1 /* 2 * jdcoefct.c 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1994-1997, Thomas G. Lane. 6 * libjpeg-turbo Modifications: 7 * Copyright 2009 Pierre Ossman <ossman (at) cendio.se> for Cendio AB 8 * Copyright (C) 2010, 2015-2016, D. R. Commander. 9 * Copyright (C) 2015, Google, Inc. 10 * For conditions of distribution and use, see the accompanying README.ijg 11 * file. 12 * 13 * This file contains the coefficient buffer controller for decompression. 14 * This controller is the top level of the JPEG decompressor proper. 15 * The coefficient buffer lies between entropy decoding and inverse-DCT steps. 16 * 17 * In buffered-image mode, this controller is the interface between 18 * input-oriented processing and output-oriented processing. 19 * Also, the input side (only) is used when reading a file for transcoding. 20 */ 21 22 #include "jinclude.h" 23 #include "jdcoefct.h" 24 #include "jpegcomp.h" 25 26 27 /* Forward declarations */ 28 METHODDEF(int) decompress_onepass(j_decompress_ptr cinfo, 29 JSAMPIMAGE output_buf); 30 #ifdef D_MULTISCAN_FILES_SUPPORTED 31 METHODDEF(int) decompress_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf); 32 #endif 33 #ifdef BLOCK_SMOOTHING_SUPPORTED 34 LOCAL(boolean) smoothing_ok(j_decompress_ptr cinfo); 35 METHODDEF(int) decompress_smooth_data(j_decompress_ptr cinfo, 36 JSAMPIMAGE output_buf); 37 #endif 38 39 40 /* 41 * Initialize for an input processing pass. 42 */ 43 44 METHODDEF(void) 45 start_input_pass(j_decompress_ptr cinfo) 46 { 47 cinfo->input_iMCU_row = 0; 48 start_iMCU_row(cinfo); 49 } 50 51 52 /* 53 * Initialize for an output processing pass. 54 */ 55 56 METHODDEF(void) 57 start_output_pass(j_decompress_ptr cinfo) 58 { 59 #ifdef BLOCK_SMOOTHING_SUPPORTED 60 my_coef_ptr coef = (my_coef_ptr)cinfo->coef; 61 62 /* If multipass, check to see whether to use block smoothing on this pass */ 63 if (coef->pub.coef_arrays != NULL) { 64 if (cinfo->do_block_smoothing && smoothing_ok(cinfo)) 65 coef->pub.decompress_data = decompress_smooth_data; 66 else 67 coef->pub.decompress_data = decompress_data; 68 } 69 #endif 70 cinfo->output_iMCU_row = 0; 71 } 72 73 74 /* 75 * Decompress and return some data in the single-pass case. 76 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 77 * Input and output must run in lockstep since we have only a one-MCU buffer. 78 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 79 * 80 * NB: output_buf contains a plane for each component in image, 81 * which we index according to the component's SOF position. 82 */ 83 84 METHODDEF(int) 85 decompress_onepass(j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 86 { 87 my_coef_ptr coef = (my_coef_ptr)cinfo->coef; 88 JDIMENSION MCU_col_num; /* index of current MCU within row */ 89 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; 90 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 91 int blkn, ci, xindex, yindex, yoffset, useful_width; 92 JSAMPARRAY output_ptr; 93 JDIMENSION start_col, output_col; 94 jpeg_component_info *compptr; 95 inverse_DCT_method_ptr inverse_DCT; 96 97 /* Loop to process as much as one whole iMCU row */ 98 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 99 yoffset++) { 100 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col; 101 MCU_col_num++) { 102 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */ 103 jzero_far((void *)coef->MCU_buffer[0], 104 (size_t)(cinfo->blocks_in_MCU * sizeof(JBLOCK))); 105 if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 106 /* Suspension forced; update state counters and exit */ 107 coef->MCU_vert_offset = yoffset; 108 coef->MCU_ctr = MCU_col_num; 109 return JPEG_SUSPENDED; 110 } 111 112 /* Only perform the IDCT on blocks that are contained within the desired 113 * cropping region. 