media/libjpeg/jdmaster.c

   1 /*
   2  * jdmaster.c
   3  *
   4  * This file was part of the Independent JPEG Group's software:
   5  * Copyright (C) 1991-1997, Thomas G. Lane.
   6  * Modified 2002-2009 by Guido Vollbeding.
   7  * libjpeg-turbo Modifications:
   8  * Copyright (C) 2009-2011, 2016, 2019, 2022, D. R. Commander.
   9  * Copyright (C) 2013, Linaro Limited.
  10  * Copyright (C) 2015, Google, Inc.
  11  * For conditions of distribution and use, see the accompanying README.ijg
  12  * file.
  13  *
  14  * This file contains master control logic for the JPEG decompressor.
  15  * These routines are concerned with selecting the modules to be executed
  16  * and with determining the number of passes and the work to be done in each
  17  * pass.
  18  */
  19
  20 #define JPEG_INTERNALS
  21 #include "jinclude.h"
  22 #include "jpeglib.h"
  23 #include "jpegcomp.h"
  24 #include "jdmaster.h"
  25
  26
  27 /*
  28  * Determine whether merged upsample/color conversion should be used.
  29  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
  30  */
  31
  32 LOCAL(boolean)
  33 use_merged_upsample(j_decompress_ptr cinfo)
  34 {
  35 #ifdef UPSAMPLE_MERGING_SUPPORTED
  36   /* Merging is the equivalent of plain box-filter upsampling */
  37   if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
  38     return FALSE;
  39   /* jdmerge.c only supports YCC=>RGB and YCC=>RGB565 color conversion */
  40   if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
  41       (cinfo->out_color_space != JCS_RGB &&
  42        cinfo->out_color_space != JCS_RGB565 &&
  43        cinfo->out_color_space != JCS_EXT_RGB &&
  44        cinfo->out_color_space != JCS_EXT_RGBX &&
  45        cinfo->out_color_space != JCS_EXT_BGR &&
  46        cinfo->out_color_space != JCS_EXT_BGRX &&
  47        cinfo->out_color_space != JCS_EXT_XBGR &&
  48        cinfo->out_color_space != JCS_EXT_XRGB &&
  49        cinfo->out_color_space != JCS_EXT_RGBA &&
  50        cinfo->out_color_space != JCS_EXT_BGRA &&
  51        cinfo->out_color_space != JCS_EXT_ABGR &&
  52        cinfo->out_color_space != JCS_EXT_ARGB))
  53     return FALSE;
  54   if ((cinfo->out_color_space == JCS_RGB565 &&
  55        cinfo->out_color_components != 3) ||
  56       (cinfo->out_color_space != JCS_RGB565 &&
  57        cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space]))
  58     return FALSE;
  59   /* and it only handles 2h1v or 2h2v sampling ratios */
  60   if (cinfo->comp_info[0].h_samp_factor != 2 ||
  61       cinfo->comp_info[1].h_samp_factor != 1 ||
  62       cinfo->comp_info[2].h_samp_factor != 1 ||
  63       cinfo->comp_info[0].v_samp_factor >  2 ||
  64       cinfo->comp_info[1].v_samp_factor != 1 ||
  65       cinfo->comp_info[2].v_samp_factor != 1)
  66     return FALSE;
  67   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
  68   if (cinfo->comp_info[0]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
  69       cinfo->comp_info[1]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
  70       cinfo->comp_info[2]._DCT_scaled_size != cinfo->_min_DCT_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  */
  85
  86 #if JPEG_LIB_VERSION >= 80
  87 GLOBAL(void)
  88 #else
  89 LOCAL(void)
  90 #endif
  91 jpeg_core_output_dimensions(j_decompress_ptr cinfo)
  92 /* Do computations that are needed before master selection phase.
  93  * This function is used for transcoding and full decompression.
