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 (C) 2010, D. R. Commander. 8 * For conditions of distribution and use, see the accompanying README file. 9 * 10 * This file contains the coefficient buffer controller for decompression. 11 * This controller is the top level of the JPEG decompressor proper. 12 * The coefficient buffer lies between entropy decoding and inverse-DCT steps. 13 * 14 * In buffered-image mode, this controller is the interface between 15 * input-oriented processing and output-oriented processing. 16 * Also, the input side (only) is used when reading a file for transcoding. 17 */ 18 19 #define JPEG_INTERNALS 20 #include "jinclude.h" 21 #include "jpeglib.h" 22 #include "jpegcomp.h" 23 24 /* Block smoothing is only applicable for progressive JPEG, so: */ 25 #ifndef D_PROGRESSIVE_SUPPORTED 26 #undef BLOCK_SMOOTHING_SUPPORTED 27 #endif 28 29 /* Private buffer controller object */ 30 31 typedef struct { 32 struct jpeg_d_coef_controller pub; /* public fields */ 33 34 /* These variables keep track of the current location of the input side. */ 35 /* cinfo->input_iMCU_row is also used for this. */ 36 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */ 37 int MCU_vert_offset; /* counts MCU rows within iMCU row */ 38 int MCU_rows_per_iMCU_row; /* number of such rows needed */ 39 40 /* The output side's location is represented by cinfo->output_iMCU_row. */ 41 42 /* In single-pass modes, it's sufficient to buffer just one MCU. 43 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks, 44 * and let the entropy decoder write into that workspace each time. 45 * (On 80x86, the workspace is FAR even though it's not really very big; 46 * this is to keep the module interfaces unchanged when a large coefficient 47 * buffer is necessary.) 48 * In multi-pass modes, this array points to the current MCU's blocks 49 * within the virtual arrays; it is used only by the input side. 50 */ 51 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU]; 52 53 /* Temporary workspace for one MCU */ 54 JCOEF * workspace; 55 56 #ifdef D_MULTISCAN_FILES_SUPPORTED 57 /* In multi-pass modes, we need a virtual block array for each component. */ 58 jvirt_barray_ptr whole_image[MAX_COMPONENTS]; 59 #endif 60 61 #ifdef BLOCK_SMOOTHING_SUPPORTED 62 /* When doing block smoothing, we latch coefficient Al values here */ 63 int * coef_bits_latch; 64 #define SAVED_COEFS 6 /* we save coef_bits[0..5] */ 65 #endif 66 } my_coef_controller; 67 68 typedef my_coef_controller * my_coef_ptr; 69 70 /* Forward declarations */ 71 METHODDEF(int) decompress_onepass 72 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 73 #ifdef D_MULTISCAN_FILES_SUPPORTED 74 METHODDEF(int) decompress_data 75 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 76 #endif 77 #ifdef BLOCK_SMOOTHING_SUPPORTED 78 LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo)); 79 METHODDEF(int) decompress_smooth_data 80 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); 81 #endif 82 83 84 LOCAL(void) 85 start_iMCU_row (j_decompress_ptr cinfo) 86 /* Reset within-iMCU-row counters for a new row (input side) */ 87 { 88 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 89 90 /* In an interleaved scan, an MCU row is the same as an iMCU row. 91 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. 