jdcoefct.c (25155B)
1 /* 2 * jdcoefct.c 3 * 4 * Copyright (C) 1994-1997, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README file. 7 * 8 * This file contains the coefficient buffer controller for decompression. 9 * This controller is the top level of the JPEG decompressor proper. 10 * The coefficient buffer lies between entropy decoding and inverse-DCT steps. 11 * 12 * In buffered-image mode, this controller is the interface between 13 * input-oriented processing and output-oriented processing. 14 * Also, the input side (only) is used when reading a file for transcoding. 15 */ 16 17 #define JPEG_INTERNALS 18 #include "jinclude.h" 19 #include "jpeglib.h" 20 21 /* Block smoothing is only applicable for progressive JPEG, so: */ 22 #ifndef D_PROGRESSIVE_SUPPORTED 23 #undef BLOCK_SMOOTHING_SUPPORTED 24 #endif 25 26 /* Private buffer controller object */ 27 28 typedef struct { 29 struct jpeg_d_coef_controller pub; /* public fields */ 30 31 /* These variables keep track of the current location of the input side. */ 32 /* cinfo->input_iMCU_row is also used for this. */ 33 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */ 34 int MCU_vert_offset; /* counts MCU rows within iMCU row */ 35 int MCU_rows_per_iMCU_row; /* number of such rows needed */ 36 37 /* The output side's location is represented by cinfo->output_iMCU_row. */ 38 39 /* In single-pass modes, it's sufficient to buffer just one MCU. 40 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks, 41 * and let the entropy decoder write into that workspace each time. 42 * (On 80x86, the workspace is FAR even though it's not really very big; 43 * this is to keep the module interfaces unchanged when a large coefficient 44 * buffer is necessary.) 45 * In multi-pass modes, this array points to the current MCU's blocks 46 * within the virtual arrays; it is used only by the input side. 47 */ 48 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU]; 49 50 #ifdef D_MULTISCAN_FILES_SUPPORTED 51 /* In multi-pass modes, we need a virtual block array for each component. */ 52 jvirt_barray_ptr whole_image[MAX_COMPONENTS]; 53 #endif 54 55 #ifdef BLOCK_SMOOTHING_SUPPORTED 56 /* When doing block smoothing, we latch coefficient Al values here */ 57 int * coef_bits_latch; 58 #define SAVED_COEFS 6 /* we save coef_bits[0..5] */ 59 #endif 60 } my_coef_controller; 61 62 typedef my_coef_controller * my_coef_ptr; 63 64 /* Forward declarations */ 65 METHODDEF(int) decompress_onepass 66 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 67 #ifdef D_MULTISCAN_FILES_SUPPORTED 68 METHODDEF(int) decompress_data 69 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 70 #endif 71 #ifdef BLOCK_SMOOTHING_SUPPORTED 72 LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo)); 73 METHODDEF(int) decompress_smooth_data 74 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 75 #endif 76 77 78 LOCAL(void) 79 start_iMCU_row (j_decompress_ptr cinfo) 80 /* Reset within-iMCU-row counters for a new row (input side) */ 81 { 82 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 83 84 /* In an interleaved scan, an MCU row is the same as an iMCU row. 85 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. 86 * But at the bottom of the image, process only what's left. 87 */ 88 if (cinfo->comps_in_scan > 1) { 89 coef->MCU_rows_per_iMCU_row = 1; 90 } else { 91 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1)) 92 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; 93 else 94 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; 95 } 96 97 coef->MCU_ctr = 0; 98 coef->MCU_vert_offset = 0; 99 } 100 101 102 /* 103 * Initialize for an input processing pass. 104 */ 105 106 METHODDEF(void) 107 start_input_pass (j_decompress_ptr cinfo) 108 { 109 cinfo->input_iMCU_row = 0; 110 start_iMCU_row(cinfo); 111 } 112 113 114 /* 115 * Initialize for an output processing pass. 116 */ 117 118 METHODDEF(void) 119 start_output_pass (j_decompress_ptr cinfo) 120 { 121 #ifdef BLOCK_SMOOTHING_SUPPORTED 122 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 123 124 /* If multipass, check to see whether to use block smoothing on this pass */ 125 if (coef->pub.coef_arrays != NULL) { 126 if (cinfo->do_block_smoothing && smoothing_ok(cinfo)) 127 coef->pub.decompress_data = decompress_smooth_data; 128 else 129 coef->pub.decompress_data = decompress_data; 130 } 131 #endif 132 cinfo->output_iMCU_row = 0; 133 } 134 135 136 /* 137 * Decompress and return some data in the single-pass case. 138 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 139 * Input and output must run in lockstep since we have only a one-MCU buffer. 