  94  */
  95 {
  96 #ifdef IDCT_SCALING_SUPPORTED
  97   int ci;
  98   jpeg_component_info *compptr;
  99
 100   /* Compute actual output image dimensions and DCT scaling choices. */
 101   if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom) {
 102     /* Provide 1/block_size scaling */
 103     cinfo->output_width = (JDIMENSION)
 104       jdiv_round_up((long)cinfo->image_width, (long)DCTSIZE);
 105     cinfo->output_height = (JDIMENSION)
 106       jdiv_round_up((long)cinfo->image_height, (long)DCTSIZE);
 107     cinfo->_min_DCT_h_scaled_size = 1;
 108     cinfo->_min_DCT_v_scaled_size = 1;
 109   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 2) {
 110     /* Provide 2/block_size scaling */
 111     cinfo->output_width = (JDIMENSION)
 112       jdiv_round_up((long)cinfo->image_width * 2L, (long)DCTSIZE);
 113     cinfo->output_height = (JDIMENSION)
 114       jdiv_round_up((long)cinfo->image_height * 2L, (long)DCTSIZE);
 115     cinfo->_min_DCT_h_scaled_size = 2;
 116     cinfo->_min_DCT_v_scaled_size = 2;
 117   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 3) {
 118     /* Provide 3/block_size scaling */
 119     cinfo->output_width = (JDIMENSION)
 120       jdiv_round_up((long)cinfo->image_width * 3L, (long)DCTSIZE);
 121     cinfo->output_height = (JDIMENSION)
 122       jdiv_round_up((long)cinfo->image_height * 3L, (long)DCTSIZE);
 123     cinfo->_min_DCT_h_scaled_size = 3;
 124     cinfo->_min_DCT_v_scaled_size = 3;
 125   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 4) {
 126     /* Provide 4/block_size scaling */
 127     cinfo->output_width = (JDIMENSION)
 128       jdiv_round_up((long)cinfo->image_width * 4L, (long)DCTSIZE);
 129     cinfo->output_height = (JDIMENSION)
 130       jdiv_round_up((long)cinfo->image_height * 4L, (long)DCTSIZE);
 131     cinfo->_min_DCT_h_scaled_size = 4;
 132     cinfo->_min_DCT_v_scaled_size = 4;
 133   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 5) {
 134     /* Provide 5/block_size scaling */
 135     cinfo->output_width = (JDIMENSION)
 136       jdiv_round_up((long)cinfo->image_width * 5L, (long)DCTSIZE);
 137     cinfo->output_height = (JDIMENSION)
 138       jdiv_round_up((long)cinfo->image_height * 5L, (long)DCTSIZE);
 139     cinfo->_min_DCT_h_scaled_size = 5;
 140     cinfo->_min_DCT_v_scaled_size = 5;
 141   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 6) {
 142     /* Provide 6/block_size scaling */
 143     cinfo->output_width = (JDIMENSION)
 144       jdiv_round_up((long)cinfo->image_width * 6L, (long)DCTSIZE);
 145     cinfo->output_height = (JDIMENSION)
 146       jdiv_round_up((long)cinfo->image_height * 6L, (long)DCTSIZE);
 147     cinfo->_min_DCT_h_scaled_size = 6;
 148     cinfo->_min_DCT_v_scaled_size = 6;
 149   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 7) {
 150     /* Provide 7/block_size scaling */
 151     cinfo->output_width = (JDIMENSION)
 152       jdiv_round_up((long)cinfo->image_width * 7L, (long)DCTSIZE);
 153     cinfo->output_height = (JDIMENSION)
 154       jdiv_round_up((long)cinfo->image_height * 7L, (long)DCTSIZE);
 155     cinfo->_min_DCT_h_scaled_size = 7;
 156     cinfo->_min_DCT_v_scaled_size = 7;
 157   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 8) {
 158     /* Provide 8/block_size scaling */
 159     cinfo->output_width = (JDIMENSION)
 160       jdiv_round_up((long)cinfo->image_width * 8L, (long)DCTSIZE);
 161     cinfo->output_height = (JDIMENSION)
 162       jdiv_round_up((long)cinfo->image_height * 8L, (long)DCTSIZE);
 163     cinfo->_min_DCT_h_scaled_size = 8;
 164     cinfo->_min_DCT_v_scaled_size = 8;
 165   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 9) {
 166     /* Provide 9/block_size scaling */
 167     cinfo->output_width = (JDIMENSION)
 168       jdiv_round_up((long)cinfo->image_width * 9L, (long)DCTSIZE);
