compiler/libjpeg/jdmaster.c

   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
  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 #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
 230 LOCAL(void)
 231 prepare_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
 270 LOCAL(void)
 271 master_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
 413 METHODDEF(void)
 414 prepare_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
 473 METHODDEF(void)
 474 finish_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
 490 GLOBAL(void)
 491 jpeg_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
 518 GLOBAL(void)
 519 jinit_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 }