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, D. R. Commander.
   9  * For conditions of distribution and use, see the accompanying README file.
  10  *
  11  * This file contains master control logic for the JPEG decompressor.
  12  * These routines are concerned with selecting the modules to be executed
  13  * and with determining the number of passes and the work to be done in each
  14  * pass.
  15  */
  16
  17 #define JPEG_INTERNALS
  18 #include "jinclude.h"
  19 #include "jpeglib.h"
  20 #include "jpegcomp.h"
  21
  22
  23 /* Private state */
  24
  25 typedef struct {
  26   struct jpeg_decomp_master pub; /* public fields */
  27
  28   int pass_number;              /* # of passes completed */
  29
  30   boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
  31
  32   /* Saved references to initialized quantizer modules,
  33    * in case we need to switch modes.
  34    */
  35   struct jpeg_color_quantizer * quantizer_1pass;
  36   struct jpeg_color_quantizer * quantizer_2pass;
  37 } my_decomp_master;
  38
  39 typedef my_decomp_master * my_master_ptr;
  40
  41
  42 /*
  43  * Determine whether merged upsample/color conversion should be used.
  44  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
  45  */
  46
  47 LOCAL(boolean)
  48 use_merged_upsample (j_decompress_ptr cinfo)
  49 {
  50 #ifdef UPSAMPLE_MERGING_SUPPORTED
  51   /* Merging is the equivalent of plain box-filter upsampling */
  52   if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
  53     return FALSE;
  54   /* jdmerge.c only supports YCC=>RGB color conversion */
  55   if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
  56       (cinfo->out_color_space != JCS_RGB &&
  57       cinfo->out_color_space != JCS_EXT_RGB &&
  58       cinfo->out_color_space != JCS_EXT_RGBX &&
  59       cinfo->out_color_space != JCS_EXT_BGR &&
  60       cinfo->out_color_space != JCS_EXT_BGRX &&
  61       cinfo->out_color_space != JCS_EXT_XBGR &&
  62       cinfo->out_color_space != JCS_EXT_XRGB &&
  63       cinfo->out_color_space != JCS_EXT_RGBA &&
  64       cinfo->out_color_space != JCS_EXT_BGRA &&
  65       cinfo->out_color_space != JCS_EXT_ABGR &&
  66       cinfo->out_color_space != JCS_EXT_ARGB) ||
  67       cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space])
  68     return FALSE;
  69   /* and it only handles 2h1v or 2h2v sampling ratios */
  70   if (cinfo->comp_info[0].h_samp_factor != 2 ||
  71       cinfo->comp_info[1].h_samp_factor != 1 ||
  72       cinfo->comp_info[2].h_samp_factor != 1 ||
  73       cinfo->comp_info[0].v_samp_factor >  2 ||
  74       cinfo->comp_info[1].v_samp_factor != 1 ||
  75       cinfo->comp_info[2].v_samp_factor != 1)
  76     return FALSE;
  77   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
  78   if (cinfo->comp_info[0]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
  79       cinfo->comp_info[1]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
  80       cinfo->comp_info[2]._DCT_scaled_size != cinfo->_min_DCT_scaled_size)
  81     return FALSE;
  82   /* ??? also need to test for upsample-time rescaling, when & if supported */
  83   return TRUE;                  /* by golly, it'll work... */
  84 #else
  85   return FALSE;
  86 #endif
  87 }
  88
  89
  90 /*
  91  * Compute output image dimensions and related values.
  92  * NOTE: this is exported for possible use by application.
  93  * Hence it mustn't do anything that can't be done twice.
  94  */
  95
  96 #if JPEG_LIB_VERSION >= 80
  97 GLOBAL(void)
  98 #else
  99 LOCAL(void)
 100 #endif
 101 jpeg_core_output_dimensions (j_decompress_ptr cinfo)
 102 /* Do computations that are needed before master selection phase.
 103  * This function is used for transcoding and full decompression.
