1/* 2 * jdmaster.c 3 * 4 * Copyright (C) 1991-1997, Thomas G. Lane. 5 * Modified 2002-2009 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 22typedef 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 36typedef 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 44LOCAL(boolean) 45use_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 87GLOBAL(void) 88jpeg_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#if RGB_PIXELSIZE != 3 162 cinfo->out_color_components = RGB_PIXELSIZE; 163 break; 164#endif /* else share code with YCbCr */ 165 case JCS_YCbCr: 166 cinfo->out_color_components = 3; 167 break; 168 case JCS_CMYK: 169 case JCS_YCCK: 170 cinfo->out_color_components = 4; 171 break; 172 default: /* else must be same colorspace as in file */ 173 cinfo->out_color_components = cinfo->num_components; 174 break; 175 } 176 cinfo->output_components = (cinfo->quantize_colors ? 1 : 177 cinfo->out_color_components); 178 179 /* See if upsampler will want to emit more than one row at a time */ 180 if (use_merged_upsample(cinfo)) 181 cinfo->rec_outbuf_height = cinfo->max_v_samp_factor; 182 else 183 cinfo->rec_outbuf_height = 1; 184} 185 186 187/* 188 * Several decompression processes need to range-limit values to the range 189 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range 190 * due to noise introduced by quantization, roundoff error, etc. These 191 * processes are inner loops and need to be as fast as possible. On most 192 * machines, particularly CPUs with pipelines or instruction prefetch, 193 * a (subscript-check-less) C table lookup 194 * x = sample_range_limit[x]; 195 * is faster than explicit tests 196 * if (x < 0) x = 0; 197 * else if (x > MAXJSAMPLE) x = MAXJSAMPLE; 198 * These processes all use a common table prepared by the routine below. 199 * 200 * For most steps we can mathematically guarantee that the initial value 201 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from 202 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial 203 * limiting step (just after the IDCT), a wildly out-of-range value is 204 * possible if the input data is corrupt. To avoid any chance of indexing 205 * off the end of memory and getting a bad-pointer trap, we perform the 206 * post-IDCT limiting thus: 207 * x = range_limit[x & MASK]; 208 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit 209 * samples. Under normal circumstances this is more than enough range and 210 * a correct output will be generated; with bogus input data the mask will 211 * cause wraparound, and we will safely generate a bogus-but-in-range output. 212 * For the post-IDCT step, we want to convert the data from signed to unsigned 213 * representation by adding CENTERJSAMPLE at the same time that we limit it. 214 * So the post-IDCT limiting table ends up looking like this: 215 * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE, 216 * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times), 217 * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times), 218 * 0,1,...,CENTERJSAMPLE-1 219 * Negative inputs select values from the upper half of the table after 220 * masking. 221 * 222 * We can save some space by overlapping the start of the post-IDCT table 223 * with the simpler range limiting table. The post-IDCT table begins at 224 * sample_range_limit + CENTERJSAMPLE. 225 * 226 * Note that the table is allocated in near data space on PCs; it's small 227 * enough and used often enough to justify this. 228 */ 229 230LOCAL(void) 231prepare_range_limit_table (j_decompress_ptr cinfo) 232/* Allocate and fill in the sample_range_limit table */ 233{ 234 JSAMPLE * table; 235 int i; 236 237 table = (JSAMPLE *) 238 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 239 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE)); 240 table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */ 241 cinfo->sample_range_limit = table; 242 /* First segment of "simple" table: limit[x] = 0 for x < 0 */ 243 MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE)); 244 /* Main part of "simple" table: limit[x] = x */ 245 for (i = 0; i <= MAXJSAMPLE; i++) 246 table[i] = (JSAMPLE) i; 247 table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */ 248 /* End of simple table, rest of first half of post-IDCT table */ 249 for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++) 250 table[i] = MAXJSAMPLE; 251 /* Second half of post-IDCT table */ 252 MEMZERO(table + (2 * (MAXJSAMPLE+1)), 253 (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE)); 254 MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE), 255 cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE)); 256} 257 258 259/* 260 * Master selection of decompression modules. 