1/* 2 * reserved comment block 3 * DO NOT REMOVE OR ALTER! 4 */ 5/* 6 * jdcoefct.c 7 * 8 * Copyright (C) 1994-1997, 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 the coefficient buffer controller for decompression. 13 * This controller is the top level of the JPEG decompressor proper. 14 * The coefficient buffer lies between entropy decoding and inverse-DCT steps. 15 * 16 * In buffered-image mode, this controller is the interface between 17 * input-oriented processing and output-oriented processing. 18 * Also, the input side (only) is used when reading a file for transcoding. 19 */ 20 21#define JPEG_INTERNALS 22#include "jinclude.h" 23#include "jpeglib.h" 24 25/* Block smoothing is only applicable for progressive JPEG, so: */ 26#ifndef D_PROGRESSIVE_SUPPORTED 27#undef BLOCK_SMOOTHING_SUPPORTED 28#endif 29 30/* Private buffer controller object */ 31 32typedef struct { 33 struct jpeg_d_coef_controller pub; /* public fields */ 34 35 /* These variables keep track of the current location of the input side. */ 36 /* cinfo->input_iMCU_row is also used for this. */ 37 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */ 38 int MCU_vert_offset; /* counts MCU rows within iMCU row */ 39 int MCU_rows_per_iMCU_row; /* number of such rows needed */ 40 41 /* The output side's location is represented by cinfo->output_iMCU_row. */ 42 43 /* In single-pass modes, it's sufficient to buffer just one MCU. 44 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks, 45 * and let the entropy decoder write into that workspace each time. 46 * (On 80x86, the workspace is FAR even though it's not really very big; 47 * this is to keep the module interfaces unchanged when a large coefficient 48 * buffer is necessary.) 49 * In multi-pass modes, this array points to the current MCU's blocks 50 * within the virtual arrays; it is used only by the input side. 51 */ 52 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU]; 53 54#ifdef D_MULTISCAN_FILES_SUPPORTED 55 /* In multi-pass modes, we need a virtual block array for each component. */ 56 jvirt_barray_ptr whole_image[MAX_COMPONENTS]; 57#endif 58 59#ifdef BLOCK_SMOOTHING_SUPPORTED 60 /* When doing block smoothing, we latch coefficient Al values here */ 61 int * coef_bits_latch; 62#define SAVED_COEFS 6 /* we save coef_bits[0..5] */ 63#endif 64} my_coef_controller; 65 66typedef my_coef_controller * my_coef_ptr; 67 68/* Forward declarations */ 69METHODDEF(int) decompress_onepass 70 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 71#ifdef D_MULTISCAN_FILES_SUPPORTED 72METHODDEF(int) decompress_data 73 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 74#endif 75#ifdef BLOCK_SMOOTHING_SUPPORTED 76LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo)); 77METHODDEF(int) decompress_smooth_data 78 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 79#endif 80 81 82LOCAL(void) 83start_iMCU_row (j_decompress_ptr cinfo) 84/* Reset within-iMCU-row counters for a new row (input side) */ 85{ 86 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 87 88 /* In an interleaved scan, an MCU row is the same as an iMCU row. 89 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. 90 * But at the bottom of the image, process only what's left. 91 */ 92 if (cinfo->comps_in_scan > 1) { 93 coef->MCU_rows_per_iMCU_row = 1; 94 } else { 95 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1)) 96 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; 97 else 98 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; 99 } 100 101 coef->MCU_ctr = 0; 102 coef->MCU_vert_offset = 0; 103} 104 105 106/* 107 * Initialize for an input processing pass. 108 */ 109 110METHODDEF(void) 111start_input_pass (j_decompress_ptr cinfo) 112{ 113 cinfo->input_iMCU_row = 0; 114 start_iMCU_row(cinfo); 115} 116 117 118/* 119 * Initialize for an output processing pass. 120 */ 121 122METHODDEF(void) 123start_output_pass (j_decompress_ptr cinfo) 124{ 125#ifdef BLOCK_SMOOTHING_SUPPORTED 126 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 127 128 /* If multipass, check to see whether to use block smoothing on this pass */ 129 if (coef->pub.coef_arrays != NULL) { 130 if (cinfo->do_block_smoothing && smoothing_ok(cinfo)) 131 coef->pub.decompress_data = decompress_smooth_data; 132 else 133 coef->pub.decompress_data = decompress_data; 134 } 135#endif 136 cinfo->output_iMCU_row = 0; 137} 138 139 140/* 141 * Decompress and return some data in the single-pass case. 142 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 143 * Input and output must run in lockstep since we have only a one-MCU buffer. 