jpeg/jdmaster.c

   1 /*
   2  * jdmaster.c
   3  *
   4  * Copyright (C) 1991-1997, Thomas G. Lane.
   5  * Copyright (C) 2009-2010, D. R. Commander.
   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 #include "jpegcomp.h"
  19
  20
  21 /* Private state */
  22
  23 typedef struct {
  24   struct jpeg_decomp_master pub; /* public fields */
  25
  26   int pass_number;              /* # of passes completed */
  27
  28   boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
  29
  30   /* Saved references to initialized quantizer modules,
  31    * in case we need to switch modes.
  32    */
  33   struct jpeg_color_quantizer * quantizer_1pass;
  34   struct jpeg_color_quantizer * quantizer_2pass;
  35 } my_decomp_master;
  36
  37 typedef my_decomp_master * my_master_ptr;
  38
  39
  40 /*
  41  * Determine whether merged upsample/color conversion should be used.
  42  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
  43  */
  44
  45 LOCAL(boolean)
  46 use_merged_upsample (j_decompress_ptr cinfo)
  47 {
  48 #ifdef UPSAMPLE_MERGING_SUPPORTED
  49   /* Merging is the equivalent of plain box-filter upsampling */
  50   if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
  51     return FALSE;
  52   /* jdmerge.c only supports YCC=>RGB color conversion */
  53   if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
  54       (cinfo->out_color_space != JCS_RGB &&
  55       cinfo->out_color_space != JCS_EXT_RGB &&
  56       cinfo->out_color_space != JCS_EXT_RGBX &&
  57       cinfo->out_color_space != JCS_EXT_BGR &&
  58       cinfo->out_color_space != JCS_EXT_BGRX &&
  59       cinfo->out_color_space != JCS_EXT_XBGR &&
  60       cinfo->out_color_space != JCS_EXT_XRGB) ||
  61       cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space])
  62     return FALSE;
  63   /* and it only handles 2h1v or 2h2v sampling ratios */
  64   if (cinfo->comp_info[0].h_samp_factor != 2 ||
  65       cinfo->comp_info[1].h_samp_factor != 1 ||
  66       cinfo->comp_info[2].h_samp_factor != 1 ||
  67       cinfo->comp_info[0].v_samp_factor >  2 ||
  68       cinfo->comp_info[1].v_samp_factor != 1 ||
  69       cinfo->comp_info[2].v_samp_factor != 1)
  70     return FALSE;
  71   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
  72   if (cinfo->comp_info[0]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
  73       cinfo->comp_info[1]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
  74       cinfo->comp_info[2]._DCT_scaled_size != cinfo->_min_DCT_scaled_size)
  75     return FALSE;
  76   /* ??? also need to test for upsample-time rescaling, when & if supported */
  77   return TRUE;                  /* by golly, it'll work... */
  78 #else
  79   return FALSE;
  80 #endif
  81 }
  82
  83
  84 /*
  85  * Compute output image dimensions and related values.
  86  * NOTE: this is exported for possible use by application.
  87  * Hence it mustn't do anything that can't be done twice.
  88  * Also note that it may be called before the master module is initialized!
  89  */
  90
  91 GLOBAL(void)
  92 jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
  93 /* Do computations that are needed before master selection phase */
  94 {
  95 #ifdef IDCT_SCALING_SUPPORTED
  96   int ci;
  97   jpeg_component_info *compptr;
  98 #endif
  99
 100   /* Prevent application from calling me at wrong times */
 101   if (cinfo->global_state != DSTATE_READY)
 102     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 103
 104 #ifdef IDCT_SCALING_SUPPORTED
 105
 106   /* Compute actual output image dimensions and DCT scaling choices. */
 107   if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
 108     /* Provide 1/8 scaling */
 109     cinfo->output_width = (JDIMENSION)
 110       jdiv_round_up((long) cinfo->image_width, 8L);
 111     cinfo->output_height = (JDIMENSION)
 112       jdiv_round_up((long) cinfo->image_height, 8L);
 113 #if JPEG_LIB_VERSION >= 70
 114     cinfo->min_DCT_h_scaled_size = cinfo->min_DCT_v_scaled_size = 1;
 115 #else
 116     cinfo->min_DCT_scaled_size = 1;
 117 #endif
 118   } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
 119     /* Provide 1/4 scaling */
 120     cinfo->output_width = (JDIMENSION)
 121       jdiv_round_up((long) cinfo->image_width, 4L);
 122     cinfo->output_height = (JDIMENSION)
 123       jdiv_round_up((long) cinfo->image_height, 4L);
 124 #if JPEG_LIB_VERSION >= 70
 125     cinfo->min_DCT_h_scaled_size = cinfo->min_DCT_v_scaled_size = 2;
 126 #else
 127     cinfo->min_DCT_scaled_size = 2;
 128 #endif
 129   } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
 130     /* Provide 1/2 scaling */
 131     cinfo->output_width = (JDIMENSION)
 132       jdiv_round_up((long) cinfo->image_width, 2L);