 169     cinfo->output_height = (JDIMENSION)
 170       jdiv_round_up((long)cinfo->image_height * 9L, (long)DCTSIZE);
 171     cinfo->_min_DCT_h_scaled_size = 9;
 172     cinfo->_min_DCT_v_scaled_size = 9;
 173   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 10) {
 174     /* Provide 10/block_size scaling */
 175     cinfo->output_width = (JDIMENSION)
 176       jdiv_round_up((long)cinfo->image_width * 10L, (long)DCTSIZE);
 177     cinfo->output_height = (JDIMENSION)
 178       jdiv_round_up((long)cinfo->image_height * 10L, (long)DCTSIZE);
 179     cinfo->_min_DCT_h_scaled_size = 10;
 180     cinfo->_min_DCT_v_scaled_size = 10;
 181   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 11) {
 182     /* Provide 11/block_size scaling */
 183     cinfo->output_width = (JDIMENSION)
 184       jdiv_round_up((long)cinfo->image_width * 11L, (long)DCTSIZE);
 185     cinfo->output_height = (JDIMENSION)
 186       jdiv_round_up((long)cinfo->image_height * 11L, (long)DCTSIZE);
 187     cinfo->_min_DCT_h_scaled_size = 11;
 188     cinfo->_min_DCT_v_scaled_size = 11;
 189   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 12) {
 190     /* Provide 12/block_size scaling */
 191     cinfo->output_width = (JDIMENSION)
 192       jdiv_round_up((long)cinfo->image_width * 12L, (long)DCTSIZE);
 193     cinfo->output_height = (JDIMENSION)
 194       jdiv_round_up((long)cinfo->image_height * 12L, (long)DCTSIZE);
 195     cinfo->_min_DCT_h_scaled_size = 12;
 196     cinfo->_min_DCT_v_scaled_size = 12;
 197   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 13) {
 198     /* Provide 13/block_size scaling */
 199     cinfo->output_width = (JDIMENSION)
 200       jdiv_round_up((long)cinfo->image_width * 13L, (long)DCTSIZE);
 201     cinfo->output_height = (JDIMENSION)
 202       jdiv_round_up((long)cinfo->image_height * 13L, (long)DCTSIZE);
 203     cinfo->_min_DCT_h_scaled_size = 13;
 204     cinfo->_min_DCT_v_scaled_size = 13;
 205   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 14) {
 206     /* Provide 14/block_size scaling */
 207     cinfo->output_width = (JDIMENSION)
 208       jdiv_round_up((long)cinfo->image_width * 14L, (long)DCTSIZE);
 209     cinfo->output_height = (JDIMENSION)
 210       jdiv_round_up((long)cinfo->image_height * 14L, (long)DCTSIZE);
 211     cinfo->_min_DCT_h_scaled_size = 14;
 212     cinfo->_min_DCT_v_scaled_size = 14;
 213   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 15) {
 214     /* Provide 15/block_size scaling */
 215     cinfo->output_width = (JDIMENSION)
 216       jdiv_round_up((long)cinfo->image_width * 15L, (long)DCTSIZE);
 217     cinfo->output_height = (JDIMENSION)
 218       jdiv_round_up((long)cinfo->image_height * 15L, (long)DCTSIZE);
 219     cinfo->_min_DCT_h_scaled_size = 15;
 220     cinfo->_min_DCT_v_scaled_size = 15;
 221   } else {
 222     /* Provide 16/block_size scaling */
 223     cinfo->output_width = (JDIMENSION)
 224       jdiv_round_up((long)cinfo->image_width * 16L, (long)DCTSIZE);
 225     cinfo->output_height = (JDIMENSION)
 226       jdiv_round_up((long)cinfo->image_height * 16L, (long)DCTSIZE);
 227     cinfo->_min_DCT_h_scaled_size = 16;
 228     cinfo->_min_DCT_v_scaled_size = 16;
 229   }
 230
 231   /* Recompute dimensions of components */
 232   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 233        ci++, compptr++) {
 234     compptr->_DCT_h_scaled_size = cinfo->_min_DCT_h_scaled_size;
 235     compptr->_DCT_v_scaled_size = cinfo->_min_DCT_v_scaled_size;
 236   }
 237
 238 #else /* !IDCT_SCALING_SUPPORTED */
 239
 240   /* Hardwire it to "no scaling" */
 241   cinfo->output_width = cinfo->image_width;
 242   cinfo->output_height = cinfo->image_height;
 243   /* jdinput.c has already initialized DCT_scaled_size,
 244    * and has computed unscaled downsampled_width and downsampled_height.