 104  */
 105 {
 106 #ifdef IDCT_SCALING_SUPPORTED
 107   int ci;
 108   jpeg_component_info *compptr;
 109
 110   /* Compute actual output image dimensions and DCT scaling choices. */
 111   if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom) {
 112     /* Provide 1/block_size scaling */
 113     cinfo->output_width = (JDIMENSION)
 114       jdiv_round_up((long) cinfo->image_width, (long) DCTSIZE);
 115     cinfo->output_height = (JDIMENSION)
 116       jdiv_round_up((long) cinfo->image_height, (long) DCTSIZE);
 117     cinfo->_min_DCT_h_scaled_size = 1;
 118     cinfo->_min_DCT_v_scaled_size = 1;
 119   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 2) {
 120     /* Provide 2/block_size scaling */
 121     cinfo->output_width = (JDIMENSION)
 122       jdiv_round_up((long) cinfo->image_width * 2L, (long) DCTSIZE);
 123     cinfo->output_height = (JDIMENSION)
 124       jdiv_round_up((long) cinfo->image_height * 2L, (long) DCTSIZE);
 125     cinfo->_min_DCT_h_scaled_size = 2;
 126     cinfo->_min_DCT_v_scaled_size = 2;
 127   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 3) {
 128     /* Provide 3/block_size scaling */
 129     cinfo->output_width = (JDIMENSION)
 130       jdiv_round_up((long) cinfo->image_width * 3L, (long) DCTSIZE);
 131     cinfo->output_height = (JDIMENSION)
 132       jdiv_round_up((long) cinfo->image_height * 3L, (long) DCTSIZE);
 133     cinfo->_min_DCT_h_scaled_size = 3;
 134     cinfo->_min_DCT_v_scaled_size = 3;
 135   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 4) {
 136     /* Provide 4/block_size scaling */
 137     cinfo->output_width = (JDIMENSION)
 138       jdiv_round_up((long) cinfo->image_width * 4L, (long) DCTSIZE);
 139     cinfo->output_height = (JDIMENSION)
 140       jdiv_round_up((long) cinfo->image_height * 4L, (long) DCTSIZE);
 141     cinfo->_min_DCT_h_scaled_size = 4;
 142     cinfo->_min_DCT_v_scaled_size = 4;
 143   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 5) {
 144     /* Provide 5/block_size scaling */
 145     cinfo->output_width = (JDIMENSION)
 146       jdiv_round_up((long) cinfo->image_width * 5L, (long) DCTSIZE);
 147     cinfo->output_height = (JDIMENSION)
 148       jdiv_round_up((long) cinfo->image_height * 5L, (long) DCTSIZE);
 149     cinfo->_min_DCT_h_scaled_size = 5;
 150     cinfo->_min_DCT_v_scaled_size = 5;
 151   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 6) {
 152     /* Provide 6/block_size scaling */
 153     cinfo->output_width = (JDIMENSION)
 154       jdiv_round_up((long) cinfo->image_width * 6L, (long) DCTSIZE);
 155     cinfo->output_height = (JDIMENSION)
 156       jdiv_round_up((long) cinfo->image_height * 6L, (long) DCTSIZE);
 157     cinfo->_min_DCT_h_scaled_size = 6;
 158     cinfo->_min_DCT_v_scaled_size = 6;
 159   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 7) {
 160     /* Provide 7/block_size scaling */
 161     cinfo->output_width = (JDIMENSION)
 162       jdiv_round_up((long) cinfo->image_width * 7L, (long) DCTSIZE);
 163     cinfo->output_height = (JDIMENSION)
 164       jdiv_round_up((long) cinfo->image_height * 7L, (long) DCTSIZE);
 165     cinfo->_min_DCT_h_scaled_size = 7;
 166     cinfo->_min_DCT_v_scaled_size = 7;
 167   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 8) {
 168     /* Provide 8/block_size scaling */
 169     cinfo->output_width = (JDIMENSION)
 170       jdiv_round_up((long) cinfo->image_width * 8L, (long) DCTSIZE);
 171     cinfo->output_height = (JDIMENSION)
 172       jdiv_round_up((long) cinfo->image_height * 8L, (long) DCTSIZE);
 173     cinfo->_min_DCT_h_scaled_size = 8;
 174     cinfo->_min_DCT_v_scaled_size = 8;
 175   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 9) {
 176     /* Provide 9/block_size scaling */
 177     cinfo->output_width = (JDIMENSION)
 178       jdiv_round_up((long) cinfo->image_width * 9L, (long) DCTSIZE);