114 */ 115 if (MCU_col_num >= cinfo->master->first_iMCU_col && 116 MCU_col_num <= cinfo->master->last_iMCU_col) { 117 /* Determine where data should go in output_buf and do the IDCT thing. 118 * We skip dummy blocks at the right and bottom edges (but blkn gets 119 * incremented past them!). Note the inner loop relies on having 120 * allocated the MCU_buffer[] blocks sequentially. 121 */ 122 blkn = 0; /* index of current DCT block within MCU */ 123 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 124 compptr = cinfo->cur_comp_info[ci]; 125 /* Don't bother to IDCT an uninteresting component. */ 126 if (!compptr->component_needed) { 127 blkn += compptr->MCU_blocks; 128 continue; 129 } 130 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index]; 131 useful_width = (MCU_col_num < last_MCU_col) ? 132 compptr->MCU_width : compptr->last_col_width; 133 output_ptr = output_buf[compptr->component_index] + 134 yoffset * compptr->_DCT_scaled_size; 135 start_col = (MCU_col_num - cinfo->master->first_iMCU_col) * 136 compptr->MCU_sample_width; 137 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 138 if (cinfo->input_iMCU_row < last_iMCU_row || 139 yoffset + yindex < compptr->last_row_height) { 140 output_col = start_col; 141 for (xindex = 0; xindex < useful_width; xindex++) { 142 (*inverse_DCT) (cinfo, compptr, 143 (JCOEFPTR)coef->MCU_buffer[blkn + xindex], 144 output_ptr, output_col); 145 output_col += compptr->_DCT_scaled_size; 146 } 147 } 148 blkn += compptr->MCU_width; 149 output_ptr += compptr->_DCT_scaled_size; 150 } 151 } 152 } 153 } 154 /* Completed an MCU row, but perhaps not an iMCU row */ 155 coef->MCU_ctr = 0; 156 } 157 /* Completed the iMCU row, advance counters for next one */ 158 cinfo->output_iMCU_row++; 159 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 160 start_iMCU_row(cinfo); 161 return JPEG_ROW_COMPLETED; 162 } 163 /* Completed the scan */ 164 (*cinfo->inputctl->finish_input_pass) (cinfo); 165 return JPEG_SCAN_COMPLETED; 166 } 167 168 169 /* 170 * Dummy consume-input routine for single-pass operation. 171 */ 172 173 METHODDEF(int) 174 dummy_consume_data(j_decompress_ptr cinfo) 175 { 176 return JPEG_SUSPENDED; /* Always indicate nothing was done */ 177 } 178 179 180 #ifdef D_MULTISCAN_FILES_SUPPORTED 181 182 /* 183 * Consume input data and store it in the full-image coefficient buffer. 184 * We read as much as one fully interleaved MCU row ("iMCU" row) per call, 185 * ie, v_samp_factor block rows for each component in the scan. 186 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 187 */ 188 189 METHODDEF(int) 190 consume_data(j_decompress_ptr cinfo) 191 { 192 my_coef_ptr coef = (my_coef_ptr)cinfo->coef; 193 JDIMENSION MCU_col_num; /* index of current MCU within row */ 194 int blkn, ci, xindex, yindex, yoffset; 195 JDIMENSION start_col; 196 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; 197 JBLOCKROW buffer_ptr; 198 jpeg_component_info *compptr; 199 200 /* Align the virtual buffers for the components used in this scan. */ 201 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 202 compptr = cinfo->cur_comp_info[ci]; 203 buffer[ci] = (*cinfo->mem->access_virt_barray) 204 ((j_common_ptr)cinfo, coef->whole_image[compptr->component_index], 205 cinfo->input_iMCU_row * compptr->v_samp_factor, 206 (JDIMENSION)compptr->v_samp_factor, TRUE); 207 /* Note: entropy decoder expects buffer to be zeroed, 208 * but this is handled automatically by the memory manager 209 * because we requested a pre-zeroed array. 