92 * But at the bottom of the image, process only what's left. 93 */ 94 if (cinfo->comps_in_scan > 1) { 95 coef->MCU_rows_per_iMCU_row = 1; 96 } else { 97 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1)) 98 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; 99 else 100 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; 101 } 102 103 coef->MCU_ctr = 0; 104 coef->MCU_vert_offset = 0; 105 } 106 107 108 /* 109 * Initialize for an input processing pass. 110 */ 111 112 METHODDEF(void) 113 start_input_pass (j_decompress_ptr cinfo) 114 { 115 cinfo->input_iMCU_row = 0; 116 start_iMCU_row(cinfo); 117 } 118 119 120 /* 121 * Initialize for an output processing pass. 122 */ 123 124 METHODDEF(void) 125 start_output_pass (j_decompress_ptr cinfo) 126 { 127 #ifdef BLOCK_SMOOTHING_SUPPORTED 128 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 129 130 /* If multipass, check to see whether to use block smoothing on this pass */ 131 if (coef->pub.coef_arrays != NULL) { 132 if (cinfo->do_block_smoothing && smoothing_ok(cinfo)) 133 coef->pub.decompress_data = decompress_smooth_data; 134 else 135 coef->pub.decompress_data = decompress_data; 136 } 137 #endif 138 cinfo->output_iMCU_row = 0; 139 } 140 141 142 /* 143 * Decompress and return some data in the single-pass case. 144 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 145 * Input and output must run in lockstep since we have only a one-MCU buffer. 146 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 147 * 148 * NB: output_buf contains a plane for each component in image, 149 * which we index according to the component's SOF position. 150 */ 151 152 METHODDEF(int) 153 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 154 { 155 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 156 JDIMENSION MCU_col_num; /* index of current MCU within row */ 157 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; 158 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 159 int blkn, ci, xindex, yindex, yoffset, useful_width; 160 JSAMPARRAY output_ptr; 161 JDIMENSION start_col, output_col; 162 jpeg_component_info *compptr; 163 inverse_DCT_method_ptr inverse_DCT; 164 165 /* Loop to process as much as one whole iMCU row */ 166 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 167 yoffset++) { 168 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col; 169 MCU_col_num++) { 170 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */ 171 jzero_far((void FAR *) coef->MCU_buffer[0], 172 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK))); 173 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 174 /* Suspension forced; update state counters and exit */ 175 coef->MCU_vert_offset = yoffset; 176 coef->MCU_ctr = MCU_col_num; 177 return JPEG_SUSPENDED; 178 } 179 /* Determine where data should go in output_buf and do the IDCT thing. 180 * We skip dummy blocks at the right and bottom edges (but blkn gets 181 * incremented past them!). Note the inner loop relies on having 182 * allocated the MCU_buffer[] blocks sequentially. 183 */ 184 blkn = 0; /* index of current DCT block within MCU */ 185 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 186 compptr = cinfo->cur_comp_info[ci]; 187 /* Don't bother to IDCT an uninteresting component. */ 188 if (! compptr->component_needed) { 189 blkn += compptr->MCU_blocks; 190 continue; 191 } 192 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index]; 193 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width 194 : compptr->last_col_width; 195 output_ptr = output_buf[compptr->component_index] + 196 yoffset * compptr->_DCT_scaled_size; 197 start_col = MCU_col_num * compptr->MCU_sample_width; 198 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 199 if (cinfo->input_iMCU_row < last_iMCU_row || 200 yoffset+yindex < compptr->last_row_height) { 201 output_col = start_col; 202 for (xindex = 0; xindex < useful_width; xindex++) { 203 (*inverse_DCT) (cinfo, compptr, 204 (JCOEFPTR) coef->MCU_buffer[blkn+xindex], 205 output_ptr, output_col); 206 output_col += compptr->_DCT_scaled_size; 207 } 208 } 209 blkn += compptr->MCU_width; 210 output_ptr += compptr->_DCT_scaled_size; 211 } 212 } 213 } 214 /* Completed an MCU row, but perhaps not an iMCU row */ 215 coef->MCU_ctr = 0; 216 } 217 /* Completed the iMCU row, advance counters for next one */ 218 cinfo->output_iMCU_row++; 219 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 220 start_iMCU_row(cinfo); 221 return JPEG_ROW_COMPLETED; 222 } 223 /* Completed the scan */ 224 (*cinfo->inputctl->finish_input_pass) (cinfo); 225 return JPEG_SCAN_COMPLETED; 226 } 227 228 229 /* 230 * Dummy consume-input routine for single-pass operation. 