 245    */
 246
 247 #endif /* IDCT_SCALING_SUPPORTED */
 248 }
 249
 250
 251 /*
 252  * Compute output image dimensions and related values.
 253  * NOTE: this is exported for possible use by application.
 254  * Hence it mustn't do anything that can't be done twice.
 255  * Also note that it may be called before the master module is initialized!
 256  */
 257
 258 GLOBAL(void)
 259 jpeg_calc_output_dimensions(j_decompress_ptr cinfo)
 260 /* Do computations that are needed before master selection phase */
 261 {
 262 #ifdef IDCT_SCALING_SUPPORTED
 263   int ci;
 264   jpeg_component_info *compptr;
 265 #endif
 266
 267   /* Prevent application from calling me at wrong times */
 268   if (cinfo->global_state != DSTATE_READY)
 269     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 270
 271   /* Compute core output image dimensions and DCT scaling choices. */
 272   jpeg_core_output_dimensions(cinfo);
 273
 274 #ifdef IDCT_SCALING_SUPPORTED
 275
 276   /* In selecting the actual DCT scaling for each component, we try to
 277    * scale up the chroma components via IDCT scaling rather than upsampling.
 278    * This saves time if the upsampler gets to use 1:1 scaling.
 279    * Note this code adapts subsampling ratios which are powers of 2.
 280    */
 281   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 282        ci++, compptr++) {
 283     int ssize = cinfo->_min_DCT_scaled_size;
 284     while (ssize < DCTSIZE &&
 285            ((cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) %
 286             (compptr->h_samp_factor * ssize * 2) == 0) &&
 287            ((cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size) %
 288             (compptr->v_samp_factor * ssize * 2) == 0)) {
 289       ssize = ssize * 2;
 290     }
 291 #if JPEG_LIB_VERSION >= 70
 292     compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = ssize;
 293 #else
 294     compptr->DCT_scaled_size = ssize;
 295 #endif
 296   }
 297
 298   /* Recompute downsampled dimensions of components;
 299    * application needs to know these if using raw downsampled data.
 300    */
 301   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 302        ci++, compptr++) {
 303     /* Size in samples, after IDCT scaling */
 304     compptr->downsampled_width = (JDIMENSION)
 305       jdiv_round_up((long)cinfo->image_width *
 306                     (long)(compptr->h_samp_factor * compptr->_DCT_scaled_size),
 307                     (long)(cinfo->max_h_samp_factor * DCTSIZE));
 308     compptr->downsampled_height = (JDIMENSION)
 309       jdiv_round_up((long)cinfo->image_height *
 310                     (long)(compptr->v_samp_factor * compptr->_DCT_scaled_size),
 311                     (long)(cinfo->max_v_samp_factor * DCTSIZE));
 312   }
 313
 314 #else /* !IDCT_SCALING_SUPPORTED */
 315
 316   /* Hardwire it to "no scaling" */
 317   cinfo->output_width = cinfo->image_width;
 318   cinfo->output_height = cinfo->image_height;
 319   /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
 320    * and has computed unscaled downsampled_width and downsampled_height.
