1 /* 2 * jdmaster.c 3 * 4 * Copyright (C) 1991-1997, 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 master control logic for the JPEG decompressor. 10 * These routines are concerned with selecting the modules to be executed 11 * and with determining the number of passes and the work to be done in each 12 * pass. 13 */ 14 15 #define JPEG_INTERNALS 16 #include "jinclude.h" 17 #include "jpeglib.h" 18 19 20 /* Private state */ 21 22 typedef struct { 23 struct jpeg_decomp_master pub; /* public fields */ 24 25 int pass_number; /* # of passes completed */ 26 27 boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */ 28 29 /* Saved references to initialized quantizer modules, 30 * in case we need to switch modes. 31 */ 32 struct jpeg_color_quantizer * quantizer_1pass; 33 struct jpeg_color_quantizer * quantizer_2pass; 34 } my_decomp_master; 35 36 typedef my_decomp_master * my_master_ptr; 37 38 39 /* 40 * Determine whether merged upsample/color conversion should be used. 41 * CRUCIAL: this must match the actual capabilities of jdmerge.c! 42 */ 43 44 LOCAL(boolean) 45 use_merged_upsample (j_decompress_ptr cinfo) 46 { 47 #ifdef UPSAMPLE_MERGING_SUPPORTED 48 /* Merging is the equivalent of plain box-filter upsampling */ 49 if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling) 50 return FALSE; 51 /* jdmerge.c only supports YCC=>RGB color conversion */ 52 if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 || 53 cinfo->out_color_space != JCS_RGB || 54 cinfo->out_color_components != RGB_PIXELSIZE) 55 return FALSE; 56 /* and it only handles 2h1v or 2h2v sampling ratios */ 57 if (cinfo->comp_info[0].h_samp_factor != 2 || 58 cinfo->comp_info[1].h_samp_factor != 1 || 59 cinfo->comp_info[2].h_samp_factor != 1 || 60 cinfo->comp_info[0].v_samp_factor > 2 || 61 cinfo->comp_info[1].v_samp_factor != 1 || 62 cinfo->comp_info[2].v_samp_factor != 1) 63 return FALSE; 64 /* furthermore, it doesn't work if we've scaled the IDCTs differently */ 65 if (cinfo->comp_info[0].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size || 66 cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size || 67 cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size || 68 cinfo->comp_info[0].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size || 69 cinfo->comp_info[1].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size || 70 cinfo->comp_info[2].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size) 71 return FALSE; 72 /* ??? also need to test for upsample-time rescaling, when & if supported */ 73 return TRUE; /* by golly, it'll work... */ 74 #else 75 return FALSE; 76 #endif 77 } 78 79 80 /* 81 * Compute output image dimensions and related values. 82 * NOTE: this is exported for possible use by application. 83 * Hence it mustn't do anything that can't be done twice. 84 * Also note that it may be called before the master module is initialized! 85 */ 86 87 GLOBAL(void) 88 jpeg_calc_output_dimensions (j_decompress_ptr cinfo) 89 /* Do computations that are needed before master selection phase. 90 * This function is used for full decompression. 91 */ 92 { 93 #ifdef IDCT_SCALING_SUPPORTED 94 int ci; 95 jpeg_component_info *compptr; 96 #endif 97 98 /* Prevent application from calling me at wrong times */ 99 if (cinfo->global_state != DSTATE_READY) 100 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 101 102 /* Compute core output image dimensions and DCT scaling choices. */ 103 jpeg_core_output_dimensions(cinfo); 104 105 #ifdef IDCT_SCALING_SUPPORTED 106 107 /* In selecting the actual DCT scaling for each component, we try to 108 * scale up the chroma components via IDCT scaling rather than upsampling. 109 * This saves time if the upsampler gets to use 1:1 scaling. 110 * Note this code adapts subsampling ratios which are powers of 2. 