 133     cinfo->output_height = (JDIMENSION)
 134       jdiv_round_up((long) cinfo->image_height, 2L);
 135 #if JPEG_LIB_VERSION >= 70
 136     cinfo->min_DCT_h_scaled_size = cinfo->min_DCT_v_scaled_size = 4;
 137 #else
 138     cinfo->min_DCT_scaled_size = 4;
 139 #endif
 140   } else {
 141     /* Provide 1/1 scaling */
 142     cinfo->output_width = cinfo->image_width;
 143     cinfo->output_height = cinfo->image_height;
 144 #if JPEG_LIB_VERSION >= 70
 145     cinfo->min_DCT_h_scaled_size = cinfo->min_DCT_v_scaled_size = DCTSIZE;
 146 #else
 147     cinfo->min_DCT_scaled_size = DCTSIZE;
 148 #endif
 149   }
 150   /* In selecting the actual DCT scaling for each component, we try to
 151    * scale up the chroma components via IDCT scaling rather than upsampling.
 152    * This saves time if the upsampler gets to use 1:1 scaling.
 153    * Note this code assumes that the supported DCT scalings are powers of 2.
 154    */
 155   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 156        ci++, compptr++) {
 157     int ssize = cinfo->_min_DCT_scaled_size;
 158     while (ssize < DCTSIZE &&
 159            (compptr->h_samp_factor * ssize * 2 <=
 160             cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) &&
 161            (compptr->v_samp_factor * ssize * 2 <=
 162             cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size)) {
 163       ssize = ssize * 2;
 164     }
 165 #if JPEG_LIB_VERSION >= 70
 166     compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = ssize;
 167 #else
 168     compptr->DCT_scaled_size = ssize;
 169 #endif
 170   }
 171
 172   /* Recompute downsampled dimensions of components;
 173    * application needs to know these if using raw downsampled data.
 174    */
 175   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 176        ci++, compptr++) {
 177     /* Size in samples, after IDCT scaling */
 178     compptr->downsampled_width = (JDIMENSION)
 179       jdiv_round_up((long) cinfo->image_width *
 180                     (long) (compptr->h_samp_factor * compptr->_DCT_scaled_size),
 181                     (long) (cinfo->max_h_samp_factor * DCTSIZE));
 182     compptr->downsampled_height = (JDIMENSION)
 183       jdiv_round_up((long) cinfo->image_height *
 184                     (long) (compptr->v_samp_factor * compptr->_DCT_scaled_size),
 185                     (long) (cinfo->max_v_samp_factor * DCTSIZE));
 186   }
 187
 188 #else /* !IDCT_SCALING_SUPPORTED */
 189
 190   /* Hardwire it to "no scaling" */
 191   cinfo->output_width = cinfo->image_width;
 192   cinfo->output_height = cinfo->image_height;
 193   /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
 194    * and has computed unscaled downsampled_width and downsampled_height.
 195    */
 196
 197 #endif /* IDCT_SCALING_SUPPORTED */
 198
 199   /* Report number of components in selected colorspace. */
 200   /* Probably this should be in the color conversion module... */
 201   switch (cinfo->out_color_space) {
 202   case JCS_GRAYSCALE:
 203     cinfo->out_color_components = 1;
 204     break;
 205   case JCS_RGB:
 206   case JCS_EXT_RGB:
 207   case JCS_EXT_RGBX:
 208   case JCS_EXT_BGR:
 209   case JCS_EXT_BGRX:
 210   case JCS_EXT_XBGR:
 211   case JCS_EXT_XRGB:
 212     cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
 213     break;
 214   case JCS_YCbCr:
 215     cinfo->out_color_components = 3;
 216     break;
 217   case JCS_CMYK:
 218   case JCS_YCCK:
 219     cinfo->out_color_components = 4;
 220     break;
 221   default:                      /* else must be same colorspace as in file */
 222     cinfo->out_color_components = cinfo->num_components;
 223     break;
 224   }
 225   cinfo->output_components = (cinfo->quantize_colors ? 1 :
 226                               cinfo->out_color_components);
 227
 228   /* See if upsampler will want to emit more than one row at a time */
 229   if (use_merged_upsample(cinfo))
 230     cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
 231   else
 232     cinfo->rec_outbuf_height = 1;
 233 }
 234
 235
 236 /*
 237  * Several decompression processes need to range-limit values to the range
 238  * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
 239  * due to noise introduced by quantization, roundoff error, etc.  These
 240  * processes are inner loops and need to be as fast as possible.  On most
 241  * machines, particularly CPUs with pipelines or instruction prefetch,
 242  * a (subscript-check-less) C table lookup
 243  *              x = sample_range_limit[x];
 244  * is faster than explicit tests
 245  *              if (x < 0)  x = 0;
 246  *              else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
 247  * These processes all use a common table prepared by the routine below.
