1 | /* |
---|---|

2 | * jcphuff.c |

3 | * |

4 | * This file was part of the Independent JPEG Group's software: |

5 | * Copyright (C) 1995-1997, Thomas G. Lane. |

6 | * libjpeg-turbo Modifications: |

7 | * Copyright (C) 2015, D. R. Commander. |

8 | * For conditions of distribution and use, see the accompanying README.ijg |

9 | * file. |

10 | * |

11 | * This file contains Huffman entropy encoding routines for progressive JPEG. |

12 | * |

13 | * We do not support output suspension in this module, since the library |

14 | * currently does not allow multiple-scan files to be written with output |

15 | * suspension. |

16 | */ |

17 | |

18 | #define JPEG_INTERNALS |

19 | #include "jinclude.h" |

20 | #include "jpeglib.h" |

21 | #include "jchuff.h" /* Declarations shared with jchuff.c */ |

22 | |

23 | #ifdef C_PROGRESSIVE_SUPPORTED |

24 | |

25 | /* Expanded entropy encoder object for progressive Huffman encoding. */ |

26 | |

27 | typedef struct { |

28 | struct jpeg_entropy_encoder pub; /* public fields */ |

29 | |

30 | /* Mode flag: TRUE for optimization, FALSE for actual data output */ |

31 | boolean gather_statistics; |

32 | |

33 | /* Bit-level coding status. |

34 | * next_output_byte/free_in_buffer are local copies of cinfo->dest fields. |

35 | */ |

36 | JOCTET *next_output_byte; /* => next byte to write in buffer */ |

37 | size_t free_in_buffer; /* # of byte spaces remaining in buffer */ |

38 | size_t put_buffer; /* current bit-accumulation buffer */ |

39 | int put_bits; /* # of bits now in it */ |

40 | j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */ |

41 | |

42 | /* Coding status for DC components */ |

43 | int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ |

44 | |

45 | /* Coding status for AC components */ |

46 | int ac_tbl_no; /* the table number of the single component */ |

47 | unsigned int EOBRUN; /* run length of EOBs */ |

48 | unsigned int BE; /* # of buffered correction bits before MCU */ |

49 | char *bit_buffer; /* buffer for correction bits (1 per char) */ |

50 | /* packing correction bits tightly would save some space but cost time... */ |