140 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 141 * 142 * NB: output_buf contains a plane for each component in image, 143 * which we index according to the component's SOF position. 144 */ 145 146 METHODDEF(int) 147 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 148 { 149 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 150 JDIMENSION MCU_col_num; /* index of current MCU within row */ 151 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; 152 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 153 int blkn, ci, xindex, yindex, yoffset, useful_width; 154 JSAMPARRAY output_ptr; 155 JDIMENSION start_col, output_col; 156 jpeg_component_info *compptr; 157 inverse_DCT_method_ptr inverse_DCT; 158 159 /* Loop to process as much as one whole iMCU row */ 160 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 161 yoffset++) { 162 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col; 163 MCU_col_num++) { 164 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */ 165 jzero_far((void FAR *) coef->MCU_buffer[0], 166 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK))); 167 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 168 /* Suspension forced; update state counters and exit */ 169 coef->MCU_vert_offset = yoffset; 170 coef->MCU_ctr = MCU_col_num; 171 return JPEG_SUSPENDED; 172 } 173 /* Determine where data should go in output_buf and do the IDCT thing. 174 * We skip dummy blocks at the right and bottom edges (but blkn gets 175 * incremented past them!). Note the inner loop relies on having 176 * allocated the MCU_buffer[] blocks sequentially. 177 */ 178 blkn = 0; /* index of current DCT block within MCU */ 179 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 180 compptr = cinfo->cur_comp_info[ci]; 181 /* Don't bother to IDCT an uninteresting component. */ 182 if (! compptr->component_needed) { 183 blkn += compptr->MCU_blocks; 184 continue; 185 } 186 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index]; 187 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width 188 : compptr->last_col_width; 189 output_ptr = output_buf[compptr->component_index] + 190 yoffset * compptr->DCT_scaled_size; 191 start_col = MCU_col_num * compptr->MCU_sample_width; 192 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 193 if (cinfo->input_iMCU_row < last_iMCU_row || 194 yoffset+yindex < compptr->last_row_height) { 195 output_col = start_col; 196 for (xindex = 0; xindex < useful_width; xindex++) { 197 (*inverse_DCT) (cinfo, compptr, 198 (JCOEFPTR) coef->MCU_buffer[blkn+xindex], 199 output_ptr, output_col); 200 output_col += compptr->DCT_scaled_size; 201 } 202 } 203 blkn += compptr->MCU_width; 204 output_ptr += compptr->DCT_scaled_size; 205 } 206 } 207 } 208 /* Completed an MCU row, but perhaps not an iMCU row */ 209 coef->MCU_ctr = 0; 210 } 211 /* Completed the iMCU row, advance counters for next one */ 212 cinfo->output_iMCU_row++; 213 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 214 start_iMCU_row(cinfo); 215 return JPEG_ROW_COMPLETED; 216 } 217 /* Completed the scan */ 218 (*cinfo->inputctl->finish_input_pass) (cinfo); 219 return JPEG_SCAN_COMPLETED; 220 } 221 222 223 /* 224 * Dummy consume-input routine for single-pass operation. 225 */ 226 227 METHODDEF(int) 228 dummy_consume_data (j_decompress_ptr cinfo) 229 { 230 return JPEG_SUSPENDED; /* Always indicate nothing was done */ 231 } 232 233 234 #ifdef D_MULTISCAN_FILES_SUPPORTED 235 236 /* 237 * Consume input data and store it in the full-image coefficient buffer. 