144 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 145 * 146 * NB: output_buf contains a plane for each component in image, 147 * which we index according to the component's SOF position. 148 */ 149 150METHODDEF(int) 151decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 152{ 153 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 154 JDIMENSION MCU_col_num; /* index of current MCU within row */ 155 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; 156 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 157 int blkn, ci, xindex, yindex, yoffset, useful_width; 158 JSAMPARRAY output_ptr; 159 JDIMENSION start_col, output_col; 160 jpeg_component_info *compptr; 161 inverse_DCT_method_ptr inverse_DCT; 162 163 /* Loop to process as much as one whole iMCU row */ 164 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 165 yoffset++) { 166 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col; 167 MCU_col_num++) { 168 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */ 169 jzero_far((void FAR *) coef->MCU_buffer[0], 170 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK))); 171 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 172 /* Suspension forced; update state counters and exit */ 173 coef->MCU_vert_offset = yoffset; 174 coef->MCU_ctr = MCU_col_num; 175 return JPEG_SUSPENDED; 176 } 177 /* Determine where data should go in output_buf and do the IDCT thing. 178 * We skip dummy blocks at the right and bottom edges (but blkn gets 179 * incremented past them!). Note the inner loop relies on having 180 * allocated the MCU_buffer[] blocks sequentially. 181 */ 182 blkn = 0; /* index of current DCT block within MCU */ 183 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 184 compptr = cinfo->cur_comp_info[ci]; 185 /* Don't bother to IDCT an uninteresting component. */ 186 if (! compptr->component_needed) { 187 blkn += compptr->MCU_blocks; 188 continue; 189 } 190 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index]; 191 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width 192 : compptr->last_col_width; 193 output_ptr = output_buf[compptr->component_index] + 194 yoffset * compptr->DCT_scaled_size; 195 start_col = MCU_col_num * compptr->MCU_sample_width; 196 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 197 if (cinfo->input_iMCU_row < last_iMCU_row || 198 yoffset+yindex < compptr->last_row_height) { 199 output_col = start_col; 200 for (xindex = 0; xindex < useful_width; xindex++) { 201 (*inverse_DCT) (cinfo, compptr, 202 (JCOEFPTR) coef->MCU_buffer[blkn+xindex], 203 output_ptr, output_col); 204 output_col += compptr->DCT_scaled_size; 205 } 206 } 207 blkn += compptr->MCU_width; 208 output_ptr += compptr->DCT_scaled_size; 209 } 210 } 211 } 212 /* Completed an MCU row, but perhaps not an iMCU row */ 213 coef->MCU_ctr = 0; 214 } 215 /* Completed the iMCU row, advance counters for next one */ 216 cinfo->output_iMCU_row++; 217 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 218 start_iMCU_row(cinfo); 219 return JPEG_ROW_COMPLETED; 220 } 221 /* Completed the scan */ 222 (*cinfo->inputctl->finish_input_pass) (cinfo); 223 return JPEG_SCAN_COMPLETED; 224} 225 226 227/* 228 * Dummy consume-input routine for single-pass operation. 229 */ 230 231METHODDEF(int) 232dummy_consume_data (j_decompress_ptr cinfo) 233{ 234 return JPEG_SUSPENDED; /* Always indicate nothing was done */ 235} 236 237 238#ifdef D_MULTISCAN_FILES_SUPPORTED 239 240/* 241 * Consume input data and store it in the full-image coefficient buffer. 