231 */ 232 233 METHODDEF(int) 234 dummy_consume_data (j_decompress_ptr cinfo) 235 { 236 return JPEG_SUSPENDED; /* Always indicate nothing was done */ 237 } 238 239 240 #ifdef D_MULTISCAN_FILES_SUPPORTED 241 242 /* 243 * Consume input data and store it in the full-image coefficient buffer. 244 * We read as much as one fully interleaved MCU row ("iMCU" row) per call, 245 * ie, v_samp_factor block rows for each component in the scan. 246 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 247 */ 248 249 METHODDEF(int) 250 consume_data (j_decompress_ptr cinfo) 251 { 252 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 253 JDIMENSION MCU_col_num; /* index of current MCU within row */ 254 int blkn, ci, xindex, yindex, yoffset; 255 JDIMENSION start_col; 256 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; 257 JBLOCKROW buffer_ptr; 258 jpeg_component_info *compptr; 259 260 /* Align the virtual buffers for the components used in this scan. */ 261 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 262 compptr = cinfo->cur_comp_info[ci]; 263 buffer[ci] = (*cinfo->mem->access_virt_barray) 264 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], 265 cinfo->input_iMCU_row * compptr->v_samp_factor, 266 (JDIMENSION) compptr->v_samp_factor, TRUE); 267 /* Note: entropy decoder expects buffer to be zeroed, 268 * but this is handled automatically by the memory manager 269 * because we requested a pre-zeroed array. 270 */ 271 } 272 273 /* Loop to process one whole iMCU row */ 274 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; 275 yoffset++) { 276 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row; 277 MCU_col_num++) { 278 /* Construct list of pointers to DCT blocks belonging to this MCU */ 279 blkn = 0; /* index of current DCT block within MCU */ 280 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { 281 compptr = cinfo->cur_comp_info[ci]; 282 start_col = MCU_col_num * compptr->MCU_width; 283 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { 284 buffer_ptr = buffer[ci][yindex+yoffset] + start_col; 285 for (xindex = 0; xindex < compptr->MCU_width; xindex++) { 286 coef->MCU_buffer[blkn++] = buffer_ptr++; 287 } 288 } 289 } 290 /* Try to fetch the MCU. */ 291 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { 292 /* Suspension forced; update state counters and exit */ 293 coef->MCU_vert_offset = yoffset; 294 coef->MCU_ctr = MCU_col_num; 295 return JPEG_SUSPENDED; 296 } 297 } 298 /* Completed an MCU row, but perhaps not an iMCU row */ 299 coef->MCU_ctr = 0; 300 } 301 /* Completed the iMCU row, advance counters for next one */ 302 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { 303 start_iMCU_row(cinfo); 304 return JPEG_ROW_COMPLETED; 305 } 306 /* Completed the scan */ 307 (*cinfo->inputctl->finish_input_pass) (cinfo); 308 return JPEG_SCAN_COMPLETED; 309 } 310 311 312 /* 313 * Decompress and return some data in the multi-pass case. 314 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). 315 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. 316 * 317 * NB: output_buf contains a plane for each component in image. 