 321    */
 322
 323 #endif /* IDCT_SCALING_SUPPORTED */
 324
 325   /* Report number of components in selected colorspace. */
 326   /* Probably this should be in the color conversion module... */
 327   switch (cinfo->out_color_space) {
 328   case JCS_GRAYSCALE:
 329     cinfo->out_color_components = 1;
 330     break;
 331   case JCS_RGB:
 332   case JCS_EXT_RGB:
 333   case JCS_EXT_RGBX:
 334   case JCS_EXT_BGR:
 335   case JCS_EXT_BGRX:
 336   case JCS_EXT_XBGR:
 337   case JCS_EXT_XRGB:
 338   case JCS_EXT_RGBA:
 339   case JCS_EXT_BGRA:
 340   case JCS_EXT_ABGR:
 341   case JCS_EXT_ARGB:
 342     cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
 343     break;
 344   case JCS_YCbCr:
 345   case JCS_RGB565:
 346     cinfo->out_color_components = 3;
 347     break;
 348   case JCS_CMYK:
 349   case JCS_YCCK:
 350     cinfo->out_color_components = 4;
 351     break;
 352   default:                      /* else must be same colorspace as in file */
 353     cinfo->out_color_components = cinfo->num_components;
 354     break;
 355   }
 356   cinfo->output_components = (cinfo->quantize_colors ? 1 :
 357                               cinfo->out_color_components);
 358
 359   /* See if upsampler will want to emit more than one row at a time */
 360   if (use_merged_upsample(cinfo))
 361     cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
 362   else
 363     cinfo->rec_outbuf_height = 1;
 364 }
 365
 366
 367 /*
 368  * Several decompression processes need to range-limit values to the range
 369  * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
 370  * due to noise introduced by quantization, roundoff error, etc.  These
 371  * processes are inner loops and need to be as fast as possible.  On most
 372  * machines, particularly CPUs with pipelines or instruction prefetch,
 373  * a (subscript-check-less) C table lookup
 374  *              x = sample_range_limit[x];
 375  * is faster than explicit tests
 376  *              if (x < 0)  x = 0;
 377  *              else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
 378  * These processes all use a common table prepared by the routine below.
 379  *
 380  * For most steps we can mathematically guarantee that the initial value
 381  * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
 382  * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
 383  * limiting step (just after the IDCT), a wildly out-of-range value is
 384  * possible if the input data is corrupt.  To avoid any chance of indexing
 385  * off the end of memory and getting a bad-pointer trap, we perform the
 386  * post-IDCT limiting thus:
 387  *              x = range_limit[x & MASK];
 388  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
 389  * samples.  Under normal circumstances this is more than enough range and
 390  * a correct output will be generated; with bogus input data the mask will
 391  * cause wraparound, and we will safely generate a bogus-but-in-range output.
 392  * For the post-IDCT step, we want to convert the data from signed to unsigned
 393  * representation by adding CENTERJSAMPLE at the same time that we limit it.
 394  * So the post-IDCT limiting table ends up looking like this:
 395  *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
 396  *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 397  *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 398  *   0,1,...,CENTERJSAMPLE-1
 399  * Negative inputs select values from the upper half of the table after
 400  * masking.
 401  *
 402  * We can save some space by overlapping the start of the post-IDCT table
 403  * with the simpler range limiting table.  The post-IDCT table begins at
 404  * sample_range_limit + CENTERJSAMPLE.
 405  */
 406
 407 LOCAL(void)
 408 prepare_range_limit_table(j_decompress_ptr cinfo)
 409 /* Allocate and fill in the sample_range_limit table */
 410 {
 411   JSAMPLE *table;
 412   int i;
 413
 414   table = (JSAMPLE *)
 415     (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
 416                 (5 * (MAXJSAMPLE + 1) + CENTERJSAMPLE) * sizeof(JSAMPLE));
 417   table += (MAXJSAMPLE + 1);    /* allow negative subscripts of simple table */
 418   cinfo->sample_range_limit = table;
 419   /* First segment of "simple" table: limit[x] = 0 for x < 0 */
 420   memset(table - (MAXJSAMPLE + 1), 0, (MAXJSAMPLE + 1) * sizeof(JSAMPLE));
 421   /* Main part of "simple" table: limit[x] = x */
 422   for (i = 0; i <= MAXJSAMPLE; i++)
 423     table[i] = (JSAMPLE)i;
 424   table += CENTERJSAMPLE;       /* Point to where post-IDCT table starts */
 425   /* End of simple table, rest of first half of post-IDCT table */
 426   for (i = CENTERJSAMPLE; i < 2 * (MAXJSAMPLE + 1); i++)
 427     table[i] = MAXJSAMPLE;
 428   /* Second half of post-IDCT table */
 429   memset(table + (2 * (MAXJSAMPLE + 1)), 0,
 430          (2 * (MAXJSAMPLE + 1) - CENTERJSAMPLE) * sizeof(JSAMPLE));
 431   memcpy(table + (4 * (MAXJSAMPLE + 1) - CENTERJSAMPLE),
 432          cinfo->sample_range_limit, CENTERJSAMPLE * sizeof(JSAMPLE));
 433 }
 434
 435
 436 /*
 437  * Master selection of decompression modules.