111 */ 112 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 113 ci++, compptr++) { 114 int ssize = 1; 115 while (cinfo->min_DCT_h_scaled_size * ssize <= 116 (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) && 117 (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) { 118 ssize = ssize * 2; 119 } 120 compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize; 121 ssize = 1; 122 while (cinfo->min_DCT_v_scaled_size * ssize <= 123 (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) && 124 (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) { 125 ssize = ssize * 2; 126 } 127 compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize; 128 129 /* We don't support IDCT ratios larger than 2. */ 130 if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2) 131 compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2; 132 else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2) 133 compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2; 134 } 135 136 /* Recompute downsampled dimensions of components; 137 * application needs to know these if using raw downsampled data. 138 */ 139 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 140 ci++, compptr++) { 141 /* Size in samples, after IDCT scaling */ 142 compptr->downsampled_width = (JDIMENSION) 143 jdiv_round_up((long) cinfo->image_width * 144 (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size), 145 (long) (cinfo->max_h_samp_factor * cinfo->block_size)); 146 compptr->downsampled_height = (JDIMENSION) 147 jdiv_round_up((long) cinfo->image_height * 148 (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size), 149 (long) (cinfo->max_v_samp_factor * cinfo->block_size)); 150 } 151 152 #endif /* IDCT_SCALING_SUPPORTED */ 153 154 /* Report number of components in selected colorspace. */ 155 /* Probably this should be in the color conversion module... */ 156 switch (cinfo->out_color_space) { 157 case JCS_GRAYSCALE: 158 cinfo->out_color_components = 1; 159 break; 160 case JCS_RGB: 161 cinfo->out_color_components = RGB_PIXELSIZE; 162 break; 163 case JCS_YCbCr: 164 cinfo->out_color_components = 3; 165 break; 166 case JCS_CMYK: 167 case JCS_YCCK: 168 cinfo->out_color_components = 4; 169 break; 170 default: /* else must be same colorspace as in file */ 171 cinfo->out_color_components = cinfo->num_components; 172 break; 173 } 174 cinfo->output_components = (cinfo->quantize_colors ? 1 : 175 cinfo->out_color_components); 176 177 /* See if upsampler will want to emit more than one row at a time */ 178 if (use_merged_upsample(cinfo)) 179 cinfo->rec_outbuf_height = cinfo->max_v_samp_factor; 180 else 181 cinfo->rec_outbuf_height = 1; 182 } 183 184 185 /* 186 * Several decompression processes need to range-limit values to the range 187 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range 188 * due to noise introduced by quantization, roundoff error, etc. These 189 * processes are inner loops and need to be as fast as possible. On most 190 * machines, particularly CPUs with pipelines or instruction prefetch, 191 * a (subscript-check-less) C table lookup 192 * x = sample_range_limit[x]; 193 * is faster than explicit tests 194 * if (x < 0) x = 0; 195 * else if (x > MAXJSAMPLE) x = MAXJSAMPLE; 196 * These processes all use a common table prepared by the routine below. 197 * 198 * For most steps we can mathematically guarantee that the initial value 199 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from 200 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial 201 * limiting step (just after the IDCT), a wildly out-of-range value is 202 * possible if the input data is corrupt. To avoid any chance of indexing 203 * off the end of memory and getting a bad-pointer trap, we perform the 204 * post-IDCT limiting thus: 205 * x = range_limit[x & MASK]; 206 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit 207 * samples. Under normal circumstances this is more than enough range and 208 * a correct output will be generated; with bogus input data the mask will 209 * cause wraparound, and we will safely generate a bogus-but-in-range output. 