 179     cinfo->output_height = (JDIMENSION)
 180       jdiv_round_up((long) cinfo->image_height * 9L, (long) DCTSIZE);
 181     cinfo->_min_DCT_h_scaled_size = 9;
 182     cinfo->_min_DCT_v_scaled_size = 9;
 183   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 10) {
 184     /* Provide 10/block_size scaling */
 185     cinfo->output_width = (JDIMENSION)
 186       jdiv_round_up((long) cinfo->image_width * 10L, (long) DCTSIZE);
 187     cinfo->output_height = (JDIMENSION)
 188       jdiv_round_up((long) cinfo->image_height * 10L, (long) DCTSIZE);
 189     cinfo->_min_DCT_h_scaled_size = 10;
 190     cinfo->_min_DCT_v_scaled_size = 10;
 191   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 11) {
 192     /* Provide 11/block_size scaling */
 193     cinfo->output_width = (JDIMENSION)
 194       jdiv_round_up((long) cinfo->image_width * 11L, (long) DCTSIZE);
 195     cinfo->output_height = (JDIMENSION)
 196       jdiv_round_up((long) cinfo->image_height * 11L, (long) DCTSIZE);
 197     cinfo->_min_DCT_h_scaled_size = 11;
 198     cinfo->_min_DCT_v_scaled_size = 11;
 199   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 12) {
 200     /* Provide 12/block_size scaling */
 201     cinfo->output_width = (JDIMENSION)
 202       jdiv_round_up((long) cinfo->image_width * 12L, (long) DCTSIZE);
 203     cinfo->output_height = (JDIMENSION)
 204       jdiv_round_up((long) cinfo->image_height * 12L, (long) DCTSIZE);
 205     cinfo->_min_DCT_h_scaled_size = 12;
 206     cinfo->_min_DCT_v_scaled_size = 12;
 207   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 13) {
 208     /* Provide 13/block_size scaling */
 209     cinfo->output_width = (JDIMENSION)
 210       jdiv_round_up((long) cinfo->image_width * 13L, (long) DCTSIZE);
 211     cinfo->output_height = (JDIMENSION)
 212       jdiv_round_up((long) cinfo->image_height * 13L, (long) DCTSIZE);
 213     cinfo->_min_DCT_h_scaled_size = 13;
 214     cinfo->_min_DCT_v_scaled_size = 13;
 215   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 14) {
 216     /* Provide 14/block_size scaling */
 217     cinfo->output_width = (JDIMENSION)
 218       jdiv_round_up((long) cinfo->image_width * 14L, (long) DCTSIZE);
 219     cinfo->output_height = (JDIMENSION)
 220       jdiv_round_up((long) cinfo->image_height * 14L, (long) DCTSIZE);
 221     cinfo->_min_DCT_h_scaled_size = 14;
 222     cinfo->_min_DCT_v_scaled_size = 14;
 223   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 15) {
 224     /* Provide 15/block_size scaling */
 225     cinfo->output_width = (JDIMENSION)
 226       jdiv_round_up((long) cinfo->image_width * 15L, (long) DCTSIZE);
 227     cinfo->output_height = (JDIMENSION)
 228       jdiv_round_up((long) cinfo->image_height * 15L, (long) DCTSIZE);
 229     cinfo->_min_DCT_h_scaled_size = 15;
 230     cinfo->_min_DCT_v_scaled_size = 15;
 231   } else {
 232     /* Provide 16/block_size scaling */
 233     cinfo->output_width = (JDIMENSION)
 234       jdiv_round_up((long) cinfo->image_width * 16L, (long) DCTSIZE);
 235     cinfo->output_height = (JDIMENSION)
 236       jdiv_round_up((long) cinfo->image_height * 16L, (long) DCTSIZE);
 237     cinfo->_min_DCT_h_scaled_size = 16;
 238     cinfo->_min_DCT_v_scaled_size = 16;
 239   }
 240
 241   /* Recompute dimensions of components */
 242   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 243        ci++, compptr++) {
 244     compptr->_DCT_h_scaled_size = cinfo->_min_DCT_h_scaled_size;
 245     compptr->_DCT_v_scaled_size = cinfo->_min_DCT_v_scaled_size;
 246   }
 247
 248 #else /* !IDCT_SCALING_SUPPORTED */
 249
 250   /* Hardwire it to "no scaling" */
 251   cinfo->output_width = cinfo->image_width;
 252   cinfo->output_height = cinfo->image_height;
 253   /* jdinput.c has already initialized DCT_scaled_size,
 254    * and has computed unscaled downsampled_width and downsampled_height.