210 */ 211 } 212 213 /* Loop to process one whole iMCU row */ 214 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 215 yoffset++) { 216 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row; 217 MCU_col_num++) { 218 /* Construct list of pointers to DCT blocks belonging to this MCU */ 219 blkn = 0; /* index of current DCT block within MCU */ 220 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 221 compptr = cinfo->cur_comp_info[ci]; 222 start_col = MCU_col_num * compptr->MCU_width; 223 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 224 buffer_ptr = buffer[ci][yindex + yoffset] + start_col; 225 for (xindex = 0; xindex < compptr->MCU_width; xindex++) { 226 coef->MCU_buffer[blkn++] = buffer_ptr++; 227 } 228 } 229 } 230 /* Try to fetch the MCU. */ 231 if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 232 /* Suspension forced; update state counters and exit */ 233 coef->MCU_vert_offset = yoffset; 234 coef->MCU_ctr = MCU_col_num; 235 return JPEG_SUSPENDED; 236 } 237 } 238 /* Completed an MCU row, but perhaps not an iMCU row */ 239 coef->MCU_ctr = 0; 240 } 241 /* Completed the iMCU row, advance counters for next one */ 242 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 243 start_iMCU_row(cinfo); 244 return JPEG_ROW_COMPLETED; 245 } 246 /* Completed the scan */ 247 (*cinfo->inputctl->finish_input_pass) (cinfo); 248 return JPEG_SCAN_COMPLETED; 249 } 250 251 252 /* 253 * Decompress and return some data in the multi-pass case. 254 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 255 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 256 * 257 * NB: output_buf contains a plane for each component in image. 258 */ 259 260 METHODDEF(int) 261 decompress_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 262 { 263 my_coef_ptr coef = (my_coef_ptr)cinfo->coef; 264 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 265 JDIMENSION block_num; 266 int ci, block_row, block_rows; 267 JBLOCKARRAY buffer; 268 JBLOCKROW buffer_ptr; 269 JSAMPARRAY output_ptr; 270 JDIMENSION output_col; 271 jpeg_component_info *compptr; 272 inverse_DCT_method_ptr inverse_DCT; 273 274 /* Force some input to be done if we are getting ahead of the input. */ 275 while (cinfo->input_scan_number < cinfo->output_scan_number || 276 (cinfo->input_scan_number == cinfo->output_scan_number && 277 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) { 278 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 279 return JPEG_SUSPENDED; 280 } 281 282 /* OK, output from the virtual arrays. */ 283 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 284 ci++, compptr++) { 285 /* Don't bother to IDCT an uninteresting component. */ 286 if (!compptr->component_needed) 287 continue; 288 /* Align the virtual buffer for this component. */ 289 buffer = (*cinfo->mem->access_virt_barray) 290 ((j_common_ptr)cinfo, coef->whole_image[ci], 291 cinfo->output_iMCU_row * compptr->v_samp_factor, 292 (JDIMENSION)compptr->v_samp_factor, FALSE); 293 /* Count non-dummy DCT block rows in this iMCU row. */ 294 if (cinfo->output_iMCU_row < last_iMCU_row) 295 block_rows = compptr->v_samp_factor; 