1 /* 2 * jdcoefct.c 3 * 4 * Copyright (C) 1994-1997, Thomas G. Lane. 5 * Modified 2002-2011 by Guido Vollbeding. 6 * This file is part of the Independent JPEG Group's software. 7 * For conditions of distribution and use, see the accompanying README file. 8 * 9 * This file contains the coefficient buffer controller for decompression. 10 * This controller is the top level of the JPEG decompressor proper. 11 * The coefficient buffer lies between entropy decoding and inverse-DCT steps. 12 * 13 * In buffered-image mode, this controller is the interface between 14 * input-oriented processing and output-oriented processing. 15 * Also, the input side (only) is used when reading a file for transcoding. 16 */ 17 18 #define JPEG_INTERNALS 19 #include "jinclude.h" 20 #include "jpeglib.h" 21 22 /* Block smoothing is only applicable for progressive JPEG, so: */ 23 #ifndef D_PROGRESSIVE_SUPPORTED 24 #undef BLOCK_SMOOTHING_SUPPORTED 25 #endif 26 27 /* Private buffer controller object */ 28 29 typedef struct { 30 struct jpeg_d_coef_controller pub; /* public fields */ 31 32 /* These variables keep track of the current location of the input side. */ 33 /* cinfo->input_iMCU_row is also used for this. */ 34 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */ 35 int MCU_vert_offset; /* counts MCU rows within iMCU row */ 36 int MCU_rows_per_iMCU_row; /* number of such rows needed */ 37 38 /* The output side's location is represented by cinfo->output_iMCU_row. */ 39 40 /* In single-pass modes, it's sufficient to buffer just one MCU. 41 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks, 42 * and let the entropy decoder write into that workspace each time. 43 * (On 80x86, the workspace is FAR even though it's not really very big; 44 * this is to keep the module interfaces unchanged when a large coefficient 45 * buffer is necessary.) 46 * In multi-pass modes, this array points to the current MCU's blocks 47 * within the virtual arrays; it is used only by the input side. 48 */ 49 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU]; 50 51 #ifdef D_MULTISCAN_FILES_SUPPORTED 52 /* In multi-pass modes, we need a virtual block array for each component. */ 53 jvirt_barray_ptr whole_image[MAX_COMPONENTS]; 54 #endif 55 56 #ifdef BLOCK_SMOOTHING_SUPPORTED 57 /* When doing block smoothing, we latch coefficient Al values here */ 58 int * coef_bits_latch; 59 #define SAVED_COEFS 6 /* we save coef_bits[0..5] */ 60 #endif 61 } my_coef_controller; 62 63 typedef my_coef_controller * my_coef_ptr; 64 65 /* Forward declarations */ 66 METHODDEF(int) decompress_onepass 67 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 68 #ifdef D_MULTISCAN_FILES_SUPPORTED 69 METHODDEF(int) decompress_data 70 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 71 #endif 72 #ifdef BLOCK_SMOOTHING_SUPPORTED 73 LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo)); 74 METHODDEF(int) decompress_smooth_data 75 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 76 #endif 77 78 79 LOCAL(void) 80 start_iMCU_row (j_decompress_ptr cinfo) 81 /* Reset within-iMCU-row counters for a new row (input side) */ 82 { 83 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 84 85 /* In an interleaved scan, an MCU row is the same as an iMCU row. 86 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. 