238 * We read as much as one fully interleaved MCU row ("iMCU" row) per call, 239 * ie, v_samp_factor block rows for each component in the scan. 240 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 241 */ 242 243 METHODDEF(int) 244 consume_data (j_decompress_ptr cinfo) 245 { 246 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 247 JDIMENSION MCU_col_num; /* index of current MCU within row */ 248 int blkn, ci, xindex, yindex, yoffset; 249 JDIMENSION start_col; 250 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; 251 JBLOCKROW buffer_ptr; 252 jpeg_component_info *compptr; 253 254 /* Align the virtual buffers for the components used in this scan. */ 255 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 256 compptr = cinfo->cur_comp_info[ci]; 257 buffer[ci] = (*cinfo->mem->access_virt_barray) 258 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], 259 cinfo->input_iMCU_row * compptr->v_samp_factor, 260 (JDIMENSION) compptr->v_samp_factor, TRUE); 261 /* Note: entropy decoder expects buffer to be zeroed, 262 * but this is handled automatically by the memory manager 263 * because we requested a pre-zeroed array. 264 */ 265 } 266 267 /* Loop to process one whole iMCU row */ 268 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 269 yoffset++) { 270 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row; 271 MCU_col_num++) { 272 /* Construct list of pointers to DCT blocks belonging to this MCU */ 273 blkn = 0; /* index of current DCT block within MCU */ 274 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 275 compptr = cinfo->cur_comp_info[ci]; 276 start_col = MCU_col_num * compptr->MCU_width; 277 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 278 buffer_ptr = buffer[ci][yindex+yoffset] + start_col; 279 for (xindex = 0; xindex < compptr->MCU_width; xindex++) { 280 coef->MCU_buffer[blkn++] = buffer_ptr++; 281 } 282 } 283 } 284 /* Try to fetch the MCU. */ 285 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 286 /* Suspension forced; update state counters and exit */ 287 coef->MCU_vert_offset = yoffset; 288 coef->MCU_ctr = MCU_col_num; 289 return JPEG_SUSPENDED; 290 } 291 } 292 /* Completed an MCU row, but perhaps not an iMCU row */ 293 coef->MCU_ctr = 0; 294 } 295 /* Completed the iMCU row, advance counters for next one */ 296 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 297 start_iMCU_row(cinfo); 298 return JPEG_ROW_COMPLETED; 299 } 300 /* Completed the scan */ 301 (*cinfo->inputctl->finish_input_pass) (cinfo); 302 return JPEG_SCAN_COMPLETED; 303 } 304 305 306 /* 307 * Decompress and return some data in the multi-pass case. 308 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 309 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 310 * 311 * NB: output_buf contains a plane for each component in image. 312 */ 313 314 METHODDEF(int) 315 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 316 { 317 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 318 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 319 JDIMENSION block_num; 320 int ci, block_row, block_rows; 321 JBLOCKARRAY buffer; 322 JBLOCKROW buffer_ptr; 323 JSAMPARRAY output_ptr; 324 JDIMENSION output_col; 325 jpeg_component_info *compptr; 326 inverse_DCT_method_ptr inverse_DCT; 327 328 /* Force some input to be done if we are getting ahead of the input. */ 329 while (cinfo->input_scan_number < cinfo->output_scan_number || 330 (cinfo->input_scan_number == cinfo->output_scan_number && 331 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) { 332 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 333 return JPEG_SUSPENDED; 334 } 335 336 /* OK, output from the virtual arrays. */ 337 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 338 ci++, compptr++) { 339 /* Don't bother to IDCT an uninteresting component. */ 340 if (! compptr->component_needed) 341 continue; 342 /* Align the virtual buffer for this component. */ 343 buffer = (*cinfo->mem->access_virt_barray) 344 ((j_common_ptr) cinfo, coef->whole_image[ci], 345 cinfo->output_iMCU_row * compptr->v_samp_factor, 346 (JDIMENSION) compptr->v_samp_factor, FALSE); 347 /* Count non-dummy DCT block rows in this iMCU row. */ 348 if (cinfo->output_iMCU_row < last_iMCU_row) 349 block_rows = compptr->v_samp_factor; 350 else { 351 /* NB: can't use last_row_height here; it is input-side-dependent! */ 352 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 353 if (block_rows == 0) block_rows = compptr->v_samp_factor; 354 } 355 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 356 output_ptr = output_buf[ci]; 357 /* Loop over all DCT blocks to be processed. */ 358 for (block_row = 0; block_row < block_rows; block_row++) { 359 buffer_ptr = buffer[block_row]; 360 output_col = 0; 361 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) { 362 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr, 363 output_ptr, output_col); 364 buffer_ptr++; 365 output_col += compptr->DCT_scaled_size; 366 } 367 output_ptr += compptr->DCT_scaled_size; 368 } 369 } 370 371 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 372 return JPEG_ROW_COMPLETED; 373 return JPEG_SCAN_COMPLETED; 374 } 375 376 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 377 378 379 #ifdef BLOCK_SMOOTHING_SUPPORTED 380 381 /* 382 * This code applies interblock smoothing as described by section K.8 383 * of the JPEG standard: the first 5 AC coefficients are estimated from 384 * the DC values of a DCT block and its 8 neighboring blocks. 385 * We apply smoothing only for progressive JPEG decoding, and only if 386 * the coefficients it can estimate are not yet known to full precision. 387 */ 388 389 /* Natural-order array positions of the first 5 zigzag-order coefficients */ 390 #define Q01_POS 1 391 #define Q10_POS 8 392 #define Q20_POS 16 393 #define Q11_POS 9 394 #define Q02_POS 2 395 396 /* 397 * Determine whether block smoothing is applicable and safe. 398 * We also latch the current states of the coef_bits[] entries for the 399 * AC coefficients; otherwise, if the input side of the decompressor 400 * advances into a new scan, we might think the coefficients are known 401 * more accurately than they really are. 402 */ 403 404 LOCAL(boolean) 405 smoothing_ok (j_decompress_ptr cinfo) 406 { 407 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 408 boolean smoothing_useful = FALSE; 409 int ci, coefi; 410 jpeg_component_info *compptr; 411 JQUANT_TBL * qtable; 412 int * coef_bits; 413 int * coef_bits_latch; 414 415 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL) 416 return FALSE; 417 418 /* Allocate latch area if not already done */ 419 if (coef->coef_bits_latch == NULL) 420 coef->coef_bits_latch = (int *) 421 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 422 cinfo->num_components * 423 (SAVED_COEFS * SIZEOF(int))); 424 coef_bits_latch = coef->coef_bits_latch; 425 426 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 427 ci++, compptr++) { 428 /* All components' quantization values must already be latched. */ 429 if ((qtable = compptr->quant_table) == NULL) 430 return FALSE; 431 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */ 432 if (qtable->quantval[0] == 0 || 433 qtable->quantval[Q01_POS] == 0 || 434 qtable->quantval[Q10_POS] == 0 || 435 qtable->quantval[Q20_POS] == 0 || 436 qtable->quantval[Q11_POS] == 0 || 437 qtable->quantval[Q02_POS] == 0) 438 return FALSE; 439 /* DC values must be at least partly known for all components. */ 440 coef_bits = cinfo->coef_bits[ci]; 441 if (coef_bits[0] < 0) 442 return FALSE; 443 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */ 444 for (coefi = 1; coefi <= 5; coefi++) { 445 coef_bits_latch[coefi] = coef_bits[coefi]; 446 if (coef_bits[coefi] != 0) 447 smoothing_useful = TRUE; 448 } 449 coef_bits_latch += SAVED_COEFS; 450 } 451 452 return smoothing_useful; 453 } 454 455 456 /* 457 * Variant of decompress_data for use when doing block smoothing. 458 */ 459 460 METHODDEF(int) 461 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 462 { 463 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 464 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 465 JDIMENSION block_num, last_block_column; 466 int ci, block_row, block_rows, access_rows; 467 JBLOCKARRAY buffer; 468 JBLOCKROW buffer_ptr, prev_block_row, next_block_row; 469 JSAMPARRAY output_ptr; 470 JDIMENSION output_col; 471 jpeg_component_info *compptr; 472 inverse_DCT_method_ptr inverse_DCT; 473 boolean first_row, last_row; 474 JBLOCK workspace; 475 int *coef_bits; 476 JQUANT_TBL *quanttbl; 477 INT32 Q00,Q01,Q02,Q10,Q11,Q20, num; 478 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9; 479 int Al, pred; 480 481 /* Force some input to be done if we are getting ahead of the input. */ 482 while (cinfo->input_scan_number <= cinfo->output_scan_number && 483 ! cinfo->inputctl->eoi_reached) { 484 if (cinfo->input_scan_number == cinfo->output_scan_number) { 485 /* If input is working on current scan, we ordinarily want it to 486 * have completed the