242 * We read as much as one fully interleaved MCU row ("iMCU" row) per call, 243 * ie, v_samp_factor block rows for each component in the scan. 244 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 245 */ 246 247METHODDEF(int) 248consume_data (j_decompress_ptr cinfo) 249{ 250 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 251 JDIMENSION MCU_col_num; /* index of current MCU within row */ 252 int blkn, ci, xindex, yindex, yoffset; 253 JDIMENSION start_col; 254 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; 255 JBLOCKROW buffer_ptr; 256 jpeg_component_info *compptr; 257 258 /* Align the virtual buffers for the components used in this scan. */ 259 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 260 compptr = cinfo->cur_comp_info[ci]; 261 buffer[ci] = (*cinfo->mem->access_virt_barray) 262 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], 263 cinfo->input_iMCU_row * compptr->v_samp_factor, 264 (JDIMENSION) compptr->v_samp_factor, TRUE); 265 /* Note: entropy decoder expects buffer to be zeroed, 266 * but this is handled automatically by the memory manager 267 * because we requested a pre-zeroed array. 268 */ 269 } 270 271 /* Loop to process one whole iMCU row */ 272 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 273 yoffset++) { 274 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row; 275 MCU_col_num++) { 276 /* Construct list of pointers to DCT blocks belonging to this MCU */ 277 blkn = 0; /* index of current DCT block within MCU */ 278 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 279 compptr = cinfo->cur_comp_info[ci]; 280 start_col = MCU_col_num * compptr->MCU_width; 281 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 282 buffer_ptr = buffer[ci][yindex+yoffset] + start_col; 283 for (xindex = 0; xindex < compptr->MCU_width; xindex++) { 284 coef->MCU_buffer[blkn++] = buffer_ptr++; 285 } 286 } 287 } 288 /* Try to fetch the MCU. */ 289 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 290 /* Suspension forced; update state counters and exit */ 291 coef->MCU_vert_offset = yoffset; 292 coef->MCU_ctr = MCU_col_num; 293 return JPEG_SUSPENDED; 294 } 295 } 296 /* Completed an MCU row, but perhaps not an iMCU row */ 297 coef->MCU_ctr = 0; 298 } 299 /* Completed the iMCU row, advance counters for next one */ 300 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 301 start_iMCU_row(cinfo); 302 return JPEG_ROW_COMPLETED; 303 } 304 /* Completed the scan */ 305 (*cinfo->inputctl->finish_input_pass) (cinfo); 306 return JPEG_SCAN_COMPLETED; 307} 308 309 310/* 311 * Decompress and return some data in the multi-pass case. 312 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 313 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 314 * 315 * NB: output_buf contains a plane for each component in image. 316 */ 317 318METHODDEF(int) 319decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 320{ 321 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 322 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 323 JDIMENSION block_num; 324 int ci, block_row, block_rows; 325 JBLOCKARRAY buffer; 326 JBLOCKROW buffer_ptr; 327 JSAMPARRAY output_ptr; 328 JDIMENSION output_col; 329 jpeg_component_info *compptr; 330 inverse_DCT_method_ptr inverse_DCT; 331 332 /* Force some input to be done if we are getting ahead of the input. */ 333 while (cinfo->input_scan_number < cinfo->output_scan_number || 334 (cinfo->input_scan_number == cinfo->output_scan_number && 335 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) { 336 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 337 return JPEG_SUSPENDED; 338 } 339 340 /* OK, output from the virtual arrays. */ 341 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 342 ci++, compptr++) { 343 /* Don't bother to IDCT an uninteresting component. */ 344 if (! compptr->component_needed) 345 continue; 346 /* Align the virtual buffer for this component. */ 347 buffer = (*cinfo->mem->access_virt_barray) 348 ((j_common_ptr) cinfo, coef->whole_image[ci], 349 cinfo->output_iMCU_row * compptr->v_samp_factor, 350 (JDIMENSION) compptr->v_samp_factor, FALSE); 351 /* Count non-dummy DCT block rows in this iMCU row. */ 352 if (cinfo->output_iMCU_row < last_iMCU_row) 353 block_rows = compptr->v_samp_factor; 354 else { 355 /* NB: can't use last_row_height here; it is input-side-dependent! */ 356 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 357 if (block_rows == 0) block_rows = compptr->v_samp_factor; 358 } 359 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 360 output_ptr = output_buf[ci]; 361 /* Loop over all DCT blocks to be processed. */ 362 for (block_row = 0; block_row < block_rows; block_row++) { 363 buffer_ptr = buffer[block_row]; 364 output_col = 0; 365 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) { 366 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr, 367 output_ptr, output_col); 368 buffer_ptr++; 369 output_col += compptr->DCT_scaled_size; 370 } 371 output_ptr += compptr->DCT_scaled_size; 372 } 373 } 374 375 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 376 return JPEG_ROW_COMPLETED; 377 return JPEG_SCAN_COMPLETED; 378} 379 380#endif /* D_MULTISCAN_FILES_SUPPORTED */ 381 382 383#ifdef BLOCK_SMOOTHING_SUPPORTED 384 385/* 386 * This code applies interblock smoothing as described by section K.8 387 * of the JPEG standard: the first 5 AC coefficients are estimated from 388 * the DC values of a DCT block and its 8 neighboring blocks. 389 * We apply smoothing only for progressive JPEG decoding, and only if 390 * the coefficients it can estimate are not yet known to full precision. 391 */ 392 393/* Natural-order array positions of the first 5 zigzag-order coefficients */ 394#define Q01_POS 1 395#define Q10_POS 8 396#define Q20_POS 16 397#define Q11_POS 9 398#define Q02_POS 2 399 400/* 401 * Determine whether block smoothing is applicable and safe. 402 * We also latch the current states of the coef_bits[] entries for the 403 * AC coefficients; otherwise, if the input side of the decompressor 404 * advances into a new scan, we might think the coefficients are known 405 * more accurately than they really are. 406 */ 407 408LOCAL(boolean) 409smoothing_ok (j_decompress_ptr cinfo) 410{ 411 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 412 boolean smoothing_useful = FALSE; 413 int ci, coefi; 414 jpeg_component_info *compptr; 415 JQUANT_TBL * qtable; 416 int * coef_bits; 417 int * coef_bits_latch; 418 419 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL) 420 return FALSE; 421 422 /* Allocate latch area if not already done */ 423 if (coef->coef_bits_latch == NULL) 424 coef->coef_bits_latch = (int *) 425 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 426 cinfo->num_components * 427 (SAVED_COEFS * SIZEOF(int))); 428 coef_bits_latch = coef->coef_bits_latch; 429 430 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 431 ci++, compptr++) { 432 /* All components' quantization values must already be latched. */ 433 if ((qtable = compptr->quant_table) == NULL) 434 return FALSE; 435 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */ 436 if (qtable->quantval[0] == 0 || 437 qtable->quantval[Q01_POS] == 0 || 438 qtable->quantval[Q10_POS] == 0 || 439 qtable->quantval[Q20_POS] == 0 || 440 qtable->quantval[Q11_POS] == 0 || 441 qtable->quantval[Q02_POS] == 0) 442 return FALSE; 443 /* DC values must be at least partly known for all components. */ 444 coef_bits = cinfo->coef_bits[ci]; 445 if (coef_bits[0] < 0) 446 return FALSE; 447 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */ 448 for (coefi = 1; coefi <= 5; coefi++) { 449 coef_bits_latch[coefi] = coef_bits[coefi]; 450 if (coef_bits[coefi] != 0) 451 smoothing_useful = TRUE; 452 } 453 coef_bits_latch += SAVED_COEFS; 454 } 455 456 return smoothing_useful; 457} 458 459 460/* 461 * Variant of decompress_data for use when doing block smoothing. 462 */ 463 464METHODDEF(int) 465decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 466{ 467 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 468 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 469 JDIMENSION block_num, last_block_column; 470 int ci, block_row, block_rows, access_rows; 471 JBLOCKARRAY buffer; 472 JBLOCKROW buffer_ptr, prev_block_row, next_block_row; 473 JSAMPARRAY output_ptr; 474 JDIMENSION output_col; 475 jpeg_component_info *compptr; 476 inverse_DCT_method_ptr inverse_DCT; 477 boolean first_row, last_row; 478 JBLOCK workspace; 479 int *coef_bits; 480 JQUANT_TBL *quanttbl; 481 INT32 Q00,Q01,Q02,Q10,Q11,Q20, num; 482 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9; 483 int Al, pred; 484 485 /* Force some input to be done if we are getting ahead of the input. */ 486 while (cinfo->input_scan_number <= cinfo->output_scan_number && 487 ! cinfo->inputctl->eoi_reached) { 488 if (cinfo->input_scan_number == cinfo->output_scan_number) { 489 /* If input is working on current scan, we ordinarily want it to 490 * have completed the current row. But if