296 else { 297 /* NB: can't use last_row_height here; it is input-side-dependent! */ 298 block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor); 299 if (block_rows == 0) block_rows = compptr->v_samp_factor; 300 } 301 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 302 output_ptr = output_buf[ci]; 303 /* Loop over all DCT blocks to be processed. */ 304 for (block_row = 0; block_row < block_rows; block_row++) { 305 buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci]; 306 output_col = 0; 307 for (block_num = cinfo->master->first_MCU_col[ci]; 308 block_num <= cinfo->master->last_MCU_col[ci]; block_num++) { 309 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)buffer_ptr, output_ptr, 310 output_col); 311 buffer_ptr++; 312 output_col += compptr->_DCT_scaled_size; 313 } 314 output_ptr += compptr->_DCT_scaled_size; 315 } 316 } 317 318 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 319 return JPEG_ROW_COMPLETED; 320 return JPEG_SCAN_COMPLETED; 321 } 322 323 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 324 325 326 #ifdef BLOCK_SMOOTHING_SUPPORTED 327 328 /* 329 * This code applies interblock smoothing as described by section K.8 330 * of the JPEG standard: the first 5 AC coefficients are estimated from 331 * the DC values of a DCT block and its 8 neighboring blocks. 332 * We apply smoothing only for progressive JPEG decoding, and only if 333 * the coefficients it can estimate are not yet known to full precision. 334 */ 335 336 /* Natural-order array positions of the first 5 zigzag-order coefficients */ 337 #define Q01_POS 1 338 #define Q10_POS 8 339 #define Q20_POS 16 340 #define Q11_POS 9 341 #define Q02_POS 2 342 343 /* 344 * Determine whether block smoothing is applicable and safe. 345 * We also latch the current states of the coef_bits[] entries for the 346 * AC coefficients; otherwise, if the input side of the decompressor 347 * advances into a new scan, we might think the coefficients are known 348 * more accurately than they really are. 349 */ 350 351 LOCAL(boolean) 352 smoothing_ok(j_decompress_ptr cinfo) 353 { 354 my_coef_ptr coef = (my_coef_ptr)cinfo->coef; 355 boolean smoothing_useful = FALSE; 356 int ci, coefi; 357 jpeg_component_info *compptr; 358 JQUANT_TBL *qtable; 359 int *coef_bits; 360 int *coef_bits_latch; 361 362 if (!cinfo->progressive_mode || cinfo->coef_bits == NULL) 363 return FALSE; 364 365 /* Allocate latch area if not already done */ 366 if (coef->coef_bits_latch == NULL) 367 coef->coef_bits_latch = (int *) 368 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE, 369 cinfo->num_components * 370 (SAVED_COEFS * sizeof(int))); 371 coef_bits_latch = coef->coef_bits_latch; 372 373 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 374 ci++, compptr++) { 375 /* All components' quantization values must already be latched. */ 376 if ((qtable = compptr->quant_table) == NULL) 377 return FALSE; 378 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */ 379 if (qtable->quantval[0] == 0 || 380 qtable->quantval[Q01_POS] == 0 || 381 qtable->quantval[Q10_POS] == 0 || 382 qtable->quantval[Q20_POS] == 0 || 383 qtable->quantval[Q11_POS] == 0 || 384 qtable->quantval[Q02_POS] == 0) 385 return FALSE; 386 /* DC values must be at least partly known for all components. */ 387 coef_bits = cinfo->coef_bits[ci]; 388 if (coef_bits[0] < 0) 389 return FALSE; 390 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */ 391 for (coefi = 1; coefi <= 5; coefi++) { 392 coef_bits_latch[coefi] = coef_bits[coefi]; 393 if (coef_bits[coefi] != 0) 394 smoothing_useful = TRUE; 395 } 396 coef_bits_latch += SAVED_COEFS; 397 } 398 399 return smoothing_useful; 400 } 401 402 403 /* 404 * Variant of decompress_data for use when doing block smoothing. 