210 * For the post-IDCT step, we want to convert the data from signed to unsigned 211 * representation by adding CENTERJSAMPLE at the same time that we limit it. 212 * So the post-IDCT limiting table ends up looking like this: 213 * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE, 214 * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times), 215 * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times), 216 * 0,1,...,CENTERJSAMPLE-1 217 * Negative inputs select values from the upper half of the table after 218 * masking. 219 * 220 * We can save some space by overlapping the start of the post-IDCT table 221 * with the simpler range limiting table. The post-IDCT table begins at 222 * sample_range_limit + CENTERJSAMPLE. 223 * 224 * Note that the table is allocated in near data space on PCs; it's small 225 * enough and used often enough to justify this. 226 */ 227 228 LOCAL(void) 229 prepare_range_limit_table (j_decompress_ptr cinfo) 230 /* Allocate and fill in the sample_range_limit table */ 231 { 232 JSAMPLE * table; 233 int i; 234 235 table = (JSAMPLE *) 236 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 237 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE)); 238 table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */ 239 cinfo->sample_range_limit = table; 240 /* First segment of "simple" table: limit[x] = 0 for x < 0 */ 241 MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE)); 242 /* Main part of "simple" table: limit[x] = x */ 243 for (i = 0; i <= MAXJSAMPLE; i++) 244 table[i] = (JSAMPLE) i; 245 table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */ 246 /* End of simple table, rest of first half of post-IDCT table */ 247 for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++) 248 table[i] = MAXJSAMPLE; 249 /* Second half of post-IDCT table */ 250 MEMZERO(table + (2 * (MAXJSAMPLE+1)), 251 (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE)); 252 MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE), 253 cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE)); 254 } 255 256 257 /* 258 * Master selection of decompression modules. 259 * This is done once at jpeg_start_decompress time. We determine 260 * which modules will be used and give them appropriate initialization calls. 261 * We also initialize the decompressor input side to begin consuming data. 262 * 263 * Since jpeg_read_header has finished, we know what is in the SOF 264 * and (first) SOS markers. We also have all the application parameter 265 * settings. 266 */ 267 268 LOCAL(void) 269 master_selection (j_decompress_ptr cinfo) 270 { 271 my_master_ptr master = (my_master_ptr) cinfo->master; 272 boolean use_c_buffer; 273 long samplesperrow; 274 JDIMENSION jd_samplesperrow; 275 276 /* Initialize dimensions and other stuff */ 277 jpeg_calc_output_dimensions(cinfo); 278 prepare_range_limit_table(cinfo); 279 280 /* Width of an output scanline must be representable as JDIMENSION. */ 281 samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components; 282 jd_samplesperrow = (JDIMENSION) samplesperrow; 283 if ((long) jd_samplesperrow != samplesperrow) 284 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW); 285 286 /* Initialize my private state */ 287 master->pass_number = 0; 288 master->using_merged_upsample = use_merged_upsample(cinfo); 289 290 /* Color quantizer selection */ 291 master->quantizer_1pass = NULL; 292 master->quantizer_2pass = NULL; 293 /* No mode changes if not using buffered-image mode. */ 294 if (! cinfo->quantize_colors || ! cinfo->buffered_image) { 295 cinfo->enable_1pass_quant = FALSE; 296 cinfo->enable_external_quant = FALSE; 297 cinfo->enable_2pass_quant = FALSE; 298 } 299 if (cinfo->quantize_colors) { 300 if (cinfo->raw_data_out) 