 248  *
 249  * For most steps we can mathematically guarantee that the initial value
 250  * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
 251  * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
 252  * limiting step (just after the IDCT), a wildly out-of-range value is
 253  * possible if the input data is corrupt.  To avoid any chance of indexing
 254  * off the end of memory and getting a bad-pointer trap, we perform the
 255  * post-IDCT limiting thus:
 256  *              x = range_limit[x & MASK];
 257  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
 258  * samples.  Under normal circumstances this is more than enough range and
 259  * a correct output will be generated; with bogus input data the mask will
 260  * cause wraparound, and we will safely generate a bogus-but-in-range output.
 261  * For the post-IDCT step, we want to convert the data from signed to unsigned
 262  * representation by adding CENTERJSAMPLE at the same time that we limit it.
 263  * So the post-IDCT limiting table ends up looking like this:
 264  *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
 265  *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 266  *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 267  *   0,1,...,CENTERJSAMPLE-1
 268  * Negative inputs select values from the upper half of the table after
 269  * masking.
 270  *
 271  * We can save some space by overlapping the start of the post-IDCT table
 272  * with the simpler range limiting table.  The post-IDCT table begins at
 273  * sample_range_limit + CENTERJSAMPLE.
 274  *
 275  * Note that the table is allocated in near data space on PCs; it's small
 276  * enough and used often enough to justify this.
 277  */
 278
 279 LOCAL(void)
 280 prepare_range_limit_table (j_decompress_ptr cinfo)
 281 /* Allocate and fill in the sample_range_limit table */
 282 {
 283   JSAMPLE * table;
 284   int i;
 285
 286   table = (JSAMPLE *)
 287     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 288                 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
 289   table += (MAXJSAMPLE+1);      /* allow negative subscripts of simple table */
 290   cinfo->sample_range_limit = table;
 291   /* First segment of "simple" table: limit[x] = 0 for x < 0 */
 292   MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
 293   /* Main part of "simple" table: limit[x] = x */
 294   for (i = 0; i <= MAXJSAMPLE; i++)
 295     table[i] = (JSAMPLE) i;
 296   table += CENTERJSAMPLE;       /* Point to where post-IDCT table starts */
 297   /* End of simple table, rest of first half of post-IDCT table */
 298   for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
 299     table[i] = MAXJSAMPLE;
 300   /* Second half of post-IDCT table */
 301   MEMZERO(table + (2 * (MAXJSAMPLE+1)),
 302           (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
 303   MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
 304           cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
 305 }
 306
 307
 308 /*
 309  * Master selection of decompression modules.
 310  * This is done once at jpeg_start_decompress time.  We determine
 311  * which modules will be used and give them appropriate initialization calls.
 312  * We also initialize the decompressor input side to begin consuming data.
 313  *
 314  * Since jpeg_read_header has finished, we know what is in the SOF
 315  * and (first) SOS markers.  We also have all the application parameter
 316  * settings.