318 */ 319 320 METHODDEF(int) 321 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 322 { 323 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 324 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 325 JDIMENSION block_num; 326 int ci, block_row, block_rows; 327 JBLOCKARRAY buffer; 328 JBLOCKROW buffer_ptr; 329 JSAMPARRAY output_ptr; 330 JDIMENSION output_col; 331 jpeg_component_info *compptr; 332 inverse_DCT_method_ptr inverse_DCT; 333 334 /* Force some input to be done if we are getting ahead of the input. */ 335 while (cinfo->input_scan_number < cinfo->output_scan_number || 336 (cinfo->input_scan_number == cinfo->output_scan_number && 337 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) { 338 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 339 return JPEG_SUSPENDED; 340 } 341 342 /* OK, output from the virtual arrays. */ 343 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 344 ci++, compptr++) { 345 /* Don't bother to IDCT an uninteresting component. */ 346 if (! compptr->component_needed) 347 continue; 348 /* Align the virtual buffer for this component. */ 349 buffer = (*cinfo->mem->access_virt_barray) 350 ((j_common_ptr) cinfo, coef->whole_image[ci], 351 cinfo->output_iMCU_row * compptr->v_samp_factor, 352 (JDIMENSION) compptr->v_samp_factor, FALSE); 353 /* Count non-dummy DCT block rows in this iMCU row. */ 354 if (cinfo->output_iMCU_row < last_iMCU_row) 355 block_rows = compptr->v_samp_factor; 356 else { 357 /* NB: can't use last_row_height here; it is input-side-dependent! */ 358 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 359 if (block_rows == 0) block_rows = compptr->v_samp_factor; 360 } 361 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 362 output_ptr = output_buf[ci]; 363 /* Loop over all DCT blocks to be processed. */ 364 for (block_row = 0; block_row < block_rows; block_row++) { 365 buffer_ptr = buffer[block_row]; 366 output_col = 0; 367 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) { 368 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr, 369 output_ptr, output_col); 370 buffer_ptr++; 371 output_col += compptr->_DCT_scaled_size; 372 } 373 output_ptr += compptr->_DCT_scaled_size; 374 } 375 } 376 377 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 378 return JPEG_ROW_COMPLETED; 379 return JPEG_SCAN_COMPLETED; 380 } 381 382 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 383 384 385 #ifdef BLOCK_SMOOTHING_SUPPORTED 386 387 /* 388 * This code applies interblock smoothing as described by section K.8 389 * of the JPEG standard: the first 5 AC coefficients are estimated from 390 * the DC values of a DCT block and its 8 neighboring blocks. 391 * We apply smoothing only for progressive JPEG decoding, and only if 392 * the coefficients it can estimate are not yet known to full precision. 393 */ 394 395 /* Natural-order array positions of the first 5 zigzag-order coefficients */ 396 #define Q01_POS 1 397 #define Q10_POS 8 398 #define Q20_POS 16 399 #define Q11_POS 9 400 #define Q02_POS 2 401 402 /* 403 * Determine whether block smoothing is applicable and safe. 404 * We also latch the current states of the coef_bits[] entries for the 405 * AC coefficients; otherwise, if the input side of the decompressor 406 * advances into a new scan, we might think the coefficients are known 407 * more accurately than they really are. 408 */ 409 410 LOCAL(boolean) 411 smoothing_ok (j_decompress_ptr cinfo) 412 { 413 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 414 boolean smoothing_useful = FALSE; 415 int ci, coefi; 416 jpeg_component_info *compptr; 417 JQUANT_TBL * qtable; 418 int * coef_bits; 419 int * coef_bits_latch; 420 421 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL) 422 return FALSE; 423 424 /* Allocate latch area if not already done */ 425 if (coef->coef_bits_latch == NULL) 426 coef->coef_bits_latch = (int *) 427 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 428 cinfo->num_components * 429 (SAVED_COEFS * SIZEOF(int))); 430 coef_bits_latch = coef->coef_bits_latch; 431 432 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 433 ci++, compptr++) { 434 /* All components' quantization values must already be latched. */ 435 if ((qtable = compptr->quant_table) == NULL) 436 return FALSE; 437 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */ 438 if (qtable->quantval[0] == 0 || 439 qtable->quantval[Q01_POS] == 0 || 440 qtable->quantval[Q10_POS] == 0 || 441 qtable->quantval[Q20_POS] == 0 || 442 qtable->quantval[Q11_POS] == 0 || 443 qtable->quantval[Q02_POS] == 0) 444 return FALSE; 445 /* DC values must be at least partly known for all components. */ 446 coef_bits = cinfo->coef_bits[ci]; 447 if (coef_bits[0] < 0) 448 return FALSE; 449 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */ 450 for (coefi = 1; coefi <= 5; coefi++) { 451 coef_bits_latch[coefi] = coef_bits[coefi]; 452 if (coef_bits[coefi] != 0) 453 smoothing_useful = TRUE; 454 } 455 coef_bits_latch += SAVED_COEFS; 456 } 457 458 return smoothing_useful; 459 } 460 461 462 /* 463 * Variant of decompress_data for use when doing block smoothing. 464 */ 465 466 METHODDEF(int) 467 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) 468 { 469 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; 470 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; 471 JDIMENSION block_num, last_block_column; 472 int ci, block_row, block_rows, access_rows; 473 JBLOCKARRAY buffer; 474 JBLOCKROW buffer_ptr, prev_block_row, next_block_row; 475 JSAMPARRAY output_ptr; 476 JDIMENSION output_col; 477 jpeg_component_info *compptr; 478 inverse_DCT_method_ptr inverse_DCT; 479 boolean first_row, last_row; 480 JCOEF * workspace; 481 int *coef_bits; 482 JQUANT_TBL *quanttbl; 483 INT32 Q00,Q01,Q02,Q10,Q11,Q20, num; 484 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9; 485 int Al, pred; 486 487 /* Keep a local variable to avoid looking it up more than once */ 488 workspace = coef->workspace; 489 490 /* Force some input to be done if we are getting ahead of the input. */ 491 while (cinfo->input_scan_number <= cinfo->output_scan_number && 492 ! cinfo->inputctl->eoi_reached) { 493 if (cinfo->input_scan_number == cinfo->output_scan_number) { 494 /* If input is working on current scan, we ordinarily want it to 495 * have completed the current row. But if input scan is DC, 496 * we want it to keep one row ahead so that next block row's DC 497 * values are up to date. 498 */ 499 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0; 500 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta) 501 break; 502 } 503 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) 504 return JPEG_SUSPENDED; 505 } 506 507 /* OK, output from the virtual arrays. */ 508 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 509 ci++, compptr++) { 510 /* Don't bother to IDCT an uninteresting component. */ 511 if (! compptr->component_needed) 512 continue; 513 /* Count non-dummy DCT block rows in this iMCU row. */ 514 if (cinfo->output_iMCU_row < last_iMCU_row) { 515 block_rows = compptr->v_samp_factor; 516 access_rows = block_rows * 2; /* this and next iMCU row */ 517 last_row = FALSE; 518 } else { 519 /* NB: can't use last_row_height here; it is input-side-dependent! */ 520 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); 521 if (block_rows == 0) block_rows = compptr->v_samp_factor; 522 access_rows = block_rows; /* this iMCU row only */ 523 last_row = TRUE; 524 } 525 /* Align the virtual buffer for this component. */ 526 if (cinfo->output_iMCU_row > 0) { 527 access_rows += compptr->v_samp_factor; /* prior