87 * But at the bottom of the image, process only what's left. 88 */ 89 if (cinfo->comps_in_scan > 1) { 90 coef->MCU_rows_per_iMCU_row = 1; 91 } else { 92 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1)) 93 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; 94 else 95 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; 96 } 97 98 coef->MCU_ctr = 0; 99 coef->MCU_vert_offset = 0; 100 } 101 102 103 /* 104 * Initialize for an input processing pass. 105 */ 106 107 METHODDEF(void) 108 start_input_pass (j_decompress_ptr cinfo) 109 { 110 cinfo->input_iMCU_row = 0; 111 start_iMCU_row(cinfo); 112 } 113 114 115 /* 116 * Initialize for an output processing pass. 117 */ 118 119 METHODDEF(void) 120 start_output_pass (j_decompress_ptr cinfo) 121 { 122 #ifdef BLOCK_SMOOTHING_SUPPORTED 123 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 124 125 /* If multipass, check to see whether to use block smoothing on this pass */ 126 if (coef->pub.coef_arrays != NULL) { 127 if (cinfo->do_block_smoothing && smoothing_ok(cinfo)) 128 coef->pub.decompress_data = decompress_smooth_data; 129 else 130 coef->pub.decompress_data = decompress_data; 131 } 132 #endif 133 cinfo->output_iMCU_row = 0; 134 } 135 136 137 /* 138 * Decompress and return some data in the single-pass case. 139 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 140 * Input and output must run in lockstep since we have only a one-MCU buffer. 141 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 142 * 143 * NB: output_buf contains a plane for each component in image, 144 * which we index according to the component's SOF position. 145 */ 146 147 METHODDEF(int) 148 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 149 { 150 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 151 JDIMENSION MCU_col_num; /* index of current MCU within row */ 152 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; 153 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 154 int blkn, ci, xindex, yindex, yoffset, useful_width; 155 JSAMPARRAY output_ptr; 156 JDIMENSION start_col, output_col; 157 jpeg_component_info *compptr; 158 inverse_DCT_method_ptr inverse_DCT; 159 160 /* Loop to process as much as one whole iMCU row */ 161 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 162 yoffset++) { 163 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col; 164 MCU_col_num++) { 165 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */ 166 if (cinfo->lim_Se) /* can bypass in DC only case */ 167 FMEMZERO((void FAR *) coef->MCU_buffer[0], 168 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK))); 169 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 170 /* Suspension forced; update state counters and exit */ 171 coef->MCU_vert_offset = yoffset; 172 coef->MCU_ctr = MCU_col_num; 173 return JPEG_SUSPENDED; 174 } 175 /* Determine where data should go in output_buf and do the IDCT thing. 176 * We skip dummy blocks at the right and bottom edges (but blkn gets 177 * incremented past them!). Note the inner loop relies on having 178 * allocated the MCU_buffer[] blocks sequentially. 179 */ 180 blkn = 0; /* index of current DCT block within MCU */ 181 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 182 compptr = cinfo->cur_comp_info[ci]; 183 /* Don't bother to IDCT an uninteresting component. */ 184 if (! compptr->component_needed) { 185 blkn += compptr->MCU_blocks; 186 continue; 187 } 188 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index]; 189 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width 190 : compptr->last_col_width; 191 output_ptr = output_buf[compptr->component_index] + 192 yoffset * compptr->DCT_v_scaled_size; 193 start_col = MCU_col_num * compptr->MCU_sample_width; 194 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 195 if (cinfo->input_iMCU_row < last_iMCU_row || 196 yoffset+yindex < compptr->last_row_height) { 197 output_col = start_col; 198 for (xindex = 0; xindex < useful_width; xindex++) { 199 (*inverse_DCT) (cinfo, compptr, 200 (JCOEFPTR) coef->MCU_buffer[blkn+xindex], 201 output_ptr, output_col); 202 output_col += compptr->DCT_h_scaled_size; 203 } 204 } 205 blkn += compptr->MCU_width; 206 output_ptr += compptr->DCT_v_scaled_size; 207 } 208 } 209 } 210 /* Completed an MCU row, but perhaps not an iMCU row */ 211 coef->MCU_ctr = 0; 212 } 213 /* Completed the iMCU row, advance counters for next one */ 214 cinfo->output_iMCU_row++; 215 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 216 start_iMCU_row(cinfo); 217 return JPEG_ROW_COMPLETED; 218 } 219 /* Completed the scan */ 220 (*cinfo->inputctl->finish_input_pass) (cinfo); 221 return JPEG_SCAN_COMPLETED; 222 } 223 224 225 /* 226 * Dummy consume-input routine for single-pass operation. 227 */ 228 229 METHODDEF(int) 230 dummy_consume_data (j_decompress_ptr cinfo) 231 { 232 return JPEG_SUSPENDED; /* Always indicate nothing was done */ 233 } 234 235 236 #ifdef D_MULTISCAN_FILES_SUPPORTED 237 238 /* 239 * Consume input data and store it in the full-image coefficient buffer. 240 * We read as much as one fully interleaved MCU row ("iMCU" row) per call, 241 * ie, v_samp_factor block rows for each component in the scan. 242 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 243 */ 244 245 METHODDEF(int) 246 consume_data (j_decompress_ptr cinfo) 247 { 248 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 249 JDIMENSION MCU_col_num; /* index of current MCU within row */ 250 int blkn, ci, xindex, yindex, yoffset; 251 JDIMENSION start_col; 252 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; 253 JBLOCKROW buffer_ptr; 254 jpeg_component_info *compptr; 255 256 /* Align the virtual buffers for the components used in this scan. */ 257 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 258 compptr = cinfo->cur_comp_info[ci]; 259 buffer[ci] = (*cinfo->mem->access_virt_barray) 260 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], 261 cinfo->input_iMCU_row * compptr->v_samp_factor, 262 (JDIMENSION) compptr->v_samp_factor, TRUE); 263 /* Note: entropy decoder expects buffer to be zeroed, 264 * but this is handled automatically by the memory manager 265 * because we requested a pre-zeroed array. 266 */ 267 } 268 269 /* Loop to process one whole iMCU row */ 270 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 271 yoffset++) { 272 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row; 273 MCU_col_num++) { 274 /* Construct list of pointers to DCT blocks belonging to this MCU */ 275 blkn = 0; /* index of current DCT block within MCU */ 276 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 277 compptr = cinfo->cur_comp_info[ci]; 278 start_col = MCU_col_num * compptr->MCU_width; 279 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 280 buffer_ptr = buffer[ci][yindex+yoffset] + start_col; 281 for (xindex = 0; xindex < compptr->MCU_width; xindex++) { 282 coef->MCU_buffer[blkn++] = buffer_ptr++; 283 } 284 } 285 } 286 /* Try to fetch the MCU. */ 287 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 288 /* Suspension forced; update state counters and exit */ 289 coef->MCU_vert_offset = yoffset; 290 coef->MCU_ctr = MCU_col_num; 291 return JPEG_SUSPENDED; 292 } 293 } 294 /* Completed an MCU row, but perhaps not an iMCU row */ 295 coef->MCU_ctr = 0; 296 } 297 /* Completed the iMCU row, advance counters for next one */ 298 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 299 start_iMCU_row(cinfo); 300 return JPEG_ROW_COMPLETED; 301 } 302 /* Completed the scan */ 303 (*cinfo->inputctl->finish_input_pass) (cinfo); 304 return JPEG_SCAN_COMPLETED; 305 } 306 307 308 /* 309 * Decompress and return some data in the multi-pass case. 310 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 311 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 312 * 313 * NB: output_buf contains a plane for each component in image. 