51 | |

52 | unsigned int restarts_to_go; /* MCUs left in this restart interval */ |

53 | int next_restart_num; /* next restart number to write (0-7) */ |

54 | |

55 | /* Pointers to derived tables (these workspaces have image lifespan). |

56 | * Since any one scan codes only DC or only AC, we only need one set |

57 | * of tables, not one for DC and one for AC. |

58 | */ |

59 | c_derived_tbl *derived_tbls[NUM_HUFF_TBLS]; |

60 | |

61 | /* Statistics tables for optimization; again, one set is enough */ |

62 | long *count_ptrs[NUM_HUFF_TBLS]; |

63 | } phuff_entropy_encoder; |

64 | |

65 | typedef phuff_entropy_encoder *phuff_entropy_ptr; |

66 | |

67 | /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit |

68 | * buffer can hold. Larger sizes may slightly improve compression, but |

69 | * 1000 is already well into the realm of overkill. |

70 | * The minimum safe size is 64 bits. |

71 | */ |

72 | |

73 | #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */ |

74 | |

75 | /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than JLONG. |

76 | * We assume that int right shift is unsigned if JLONG right shift is, |

77 | * which should be safe. |

78 | */ |

79 | |

80 | #ifdef RIGHT_SHIFT_IS_UNSIGNED |

81 | #define ISHIFT_TEMPS int ishift_temp; |

82 | #define IRIGHT_SHIFT(x,shft) \ |

83 | ((ishift_temp = (x)) < 0 ? \ |

84 | (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \ |

85 | (ishift_temp >> (shft))) |

86 | #else |

87 | #define ISHIFT_TEMPS |

88 | #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) |

89 | #endif |

90 | |

91 | /* Forward declarations */ |

92 | METHODDEF(boolean) encode_mcu_DC_first (j_compress_ptr cinfo, |

93 | JBLOCKROW *MCU_data); |

94 | METHODDEF(boolean) encode_mcu_AC_first (j_compress_ptr cinfo, |

95 | JBLOCKROW *MCU_data); |

96 | METHODDEF(boolean) encode_mcu_DC_refine (j_compress_ptr cinfo, |

97 | JBLOCKROW *MCU_data); |

98 | METHODDEF(boolean) encode_mcu_AC_refine (j_compress_ptr cinfo, |

99 | JBLOCKROW *MCU_data); |

100 | METHODDEF(void) finish_pass_phuff (j_compress_ptr cinfo); |

101 | METHODDEF(void) finish_pass_gather_phuff (j_compress_ptr cinfo); |

102 | |

103 | |

104 | /* |

105 | * Initialize for a Huffman-compressed scan using progressive JPEG. |

106 | */ |

107 | |

108 | METHODDEF(void) |

109 | start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics) |

110 | { |

111 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |

112 | boolean is_DC_band; |

113 | int ci, tbl; |

114 | jpeg_component_info *compptr; |

115 | |

116 | entropy->cinfo = cinfo; |

117 | entropy->gather_statistics = gather_statistics; |

118 | |

119 | is_DC_band = (cinfo->Ss == 0); |

120 | |

121 | /* We assume jcmaster.c already validated the scan parameters. */ |

122 | |

123 | /* Select execution routines */ |

124 | if (cinfo->Ah == 0) { |

125 | if (is_DC_band) |

126 | entropy->pub.encode_mcu = encode_mcu_DC_first; |

127 | else |

128 | entropy->pub.encode_mcu = encode_mcu_AC_first; |

129 | } else { |

130 | if (is_DC_band) |

131 | entropy->pub.encode_mcu = encode_mcu_DC_refine; |

132 | else { |

133 | entropy->pub.encode_mcu = encode_mcu_AC_refine; |

134 | /* AC refinement needs a correction bit buffer */ |

135 | if (entropy->bit_buffer == NULL) |

136 | entropy->bit_buffer = (char *) |

137 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

138 | MAX_CORR_BITS * sizeof(char)); |

139 | } |

140 | } |

141 | if (gather_statistics) |

142 | entropy->pub.finish_pass = finish_pass_gather_phuff; |

143 | else |

144 | entropy->pub.finish_pass = finish_pass_phuff; |

145 | |

146 | /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1 |

147 | * for AC coefficients. |

148 | */ |

149 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |

150 | compptr = cinfo->cur_comp_info[ci]; |

151 | /* Initialize DC predictions to 0 */ |

152 | entropy->last_dc_val[ci] = 0; |

153 | /* Get table index */ |

154 | if (is_DC_band) { |

155 | if (cinfo->Ah != 0) /* DC refinement needs no table */ |

156 | continue; |

157 | tbl = compptr->dc_tbl_no; |

158 | } else { |

159 | entropy->ac_tbl_no = tbl = compptr->ac_tbl_no; |

160 | } |

161 | if (gather_statistics) { |

162 | /* Check for invalid table index */ |

163 | /* (make_c_derived_tbl does this in the other path) */ |

164 | if (tbl < 0 || tbl >= NUM_HUFF_TBLS) |

165 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); |

166 | /* Allocate and zero the statistics tables */ |

167 | /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ |

168 | if (entropy->count_ptrs[tbl] == NULL) |

169 | entropy->count_ptrs[tbl] = (long *) |

170 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

171 | 257 * sizeof(long)); |

172 | MEMZERO(entropy->count_ptrs[tbl], 257 * sizeof(long)); |

173 | } else { |

174 | /* Compute derived values for Huffman table */ |

175 | /* We may do this more than once for a table, but it's not expensive */ |

176 | jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl, |

177 | & entropy->derived_tbls[tbl]); |

178 | } |

179 | } |

180 | |

181 | /* Initialize AC stuff */ |

182 | entropy->EOBRUN = 0; |

183 | entropy->BE = 0; |

184 | |

185 | /* Initialize bit buffer to empty */ |

186 | entropy->put_buffer = 0; |

187 | entropy->put_bits = 0; |

188 | |

189 | /* Initialize restart stuff */ |

190 | entropy->restarts_to_go = cinfo->restart_interval; |

191 | entropy->next_restart_num = 0; |

192 | } |

193 | |

194 | |

195 | /* Outputting bytes to the file. |

196 | * NB: these must be called only when actually outputting, |

197 | * that is, entropy->gather_statistics == FALSE. |

198 | */ |

199 | |

200 | /* Emit a byte */ |

201 | #define emit_byte(entropy,val) \ |

202 | { *(entropy)->next_output_byte++ = (JOCTET) (val); \ |

203 | if (--(entropy)->free_in_buffer == 0) \ |

204 | dump_buffer(entropy); } |

205 | |

206 | |

207 | LOCAL(void) |

208 | dump_buffer (phuff_entropy_ptr entropy) |

209 | /* Empty the output buffer; we do not support suspension in this module. */ |

210 | { |

211 | struct jpeg_destination_mgr *dest = entropy->cinfo->dest; |

212 | |

213 | if (! (*dest->empty_output_buffer) (entropy->cinfo)) |

214 | ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND); |

215 | /* After a successful buffer dump, must reset buffer pointers */ |

216 | entropy->next_output_byte = dest->next_output_byte; |

217 | entropy->free_in_buffer = dest->free_in_buffer; |

218 | } |

219 | |

220 | |

221 | /* Outputting bits to the file */ |

222 | |

223 | /* Only the right 24 bits of put_buffer are used; the valid bits are |

224 | * left-justified in this part. At most 16 bits can be passed to emit_bits |

225 | * in one call, and we never retain more than 7 bits in put_buffer |

226 | * between calls, so 24 bits are sufficient. |

227 | */ |

228 | |

229 | LOCAL(void) |

230 | emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size) |

231 | /* Emit some bits, unless we are in gather mode */ |

232 | { |

233 | /* This routine is heavily used, so it's worth coding tightly. */ |

234 | register size_t put_buffer = (size_t) code; |

235 | register int put_bits = entropy->put_bits; |

236 | |

237 | /* if size is 0, caller used an invalid Huffman table entry */ |

238 | if (size == 0) |

239 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); |

240 | |

241 | if (entropy->gather_statistics) |

242 | return; /* do nothing if we're only getting stats */ |

243 | |

244 | put_buffer &= (((size_t) 1)<<size) - 1; /* mask off any extra bits in code */ |