input scan is DC, 491 * we want it to keep one row ahead so that next block row's DC 492 * values are up to date. 493 */ 494 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0; 495 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta) 496 break; 497 } 498 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 499 return JPEG_SUSPENDED; 500 } 501 502 /* OK, output from the virtual arrays. */ 503 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 504 ci++, compptr++) { 505 /* Don't bother to IDCT an uninteresting component. */ 506 if (! compptr->component_needed) 507 continue; 508 /* Count non-dummy DCT block rows in this iMCU row. */ 509 if (cinfo->output_iMCU_row < last_iMCU_row) { 510 block_rows = compptr->v_samp_factor; 511 access_rows = block_rows * 2; /* this and next iMCU row */ 512 last_row = FALSE; 513 } else { 514 /* NB: can't use last_row_height here; it is input-side-dependent! */ 515 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 516 if (block_rows == 0) block_rows = compptr->v_samp_factor; 517 access_rows = block_rows; /* this iMCU row only */ 518 last_row = TRUE; 519 } 520 /* Align the virtual buffer for this component. */ 521 if (cinfo->output_iMCU_row > 0) { 522 access_rows += compptr->v_samp_factor; /* prior iMCU row too */ 523 buffer = (*cinfo->mem->access_virt_barray) 524 ((j_common_ptr) cinfo, coef->whole_image[ci], 525 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor, 526 (JDIMENSION) access_rows, FALSE); 527 buffer += compptr->v_samp_factor; /* point to current iMCU row */ 528 first_row = FALSE; 529 } else { 530 buffer = (*cinfo->mem->access_virt_barray) 531 ((j_common_ptr) cinfo, coef->whole_image[ci], 532 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE); 533 first_row = TRUE; 534 } 535 /* Fetch component-dependent info */ 536 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS); 537 quanttbl = compptr->quant_table; 538 Q00 = quanttbl->quantval[0]; 539 Q01 = quanttbl->quantval[Q01_POS]; 540 Q10 = quanttbl->quantval[Q10_POS]; 541 Q20 = quanttbl->quantval[Q20_POS]; 542 Q11 = quanttbl->quantval[Q11_POS]; 543 Q02 = quanttbl->quantval[Q02_POS]; 544 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 545 output_ptr = output_buf[ci]; 546 /* Loop over all DCT blocks to be processed. */ 547 for (block_row = 0; block_row < block_rows; block_row++) { 548 buffer_ptr = buffer[block_row]; 549 if (first_row && block_row == 0) 550 prev_block_row = buffer_ptr; 551 else 552 prev_block_row = buffer[block_row-1]; 553 if (last_row && block_row == block_rows-1) 554 next_block_row = buffer_ptr; 555 else 556 next_block_row = buffer[block_row+1]; 557 /* We fetch the surrounding DC values using a sliding-register approach. 558 * Initialize all nine here so as to do the right thing on narrow pics. 559 */ 560 DC1 = DC2 = DC3 = (int) prev_block_row[0][0]; 561 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0]; 562 DC7 = DC8 = DC9 = (int) next_block_row[0][0]; 563 output_col = 0; 564 last_block_column = compptr->width_in_blocks - 1; 565 for (block_num = 0; block_num <= last_block_column; block_num++) { 566 /* Fetch current DCT block into workspace so we can modify it. */ 567 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1); 568 /* Update DC values */ 569 if (block_num < last_block_column) { 570 DC3 = (int) prev_block_row[1][0]; 571 DC6 = (int) buffer_ptr[1][0]; 572 DC9 = (int) next_block_row[1][0]; 573 } 574 /* Compute coefficient estimates per K.8. 575 * An estimate is applied only if coefficient is still zero, 576 * and is not known to be fully accurate. 577 */ 578 /* AC01 */ 579 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) { 580 num = 36 * Q00 * (DC4 - DC6); 581 if (num >= 0) { 582 pred = (int) (((Q01<<7) + num) / (Q01<<8)); 583 if (Al > 0 && pred >= (1<<Al)) 584 pred = (1<<Al)-1; 585 } else { 586 pred = (int) (((Q01<<7) - num) / (Q01<<8)); 587 if (Al > 0 && pred >= (1<<Al)) 588 pred = (1<<Al)-1; 589 pred = -pred; 590 } 591 workspace[1] = (JCOEF) pred; 592 } 593 /* AC10 */ 594 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) { 595 num = 36 * Q00 * (DC2 - DC8); 596 if (num >= 0) { 597 pred = (int) (((Q10<<7) + num) / (Q10<<8)); 598 if (Al > 0 && pred >= (1<<Al)) 599 pred = (1<<Al)-1; 600 } else { 601 pred = (int) (((Q10<<7) - num) / (Q10<<8)); 