 255    */
 256
 257 #endif /* IDCT_SCALING_SUPPORTED */
 258 }
 259
 260
 261 /*
 262  * Compute output image dimensions and related values.
 263  * NOTE: this is exported for possible use by application.
 264  * Hence it mustn't do anything that can't be done twice.
 265  * Also note that it may be called before the master module is initialized!
 266  */
 267
 268 GLOBAL(void)
 269 jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
 270 /* Do computations that are needed before master selection phase */
 271 {
 272 #ifdef IDCT_SCALING_SUPPORTED
 273   int ci;
 274   jpeg_component_info *compptr;
 275 #endif
 276
 277   /* Prevent application from calling me at wrong times */
 278   if (cinfo->global_state != DSTATE_READY)
 279     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 280
 281   /* Compute core output image dimensions and DCT scaling choices. */
 282   jpeg_core_output_dimensions(cinfo);
 283
 284 #ifdef IDCT_SCALING_SUPPORTED
 285
 286   /* In selecting the actual DCT scaling for each component, we try to
 287    * scale up the chroma components via IDCT scaling rather than upsampling.
 288    * This saves time if the upsampler gets to use 1:1 scaling.
 289    * Note this code adapts subsampling ratios which are powers of 2.
 290    */
 291   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 292        ci++, compptr++) {
 293     int ssize = cinfo->_min_DCT_scaled_size;
 294     while (ssize < DCTSIZE &&
 295            ((cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) %
 296             (compptr->h_samp_factor * ssize * 2) == 0) &&
 297            ((cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size) %
 298             (compptr->v_samp_factor * ssize * 2) == 0)) {
 299       ssize = ssize * 2;
 300     }
 301 #if JPEG_LIB_VERSION >= 70
 302     compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = ssize;
 303 #else
 304     compptr->DCT_scaled_size = ssize;
 305 #endif
 306   }
 307
 308   /* Recompute downsampled dimensions of components;
 309    * application needs to know these if using raw downsampled data.
 310    */
 311   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 312        ci++, compptr++) {
 313     /* Size in samples, after IDCT scaling */
 314     compptr->downsampled_width = (JDIMENSION)
 315       jdiv_round_up((long) cinfo->image_width *
 316                     (long) (compptr->h_samp_factor * compptr->_DCT_scaled_size),
 317                     (long) (cinfo->max_h_samp_factor * DCTSIZE));
 318     compptr->downsampled_height = (JDIMENSION)
 319       jdiv_round_up((long) cinfo->image_height *
 320                     (long) (compptr->v_samp_factor * compptr->_DCT_scaled_size),
 321                     (long) (cinfo->max_v_samp_factor * DCTSIZE));
 322   }
 323
 324 #else /* !IDCT_SCALING_SUPPORTED */
 325
 326   /* Hardwire it to "no scaling" */
 327   cinfo->output_width = cinfo->image_width;
 328   cinfo->output_height = cinfo->image_height;
 329   /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
 330    * and has computed unscaled downsampled_width and downsampled_height.