iMCU row too */ 528 buffer = (*cinfo->mem->access_virt_barray) 529 ((j_common_ptr) cinfo, coef->whole_image[ci], 530 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor, 531 (JDIMENSION) access_rows, FALSE); 532 buffer += compptr->v_samp_factor; /* point to current iMCU row */ 533 first_row = FALSE; 534 } else { 535 buffer = (*cinfo->mem->access_virt_barray) 536 ((j_common_ptr) cinfo, coef->whole_image[ci], 537 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE); 538 first_row = TRUE; 539 } 540 /* Fetch component-dependent info */ 541 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS); 542 quanttbl = compptr->quant_table; 543 Q00 = quanttbl->quantval[0]; 544 Q01 = quanttbl->quantval[Q01_POS]; 545 Q10 = quanttbl->quantval[Q10_POS]; 546 Q20 = quanttbl->quantval[Q20_POS]; 547 Q11 = quanttbl->quantval[Q11_POS]; 548 Q02 = quanttbl->quantval[Q02_POS]; 549 inverse_DCT = cinfo->idct->inverse_DCT[ci]; 550 output_ptr = output_buf[ci]; 551 /* Loop over all DCT blocks to be processed. */ 552 for (block_row = 0; block_row < block_rows; block_row++) { 553 buffer_ptr = buffer[block_row]; 554 if (first_row && block_row == 0) 555 prev_block_row = buffer_ptr; 556 else 557 prev_block_row = buffer[block_row-1]; 558 if (last_row && block_row == block_rows-1) 559 next_block_row = buffer_ptr; 560 else 561 next_block_row = buffer[block_row+1]; 562 /* We fetch the surrounding DC values using a sliding-register approach. 563 * Initialize all nine here so as to do the right thing on narrow pics. 564 */ 565 DC1 = DC2 = DC3 = (int) prev_block_row[0][0]; 566 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0]; 567 DC7 = DC8 = DC9 = (int) next_block_row[0][0]; 568 output_col = 0; 569 last_block_column = compptr->width_in_blocks - 1; 570 for (block_num = 0; block_num <= last_block_column; block_num++) { 571 /* Fetch current DCT block into workspace so we can modify it. */ 572 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1); 573 /* Update DC values */ 574 if (block_num < last_block_column) { 575 DC3 = (int) prev_block_row[1][0]; 576 DC6 = (int) buffer_ptr[1][0]; 577 DC9 = (int) next_block_row[1][0]; 578 } 579 /* Compute coefficient estimates per K.8. 580 * An estimate is applied only if coefficient is still zero, 581 * and is not known to be fully accurate. 582 */ 583 /* AC01 */ 584 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) { 585 num = 36 * Q00 * (DC4 - DC6); 586 if (num >= 0) { 587 pred = (int) (((Q01<<7) + num) / (Q01<<8)); 588 if (Al > 0 && pred >= (1<<Al)) 589 pred = (1<<Al)-1; 590 } else { 591 pred = (int) (((Q01<<7) - num) / (Q01<<8)); 592 if (Al > 0 && pred >= (1<<Al)) 593 pred = (1<<Al)-1; 594 pred = -pred; 595 } 596 workspace[1] = (JCOEF) pred; 597 } 598 /* AC10 */ 599 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) { 600 num = 36 * Q00 * (DC2 - DC8); 601 if (num >= 0) { 602 pred = (int) (((Q10<<7) + num) / (Q10<<8)); 603 if (Al > 0 && pred >= (1<<Al)) 604 pred = (1<<Al)-1; 605 } else { 606 pred = (int) (((Q10<<7) - num) / (Q10<<8)); 607 if (Al > 0 && pred >= (1<<Al)) 608 pred = (1<<Al)-1; 609 pred = -pred; 610 } 611 workspace[8] = (JCOEF) pred; 612 } 613 /* AC20 */ 614 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) { 615 num = 9 * Q00 * (DC2 + DC8 - 2*DC5); 616 if (num >= 0) { 617 pred = (int) (((Q20<<7) + num) / (Q20<<8)); 618 if (Al > 0 && pred >= (1<<Al)) 619 pred = (1<<Al)-1; 620 } else { 621 pred = (int) (((Q20<<7) - num) / (Q20<<8)); 622 if (Al > 0 && pred >= (1<<Al)) 623 pred = (1<<Al)-1; 624 pred = -pred; 625 } 626 workspace[16] = (JCOEF) pred; 627 } 628 /* AC11 */ 629 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) { 630 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9); 631 if (num >= 0) { 