301 ERREXIT(cinfo, JERR_NOTIMPL); 302 /* 2-pass quantizer only works in 3-component color space. */ 303 if (cinfo->out_color_components != 3) { 304 cinfo->enable_1pass_quant = TRUE; 305 cinfo->enable_external_quant = FALSE; 306 cinfo->enable_2pass_quant = FALSE; 307 cinfo->colormap = NULL; 308 } else if (cinfo->colormap != NULL) { 309 cinfo->enable_external_quant = TRUE; 310 } else if (cinfo->two_pass_quantize) { 311 cinfo->enable_2pass_quant = TRUE; 312 } else { 313 cinfo->enable_1pass_quant = TRUE; 314 } 315 316 if (cinfo->enable_1pass_quant) { 317 #ifdef QUANT_1PASS_SUPPORTED 318 jinit_1pass_quantizer(cinfo); 319 master->quantizer_1pass = cinfo->cquantize; 320 #else 321 ERREXIT(cinfo, JERR_NOT_COMPILED); 322 #endif 323 } 324 325 /* We use the 2-pass code to map to external colormaps. */ 326 if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) { 327 #ifdef QUANT_2PASS_SUPPORTED 328 jinit_2pass_quantizer(cinfo); 329 master->quantizer_2pass = cinfo->cquantize; 330 #else 331 ERREXIT(cinfo, JERR_NOT_COMPILED); 332 #endif 333 } 334 /* If both quantizers are initialized, the 2-pass one is left active; 335 * this is necessary for starting with quantization to an external map. 336 */ 337 } 338 339 /* Post-processing: in particular, color conversion first */ 340 if (! cinfo->raw_data_out) { 341 if (master->using_merged_upsample) { 342 #ifdef UPSAMPLE_MERGING_SUPPORTED 343 jinit_merged_upsampler(cinfo); /* does color conversion too */ 344 #else 345 ERREXIT(cinfo, JERR_NOT_COMPILED); 346 #endif 347 } else { 348 jinit_color_deconverter(cinfo); 349 jinit_upsampler(cinfo); 350 } 351 jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant); 352 } 353 /* Inverse DCT */ 354 jinit_inverse_dct(cinfo); 355 /* Entropy decoding: either Huffman or arithmetic coding. */ 356 if (cinfo->arith_code) 357 jinit_arith_decoder(cinfo); 358 else { 359 jinit_huff_decoder(cinfo); 360 } 361 362 /* Initialize principal buffer controllers. */ 363 use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image; 364 jinit_d_coef_controller(cinfo, use_c_buffer); 365 366 if (! cinfo->raw_data_out) 367 jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */); 368 369 /* We can now tell the memory manager to allocate virtual arrays. */ 370 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo); 371 372 /* Initialize input side of decompressor to consume first scan. */ 373 (*cinfo->inputctl->start_input_pass) (cinfo); 374 375 #ifdef D_MULTISCAN_FILES_SUPPORTED 376 /* If jpeg_start_decompress will read the whole file, initialize 377 * progress monitoring appropriately. The input step is counted 378 * as one pass. 379 */ 380 if (cinfo->progress != NULL && ! cinfo->buffered_image && 381 cinfo->inputctl->has_multiple_scans) { 382 int nscans; 383 /* Estimate number of scans to set pass_limit. */ 384 if (cinfo->progressive_mode) { 385 /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */ 386 nscans = 2 + 3 * cinfo->num_components; 387 } else { 388 /* For a nonprogressive multiscan file, estimate 1 scan per component. */ 389 nscans = cinfo->num_components; 390 } 391 cinfo->progress->pass_counter = 0L; 392 cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans; 393 cinfo->progress->completed_passes = 0; 394 cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2); 395 /* Count the input pass as done */ 396 master->pass_number++; 397 } 398 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 399 } 400 401 402 /* 403 * Per-pass setup. 404 * This is called at the beginning of each output pass. We determine which 405 * modules will be active during this pass and give them appropriate 406 * start_pass calls. We also set is_dummy_pass to indicate whether this 407 * is a "real" output pass or a dummy pass for color quantization. 408 * (In the latter case, jdapistd.c will crank the pass to completion.) 