245 | |

246 | put_bits += size; /* new number of bits in buffer */ |

247 | |

248 | put_buffer <<= 24 - put_bits; /* align incoming bits */ |

249 | |

250 | put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */ |

251 | |

252 | while (put_bits >= 8) { |

253 | int c = (int) ((put_buffer >> 16) & 0xFF); |

254 | |

255 | emit_byte(entropy, c); |

256 | if (c == 0xFF) { /* need to stuff a zero byte? */ |

257 | emit_byte(entropy, 0); |

258 | } |

259 | put_buffer <<= 8; |

260 | put_bits -= 8; |

261 | } |

262 | |

263 | entropy->put_buffer = put_buffer; /* update variables */ |

264 | entropy->put_bits = put_bits; |

265 | } |

266 | |

267 | |

268 | LOCAL(void) |

269 | flush_bits (phuff_entropy_ptr entropy) |

270 | { |

271 | emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */ |

272 | entropy->put_buffer = 0; /* and reset bit-buffer to empty */ |

273 | entropy->put_bits = 0; |

274 | } |

275 | |

276 | |

277 | /* |

278 | * Emit (or just count) a Huffman symbol. |

279 | */ |

280 | |

281 | LOCAL(void) |

282 | emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol) |

283 | { |

284 | if (entropy->gather_statistics) |

285 | entropy->count_ptrs[tbl_no][symbol]++; |

286 | else { |

287 | c_derived_tbl *tbl = entropy->derived_tbls[tbl_no]; |

288 | emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]); |

289 | } |

290 | } |

291 | |

292 | |

293 | /* |

294 | * Emit bits from a correction bit buffer. |

295 | */ |

296 | |

297 | LOCAL(void) |

298 | emit_buffered_bits (phuff_entropy_ptr entropy, char *bufstart, |

299 | unsigned int nbits) |

300 | { |

301 | if (entropy->gather_statistics) |

302 | return; /* no real work */ |

303 | |

304 | while (nbits > 0) { |

305 | emit_bits(entropy, (unsigned int) (*bufstart), 1); |

306 | bufstart++; |

307 | nbits--; |

308 | } |

309 | } |

310 | |

311 | |

312 | /* |

313 | * Emit any pending EOBRUN symbol. |

314 | */ |

315 | |

316 | LOCAL(void) |

317 | emit_eobrun (phuff_entropy_ptr entropy) |

318 | { |

319 | register int temp, nbits; |

320 | |

321 | if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */ |

322 | temp = entropy->EOBRUN; |

323 | nbits = 0; |

324 | while ((temp >>= 1)) |

325 | nbits++; |

326 | /* safety check: shouldn't happen given limited correction-bit buffer */ |

327 | if (nbits > 14) |

328 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); |

329 | |

330 | emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4); |

331 | if (nbits) |

332 | emit_bits(entropy, entropy->EOBRUN, nbits); |

333 | |

334 | entropy->EOBRUN = 0; |

335 | |

336 | /* Emit any buffered correction bits */ |

337 | emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE); |

338 | entropy->BE = 0; |

339 | } |

340 | } |

341 | |

342 | |

343 | /* |

344 | * Emit a restart marker & resynchronize predictions. |

345 | */ |

346 | |

347 | LOCAL(void) |

348 | emit_restart (phuff_entropy_ptr entropy, int restart_num) |

349 | { |

350 | int ci; |

351 | |

352 | emit_eobrun(entropy); |

353 | |

354 | if (! entropy->gather_statistics) { |

355 | flush_bits(entropy); |

356 | emit_byte(entropy, 0xFF); |

357 | emit_byte(entropy, JPEG_RST0 + restart_num); |

358 | } |

359 | |

360 | if (entropy->cinfo->Ss == 0) { |

361 | /* Re-initialize DC predictions to 0 */ |

362 | for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++) |

363 | entropy->last_dc_val[ci] = 0; |

364 | } else { |

365 | /* Re-initialize all AC-related fields to 0 */ |

366 | entropy->EOBRUN = 0; |

367 | entropy->BE = 0; |

368 | } |

369 | } |

370 | |

371 | |

372 | /* |

373 | * MCU encoding for DC initial scan (either spectral selection, |

374 | * or first pass of successive approximation). |

375 | */ |

376 | |

377 | METHODDEF(boolean) |

378 | encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |

379 | { |

380 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |

381 | register int temp, temp2; |

382 | register int nbits; |

383 | int blkn, ci; |

384 | int Al = cinfo->Al; |

385 | JBLOCKROW block; |

386 | jpeg_component_info *compptr; |

387 | ISHIFT_TEMPS |

388 | |

389 | entropy->next_output_byte = cinfo->dest->next_output_byte; |

390 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |

391 | |

392 | /* Emit restart marker if needed */ |

393 | if (cinfo->restart_interval) |

394 | if (entropy->restarts_to_go == 0) |

395 | emit_restart(entropy, entropy->next_restart_num); |

396 | |

397 | /* Encode the MCU data blocks */ |

398 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |

399 | block = MCU_data[blkn]; |

400 | ci = cinfo->MCU_membership[blkn]; |

401 | compptr = cinfo->cur_comp_info[ci]; |

402 | |

403 | /* Compute the DC value after the required point transform by Al. |

404 | * This is simply an arithmetic right shift. |

405 | */ |

406 | temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al); |

407 | |

408 | /* DC differences are figured on the point-transformed values. */ |

409 | temp = temp2 - entropy->last_dc_val[ci]; |

410 | entropy->last_dc_val[ci] = temp2; |

411 | |

412 | /* Encode the DC coefficient difference per section G.1.2.1 */ |

413 | temp2 = temp; |

414 | if (temp < 0) { |

415 | temp = -temp; /* temp is abs value of input */ |

416 | /* For a negative input, want temp2 = bitwise complement of abs(input) */ |