261 * This is done once at jpeg_start_decompress time. We determine 262 * which modules will be used and give them appropriate initialization calls. 263 * We also initialize the decompressor input side to begin consuming data. 264 * 265 * Since jpeg_read_header has finished, we know what is in the SOF 266 * and (first) SOS markers. We also have all the application parameter 267 * settings. 268 */ 269 270LOCAL(void) 271master_selection (j_decompress_ptr cinfo) 272{ 273 my_master_ptr master = (my_master_ptr) cinfo->master; 274 boolean use_c_buffer; 275 long samplesperrow; 276 JDIMENSION jd_samplesperrow; 277 278 /* Initialize dimensions and other stuff */ 279 jpeg_calc_output_dimensions(cinfo); 280 prepare_range_limit_table(cinfo); 281 282 /* Width of an output scanline must be representable as JDIMENSION. */ 283 samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components; 284 jd_samplesperrow = (JDIMENSION) samplesperrow; 285 if ((long) jd_samplesperrow != samplesperrow) 286 ERREXIT(cinfo, JERR_WIDTH_OVERFLOW); 287 288 /* Initialize my private state */ 289 master->pass_number = 0; 290 master->using_merged_upsample = use_merged_upsample(cinfo); 291 292 /* Color quantizer selection */ 293 master->quantizer_1pass = NULL; 294 master->quantizer_2pass = NULL; 295 /* No mode changes if not using buffered-image mode. */ 296 if (! cinfo->quantize_colors || ! cinfo->buffered_image) { 297 cinfo->enable_1pass_quant = FALSE; 298 cinfo->enable_external_quant = FALSE; 299 cinfo->enable_2pass_quant = FALSE; 300 } 301 if (cinfo->quantize_colors) { 302 if (cinfo->raw_data_out) 303 ERREXIT(cinfo, JERR_NOTIMPL); 304 /* 2-pass quantizer only works in 3-component color space. */ 305 if (cinfo->out_color_components != 3) { 306 cinfo->enable_1pass_quant = TRUE; 307 cinfo->enable_external_quant = FALSE; 308 cinfo->enable_2pass_quant = FALSE; 309 cinfo->colormap = NULL; 310 } else if (cinfo->colormap != NULL) { 311 cinfo->enable_external_quant = TRUE; 312 } else if (cinfo->two_pass_quantize) { 313 cinfo->enable_2pass_quant = TRUE; 314 } else { 315 cinfo->enable_1pass_quant = TRUE; 316 } 317 318 if (cinfo->enable_1pass_quant) { 319#ifdef QUANT_1PASS_SUPPORTED 320 jinit_1pass_quantizer(cinfo); 321 master->quantizer_1pass = cinfo->cquantize; 322#else 323 ERREXIT(cinfo, JERR_NOT_COMPILED); 324#endif 325 } 326 327 /* We use the 2-pass code to map to external colormaps. */ 328 if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) { 329#ifdef QUANT_2PASS_SUPPORTED 330 jinit_2pass_quantizer(cinfo); 331 master->quantizer_2pass = cinfo->cquantize; 332#else 333 ERREXIT(cinfo, JERR_NOT_COMPILED); 334#endif 335 } 336 /* If both quantizers are initialized, the 2-pass one is left active; 337 * this is necessary for starting with quantization to an external map. 338 */ 339 } 340 341 /* Post-processing: in particular, color conversion first */ 342 if (! cinfo->raw_data_out) { 343 if (master->using_merged_upsample) { 344#ifdef UPSAMPLE_MERGING_SUPPORTED 345 jinit_merged_upsampler(cinfo); /* does color conversion too */ 346#else 347 ERREXIT(cinfo, JERR_NOT_COMPILED); 348#endif 349 } else { 350 jinit_color_deconverter(cinfo); 351 jinit_upsampler(cinfo); 352 } 353 jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant); 354 } 355 /* Inverse DCT */ 356 jinit_inverse_dct(cinfo); 357 /* Entropy decoding: either Huffman or arithmetic coding. */ 358 if (cinfo->arith_code) 359 jinit_arith_decoder(cinfo); 360 else { 361 jinit_huff_decoder(cinfo); 362 } 363 364 /* Initialize principal buffer controllers. */ 365 use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image; 366 jinit_d_coef_controller(cinfo, use_c_buffer); 367 368 if (! cinfo->raw_data_out) 369 jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */); 370 371 /* We can now tell the memory manager to allocate virtual arrays. */ 372 (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo); 373 374 /* Initialize input side of decompressor to consume first scan. */ 375 (*cinfo->inputctl->start_input_pass) (cinfo); 376 377#ifdef D_MULTISCAN_FILES_SUPPORTED 378 /* If jpeg_start_decompress will read the whole file, initialize 379 * progress monitoring appropriately. The input step is counted 380 * as one pass. 381 */ 382 if (cinfo->progress != NULL && ! cinfo->buffered_image && 383 cinfo->inputctl->has_multiple_scans) { 384 int nscans; 385 /* Estimate number of scans to set pass_limit. */ 386 if (cinfo->progressive_mode) { 387 /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */ 388 nscans = 2 + 3 * cinfo->num_components; 389 } else { 390 /* For a nonprogressive multiscan file, estimate 1 scan per component. */ 391 nscans = cinfo->num_components; 392 } 393 cinfo->progress->pass_counter = 0L; 394 cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans; 395 cinfo->progress->completed_passes = 0; 396 cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2); 397 /* Count the input pass as done */ 398 master->pass_number++; 399 } 400#endif /* D_MULTISCAN_FILES_SUPPORTED */ 401} 402 403 404/* 405 * Per-pass setup. 