314 */ 315 316 METHODDEF(int) 317 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 318 { 319 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 320 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 321 JDIMENSION block_num; 322 int ci, block_row, block_rows; 323 JBLOCKARRAY buffer; 324 JBLOCKROW buffer_ptr; 325 JSAMPARRAY output_ptr; 326 JDIMENSION output_col; 327 jpeg_component_info *compptr; 328 inverse_DCT_method_ptr inverse_DCT; 329 330 /* Force some input to be done if we are getting ahead of the input. */ 331 while (cinfo->input_scan_number < cinfo->output_scan_number || 332 (cinfo->input_scan_number == cinfo->output_scan_number && 333 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) { 334 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 335 return JPEG_SUSPENDED; 336 } 337 338 /* OK, output from the virtual arrays. */ 339 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 340 ci++, compptr++) { 341 /* Don't bother to IDCT an uninteresting component. */ 342 if (! compptr->component_needed) 343 continue; 344 /* Align the virtual buffer for this component. */ 345 buffer = (*cinfo->mem->access_virt_barray) 346 ((j_common_ptr) cinfo, coef->whole_image[ci], 347 cinfo->output_iMCU_row * compptr->v_samp_factor, 348 (JDIMENSION) compptr->v_samp_factor, FALSE); 349 /* Count non-dummy DCT block rows in this iMCU row. */ 350 if (cinfo->output_iMCU_row < last_iMCU_row) 351 block_rows = compptr->v_samp_factor; 352 else { 353 /* NB: can't use last_row_height here; it is input-side-dependent! */ 354 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 355 if (block_rows == 0) block_rows = compptr->v_samp_factor; 356 } 357 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 358 output_ptr = output_buf[ci]; 359 /* Loop over all DCT blocks to be processed. */ 360 for (block_row = 0; block_row < block_rows; block_row++) { 361 buffer_ptr = buffer[block_row]; 362 output_col = 0; 363 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) { 364 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr, 365 output_ptr, output_col); 366 buffer_ptr++; 367 output_col += compptr->DCT_h_scaled_size; 368 } 369 output_ptr += compptr->DCT_v_scaled_size; 370 } 371 } 372 373 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 374 return JPEG_ROW_COMPLETED; 375 return JPEG_SCAN_COMPLETED; 376 } 377 378 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 379 380 381 #ifdef BLOCK_SMOOTHING_SUPPORTED 382 383 /* 384 * This code applies interblock smoothing as described by section K.8 385 * of the JPEG standard: the first 5 AC coefficients are estimated from 386 * the DC values of a DCT block and its 8 neighboring blocks. 387 * We apply smoothing only for progressive JPEG decoding, and only if 388 * the coefficients it can estimate are not yet known to full precision. 389 */ 390 391 /* Natural-order array positions of the first 5 zigzag-order coefficients */ 392 #define Q01_POS 1 393 #define Q10_POS 8 394 #define Q20_POS 16 395 #define Q11_POS 9 396 #define Q02_POS 2 397 398 /* 399 * Determine whether block smoothing is applicable and safe. 400 * We also latch the current states of the coef_bits[] entries for the 401 * AC coefficients; otherwise, if the input side of the decompressor 402 * advances into a new scan, we might think the coefficients are known 403 * more accurately than they really are. 404 */ 405 406 LOCAL(boolean) 407 smoothing_ok (j_decompress_ptr cinfo) 408 { 409 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 410 boolean smoothing_useful = FALSE; 411 int ci, coefi; 412 jpeg_component_info *compptr; 413 JQUANT_TBL * qtable; 414 int * coef_bits; 415 int * coef_bits_latch; 416 417 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL) 418 return FALSE; 419 420 /* Allocate