417 | /* This code assumes we are on a two's complement machine */ |

418 | temp2--; |

419 | } |

420 | |

421 | /* Find the number of bits needed for the magnitude of the coefficient */ |

422 | nbits = 0; |

423 | while (temp) { |

424 | nbits++; |

425 | temp >>= 1; |

426 | } |

427 | /* Check for out-of-range coefficient values. |

428 | * Since we're encoding a difference, the range limit is twice as much. |

429 | */ |

430 | if (nbits > MAX_COEF_BITS+1) |

431 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |

432 | |

433 | /* Count/emit the Huffman-coded symbol for the number of bits */ |

434 | emit_symbol(entropy, compptr->dc_tbl_no, nbits); |

435 | |

436 | /* Emit that number of bits of the value, if positive, */ |

437 | /* or the complement of its magnitude, if negative. */ |

438 | if (nbits) /* emit_bits rejects calls with size 0 */ |

439 | emit_bits(entropy, (unsigned int) temp2, nbits); |

440 | } |

441 | |

442 | cinfo->dest->next_output_byte = entropy->next_output_byte; |

443 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |

444 | |

445 | /* Update restart-interval state too */ |

446 | if (cinfo->restart_interval) { |

447 | if (entropy->restarts_to_go == 0) { |

448 | entropy->restarts_to_go = cinfo->restart_interval; |

449 | entropy->next_restart_num++; |

450 | entropy->next_restart_num &= 7; |

451 | } |

452 | entropy->restarts_to_go--; |

453 | } |

454 | |

455 | return TRUE; |

456 | } |

457 | |

458 | |

459 | /* |

460 | * MCU encoding for AC initial scan (either spectral selection, |

461 | * or first pass of successive approximation). |

462 | */ |

463 | |

464 | METHODDEF(boolean) |

465 | encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |

466 | { |

467 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |

468 | register int temp, temp2; |

469 | register int nbits; |

470 | register int r, k; |

471 | int Se = cinfo->Se; |

472 | int Al = cinfo->Al; |

473 | JBLOCKROW block; |

474 | |

475 | entropy->next_output_byte = cinfo->dest->next_output_byte; |

476 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |

477 | |

478 | /* Emit restart marker if needed */ |

479 | if (cinfo->restart_interval) |

480 | if (entropy->restarts_to_go == 0) |

481 | emit_restart(entropy, entropy->next_restart_num); |

482 | |

483 | /* Encode the MCU data block */ |

484 | block = MCU_data[0]; |

485 | |

486 | /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */ |

487 | |

488 | r = 0; /* r = run length of zeros */ |

489 | |

490 | for (k = cinfo->Ss; k <= Se; k++) { |

491 | if ((temp = (*block)[jpeg_natural_order[k]]) == 0) { |

492 | r++; |

493 | continue; |

494 | } |

495 | /* We must apply the point transform by Al. For AC coefficients this |

496 | * is an integer division with rounding towards 0. To do this portably |

497 | * in C, we shift after obtaining the absolute value; so the code is |

498 | * interwoven with finding the abs value (temp) and output bits (temp2). |

499 | */ |

500 | if (temp < 0) { |

501 | temp = -temp; /* temp is abs value of input */ |

502 | temp >>= Al; /* apply the point transform */ |

503 | /* For a negative coef, want temp2 = bitwise complement of abs(coef) */ |

504 | temp2 = ~temp; |

505 | } else { |

506 | temp >>= Al; /* apply the point transform */ |

507 | temp2 = temp; |

508 | } |

509 | /* Watch out for case that nonzero coef is zero after point transform */ |

510 | if (temp == 0) { |

511 | r++; |

512 | continue; |

513 | } |

514 | |

515 | /* Emit any pending EOBRUN */ |

516 | if (entropy->EOBRUN > 0) |

517 | emit_eobrun(entropy); |

518 | /* if run length > 15, must emit special run-length-16 codes (0xF0) */ |

519 | while (r > 15) { |

520 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); |

521 | r -= 16; |

522 | } |

523 | |

524 | /* Find the number of bits needed for the magnitude of the coefficient */ |