406 * This is called at the beginning of each output pass. We determine which 407 * modules will be active during this pass and give them appropriate 408 * start_pass calls. We also set is_dummy_pass to indicate whether this 409 * is a "real" output pass or a dummy pass for color quantization. 410 * (In the latter case, jdapistd.c will crank the pass to completion.) 411 */ 412 413METHODDEF(void) 414prepare_for_output_pass (j_decompress_ptr cinfo) 415{ 416 my_master_ptr master = (my_master_ptr) cinfo->master; 417 418 if (master->pub.is_dummy_pass) { 419#ifdef QUANT_2PASS_SUPPORTED 420 /* Final pass of 2-pass quantization */ 421 master->pub.is_dummy_pass = FALSE; 422 (*cinfo->cquantize->start_pass) (cinfo, FALSE); 423 (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST); 424 (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST); 425#else 426 ERREXIT(cinfo, JERR_NOT_COMPILED); 427#endif /* QUANT_2PASS_SUPPORTED */ 428 } else { 429 if (cinfo->quantize_colors && cinfo->colormap == NULL) { 430 /* Select new quantization method */ 431 if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) { 432 cinfo->cquantize = master->quantizer_2pass; 433 master->pub.is_dummy_pass = TRUE; 434 } else if (cinfo->enable_1pass_quant) { 435 cinfo->cquantize = master->quantizer_1pass; 436 } else { 437 ERREXIT(cinfo, JERR_MODE_CHANGE); 438 } 439 } 440 (*cinfo->idct->start_pass) (cinfo); 441 (*cinfo->coef->start_output_pass) (cinfo); 442 if (! cinfo->raw_data_out) { 443 if (! master->using_merged_upsample) 444 (*cinfo->cconvert->start_pass) (cinfo); 445 (*cinfo->upsample->start_pass) (cinfo); 446 if (cinfo->quantize_colors) 447 (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass); 448 (*cinfo->post->start_pass) (cinfo, 449 (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU)); 450 (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU); 451 } 452 } 453 454 /* Set up progress monitor's pass info if present */ 455 if (cinfo->progress != NULL) { 456 cinfo->progress->completed_passes = master->pass_number; 457 cinfo->progress->total_passes = master->pass_number + 458 (master->pub.is_dummy_pass ? 2 : 1); 459 /* In buffered-image mode, we assume one more output pass if EOI not 460 * yet reached, but no more passes if EOI has been reached. 461 */ 462 if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) { 463 cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1); 464 } 465 } 466} 467 468 469/* 470 * Finish up at end of an output pass. 471 */ 472 473METHODDEF(void) 474finish_output_pass (j_decompress_ptr cinfo) 475{ 476 my_master_ptr master = (my_master_ptr) cinfo->master; 477 478 if (cinfo->quantize_colors) 479 (*cinfo->cquantize->finish_pass) (cinfo); 480 master->pass_number++; 481} 482 483 484#ifdef D_MULTISCAN_FILES_SUPPORTED 485 486/* 487 * Switch to a new external colormap between output passes. 488 */ 489 490GLOBAL(void) 491jpeg_new_colormap (j_decompress_ptr cinfo) 492{ 493 my_master_ptr master = (my_master_ptr) cinfo->master; 494 495 /* Prevent application from calling me at wrong times */ 496 if (cinfo->global_state != DSTATE_BUFIMAGE) 497 ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); 498 499 if (cinfo->quantize_colors && cinfo->enable_external_quant && 500 cinfo->colormap != NULL) { 501 /* Select 2-pass quantizer for external colormap use */ 502 cinfo->cquantize = master->quantizer_2pass; 503 /* Notify quantizer of colormap change */ 504 (*cinfo->cquantize->new_color_map) (cinfo); 505 master->pub.is_dummy_pass = FALSE; /* just in case */ 506 } else 507 ERREXIT(cinfo, JERR_MODE_CHANGE); 508} 509 510#endif /* D_MULTISCAN_FILES_SUPPORTED */ 511 512 513/* 514 * Initialize master decompression control and select active modules. 515 * This is performed at the start of jpeg_start_decompress. 516 */ 517 518GLOBAL(void) 519jinit_master_decompress (j_decompress_ptr cinfo) 520{ 521 my_master_ptr master; 522 523 master = (my_master_ptr) 524 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 525 SIZEOF(my_decomp_master)); 526 cinfo->master = (struct jpeg_decomp_master *) master; 527 master->pub.prepare_for_output_pass = prepare_for_output_pass; 528 master->pub.finish_output_pass = finish_output_pass; 529 530 master->pub.is_dummy_pass = FALSE; 531 532 master_selection(cinfo); 533} 534