 317  */
 318
 319 LOCAL(void)
 320 master_selection (j_decompress_ptr cinfo)
 321 {
 322   my_master_ptr master = (my_master_ptr) cinfo->master;
 323   boolean use_c_buffer;
 324   long samplesperrow;
 325   JDIMENSION jd_samplesperrow;
 326
 327   /* Initialize dimensions and other stuff */
 328   jpeg_calc_output_dimensions(cinfo);
 329   prepare_range_limit_table(cinfo);
 330
 331   /* Width of an output scanline must be representable as JDIMENSION. */
 332   samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
 333   jd_samplesperrow = (JDIMENSION) samplesperrow;
 334   if ((long) jd_samplesperrow != samplesperrow)
 335     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 336
 337   /* Initialize my private state */
 338   master->pass_number = 0;
 339   master->using_merged_upsample = use_merged_upsample(cinfo);
 340
 341   /* Color quantizer selection */
 342   master->quantizer_1pass = NULL;
 343   master->quantizer_2pass = NULL;
 344   /* No mode changes if not using buffered-image mode. */
 345   if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
 346     cinfo->enable_1pass_quant = FALSE;
 347     cinfo->enable_external_quant = FALSE;
 348     cinfo->enable_2pass_quant = FALSE;
 349   }
 350   if (cinfo->quantize_colors) {
 351     if (cinfo->raw_data_out)
 352       ERREXIT(cinfo, JERR_NOTIMPL);
 353     /* 2-pass quantizer only works in 3-component color space. */
 354     if (cinfo->out_color_components != 3) {
 355       cinfo->enable_1pass_quant = TRUE;
 356       cinfo->enable_external_quant = FALSE;
 357       cinfo->enable_2pass_quant = FALSE;
 358       cinfo->colormap = NULL;
 359     } else if (cinfo->colormap != NULL) {
 360       cinfo->enable_external_quant = TRUE;
 361     } else if (cinfo->two_pass_quantize) {
 362       cinfo->enable_2pass_quant = TRUE;
 363     } else {
 364       cinfo->enable_1pass_quant = TRUE;
 365     }
 366
 367     if (cinfo->enable_1pass_quant) {
 368 #ifdef QUANT_1PASS_SUPPORTED
 369       jinit_1pass_quantizer(cinfo);
 370       master->quantizer_1pass = cinfo->cquantize;
 371 #else
 372       ERREXIT(cinfo, JERR_NOT_COMPILED);
 373 #endif
 374     }
 375
 376     /* We use the 2-pass code to map to external colormaps. */
 377     if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
 378 #ifdef QUANT_2PASS_SUPPORTED
 379       jinit_2pass_quantizer(cinfo);
 380       master->quantizer_2pass = cinfo->cquantize;
 381 #else
 382       ERREXIT(cinfo, JERR_NOT_COMPILED);
 383 #endif
 384     }
 385     /* If both quantizers are initialized, the 2-pass one is left active;
 386      * this is necessary for starting with quantization to an external map.
 387      */
 388   }
 389
 390   /* Post-processing: in particular, color conversion first */
 391   if (! cinfo->raw_data_out) {
 392     if (master->using_merged_upsample) {
 393 #ifdef UPSAMPLE_MERGING_SUPPORTED
 394       jinit_merged_upsampler(cinfo); /* does color conversion too */
 395 #else
 396       ERREXIT(cinfo, JERR_NOT_COMPILED);
 397 #endif
 398     } else {
 399       jinit_color_deconverter(cinfo);
 400       jinit_upsampler(cinfo);
 401     }
 402     jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
 403   }
 404   /* Inverse DCT */
 405   jinit_inverse_dct(cinfo);
 406   /* Entropy decoding: either Huffman or arithmetic coding. */
 407   if (cinfo->arith_code) {
 408 #ifdef D_ARITH_CODING_SUPPORTED
 409     jinit_arith_decoder(cinfo);
 410 #else
 411     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
 412 #endif
 413   } else {
 414     if (cinfo->progressive_mode) {
 415 #ifdef D_PROGRESSIVE_SUPPORTED
 416       jinit_phuff_decoder(cinfo);
 417 #else
 418       ERREXIT(cinfo, JERR_NOT_COMPILED);
 419 #endif
 420     } else
 421       jinit_huff_decoder(cinfo);
 422   }
 423
 424   /* Initialize principal buffer controllers. */
 425   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
 426   jinit_d_coef_controller(cinfo, use_c_buffer);
 427
 428   if (! cinfo->raw_data_out)
 429     jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
 430
 431   /* We can now tell the memory manager to allocate virtual arrays. */
 432   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
 433
 434   /* Initialize input side of decompressor to consume first scan. */
 435   (*cinfo->inputctl->start_input_pass) (cinfo);
 436
 437 #ifdef D_MULTISCAN_FILES_SUPPORTED
 438   /* If jpeg_start_decompress will read the whole file, initialize
 439    * progress monitoring appropriately.  The input step is counted
 440    * as one pass.
 441    */
 442   if (cinfo->progress != NULL && ! cinfo->buffered_image &&
 443       cinfo->inputctl->has_multiple_scans) {
 444     int nscans;
 445     /* Estimate number of scans to set pass_limit. */
 446     if (cinfo->progressive_mode) {
 447       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
 448       nscans = 2 + 3 * cinfo->num_components;
 449     } else {
 450       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
 451       nscans = cinfo->num_components;
 452     }
 453     cinfo->progress->pass_counter = 0L;
 454     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
 455     cinfo->progress->completed_passes = 0;
 456     cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
 457     /* Count the input pass as done */
 458     master->pass_number++;
 459   }
 460 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 461 }
 462
 463
 464 /*
 465  * Per-pass setup.