525 | nbits = 1; /* there must be at least one 1 bit */ |

526 | while ((temp >>= 1)) |

527 | nbits++; |

528 | /* Check for out-of-range coefficient values */ |

529 | if (nbits > MAX_COEF_BITS) |

530 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |

531 | |

532 | /* Count/emit Huffman symbol for run length / number of bits */ |

533 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits); |

534 | |

535 | /* Emit that number of bits of the value, if positive, */ |

536 | /* or the complement of its magnitude, if negative. */ |

537 | emit_bits(entropy, (unsigned int) temp2, nbits); |

538 | |

539 | r = 0; /* reset zero run length */ |

540 | } |

541 | |

542 | if (r > 0) { /* If there are trailing zeroes, */ |

543 | entropy->EOBRUN++; /* count an EOB */ |

544 | if (entropy->EOBRUN == 0x7FFF) |

545 | emit_eobrun(entropy); /* force it out to avoid overflow */ |

546 | } |

547 | |

548 | cinfo->dest->next_output_byte = entropy->next_output_byte; |

549 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |

550 | |

551 | /* Update restart-interval state too */ |

552 | if (cinfo->restart_interval) { |

553 | if (entropy->restarts_to_go == 0) { |

554 | entropy->restarts_to_go = cinfo->restart_interval; |

555 | entropy->next_restart_num++; |

556 | entropy->next_restart_num &= 7; |

557 | } |

558 | entropy->restarts_to_go--; |

559 | } |

560 | |

561 | return TRUE; |

562 | } |

563 | |

564 | |

565 | /* |

566 | * MCU encoding for DC successive approximation refinement scan. |

567 | * Note: we assume such scans can be multi-component, although the spec |

568 | * is not very clear on the point. |

569 | */ |

570 | |

571 | METHODDEF(boolean) |

572 | encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |

573 | { |

574 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |

575 | register int temp; |

576 | int blkn; |

577 | int Al = cinfo->Al; |

578 | JBLOCKROW block; |

579 | |

580 | entropy->next_output_byte = cinfo->dest->next_output_byte; |

581 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |

582 | |

583 | /* Emit restart marker if needed */ |

584 | if (cinfo->restart_interval) |

585 | if (entropy->restarts_to_go == 0) |

586 | emit_restart(entropy, entropy->next_restart_num); |

587 | |

588 | /* Encode the MCU data blocks */ |

589 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |

590 | block = MCU_data[blkn]; |

591 | |

592 | /* We simply emit the Al'th bit of the DC coefficient value. */ |

593 | temp = (*block)[0]; |

594 | emit_bits(entropy, (unsigned int) (temp >> Al), 1); |

595 | } |

596 | |

597 | cinfo->dest->next_output_byte = entropy->next_output_byte; |

598 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |

599 | |

600 | /* Update restart-interval state too */ |

601 | if (cinfo->restart_interval) { |

602 | if (entropy->restarts_to_go == 0) { |

603 | entropy->restarts_to_go = cinfo->restart_interval; |

604 | entropy->next_restart_num++; |

605 | entropy->next_restart_num &= 7; |

606 | } |

607 | entropy->restarts_to_go--; |

608 | } |

609 | |

610 | return TRUE; |

611 | } |

612 | |

613 | |

614 | /* |

615 | * MCU encoding for AC successive approximation refinement scan. |

616 | */ |

617 | |

618 | METHODDEF(boolean) |

619 | encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |

620 | { |

621 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |

622 | register int temp; |