405 */ 406 407 METHODDEF(int) 408 decompress_smooth_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 409 { 410 my_coef_ptr coef = (my_coef_ptr)cinfo->coef; 411 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 412 JDIMENSION block_num, last_block_column; 413 int ci, block_row, block_rows, access_rows; 414 JBLOCKARRAY buffer; 415 JBLOCKROW buffer_ptr, prev_block_row, next_block_row; 416 JSAMPARRAY output_ptr; 417 JDIMENSION output_col; 418 jpeg_component_info *compptr; 419 inverse_DCT_method_ptr inverse_DCT; 420 boolean first_row, last_row; 421 JCOEF *workspace; 422 int *coef_bits; 423 JQUANT_TBL *quanttbl; 424 JLONG Q00, Q01, Q02, Q10, Q11, Q20, num; 425 int DC1, DC2, DC3, DC4, DC5, DC6, DC7, DC8, DC9; 426 int Al, pred; 427 428 /* Keep a local variable to avoid looking it up more than once */ 429 workspace = coef->workspace; 430 431 /* Force some input to be done if we are getting ahead of the input. */ 432 while (cinfo->input_scan_number <= cinfo->output_scan_number && 433 !cinfo->inputctl->eoi_reached) { 434 if (cinfo->input_scan_number == cinfo->output_scan_number) { 435 /* If input is working on current scan, we ordinarily want it to 436 * have completed the current row. But if input scan is DC, 437 * we want it to keep one row ahead so that next block row's DC 438 * values are up to date. 439 */ 440 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0; 441 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row + delta) 442 break; 443 } 444 if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) 445 return JPEG_SUSPENDED; 446 } 447 448 /* OK, output from the virtual arrays. */ 449 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 450 ci++, compptr++) { 451 /* Don't bother to IDCT an uninteresting component. */ 452 if (!compptr->component_needed) 453 continue; 454 /* Count non-dummy DCT block rows in this iMCU row. */ 455 if (cinfo->output_iMCU_row < last_iMCU_row) { 456 block_rows = compptr->v_samp_factor; 457 access_rows = block_rows * 2; /* this and next iMCU row */ 458 last_row = FALSE; 459 } else { 460 /* NB: can't use last_row_height here; it is input-side-dependent! */ 461 block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor); 462 if (block_rows == 0) block_rows = compptr->v_samp_factor; 463 access_rows = block_rows; /* this iMCU row only */ 464 last_row = TRUE; 465 } 466 /* Align the virtual buffer for this component. */ 467 if (cinfo->output_iMCU_row > 0) { 468 access_rows += compptr->v_samp_factor; /* prior iMCU row too */ 469 buffer = (*cinfo->mem->access_virt_barray) 470 ((j_common_ptr)cinfo, coef->whole_image[ci], 471 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor, 472 (JDIMENSION)access_rows, FALSE); 473 buffer += compptr->v_samp_factor; /* point to current iMCU row */ 474 first_row = FALSE; 475 } else { 476 buffer = (*cinfo->mem->access_virt_barray) 477 ((j_common_ptr)cinfo, coef->whole_image[ci], 478 (JDIMENSION)0, (JDIMENSION)access_rows, FALSE); 479 first_row = TRUE; 480 } 481 /* Fetch component-dependent info */ 482 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS); 483 quanttbl = compptr->quant_table; 484 Q00 = quanttbl->quantval[0]; 485 Q01 = quanttbl->quantval[Q01_POS]; 486 Q10 = quanttbl->quantval[Q10_POS]; 487 Q20 = quanttbl->quantval[Q20_POS]; 488 Q11 = quanttbl->quantval[Q11_POS]; 489 Q02 = quanttbl->quantval[Q02_POS]; 490 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 491 output_ptr = output_buf[ci]; 492 /* Loop over all DCT blocks to be processed. */ 493 for (block_row = 0; block_row < block_rows; block_row++) { 494 buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci]; 495 if (first_row && block_row == 0) 496 prev_block_row = buffer_ptr; 497 else 498 prev_block_row = buffer[block_row - 1]; 499 if (last_row && block_row == block_rows - 1) 500 next_block_row = buffer_ptr; 501 else 502 next_block_row = buffer[block_row + 1]; 503 /* We fetch the surrounding DC values using a sliding-register approach. 504 * Initialize all nine here so as to do the right thing on narrow pics. 505 */ 506 DC1 = DC2 = DC3 = (int)prev_block_row[0][0]; 507 DC4 = DC5 = DC6 = (int)buffer_ptr[0][0]; 508 DC7 = DC8 = DC9 = (int)next_block_row[0][0]; 509 output_col = 0; 510 last_block_column = compptr->width_in_blocks - 1; 511 for (block_num = cinfo->master->first_MCU_col[ci]; 512 block_num <= cinfo->master->last_MCU_col[ci]; block_num++) { 513 /* Fetch current DCT block into workspace so we can modify it. */ 514 jcopy_block_row(buffer_ptr, (JBLOCKROW)workspace, (JDIMENSION)1); 515 /* Update DC values */ 516 if (block_num < last_block_column) { 517 DC3 = (int)prev_block_row[1][0]; 518 DC6 = (int)buffer_ptr[1][0]; 519 DC9 = (int)next_block_row[1][0]; 520 } 521 /* Compute coefficient estimates per K.8. 522 * An estimate is applied only if coefficient is still zero, 523 * and is not known to be fully accurate. 524 */ 525 /* AC01 */ 526 if ((Al = coef_bits[1]) != 0 && workspace[1] == 0) { 527 num = 36 * Q00 * (DC4 - DC6); 528 if (num >= 0) { 529 pred = (int)(((Q01 << 7) + num) / (Q01 << 8)); 530 if (Al > 0 && pred >= (1 << Al)) 531 pred = (1 << Al) - 1; 532 } else { 533 pred = (int)(((Q01 << 7) - num) / (Q01 << 8)); 534 if (Al > 0 && pred >= (1 << Al)) 535 pred = (1 << Al) - 1; 536 pred = -pred; 537 } 538 workspace[1] = (JCOEF)pred; 539 } 540 /* AC10 */ 541 if ((Al = coef_bits[2]) != 0 && workspace[8] == 0) { 542 num = 36 * Q00 * (DC2 - DC8); 543 if (num >= 0) { 544 pred = (int)(((Q10 << 7) + num) / (Q10 << 8)); 545 if (Al > 0 && pred >= (1 << Al)) 546 pred = (1 << Al) - 1; 547 } else { 548 pred = (int)(((Q10 << 7) - num) / (Q10 << 8)); 549 if (Al > 0 && pred >= (1 << Al)) 550 pred = (1 << Al) - 1; 551 pred = -pred; 552 } 553 workspace[8] = (JCOEF)pred; 554 } 555 /* AC20 */ 556 if ((Al = coef_bits[3]) != 0 && workspace[16] == 0) { 557 num = 9 * Q00 * (DC2 + DC8 - 2 * DC5); 558 if (num >= 0) { 559 pred = (int)(((Q20 << 7) + num) / (Q20 << 8)); 560 if (Al > 0 && pred >= (1 << Al)) 561 pred = (1 << Al) - 1; 562 } else { 563 pred = (int)(((Q20 << 7) - num) / (Q20 << 8)); 564 if (Al > 0 && pred >= (1 << Al)) 565 pred = (1 << Al) - 1; 566 pred = -pred; 567 } 568 workspace[16] = (JCOEF)pred; 569 } 570 /* AC11 */ 571 if ((Al = coef_bits[4]) != 0 && workspace[9] == 0) { 572 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9); 573 if (num >= 0) { 574 pred = (int)(((Q11 << 7) + num) / (Q11 << 8)); 575 if (Al > 0 && pred >= (1 << Al)) 576 pred = (1 << Al) - 1; 577 } else { 578 pred = (int)(((Q11 << 7) - num) / (Q11 << 8)); 579 if (Al > 0 && pred >= (1 << Al)) 580 pred = (1 << Al) - 1; 581 pred = -pred; 582 } 583 workspace[9] = (JCOEF)pred; 584 } 585 /* AC02 */ 586 if ((Al = coef_bits[5]) != 0 && workspace[2] == 0) { 587 num = 9 * Q00 * (DC4 + DC6 - 2 * DC5); 588 if (num >= 0) { 589 pred = (int)(((Q02 << 7) + num) / (Q02 << 8)); 590 if (Al > 0 && pred >= (1 << Al)) 591 pred = (1 << Al) - 1; 592 } else { 593 pred = (int)(((Q02 << 7) - num) / (Q02 << 8)); 594 if (Al > 0 && pred >= (1 << Al)) 595 pred = (1 << Al) - 1; 596 pred = -pred; 597 } 598 workspace[2] = (JCOEF)pred; 599 } 600 /* OK, do the IDCT */ 601 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)workspace, output_ptr, 602 output_col); 603 /* Advance for next column */ 604 DC1 = DC2; DC2 = DC3; 605 DC4 = DC5; DC5 = DC6; 606 DC7 = DC8; DC8 = DC9; 607 buffer_ptr++, prev_block_row++, next_block_row++; 608 output_col += compptr->_DCT_scaled_size; 609 } 610 output_ptr += compptr->_DCT_scaled_size; 611 } 612 } 613 614 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 615 return JPEG_ROW_COMPLETED; 616 return JPEG_SCAN_COMPLETED; 617 } 618 619 #endif /* BLOCK_SMOOTHING_SUPPORTED */ 620 621 622 /* 623 * Initialize coefficient buffer controller. 624 */ 625 626 GLOBAL(void) 627 jinit_d_coef_controller(j_decompress_ptr cinfo, boolean need_full_buffer) 628 { 629 my_coef_ptr coef; 630 631 coef = (my_coef_ptr) 632 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE, 633 sizeof(my_coef_controller)); 634 cinfo->coef = (struct jpeg_d_coef_controller *)coef; 635 coef->pub.start_input_pass = start_input_pass; 636 coef->pub.start_output_pass = start_output_pass; 637 #ifdef BLOCK_SMOOTHING_SUPPORTED 638 coef->coef_bits_latch = NULL; 639 #endif 640 641 /* Create the coefficient buffer. */ 642 if (need_full_buffer) { 643 #ifdef D_MULTISCAN_FILES_SUPPORTED 644 /* Allocate a full-image virtual array for each component, */ 645 /* padded to a multiple of samp_factor DCT blocks in each direction. */ 646 /* Note we ask for a pre-zeroed array. */ 647 int ci, access_rows; 648 jpeg_component_info *compptr; 649 650 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 651 ci++, compptr++) { 652 access_rows = compptr->v_samp_factor; 653 #ifdef BLOCK_SMOOTHING_SUPPORTED 654 /* If block smoothing could be used, need a bigger window */ 655 if (cinfo->progressive_mode) 656 access_rows *= 3; 657 #endif 658 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) 659 ((j_common_ptr)cinfo, JPOOL_IMAGE, TRUE, 660 (JDIMENSION)jround_up((long)compptr->width_in_blocks, 661 (long)compptr->h_samp_factor), 662 (JDIMENSION)jround_up((long)compptr->height_in_blocks, 663 (long)compptr->v_samp_factor), 664 (JDIMENSION)access_rows); 665 } 666 coef->pub.consume_data = consume_data; 667 coef->pub.decompress_data = decompress_data; 668 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */ 669 #else 670 ERREXIT(cinfo, JERR_NOT_COMPILED); 671 #endif 672 } else { 673 /* We only need a single-MCU buffer. */ 674 JBLOCKROW buffer; 675 int i; 676 677 buffer = (JBLOCKROW) 678 (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE, 679 D_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK)); 680 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) { 681 coef->MCU_buffer[i] = buffer + i; 682 } 683 coef->pub.consume_data = dummy_consume_data; 684 coef->pub.decompress_data = decompress_onepass; 685 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */ 686 } 687 688 /* Allocate the workspace buffer */ 689 coef->workspace = (JCOEF *) 690 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE, 691 sizeof(JCOEF) * DCTSIZE2); 692 } 693