 331    */
 332
 333 #endif /* IDCT_SCALING_SUPPORTED */
 334
 335   /* Report number of components in selected colorspace. */
 336   /* Probably this should be in the color conversion module... */
 337   switch (cinfo->out_color_space) {
 338   case JCS_GRAYSCALE:
 339     cinfo->out_color_components = 1;
 340     break;
 341   case JCS_RGB:
 342   case JCS_EXT_RGB:
 343   case JCS_EXT_RGBX:
 344   case JCS_EXT_BGR:
 345   case JCS_EXT_BGRX:
 346   case JCS_EXT_XBGR:
 347   case JCS_EXT_XRGB:
 348   case JCS_EXT_RGBA:
 349   case JCS_EXT_BGRA:
 350   case JCS_EXT_ABGR:
 351   case JCS_EXT_ARGB:
 352     cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
 353     break;
 354   case JCS_YCbCr:
 355     cinfo->out_color_components = 3;
 356     break;
 357   case JCS_CMYK:
 358   case JCS_YCCK:
 359     cinfo->out_color_components = 4;
 360     break;
 361   default:                      /* else must be same colorspace as in file */
 362     cinfo->out_color_components = cinfo->num_components;
 363     break;
 364   }
 365   cinfo->output_components = (cinfo->quantize_colors ? 1 :
 366                               cinfo->out_color_components);
 367
 368   /* See if upsampler will want to emit more than one row at a time */
 369   if (use_merged_upsample(cinfo))
 370     cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
 371   else
 372     cinfo->rec_outbuf_height = 1;
 373 }
 374
 375
 376 /*
 377  * Several decompression processes need to range-limit values to the range
 378  * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
 379  * due to noise introduced by quantization, roundoff error, etc.  These
 380  * processes are inner loops and need to be as fast as possible.  On most
 381  * machines, particularly CPUs with pipelines or instruction prefetch,
 382  * a (subscript-check-less) C table lookup
 383  *              x = sample_range_limit[x];
 384  * is faster than explicit tests
 385  *              if (x < 0)  x = 0;
 386  *              else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
 387  * These processes all use a common table prepared by the routine below.
 388  *
 389  * For most steps we can mathematically guarantee that the initial value
 390  * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
 391  * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
 392  * limiting step (just after the IDCT), a wildly out-of-range value is
 393  * possible if the input data is corrupt.  To avoid any chance of indexing
 394  * off the end of memory and getting a bad-pointer trap, we perform the
 395  * post-IDCT limiting thus:
 396  *              x = range_limit[x & MASK];
 397  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
 398  * samples.  Under normal circumstances this is more than enough range and
 399  * a correct output will be generated; with bogus input data the mask will
 400  * cause wraparound, and we will safely generate a bogus-but-in-range output.
 401  * For the post-IDCT step, we want to convert the data from signed to unsigned
 402  * representation by adding CENTERJSAMPLE at the same time that we limit it.
 403  * So the post-IDCT limiting table ends up looking like this:
 404  *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
 405  *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 406  *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 407  *   0,1,...,CENTERJSAMPLE-1
 408  * Negative inputs select values from the upper half of the table after
 409  * masking.
 410  *
 411  * We can save some space by overlapping the start of the post-IDCT table
 412  * with the simpler range limiting table.  The post-IDCT table begins at
 413  * sample_range_limit + CENTERJSAMPLE.
 414  *
 415  * Note that the table is allocated in near data space on PCs; it's small
 416  * enough and used often enough to justify this.