 438  * This is done once at jpeg_start_decompress time.  We determine
 439  * which modules will be used and give them appropriate initialization calls.
 440  * We also initialize the decompressor input side to begin consuming data.
 441  *
 442  * Since jpeg_read_header has finished, we know what is in the SOF
 443  * and (first) SOS markers.  We also have all the application parameter
 444  * settings.
 445  */
 446
 447 LOCAL(void)
 448 master_selection(j_decompress_ptr cinfo)
 449 {
 450   my_master_ptr master = (my_master_ptr)cinfo->master;
 451   boolean use_c_buffer;
 452   long samplesperrow;
 453   JDIMENSION jd_samplesperrow;
 454
 455   /* Initialize dimensions and other stuff */
 456   jpeg_calc_output_dimensions(cinfo);
 457   prepare_range_limit_table(cinfo);
 458
 459   /* Width of an output scanline must be representable as JDIMENSION. */
 460   samplesperrow = (long)cinfo->output_width *
 461                   (long)cinfo->out_color_components;
 462   jd_samplesperrow = (JDIMENSION)samplesperrow;
 463   if ((long)jd_samplesperrow != samplesperrow)
 464     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 465
 466   /* Initialize my private state */
 467   master->pass_number = 0;
 468   master->using_merged_upsample = use_merged_upsample(cinfo);
 469
 470   /* Color quantizer selection */
 471   master->quantizer_1pass = NULL;
 472   master->quantizer_2pass = NULL;
 473   /* No mode changes if not using buffered-image mode. */
 474   if (!cinfo->quantize_colors || !cinfo->buffered_image) {
 475     cinfo->enable_1pass_quant = FALSE;
 476     cinfo->enable_external_quant = FALSE;
 477     cinfo->enable_2pass_quant = FALSE;
 478   }
 479   if (cinfo->quantize_colors) {
 480     if (cinfo->raw_data_out)
 481       ERREXIT(cinfo, JERR_NOTIMPL);
 482     /* 2-pass quantizer only works in 3-component color space. */
 483     if (cinfo->out_color_components != 3) {
 484       cinfo->enable_1pass_quant = TRUE;
 485       cinfo->enable_external_quant = FALSE;
 486       cinfo->enable_2pass_quant = FALSE;
 487       cinfo->colormap = NULL;
 488     } else if (cinfo->colormap != NULL) {
 489       cinfo->enable_external_quant = TRUE;
 490     } else if (cinfo->two_pass_quantize) {
 491       cinfo->enable_2pass_quant = TRUE;
 492     } else {
 493       cinfo->enable_1pass_quant = TRUE;
 494     }
 495
 496     if (cinfo->enable_1pass_quant) {
 497 #ifdef QUANT_1PASS_SUPPORTED
 498       jinit_1pass_quantizer(cinfo);
 499       master->quantizer_1pass = cinfo->cquantize;
 500 #else
 501       ERREXIT(cinfo, JERR_NOT_COMPILED);
 502 #endif
 503     }
 504
 505     /* We use the 2-pass code to map to external colormaps. */
 506     if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
 507 #ifdef QUANT_2PASS_SUPPORTED
 508       jinit_2pass_quantizer(cinfo);
 509       master->quantizer_2pass = cinfo->cquantize;
 510 #else
 511       ERREXIT(cinfo, JERR_NOT_COMPILED);
 512 #endif
 513     }
 514     /* If both quantizers are initialized, the 2-pass one is left active;
 515      * this is necessary for starting with quantization to an external map.