409 */ 410 411 METHODDEF(void) 412 prepare_for_output_pass (j_decompress_ptr cinfo) 413 { 414 my_master_ptr master = (my_master_ptr) cinfo->master; 415 416 if (master->pub.is_dummy_pass) { 417 #ifdef QUANT_2PASS_SUPPORTED 418 /* Final pass of 2-pass quantization */ 419 master->pub.is_dummy_pass = FALSE; 420 (*cinfo->cquantize->start_pass) (cinfo, FALSE); 421 (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST); 422 (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST); 423 #else 424 ERREXIT(cinfo, JERR_NOT_COMPILED); 425 #endif /* QUANT_2PASS_SUPPORTED */ 426 } else { 427 if (cinfo->quantize_colors && cinfo->colormap == NULL) { 428 /* Select new quantization method */ 429 if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) { 430 cinfo->cquantize = master->quantizer_2pass; 431 master->pub.is_dummy_pass = TRUE; 432 } else if (cinfo->enable_1pass_quant) { 433 cinfo->cquantize = master->quantizer_1pass; 434 } else { 435 ERREXIT(cinfo, JERR_MODE_CHANGE); 436 } 437 } 438 (*cinfo->idct->start_pass) (cinfo); 439 (*cinfo->coef->start_output_pass) (cinfo); 440 if (! cinfo->raw_data_out) { 441 if (! master->using_merged_upsample) 442 (*cinfo->cconvert->start_pass) (cinfo); 443 (*cinfo->upsample->start_pass) (cinfo); 444 if (cinfo->quantize_colors) 445 (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass); 446 (*cinfo->post->start_pass) (cinfo, 447 (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU)); 448 (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU); 449 } 450 } 451 452 /* Set up progress monitor's pass info if present */ 453 if (cinfo->progress != NULL) { 454 cinfo->progress->completed_passes = master->pass_number; 455 cinfo->progress->total_passes = master->pass_number + 456 (master->pub.is_dummy_pass ? 2 : 1); 457 /* In buffered-image mode, we assume one more output pass if EOI not 458 * yet reached, but no more passes if EOI has been reached. 459 */ 460 if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) { 461 cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1); 462 } 463 } 464 } 465 466 467 /* 468 * Finish up at end of an output pass. 469 */ 470 471 METHODDEF(void) 472 finish_output_pass (j_decompress_ptr cinfo) 473 { 474 my_master_ptr master = (my_master_ptr) cinfo->master; 475 476 if (cinfo->quantize_colors) 477 (*cinfo->cquantize->finish_pass) (cinfo); 478 master->pass_number++; 479 } 480 481 482 #ifdef D_MULTISCAN_FILES_SUPPORTED 483 484 /* 485 * Switch to a new external colormap between output passes. 486 */ 487 488 GLOBAL(void) 489 jpeg_new_colormap (j_decompress_ptr cinfo) 490 { 491 my_master_ptr master = (my_master_ptr) cinfo->master; 492 493 /* Prevent application from calling me at wrong times */ 494 if (cinfo->global_state != DSTATE_BUFIMAGE) 495 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 496 497 if (cinfo->quantize_colors && cinfo->enable_external_quant && 498 cinfo->colormap != NULL) { 499 /* Select 2-pass quantizer for external colormap use */ 500 cinfo->cquantize = master->quantizer_2pass; 501 /* Notify quantizer of colormap change */ 502 (*cinfo->cquantize->new_color_map) (cinfo); 503 master->pub.is_dummy_pass = FALSE; /* just in case */ 504 } else 505 ERREXIT(cinfo, JERR_MODE_CHANGE); 506 } 507 508 #endif /* D_MULTISCAN_FILES_SUPPORTED */ 509 510 511 /* 512 * Initialize master decompression control and select active modules. 513 * This is performed at the start of jpeg_start_decompress. 514 */ 515 516 GLOBAL(void) 517 jinit_master_decompress (j_decompress_ptr cinfo) 518 { 519 my_master_ptr master; 520 521 master = (my_master_ptr) 522 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 523 SIZEOF(my_decomp_master)); 524 cinfo->master = (struct jpeg_decomp_master *) master; 525 master->pub.prepare_for_output_pass = prepare_for_output_pass; 526 master->pub.finish_output_pass = finish_output_pass; 527 528 master->pub.is_dummy_pass = FALSE; 529 530 master_selection(cinfo); 531 } 532