 417  */
 418
 419 LOCAL(void)
 420 prepare_range_limit_table (j_decompress_ptr cinfo)
 421 /* Allocate and fill in the sample_range_limit table */
 422 {
 423   JSAMPLE * table;
 424   int i;
 425
 426   table = (JSAMPLE *)
 427     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 428                 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
 429   table += (MAXJSAMPLE+1);      /* allow negative subscripts of simple table */
 430   cinfo->sample_range_limit = table;
 431   /* First segment of "simple" table: limit[x] = 0 for x < 0 */
 432   MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
 433   /* Main part of "simple" table: limit[x] = x */
 434   for (i = 0; i <= MAXJSAMPLE; i++)
 435     table[i] = (JSAMPLE) i;
 436   table += CENTERJSAMPLE;       /* Point to where post-IDCT table starts */
 437   /* End of simple table, rest of first half of post-IDCT table */
 438   for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
 439     table[i] = MAXJSAMPLE;
 440   /* Second half of post-IDCT table */
 441   MEMZERO(table + (2 * (MAXJSAMPLE+1)),
 442           (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
 443   MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
 444           cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
 445 }
 446
 447
 448 /*
 449  * Master selection of decompression modules.
 450  * This is done once at jpeg_start_decompress time.  We determine
 451  * which modules will be used and give them appropriate initialization calls.
 452  * We also initialize the decompressor input side to begin consuming data.
 453  *
 454  * Since jpeg_read_header has finished, we know what is in the SOF
 455  * and (first) SOS markers.  We also have all the application parameter
 456  * settings.
 457  */
 458
 459 LOCAL(void)
 460 master_selection (j_decompress_ptr cinfo)
 461 {
 462   my_master_ptr master = (my_master_ptr) cinfo->master;
 463   boolean use_c_buffer;
 464   long samplesperrow;
 465   JDIMENSION jd_samplesperrow;
 466
 467   /* Initialize dimensions and other stuff */
 468   jpeg_calc_output_dimensions(cinfo);
 469   prepare_range_limit_table(cinfo);
 470
 471   /* Width of an output scanline must be representable as JDIMENSION. */
 472   samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
 473   jd_samplesperrow = (JDIMENSION) samplesperrow;
 474   if ((long) jd_samplesperrow != samplesperrow)
 475     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 476
 477   /* Initialize my private state */
 478   master->pass_number = 0;
 479   master->using_merged_upsample = use_merged_upsample(cinfo);
 480
 481   /* Color quantizer selection */
 482   master->quantizer_1pass = NULL;
 483   master->quantizer_2pass = NULL;
 484   /* No mode changes if not using buffered-image mode. */
 485   if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
 486     cinfo->enable_1pass_quant = FALSE;
 487     cinfo->enable_external_quant = FALSE;
 488     cinfo->enable_2pass_quant = FALSE;
 489   }
 490   if (cinfo->quantize_colors) {
 491     if (cinfo->raw_data_out)
 492       ERREXIT(cinfo, JERR_NOTIMPL);
 493     /* 2-pass quantizer only works in 3-component color space. */
 494     if (cinfo->out_color_components != 3) {
 495       cinfo->enable_1pass_quant = TRUE;
 496       cinfo->enable_external_quant = FALSE;
 497       cinfo->enable_2pass_quant = FALSE;
 498       cinfo->colormap = NULL;
 499     } else if (cinfo->colormap != NULL) {
 500       cinfo->enable_external_quant = TRUE;
 501     } else if (cinfo->two_pass_quantize) {
 502       cinfo->enable_2pass_quant = TRUE;
 503     } else {
 504       cinfo->enable_1pass_quant = TRUE;
 505     }
 506
 507     if (cinfo->enable_1pass_quant) {
 508 #ifdef QUANT_1PASS_SUPPORTED
 509       jinit_1pass_quantizer(cinfo);
 510       master->quantizer_1pass = cinfo->cquantize;
 511 #else
 512       ERREXIT(cinfo, JERR_NOT_COMPILED);
 513 #endif
 514     }
 515
 516     /* We use the 2-pass code to map to external colormaps. */
 517     if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
 518 #ifdef QUANT_2PASS_SUPPORTED
 519       jinit_2pass_quantizer(cinfo);
 520       master->quantizer_2pass = cinfo->cquantize;
 521 #else
 522       ERREXIT(cinfo, JERR_NOT_COMPILED);
 523 #endif
 524     }
 525     /* If both quantizers are initialized, the 2-pass one is left active;
 526      * this is necessary for starting with quantization to an external map.