latch area if not already done */ 421 if (coef->coef_bits_latch == NULL) 422 coef->coef_bits_latch = (int *) 423 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 424 cinfo->num_components * 425 (SAVED_COEFS * SIZEOF(int))); 426 coef_bits_latch = coef->coef_bits_latch; 427 428 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 429 ci++, compptr++) { 430 /* All components' quantization values must already be latched. */ 431 if ((qtable = compptr->quant_table) == NULL) 432 return FALSE; 433 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */ 434 if (qtable->quantval[0] == 0 || 435 qtable->quantval[Q01_POS] == 0 || 436 qtable->quantval[Q10_POS] == 0 || 437 qtable->quantval[Q20_POS] == 0 || 438 qtable->quantval[Q11_POS] == 0 || 439 qtable->quantval[Q02_POS] == 0) 440 return FALSE; 441 /* DC values must be at least partly known for all components. */ 442 coef_bits = cinfo->coef_bits[ci]; 443 if (coef_bits[0] < 0) 444 return FALSE; 445 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */ 446 for (coefi = 1; coefi <= 5; coefi++) { 447 coef_bits_latch[coefi] = coef_bits[coefi]; 448 if (coef_bits[coefi] != 0) 449 smoothing_useful = TRUE; 450 } 451 coef_bits_latch += SAVED_COEFS; 452 } 453 454 return smoothing_useful; 455 } 456 457 458 /* 459 * Variant of decompress_data for use when doing block smoothing. 460 */ 461 462 METHODDEF(int) 463 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 464 { 465 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 466 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 467 JDIMENSION block_num, last_block_column; 468 int ci, block_row, block_rows, access_rows; 469 JBLOCKARRAY buffer; 470 JBLOCKROW buffer_ptr, prev_block_row, next_block_row; 471 JSAMPARRAY output_ptr; 472 JDIMENSION output_col; 473 jpeg_component_info *compptr; 474 inverse_DCT_method_ptr inverse_DCT; 475 boolean first_row, last_row; 476 JBLOCK workspace; 477 int *coef_bits; 478 JQUANT_TBL *quanttbl; 479 INT32 Q00,Q01,Q02,Q10,Q11,Q20, num; 480 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9; 481 int Al, pred; 482 483 /* Force some input to be done if we are getting ahead of the input. */ 484 while (cinfo->input_scan_number <= cinfo->output_scan_number && 485 ! cinfo->inputctl->eoi_reached) { 486 if (cinfo->input_scan_number == cinfo->output_scan_number) { 487 /* If input is working on current scan, we ordinarily want it to 488 * have completed the current row. But if input scan is DC, 489 * we want it to keep one row ahead so that next block row's DC 490 * values are up to date. 491 */ 492 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0; 493 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta) 494 break; 495 } 496 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 497 return JPEG_SUSPENDED; 498 } 499 500 /* OK, output from the virtual arrays. */ 501 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 502 ci++, compptr++) { 503 /* Don't bother to IDCT an uninteresting component. */ 504 if (! compptr->component_needed) 505 continue; 506 /* Count non-dummy DCT block rows in this iMCU row. */ 507 if (cinfo->output_iMCU_row < last_iMCU_row) { 508 block_rows = compptr->v_samp_factor; 509 access_rows = block_rows * 2; /* this and next iMCU row */ 510 last_row = FALSE; 511 } else { 512 /* NB: can't use last_row_height here; it is input-side-dependent! */ 513 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 514 if (block_rows == 0) block_rows = compptr->v_samp_factor; 515 access_rows = block_rows; /* this iMCU row only */ 516 last_row = TRUE; 517 } 518 /* Align the virtual buffer for this component. */ 519 if (cinfo->output_iMCU_row > 0) { 520 access_rows += compptr->v_samp_factor; /* prior iMCU row too */ 521 