623 | register int r, k; |

624 | int EOB; |

625 | char *BR_buffer; |

626 | unsigned int BR; |

627 | int Se = cinfo->Se; |

628 | int Al = cinfo->Al; |

629 | JBLOCKROW block; |

630 | int absvalues[DCTSIZE2]; |

631 | |

632 | entropy->next_output_byte = cinfo->dest->next_output_byte; |

633 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |

634 | |

635 | /* Emit restart marker if needed */ |

636 | if (cinfo->restart_interval) |

637 | if (entropy->restarts_to_go == 0) |

638 | emit_restart(entropy, entropy->next_restart_num); |

639 | |

640 | /* Encode the MCU data block */ |

641 | block = MCU_data[0]; |

642 | |

643 | /* It is convenient to make a pre-pass to determine the transformed |

644 | * coefficients' absolute values and the EOB position. |

645 | */ |

646 | EOB = 0; |

647 | for (k = cinfo->Ss; k <= Se; k++) { |

648 | temp = (*block)[jpeg_natural_order[k]]; |

649 | /* We must apply the point transform by Al. For AC coefficients this |

650 | * is an integer division with rounding towards 0. To do this portably |

651 | * in C, we shift after obtaining the absolute value. |

652 | */ |

653 | if (temp < 0) |

654 | temp = -temp; /* temp is abs value of input */ |

655 | temp >>= Al; /* apply the point transform */ |

656 | absvalues[k] = temp; /* save abs value for main pass */ |

657 | if (temp == 1) |

658 | EOB = k; /* EOB = index of last newly-nonzero coef */ |

659 | } |

660 | |

661 | /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */ |

662 | |

663 | r = 0; /* r = run length of zeros */ |

664 | BR = 0; /* BR = count of buffered bits added now */ |

665 | BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */ |

666 | |

667 | for (k = cinfo->Ss; k <= Se; k++) { |

668 | if ((temp = absvalues[k]) == 0) { |

669 | r++; |

670 | continue; |

671 | } |

672 | |

673 | /* Emit any required ZRLs, but not if they can be folded into EOB */ |

674 | while (r > 15 && k <= EOB) { |

675 | /* emit any pending EOBRUN and the BE correction bits */ |

676 | emit_eobrun(entropy); |

677 | /* Emit ZRL */ |

678 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); |

679 | r -= 16; |

680 | /* Emit buffered correction bits that must be associated with ZRL */ |

681 | emit_buffered_bits(entropy, BR_buffer, BR); |

682 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ |

683 | BR = 0; |

684 | } |

685 | |

686 | /* If the coef was previously nonzero, it only needs a correction bit. |

687 | * NOTE: a straight translation of the spec's figure G.7 would suggest |

688 | * that we also need to test r > 15. But if r > 15, we can only get here |

689 | * if k > EOB, which implies that this coefficient is not 1. |

690 | */ |

691 | if (temp > 1) { |

692 | /* The correction bit is the next bit of the absolute value. */ |

693 | BR_buffer[BR++] = (char) (temp & 1); |

694 | continue; |

695 | } |

696 | |

697 | /* Emit any pending EOBRUN and the BE correction bits */ |

698 | emit_eobrun(entropy); |

699 | |

700 | /* Count/emit Huffman symbol for run length / number of bits */ |

701 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1); |

702 | |

703 | /* Emit output bit for newly-nonzero coef */ |

704 | temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1; |

705 | emit_bits(entropy, (unsigned int) temp, 1); |

706 | |

707 | /* Emit buffered correction bits that must be associated with this code */ |