 527      */
 528   }
 529
 530   /* Post-processing: in particular, color conversion first */
 531   if (! cinfo->raw_data_out) {
 532     if (master->using_merged_upsample) {
 533 #ifdef UPSAMPLE_MERGING_SUPPORTED
 534       jinit_merged_upsampler(cinfo); /* does color conversion too */
 535 #else
 536       ERREXIT(cinfo, JERR_NOT_COMPILED);
 537 #endif
 538     } else {
 539       jinit_color_deconverter(cinfo);
 540       jinit_upsampler(cinfo);
 541     }
 542     jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
 543   }
 544   /* Inverse DCT */
 545   jinit_inverse_dct(cinfo);
 546   /* Entropy decoding: either Huffman or arithmetic coding. */
 547   if (cinfo->arith_code) {
 548 #ifdef D_ARITH_CODING_SUPPORTED
 549     jinit_arith_decoder(cinfo);
 550 #else
 551     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
 552 #endif
 553   } else {
 554     if (cinfo->progressive_mode) {
 555 #ifdef D_PROGRESSIVE_SUPPORTED
 556       jinit_phuff_decoder(cinfo);
 557 #else
 558       ERREXIT(cinfo, JERR_NOT_COMPILED);
 559 #endif
 560     } else
 561       jinit_huff_decoder(cinfo);
 562   }
 563
 564   /* Initialize principal buffer controllers. */
 565   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
 566   jinit_d_coef_controller(cinfo, use_c_buffer);
 567
 568   if (! cinfo->raw_data_out)
 569     jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
 570
 571   /* We can now tell the memory manager to allocate virtual arrays. */
 572   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
 573
 574   /* Initialize input side of decompressor to consume first scan. */
 575   (*cinfo->inputctl->start_input_pass) (cinfo);
 576
 577 #ifdef D_MULTISCAN_FILES_SUPPORTED
 578   /* If jpeg_start_decompress will read the whole file, initialize
 579    * progress monitoring appropriately.  The input step is counted
 580    * as one pass.
 581    */
 582   if (cinfo->progress != NULL && ! cinfo->buffered_image &&
 583       cinfo->inputctl->has_multiple_scans) {
 584     int nscans;
 585     /* Estimate number of scans to set pass_limit. */
 586     if (cinfo->progressive_mode) {
 587       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
 588       nscans = 2 + 3 * cinfo->num_components;
 589     } else {
 590       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
 591       nscans = cinfo->num_components;
 592     }
 593     cinfo->progress->pass_counter = 0L;
 594     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
 595     cinfo->progress->completed_passes = 0;
 596     cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
 597     /* Count the input pass as done */
 598     master->pass_number++;
 599   }
 600 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 601 }
 602
 603
 604 /*
 605  * Per-pass setup.
 606  * This is called at the beginning of each output pass.  We determine which
 607  * modules will be active during this pass and give them appropriate
 608  * start_pass calls.  We also set is_dummy_pass to indicate whether this
 609  * is a "real" output pass or a dummy pass for color quantization.
 610  * (In the latter case, jdapistd.c will crank the pass to completion.)