buffer = (*cinfo->mem->access_virt_barray) 522 ((j_common_ptr) cinfo, coef->whole_image[ci], 523 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor, 524 (JDIMENSION) access_rows, FALSE); 525 buffer += compptr->v_samp_factor; /* point to current iMCU row */ 526 first_row = FALSE; 527 } else { 528 buffer = (*cinfo->mem->access_virt_barray) 529 ((j_common_ptr) cinfo, coef->whole_image[ci], 530 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE); 531 first_row = TRUE; 532 } 533 /* Fetch component-dependent info */ 534 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS); 535 quanttbl = compptr->quant_table; 536 Q00 = quanttbl->quantval[0]; 537 Q01 = quanttbl->quantval[Q01_POS]; 538 Q10 = quanttbl->quantval[Q10_POS]; 539 Q20 = quanttbl->quantval[Q20_POS]; 540 Q11 = quanttbl->quantval[Q11_POS]; 541 Q02 = quanttbl->quantval[Q02_POS]; 542 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 543 output_ptr = output_buf[ci]; 544 /* Loop over all DCT blocks to be processed. */ 545 for (block_row = 0; block_row < block_rows; block_row++) { 546 buffer_ptr = buffer[block_row]; 547 if (first_row && block_row == 0) 548 prev_block_row = buffer_ptr; 549 else 550 prev_block_row = buffer[block_row-1]; 551 if (last_row && block_row == block_rows-1) 552 next_block_row = buffer_ptr; 553 else 554 next_block_row = buffer[block_row+1]; 555 /* We fetch the surrounding DC values using a sliding-register approach. 556 * Initialize all nine here so as to do the right thing on narrow pics. 557 */ 558 DC1 = DC2 = DC3 = (int) prev_block_row[0][0]; 559 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0]; 560 DC7 = DC8 = DC9 = (int) next_block_row[0][0]; 561 output_col = 0; 562 last_block_column = compptr->width_in_blocks - 1; 563 for (block_num = 0; block_num <= last_block_column; block_num++) { 564 /* Fetch current DCT block into workspace so we can modify it. */ 565 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1); 566 /* Update DC values */ 567 if (block_num < last_block_column) { 568 DC3 = (int) prev_block_row[1][0]; 569 DC6 = (int) buffer_ptr[1][0]; 570 DC9 = (int) next_block_row[1][0]; 571 } 572 /* Compute coefficient estimates per K.8. 573 * An estimate is applied only if coefficient is still zero, 574 * and is not known to be fully accurate. 575 */ 576 /* AC01 */ 577 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) { 578 num = 36 * Q00 * (DC4 - DC6); 579 if (num >= 0) { 580 pred = (int) (((Q01<<7) + num) / (Q01<<8)); 581 if (Al > 0 && pred >= (1<<Al)) 582 pred = (1<<Al)-1; 583 } else { 584 pred = (int) (((Q01<<7) - num) / (Q01<<8)); 585 if (Al > 0 && pred >= (1<<Al)) 586 pred = (1<<Al)-1; 587 pred = -pred; 588 } 589 workspace[1] = (JCOEF) pred; 590 } 591 /* AC10 */ 592 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) { 593 num = 36 * Q00 * (DC2 - DC8); 594 if (num >= 0) { 595 pred = (int) (((Q10<<7) + num) / (Q10<<8)); 596 if (Al > 0 && pred >= (1<<Al)) 597 pred = (1<<Al)-1; 598 } else { 599 pred = (int) (((Q10<<7) - num) / (Q10<<8)); 600 if (Al > 0 && pred >= (1<<Al)) 601 pred = (1<<Al)-1; 602 pred = -pred; 603 } 604 workspace[8] = (JCOEF) pred; 605 } 606 /* AC20 */ 607 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) { 608 num = 9 * Q00 * (DC2 + DC8 - 2*DC5); 609 if (num >= 0) { 610 pred = (int) (((Q20<<7) + num) / (Q20<<8)); 611 if (Al > 0 && pred >= (1<<Al)) 612 pred = (1<<Al)-1; 613 } else { 614 pred = (int) (((Q20<<7) - num) / (Q20<<8)); 615 if (Al > 0 && pred >= (1<<Al)) 616 pred = (1<<Al)-1; 617 pred = -pred; 618 } 619 workspace[16] = (JCOEF) pred; 620 } 621 /* AC11 */ 622 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) { 623 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9); 624 if (num >= 0) { 625 pred = (int) (((Q11<<7) + num) / (Q11<<8)); 626 if (Al > 0 && pred >= (1<<Al)) 627 pred = (1<<Al)-1; 628 } else { 629 pred = (int) (((Q11<<7) - num) / (Q11<<8)); 630 if (Al > 0 && pred >= (1<<Al)) 631 pred = (1<<Al)-1; 632 pred = -pred; 633 } 634 workspace[9] = (JCOEF) pred; 635 } 636 /* AC02 */ 637 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) { 638 num = 9 * Q00 * (DC4 + DC6 - 2*DC5); 639 if (num >= 0) { 640 pred = (int) (((Q02<<7) + num) / (Q02<<8)); 641 if (Al > 0 && pred >= (1<<Al)) 642 pred = (1<<Al)-1; 643 } else { 644 pred = (int) (((Q02<<7) - num) / (Q02<<8)); 645 if (Al > 0 && pred >= (1<<Al)) 646 pred = (1<<Al)-1; 647 pred = -pred; 648 } 649 workspace[2] = (JCOEF) pred; 650 } 651 /* OK, do the IDCT */ 652 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace, 653 output_ptr, output_col); 654 /* Advance for next column */ 655 DC1 = DC2; DC2 = DC3; 656 DC4 = DC5; DC5 = DC6; 657 DC7 = DC8; DC8 = DC9; 658 buffer_ptr++, prev_block_row++, next_block_row++; 659 output_col += compptr->DCT_h_scaled_size; 660 } 661 output_ptr += compptr->DCT_v_scaled_size; 662 } 663 } 664 665 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 666 return JPEG_ROW_COMPLETED; 667 return JPEG_SCAN_COMPLETED; 668 } 669 670 #endif /* BLOCK_SMOOTHING_SUPPORTED */ 671 672 673 /* 674 * Initialize coefficient buffer controller. 675 */ 676 677 GLOBAL(void) 678 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer) 679 { 680 my_coef_ptr coef; 681 682 coef = (my_coef_ptr) 683 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 684 SIZEOF(my_coef_controller)); 685 cinfo->coef = (struct jpeg_d_coef_controller *) coef; 686 coef->pub.start_input_pass = start_input_pass; 687 coef->pub.start_output_pass = start_output_pass; 688 #ifdef BLOCK_SMOOTHING_SUPPORTED 689 coef->coef_bits_latch = NULL; 690 #endif 691 692 /* Create the coefficient buffer. */ 693 if (need_full_buffer) { 694 #ifdef D_MULTISCAN_FILES_SUPPORTED 695 /* Allocate a full-image virtual array for each component, */ 696 /* padded to a multiple of samp_factor DCT blocks in each direction. */ 697 /* Note we ask for a pre-zeroed array. */ 698 int ci, access_rows; 699 jpeg_component_info *compptr; 700 701 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 702 ci++, compptr++) { 703 access_rows = compptr->v_samp_factor; 704 #ifdef BLOCK_SMOOTHING_SUPPORTED 705 /* If block smoothing could be used, need a bigger window */ 706 if (cinfo->progressive_mode) 707 access_rows *= 3; 708 #endif 709 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) 710 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE, 711 (JDIMENSION) jround_up((long) compptr->width_in_blocks, 712 (long) compptr->h_samp_factor), 713 (JDIMENSION) jround_up((long) compptr->height_in_blocks, 714 (long) compptr->v_samp_factor), 715 (JDIMENSION) access_rows); 716 } 717 coef->pub.consume_data = consume_data; 718 coef->pub.decompress_data = decompress_data; 719 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */ 720 #else 721 ERREXIT(cinfo, JERR_NOT_COMPILED); 722 #endif 723 } else { 724 /* We only need a single-MCU buffer. */ 725 JBLOCKROW buffer; 726 int i; 727 728 buffer = (JBLOCKROW) 729 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, 730 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); 731 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) { 732 coef->MCU_buffer[i] = buffer + i; 733 } 734 if (cinfo->lim_Se == 0) /* DC only case: want to bypass later */ 735 FMEMZERO((void FAR *) buffer, 736 (size_t) (D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK))); 737 coef->pub.consume_data = dummy_consume_data; 738 coef->pub.decompress_data = decompress_onepass; 739 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */ 740 } 741 } 742