 516      */
 517   }
 518
 519   /* Post-processing: in particular, color conversion first */
 520   if (!cinfo->raw_data_out) {
 521     if (master->using_merged_upsample) {
 522 #ifdef UPSAMPLE_MERGING_SUPPORTED
 523       jinit_merged_upsampler(cinfo); /* does color conversion too */
 524 #else
 525       ERREXIT(cinfo, JERR_NOT_COMPILED);
 526 #endif
 527     } else {
 528       jinit_color_deconverter(cinfo);
 529       jinit_upsampler(cinfo);
 530     }
 531     jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
 532   }
 533   /* Inverse DCT */
 534   jinit_inverse_dct(cinfo);
 535   /* Entropy decoding: either Huffman or arithmetic coding. */
 536   if (cinfo->arith_code) {
 537 #ifdef D_ARITH_CODING_SUPPORTED
 538     jinit_arith_decoder(cinfo);
 539 #else
 540     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
 541 #endif
 542   } else {
 543     if (cinfo->progressive_mode) {
 544 #ifdef D_PROGRESSIVE_SUPPORTED
 545       jinit_phuff_decoder(cinfo);
 546 #else
 547       ERREXIT(cinfo, JERR_NOT_COMPILED);
 548 #endif
 549     } else
 550       jinit_huff_decoder(cinfo);
 551   }
 552
 553   /* Initialize principal buffer controllers. */
 554   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
 555   jinit_d_coef_controller(cinfo, use_c_buffer);
 556
 557   if (!cinfo->raw_data_out)
 558     jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
 559
 560   /* We can now tell the memory manager to allocate virtual arrays. */
 561   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);
 562
 563   /* Initialize input side of decompressor to consume first scan. */
 564   (*cinfo->inputctl->start_input_pass) (cinfo);
 565
 566   /* Set the first and last iMCU columns to decompress from single-scan images.
 567    * By default, decompress all of the iMCU columns.
 568    */
 569   cinfo->master->first_iMCU_col = 0;
 570   cinfo->master->last_iMCU_col = cinfo->MCUs_per_row - 1;
 571   cinfo->master->last_good_iMCU_row = 0;
 572
 573 #ifdef D_MULTISCAN_FILES_SUPPORTED
 574   /* If jpeg_start_decompress will read the whole file, initialize
 575    * progress monitoring appropriately.  The input step is counted
 576    * as one pass.
 577    */
 578   if (cinfo->progress != NULL && !cinfo->buffered_image &&
 579       cinfo->inputctl->has_multiple_scans) {
 580     int nscans;
 581     /* Estimate number of scans to set pass_limit. */
 582     if (cinfo->progressive_mode) {
 583       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
 584       nscans = 2 + 3 * cinfo->num_components;
 585     } else {
 586       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
 587       nscans = cinfo->num_components;
 588     }
 589     cinfo->progress->pass_counter = 0L;
 590     cinfo->progress->pass_limit = (long)cinfo->total_iMCU_rows * nscans;
 591     cinfo->progress->completed_passes = 0;
 592     cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
 593     /* Count the input pass as done */
 594     master->pass_number++;
 595   }
 596 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 597 }
 598
 599
 600 /*
 601  * Per-pass setup.
 602  * This is called at the beginning of each output pass.  We determine which
 603  * modules will be active during this pass and give them appropriate
 604  * start_pass calls.  We also set is_dummy_pass to indicate whether this
 605  * is a "real" output pass or a dummy pass for color quantization.
 606  * (In the latter case, jdapistd.c will crank the pass to completion.)
