac_tbl_no; |
| 798 | } |
| 799 | if (! did[tbl]) { |
| 800 | if (is_DC_band) |
| 801 | htblptr = & cinfo->dc_huff_tbl_ptrs[tbl]; |
| 802 | else |
| 803 | htblptr = & cinfo->ac_huff_tbl_ptrs[tbl]; |
| 804 | if (*htblptr == NULL) |
| 805 | *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); |
| 806 | jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]); |
| 807 | did[tbl] = TRUE; |
| 808 | } |
| 809 | } |
| 810 | } |
| 811 | |
| 812 | |
| 813 | /* |
| 814 | * Module initialization routine for progressive Huffman entropy encoding. |
| 815 | */ |
| 816 | |
| 817 | GLOBAL(void) |
| 818 | jinit_phuff_encoder (j_compress_ptr cinfo) |
| 819 | { |
| 820 | phuff_entropy_ptr entropy; |
| 821 | int i; |
| 822 | |
| 823 | entropy = (phuff_entropy_ptr) |
| 824 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 825 | SIZEOF(phuff_entropy_encoder)); |
| 826 | cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; |
| 827 | entropy->pub.start_pass = start_pass_phuff; |
| 828 | |
| 829 | /* Mark tables unallocated */ |
| 830 | for (i = 0; i < NUM_HUFF_TBLS; i++) { |
| 831 | entropy->derived_tbls[i] = NULL; |
| 832 | entropy->count_ptrs[i] = NULL; |
| 833 | } |
| 834 | entropy->bit_buffer = NULL; /* needed only in AC refinement scan */ |
| 835 | } |
| 836 | |
| 837 | #endif /* C_PROGRESSIVE_SUPPORTED */ |