602 if (Al > 0 && pred >= (1<<Al)) 603 pred = (1<<Al)-1; 604 pred = -pred; 605 } 606 workspace[8] = (JCOEF) pred; 607 } 608 /* AC20 */ 609 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) { 610 num = 9 * Q00 * (DC2 + DC8 - 2*DC5); 611 if (num >= 0) { 612 pred = (int) (((Q20<<7) + num) / (Q20<<8)); 613 if (Al > 0 && pred >= (1<<Al)) 614 pred = (1<<Al)-1; 615 } else { 616 pred = (int) (((Q20<<7) - num) / (Q20<<8)); 617 if (Al > 0 && pred >= (1<<Al)) 618 pred = (1<<Al)-1; 619 pred = -pred; 620 } 621 workspace[16] = (JCOEF) pred; 622 } 623 /* AC11 */ 624 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) { 625 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9); 626 if (num >= 0) { 627 pred = (int) (((Q11<<7) + num) / (Q11<<8)); 628 if (Al > 0 && pred >= (1<<Al)) 629 pred = (1<<Al)-1; 630 } else { 631 pred = (int) (((Q11<<7) - num) / (Q11<<8)); 632 if (Al > 0 && pred >= (1<<Al)) 633 pred = (1<<Al)-1; 634 pred = -pred; 635 } 636 workspace[9] = (JCOEF) pred; 637 } 638 /* AC02 */ 639 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) { 640 num = 9 * Q00 * (DC4 + DC6 - 2*DC5); 641 if (num >= 0) { 642 pred = (int) (((Q02<<7) + num) / (Q02<<8)); 643 if (Al > 0 && pred >= (1<<Al)) 644 pred = (1<<Al)-1; 645 } else { 646 pred = (int) (((Q02<<7) - num) / (Q02<<8)); 647 if (Al > 0 && pred >= (1<<Al)) 648 pred = (1<<Al)-1; 649 pred = -pred; 650 } 651 workspace[2] = (JCOEF) pred; 652 } 653 /* OK, do the IDCT */ 654 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace, 655 output_ptr, output_col); 656 /* Advance for next column */ 657 DC1 = DC2; DC2 = DC3; 658 DC4 = DC5; DC5 = DC6; 659 DC7 = DC8; DC8 = DC9; 660 buffer_ptr++, prev_block_row++, next_block_row++; 661 output_col += compptr->DCT_scaled_size; 662 } 663 output_ptr += compptr->DCT_scaled_size; 664 } 665 } 666 667 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 668 return JPEG_ROW_COMPLETED; 669 return JPEG_SCAN_COMPLETED; 670} 671 672#endif /* BLOCK_SMOOTHING_SUPPORTED */ 673 674 675/* 676 * Initialize coefficient buffer controller. 677 */ 678 679GLOBAL(void) 680jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer) 681{ 682 my_coef_ptr coef; 683 684 coef = (my_coef_ptr) 685 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 686 SIZEOF(my_coef_controller)); 687 cinfo->coef = (struct jpeg_d_coef_controller *) coef; 688 coef->pub.start_input_pass = start_input_pass; 689 coef->pub.start_output_pass = start_output_pass; 690#ifdef BLOCK_SMOOTHING_SUPPORTED 691 coef->coef_bits_latch = NULL; 692#endif 693 694 /* Create the coefficient buffer. */ 695 if (need_full_buffer) { 696#ifdef D_MULTISCAN_FILES_SUPPORTED 697 /* Allocate a full-image virtual array for each component, */ 698 /* padded to a multiple of samp_factor DCT blocks in each direction. */ 699 /* Note we ask for a pre-zeroed array. */ 700 int ci, access_rows; 701 jpeg_component_info *compptr; 702 703 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 704 ci++, compptr++) { 705 access_rows = compptr->v_samp_factor; 706#ifdef BLOCK_SMOOTHING_SUPPORTED 707 /* If block smoothing could be used, need a bigger window */ 708 if (cinfo->progressive_mode) 709 access_rows *= 3; 710#endif 711 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) 712 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE, 713 (JDIMENSION) jround_up((long) compptr->width_in_blocks, 714 (long) compptr->h_samp_factor), 715 (JDIMENSION) jround_up((long) compptr->height_in_blocks, 716 (long) compptr->v_samp_factor), 717 (JDIMENSION) access_rows); 718 } 719 coef->pub.consume_data = consume_data; 720 coef->pub.decompress_data = decompress_data; 721 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */ 722#else 723 ERREXIT(cinfo, JERR_NOT_COMPILED); 724#endif 725 } else { 726 /* We only need a single-MCU buffer. */ 727 JBLOCKROW buffer; 728 int i; 729 730 buffer = (JBLOCKROW) 731 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, 732 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); 733 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) { 734 coef->MCU_buffer[i] = buffer + i; 735 } 736 coef->pub.consume_data = dummy_consume_data; 737 coef->pub.decompress_data = decompress_onepass; 738 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */ 739 } 740} 741