current row. But if input scan is DC, 487 * we want it to keep one row ahead so that next block row's DC 488 * values are up to date. 489 */ 490 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0; 491 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta) 492 break; 493 } 494 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 495 return JPEG_SUSPENDED; 496 } 497 498 /* OK, output from the virtual arrays. */ 499 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 500 ci++, compptr++) { 501 /* Don't bother to IDCT an uninteresting component. */ 502 if (! compptr->component_needed) 503 continue; 504 /* Count non-dummy DCT block rows in this iMCU row. */ 505 if (cinfo->output_iMCU_row < last_iMCU_row) { 506 block_rows = compptr->v_samp_factor; 507 access_rows = block_rows * 2; /* this and next iMCU row */ 508 last_row = FALSE; 509 } else { 510 /* NB: can't use last_row_height here; it is input-side-dependent! */ 511 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 512 if (block_rows == 0) block_rows = compptr->v_samp_factor; 513 access_rows = block_rows; /* this iMCU row only */ 514 last_row = TRUE; 515 } 516 /* Align the virtual buffer for this component. */ 517 if (cinfo->output_iMCU_row > 0) { 518 access_rows += compptr->v_samp_factor; /* prior iMCU row too */ 519 buffer = (*cinfo->mem->access_virt_barray) 520 ((j_common_ptr) cinfo, coef->whole_image[ci], 521 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor, 522 (JDIMENSION) access_rows, FALSE); 523 buffer += compptr->v_samp_factor; /* point to current iMCU row */ 524 first_row = FALSE; 525 } else { 526 buffer = (*cinfo->mem->access_virt_barray) 527 ((j_common_ptr) cinfo, coef->whole_image[ci], 528 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE); 529 first_row = TRUE; 530 } 531 /* Fetch component-dependent info */ 532 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS); 533 quanttbl = compptr->quant_table; 534 Q00 = quanttbl->quantval[0]; 535 Q01 = quanttbl->quantval[Q01_POS]; 536 Q10 = quanttbl->quantval[Q10_POS]; 537 Q20 = quanttbl->quantval[Q20_POS]; 538 Q11 = quanttbl->quantval[Q11_POS]; 539 Q02 = quanttbl->quantval[Q02_POS]; 540 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 541 output_ptr = output_buf[ci]; 542 /* Loop over all DCT blocks to be processed. */ 543 for (block_row = 0; block_row < block_rows; block_row++) { 544 buffer_ptr = buffer[block_row]; 545 if (first_row && block_row == 0) 546 prev_block_row = buffer_ptr; 547 else 548 prev_block_row = buffer[block_row-1]; 549 if (last_row && block_row == block_rows-1) 550 next_block_row = buffer_ptr; 551 else 552 next_block_row = buffer[block_row+1]; 553 /* We fetch the surrounding DC values using a sliding-register approach. 554 * Initialize all nine here so as to do the right thing on narrow pics. 555 */ 556 DC1 = DC2 = DC3 = (int) prev_block_row[0][0]; 557 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0]; 558 DC7 = DC8 = DC9 = (int) next_block_row[0][0]; 559 output_col = 0; 560 last_block_column = compptr->width_in_blocks - 1; 561 for (block_num = 0; block_num <= last_block_column; block_num++) { 562 /* Fetch current DCT block into workspace so we can modify it. */ 563 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1); 564 /* Update DC values */ 565 if (block_num < last_block_column) { 566 DC3 = (int) prev_block_row[1][0]; 567 DC6 = (int) buffer_ptr[1][0]; 568 DC9 = (int) next_block_row[1][0]; 569 } 570 /* Compute coefficient estimates per K.8. 571 * An estimate is applied only if coefficient is still zero, 572 * and is not known to be fully accurate. 573 */ 574 /* AC01 */ 575 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) { 576 num = 36 * Q00 * (DC4 - DC6); 577 if (num >= 0) { 578 pred = (int) (((Q01<<7) + num) / (Q01<<8)); 579 if (Al > 0 && pred >= (1<<Al)) 580 pred = (1<<Al)-1; 581 } else { 582 pred = (int) (((Q01<<7) - num) / (Q01<<8)); 583 if (Al > 0 && pred >= (1<<Al)) 584 pred = (1<<Al)-1; 585 pred = -pred; 586 } 587 workspace[1] = (JCOEF) pred; 588 } 589 /* AC10 */ 590 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) { 591 num = 36 * Q00 * (DC2 - DC8); 592 if (num >= 0) { 593 pred = (int) (((Q10<<7) + num) / (Q10<<8)); 594 if (Al > 0 && pred >= (1<<Al)) 595 pred = (1<<Al)-1; 596 } else { 597 pred = (int) (((Q10<<7) - num) / (Q10<<8)); 598 if (Al > 0 && pred >= (1<<Al)) 599 pred = (1<<Al)-1; 600 pred = -pred; 601 } 602 workspace[8] = (JCOEF) pred; 603 } 604 /* AC20 */ 605 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) { 606 num = 9 * Q00 * (DC2 + DC8 - 2*DC5); 607 if (num >= 0) { 608 pred = (int) (((Q20<<7) + num) / (Q20<<8)); 609 if (Al > 0 && pred >= (1<<Al)) 610 pred = (1<<Al)-1; 611 } else { 612 pred = (int) (((Q20<<7) - num) / (Q20<<8)); 613 if (Al > 0 && pred >= (1<<Al)) 614 pred = (1<<Al)-1; 615 pred = -pred; 616 } 617 workspace[16] = (JCOEF) pred; 618 } 619 /* AC11 */ 620 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) { 621 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9); 622 if (num >= 0) { 623 pred = (int) (((Q11<<7) + num) / (Q11<<8)); 624 if (Al > 0 && pred >= (1<<Al)) 625 pred = (1<<Al)-1; 626 } else { 627 pred = (int) (((Q11<<7) - num) / (Q11<<8)); 628 if (Al > 0 && pred >= (1<<Al)) 629 pred = (1<<Al)-1; 630 pred = -pred; 631 } 632 workspace[9] = (JCOEF) pred; 633 } 634 /* AC02 */ 635 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) { 636 num = 9 * Q00 * (DC4 + DC6 - 2*DC5); 637 if (num >= 0) { 638 pred = (int) (((Q02<<7) + num) / (Q02<<8)); 639 if (Al > 0 && pred >= (1<<Al)) 640 pred = (1<<Al)-1; 641 } else { 642 pred = (int) (((Q02<<7) - num) / (Q02<<8)); 643 if (Al > 0 && pred >= (1<<Al)) 644 pred = (1<<Al)-1; 645 pred = -pred; 646 } 647 workspace[2] = (JCOEF) pred; 648 } 649 /* OK, do the IDCT */ 650 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace, 651 output_ptr, output_col); 652 /* Advance for next column */ 653 DC1 = DC2; DC2 = DC3; 654 DC4 = DC5; DC5 = DC6; 655 DC7 = DC8; DC8 = DC9; 656 buffer_ptr++, prev_block_row++, next_block_row++; 657 output_col += compptr->DCT_scaled_size; 658 } 659 output_ptr += compptr->DCT_scaled_size; 660 } 661 } 662 663 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 664 return JPEG_ROW_COMPLETED; 665 return JPEG_SCAN_COMPLETED; 666 } 667 668 #endif /* BLOCK_SMOOTHING_SUPPORTED */ 669 670 671 /* 672 * Initialize coefficient buffer controller. 673 */ 674 675 GLOBAL(void) 676 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer) 677 { 678 my_coef_ptr coef; 679 680 coef = (my_coef_ptr) 681 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 682 SIZEOF(my_coef_controller)); 683 cinfo->coef = (struct jpeg_d_coef_controller *) coef; 684 coef->pub.start_input_pass = start_input_pass; 685 coef->pub.start_output_pass = start_output_pass; 686 #ifdef BLOCK_SMOOTHING_SUPPORTED 687 coef->coef_bits_latch = NULL; 688 #endif 689 690 /* Create the coefficient buffer. */ 691 if (need_full_buffer) { 692 #ifdef D_MULTISCAN_FILES_SUPPORTED 693 /* Allocate a full-image virtual array for each component, */ 694 /* padded to a multiple of samp_factor DCT blocks in each direction. */ 695 /* Note we ask for a pre-zeroed array. */ 696 int ci, access_rows; 697 jpeg_component_info *compptr; 698 699 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 700 ci++, compptr++) { 701 access_rows = compptr->v_samp_factor; 702 #ifdef BLOCK_SMOOTHING_SUPPORTED 703 /* If block smoothing could be used, need a bigger window */ 704 if (cinfo->progressive_mode) 705 access_rows *= 3; 706 #endif 707 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) 708 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE, 709 (JDIMENSION) jround_up((long) compptr->width_in_blocks, 710 (long) compptr->h_samp_factor), 711 (JDIMENSION) jround_up((long) compptr->height_in_blocks, 712 (long) compptr->v_samp_factor), 713 (JDIMENSION) access_rows); 714 } 715 coef->pub.consume_data = consume_data; 716 coef->pub.decompress_data = decompress_data; 717 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */ 718 #else 719 ERREXIT(cinfo, JERR_NOT_COMPILED); 720 #endif 721 } else { 722 /* We only need a single-MCU buffer. */ 723 JBLOCKROW buffer; 724 int i; 725 726 buffer = (JBLOCKROW) 727 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, 728 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); 729 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) { 730 coef->MCU_buffer[i] = buffer + i; 731 } 732 coef->pub.consume_data = dummy_consume_data; 733 coef->pub.decompress_data = decompress_onepass; 734 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */ 735 } 736 }