 611  */
 612
 613 METHODDEF(void)
 614 prepare_for_output_pass (j_decompress_ptr cinfo)
 615 {
 616   my_master_ptr master = (my_master_ptr) cinfo->master;
 617
 618   if (master->pub.is_dummy_pass) {
 619 #ifdef QUANT_2PASS_SUPPORTED
 620     /* Final pass of 2-pass quantization */
 621     master->pub.is_dummy_pass = FALSE;
 622     (*cinfo->cquantize->start_pass) (cinfo, FALSE);
 623     (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
 624     (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
 625 #else
 626     ERREXIT(cinfo, JERR_NOT_COMPILED);
 627 #endif /* QUANT_2PASS_SUPPORTED */
 628   } else {
 629     if (cinfo->quantize_colors && cinfo->colormap == NULL) {
 630       /* Select new quantization method */
 631       if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
 632         cinfo->cquantize = master->quantizer_2pass;
 633         master->pub.is_dummy_pass = TRUE;
 634       } else if (cinfo->enable_1pass_quant) {
 635         cinfo->cquantize = master->quantizer_1pass;
 636       } else {
 637         ERREXIT(cinfo, JERR_MODE_CHANGE);
 638       }
 639     }
 640     (*cinfo->idct->start_pass) (cinfo);
 641     (*cinfo->coef->start_output_pass) (cinfo);
 642     if (! cinfo->raw_data_out) {
 643       if (! master->using_merged_upsample)
 644         (*cinfo->cconvert->start_pass) (cinfo);
 645       (*cinfo->upsample->start_pass) (cinfo);
 646       if (cinfo->quantize_colors)
 647         (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
 648       (*cinfo->post->start_pass) (cinfo,
 649             (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 650       (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 651     }
 652   }
 653
 654   /* Set up progress monitor's pass info if present */
 655   if (cinfo->progress != NULL) {
 656     cinfo->progress->completed_passes = master->pass_number;
 657     cinfo->progress->total_passes = master->pass_number +
 658                                     (master->pub.is_dummy_pass ? 2 : 1);
 659     /* In buffered-image mode, we assume one more output pass if EOI not
 660      * yet reached, but no more passes if EOI has been reached.
 661      */
 662     if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
 663       cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
 664     }
 665   }
 666 }
 667
 668
 669 /*
 670  * Finish up at end of an output pass.
 671  */
 672
 673 METHODDEF(void)
 674 finish_output_pass (j_decompress_ptr cinfo)
 675 {
 676   my_master_ptr master = (my_master_ptr) cinfo->master;
 677
 678   if (cinfo->quantize_colors)
 679     (*cinfo->cquantize->finish_pass) (cinfo);
 680   master->pass_number++;
 681 }
 682
 683
 684 #ifdef D_MULTISCAN_FILES_SUPPORTED
 685
 686 /*
 687  * Switch to a new external colormap between output passes.
 688  */
 689
 690 GLOBAL(void)
 691 jpeg_new_colormap (j_decompress_ptr cinfo)
 692 {
 693   my_master_ptr master = (my_master_ptr) cinfo->master;
 694
 695   /* Prevent application from calling me at wrong times */
 696   if (cinfo->global_state != DSTATE_BUFIMAGE)
 697     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 698
 699   if (cinfo->quantize_colors && cinfo->enable_external_quant &&
 700       cinfo->colormap != NULL) {
 701     /* Select 2-pass quantizer for external colormap use */
 702     cinfo->cquantize = master->quantizer_2pass;
 703     /* Notify quantizer of colormap change */
 704     (*cinfo->cquantize->new_color_map) (cinfo);
 705     master->pub.is_dummy_pass = FALSE; /* just in case */
 706   } else
 707     ERREXIT(cinfo, JERR_MODE_CHANGE);
 708 }
 709
 710 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 711
 712
 713 /*
 714  * Initialize master decompression control and select active modules.
 715  * This is performed at the start of jpeg_start_decompress.
 716  */
 717
 718 GLOBAL(void)
 719 jinit_master_decompress (j_decompress_ptr cinfo)
 720 {
 721   my_master_ptr master;
 722
 723   master = (my_master_ptr)
 724       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 725                                   SIZEOF(my_decomp_master));
 726   cinfo->master = (struct jpeg_decomp_master *) master;
 727   master->pub.prepare_for_output_pass = prepare_for_output_pass;
 728   master->pub.finish_output_pass = finish_output_pass;
 729
 730   master->pub.is_dummy_pass = FALSE;
 731
 732   master_selection(cinfo);
 733 }