632 pred = (int) (((Q11<<7) + num) / (Q11<<8)); 633 if (Al > 0 && pred >= (1<<Al)) 634 pred = (1<<Al)-1; 635 } else { 636 pred = (int) (((Q11<<7) - num) / (Q11<<8)); 637 if (Al > 0 && pred >= (1<<Al)) 638 pred = (1<<Al)-1; 639 pred = -pred; 640 } 641 workspace[9] = (JCOEF) pred; 642 } 643 /* AC02 */ 644 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) { 645 num = 9 * Q00 * (DC4 + DC6 - 2*DC5); 646 if (num >= 0) { 647 pred = (int) (((Q02<<7) + num) / (Q02<<8)); 648 if (Al > 0 && pred >= (1<<Al)) 649 pred = (1<<Al)-1; 650 } else { 651 pred = (int) (((Q02<<7) - num) / (Q02<<8)); 652 if (Al > 0 && pred >= (1<<Al)) 653 pred = (1<<Al)-1; 654 pred = -pred; 655 } 656 workspace[2] = (JCOEF) pred; 657 } 658 /* OK, do the IDCT */ 659 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace, 660 output_ptr, output_col); 661 /* Advance for next column */ 662 DC1 = DC2; DC2 = DC3; 663 DC4 = DC5; DC5 = DC6; 664 DC7 = DC8; DC8 = DC9; 665 buffer_ptr++, prev_block_row++, next_block_row++; 666 output_col += compptr->_DCT_scaled_size; 667 } 668 output_ptr += compptr->_DCT_scaled_size; 669 } 670 } 671 672 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) 673 return JPEG_ROW_COMPLETED; 674 return JPEG_SCAN_COMPLETED; 675 } 676 677 #endif /* BLOCK_SMOOTHING_SUPPORTED */ 678 679 680 /* 681 * Initialize coefficient buffer controller. 682 */ 683 684 GLOBAL(void) 685 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer) 686 { 687 my_coef_ptr coef; 688 689 coef = (my_coef_ptr) 690 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 691 SIZEOF(my_coef_controller)); 692 cinfo->coef = (struct jpeg_d_coef_controller *) coef; 693 coef->pub.start_input_pass = start_input_pass; 694 coef->pub.start_output_pass = start_output_pass; 695 #ifdef BLOCK_SMOOTHING_SUPPORTED 696 coef->coef_bits_latch = NULL; 697 #endif 698 699 /* Create the coefficient buffer. */ 700 if (need_full_buffer) { 701 #ifdef D_MULTISCAN_FILES_SUPPORTED 702 /* Allocate a full-image virtual array for each component, */ 703 /* padded to a multiple of samp_factor DCT blocks in each direction. */ 704 /* Note we ask for a pre-zeroed array. */ 705 int ci, access_rows; 706 jpeg_component_info *compptr; 707 708 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 709 ci++, compptr++) { 710 access_rows = compptr->v_samp_factor; 711 #ifdef BLOCK_SMOOTHING_SUPPORTED 712 /* If block smoothing could be used, need a bigger window */ 713 if (cinfo->progressive_mode) 714 access_rows *= 3; 715 #endif 716 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) 717 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE, 718 (JDIMENSION) jround_up((long) compptr->width_in_blocks, 719 (long) compptr->h_samp_factor), 720 (JDIMENSION) jround_up((long) compptr->height_in_blocks, 721 (long) compptr->v_samp_factor), 722 (JDIMENSION) access_rows); 723 } 724 coef->pub.consume_data = consume_data; 725 coef->pub.decompress_data = decompress_data; 726 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */ 727 #else 728 ERREXIT(cinfo, JERR_NOT_COMPILED); 729 #endif 730 } else { 731 /* We only need a single-MCU buffer. */ 732 JBLOCKROW buffer; 733 int i; 734 735 buffer = (JBLOCKROW) 736 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, 737 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); 738 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) { 739 coef->MCU_buffer[i] = buffer + i; 740 } 741 coef->pub.consume_data = dummy_consume_data; 742 coef->pub.decompress_data = decompress_onepass; 743 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */ 744 } 745 746 /* Allocate the workspace buffer */ 747 coef->workspace = (JCOEF *) 748 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 749 SIZEOF(JCOEF) * DCTSIZE2); 750 } 751