708 | emit_buffered_bits(entropy, BR_buffer, BR); |

709 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ |

710 | BR = 0; |

711 | r = 0; /* reset zero run length */ |

712 | } |

713 | |

714 | if (r > 0 || BR > 0) { /* If there are trailing zeroes, */ |

715 | entropy->EOBRUN++; /* count an EOB */ |

716 | entropy->BE += BR; /* concat my correction bits to older ones */ |

717 | /* We force out the EOB if we risk either: |

718 | * 1. overflow of the EOB counter; |

719 | * 2. overflow of the correction bit buffer during the next MCU. |

720 | */ |

721 | if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1)) |

722 | emit_eobrun(entropy); |

723 | } |

724 | |

725 | cinfo->dest->next_output_byte = entropy->next_output_byte; |

726 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |

727 | |

728 | /* Update restart-interval state too */ |

729 | if (cinfo->restart_interval) { |

730 | if (entropy->restarts_to_go == 0) { |

731 | entropy->restarts_to_go = cinfo->restart_interval; |

732 | entropy->next_restart_num++; |

733 | entropy->next_restart_num &= 7; |

734 | } |

735 | entropy->restarts_to_go--; |

736 | } |

737 | |

738 | return TRUE; |

739 | } |

740 | |

741 | |

742 | /* |

743 | * Finish up at the end of a Huffman-compressed progressive scan. |

744 | */ |

745 | |

746 | METHODDEF(void) |

747 | finish_pass_phuff (j_compress_ptr cinfo) |

748 | { |

749 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |

750 | |

751 | entropy->next_output_byte = cinfo->dest->next_output_byte; |

752 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |

753 | |

754 | /* Flush out any buffered data */ |

755 | emit_eobrun(entropy); |

756 | flush_bits(entropy); |

757 | |

758 | cinfo->dest->next_output_byte = entropy->next_output_byte; |

759 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |

760 | } |

761 | |

762 | |

763 | /* |

764 | * Finish up a statistics-gathering pass and create the new Huffman tables. |

765 | */ |

766 | |

767 | METHODDEF(void) |

768 | finish_pass_gather_phuff (j_compress_ptr cinfo) |

769 | { |

770 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; |

771 | boolean is_DC_band; |

772 | int ci, tbl; |

773 | jpeg_component_info *compptr; |

774 | JHUFF_TBL **htblptr; |

775 | boolean did[NUM_HUFF_TBLS]; |

776 | |

777 | /* Flush out buffered data (all we care about is counting the EOB symbol) */ |

778 | emit_eobrun(entropy); |

779 | |

780 | is_DC_band = (cinfo->Ss == 0); |

781 | |

782 | /* It's important not to apply jpeg_gen_optimal_table more than once |

783 | * per table, because it clobbers the input frequency counts! |

784 | */ |

785 | MEMZERO(did, sizeof(did)); |

786 | |

787 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |

788 | compptr = cinfo->cur_comp_info[ci]; |

789 | if (is_DC_band) { |

790 | if (cinfo->Ah != 0) /* DC refinement needs no table */ |

791 | continue; |

792 | tbl = compptr->dc_tbl_no; |

793 | } else { |

794 | tbl = compptr->ac_tbl_no; |

795 | } |

796 | if (! did[tbl]) { |

797 | if (is_DC_band) |

798 | htblptr = & cinfo->dc_huff_tbl_ptrs[tbl]; |

799 | else |

800 | htblptr = & cinfo->ac_huff_tbl_ptrs[tbl]; |

801 | if (*htblptr == NULL) |

802 | *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); |

803 | jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]); |

804 | did[tbl] = TRUE; |

805 | } |

806 | } |

807 | } |

808 | |

809 | |

810 | /* |

811 | * Module initialization routine for progressive Huffman entropy encoding. |

812 | */ |

813 | |

814 | GLOBAL(void) |

815 | jinit_phuff_encoder (j_compress_ptr cinfo) |

816 | { |

817 | phuff_entropy_ptr entropy; |

818 | int i; |

819 | |

820 | entropy = (phuff_entropy_ptr) |

821 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |

822 | sizeof(phuff_entropy_encoder)); |

823 | cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; |

824 | entropy->pub.start_pass = start_pass_phuff; |

825 | |

826 | /* Mark tables unallocated */ |

827 | for (i = 0; i < NUM_HUFF_TBLS; i++) { |

828 | entropy->derived_tbls[i] = NULL; |

829 | entropy->count_ptrs[i] = NULL; |

830 | } |

831 | entropy->bit_buffer = NULL; /* needed only in AC refinement scan */ |

832 | } |

833 | |

834 | #endif /* C_PROGRESSIVE_SUPPORTED */ |

835 |