 607  */
 608
 609 METHODDEF(void)
 610 prepare_for_output_pass(j_decompress_ptr cinfo)
 611 {
 612   my_master_ptr master = (my_master_ptr)cinfo->master;
 613
 614   if (master->pub.is_dummy_pass) {
 615 #ifdef QUANT_2PASS_SUPPORTED
 616     /* Final pass of 2-pass quantization */
 617     master->pub.is_dummy_pass = FALSE;
 618     (*cinfo->cquantize->start_pass) (cinfo, FALSE);
 619     (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
 620     (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
 621 #else
 622     ERREXIT(cinfo, JERR_NOT_COMPILED);
 623 #endif /* QUANT_2PASS_SUPPORTED */
 624   } else {
 625     if (cinfo->quantize_colors && cinfo->colormap == NULL) {
 626       /* Select new quantization method */
 627       if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
 628         cinfo->cquantize = master->quantizer_2pass;
 629         master->pub.is_dummy_pass = TRUE;
 630       } else if (cinfo->enable_1pass_quant) {
 631         cinfo->cquantize = master->quantizer_1pass;
 632       } else {
 633         ERREXIT(cinfo, JERR_MODE_CHANGE);
 634       }
 635     }
 636     (*cinfo->idct->start_pass) (cinfo);
 637     (*cinfo->coef->start_output_pass) (cinfo);
 638     if (!cinfo->raw_data_out) {
 639       if (!master->using_merged_upsample)
 640         (*cinfo->cconvert->start_pass) (cinfo);
 641       (*cinfo->upsample->start_pass) (cinfo);
 642       if (cinfo->quantize_colors)
 643         (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
 644       (*cinfo->post->start_pass) (cinfo,
 645             (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 646       (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 647     }
 648   }
 649
 650   /* Set up progress monitor's pass info if present */
 651   if (cinfo->progress != NULL) {
 652     cinfo->progress->completed_passes = master->pass_number;
 653     cinfo->progress->total_passes = master->pass_number +
 654                                     (master->pub.is_dummy_pass ? 2 : 1);
 655     /* In buffered-image mode, we assume one more output pass if EOI not
 656      * yet reached, but no more passes if EOI has been reached.
 657      */
 658     if (cinfo->buffered_image && !cinfo->inputctl->eoi_reached) {
 659       cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
 660     }
 661   }
 662 }
 663
 664
 665 /*
 666  * Finish up at end of an output pass.
 667  */
 668
 669 METHODDEF(void)
 670 finish_output_pass(j_decompress_ptr cinfo)
 671 {
 672   my_master_ptr master = (my_master_ptr)cinfo->master;
 673
 674   if (cinfo->quantize_colors)
 675     (*cinfo->cquantize->finish_pass) (cinfo);
 676   master->pass_number++;
 677 }
 678
 679
 680 #ifdef D_MULTISCAN_FILES_SUPPORTED
 681
 682 /*
 683  * Switch to a new external colormap between output passes.
 684  */
 685
 686 GLOBAL(void)
 687 jpeg_new_colormap(j_decompress_ptr cinfo)
 688 {
 689   my_master_ptr master = (my_master_ptr)cinfo->master;
 690
 691   /* Prevent application from calling me at wrong times */
 692   if (cinfo->global_state != DSTATE_BUFIMAGE)
 693     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 694
 695   if (cinfo->quantize_colors && cinfo->enable_external_quant &&
 696       cinfo->colormap != NULL) {
 697     /* Select 2-pass quantizer for external colormap use */
 698     cinfo->cquantize = master->quantizer_2pass;
 699     /* Notify quantizer of colormap change */
 700     (*cinfo->cquantize->new_color_map) (cinfo);
 701     master->pub.is_dummy_pass = FALSE; /* just in case */
 702   } else
 703     ERREXIT(cinfo, JERR_MODE_CHANGE);
 704 }
 705
 706 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 707
 708
 709 /*
 710  * Initialize master decompression control and select active modules.
 711  * This is performed at the start of jpeg_start_decompress.
 712  */
 713
 714 GLOBAL(void)
 715 jinit_master_decompress(j_decompress_ptr cinfo)
 716 {
 717   my_master_ptr master = (my_master_ptr)cinfo->master;
 718
 719   master->pub.prepare_for_output_pass = prepare_for_output_pass;
 720   master->pub.finish_output_pass = finish_output_pass;
 721
 722   master->pub.is_dummy_pass = FALSE;
 723   master->pub.jinit_upsampler_no_alloc = FALSE;
 724
 725   master_selection(cinfo);
 726 }