 466  * This is called at the beginning of each output pass.  We determine which
 467  * modules will be active during this pass and give them appropriate
 468  * start_pass calls.  We also set is_dummy_pass to indicate whether this
 469  * is a "real" output pass or a dummy pass for color quantization.
 470  * (In the latter case, jdapistd.c will crank the pass to completion.)
 471  */
 472
 473 METHODDEF(void)
 474 prepare_for_output_pass (j_decompress_ptr cinfo)
 475 {
 476   my_master_ptr master = (my_master_ptr) cinfo->master;
 477
 478   if (master->pub.is_dummy_pass) {
 479 #ifdef QUANT_2PASS_SUPPORTED
 480     /* Final pass of 2-pass quantization */
 481     master->pub.is_dummy_pass = FALSE;
 482     (*cinfo->cquantize->start_pass) (cinfo, FALSE);
 483     (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
 484     (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
 485 #else
 486     ERREXIT(cinfo, JERR_NOT_COMPILED);
 487 #endif /* QUANT_2PASS_SUPPORTED */
 488   } else {
 489     if (cinfo->quantize_colors && cinfo->colormap == NULL) {
 490       /* Select new quantization method */
 491       if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
 492         cinfo->cquantize = master->quantizer_2pass;
 493         master->pub.is_dummy_pass = TRUE;
 494       } else if (cinfo->enable_1pass_quant) {
 495         cinfo->cquantize = master->quantizer_1pass;
 496       } else {
 497         ERREXIT(cinfo, JERR_MODE_CHANGE);
 498       }
 499     }
 500     (*cinfo->idct->start_pass) (cinfo);
 501     (*cinfo->coef->start_output_pass) (cinfo);
 502     if (! cinfo->raw_data_out) {
 503       if (! master->using_merged_upsample)
 504         (*cinfo->cconvert->start_pass) (cinfo);
 505       (*cinfo->upsample->start_pass) (cinfo);
 506       if (cinfo->quantize_colors)
 507         (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
 508       (*cinfo->post->start_pass) (cinfo,
 509             (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 510       (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 511     }
 512   }
 513
 514   /* Set up progress monitor's pass info if present */
 515   if (cinfo->progress != NULL) {
 516     cinfo->progress->completed_passes = master->pass_number;
 517     cinfo->progress->total_passes = master->pass_number +
 518                                     (master->pub.is_dummy_pass ? 2 : 1);
 519     /* In buffered-image mode, we assume one more output pass if EOI not
 520      * yet reached, but no more passes if EOI has been reached.
 521      */
 522     if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
 523       cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
 524     }
 525   }
 526 }
 527
 528
 529 /*
 530  * Finish up at end of an output pass.
 531  */
 532
 533 METHODDEF(void)
 534 finish_output_pass (j_decompress_ptr cinfo)
 535 {
 536   my_master_ptr master = (my_master_ptr) cinfo->master;
 537
 538   if (cinfo->quantize_colors)
 539     (*cinfo->cquantize->finish_pass) (cinfo);
 540   master->pass_number++;
 541 }
 542
 543
 544 #ifdef D_MULTISCAN_FILES_SUPPORTED
 545
 546 /*
 547  * Switch to a new external colormap between output passes.
 548  */
 549
 550 GLOBAL(void)
 551 jpeg_new_colormap (j_decompress_ptr cinfo)
 552 {
 553   my_master_ptr master = (my_master_ptr) cinfo->master;
 554
 555   /* Prevent application from calling me at wrong times */
 556   if (cinfo->global_state != DSTATE_BUFIMAGE)
 557     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 558
 559   if (cinfo->quantize_colors && cinfo->enable_external_quant &&
 560       cinfo->colormap != NULL) {
 561     /* Select 2-pass quantizer for external colormap use */
 562     cinfo->cquantize = master->quantizer_2pass;
 563     /* Notify quantizer of colormap change */
 564     (*cinfo->cquantize->new_color_map) (cinfo);
 565     master->pub.is_dummy_pass = FALSE; /* just in case */
 566   } else
 567     ERREXIT(cinfo, JERR_MODE_CHANGE);
 568 }
 569
 570 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 571
 572
 573 /*
 574  * Initialize master decompression control and select active modules.
 575  * This is performed at the start of jpeg_start_decompress.
 576  */
 577
 578 GLOBAL(void)
 579 jinit_master_decompress (j_decompress_ptr cinfo)
 580 {
 581   my_master_ptr master;
 582
 583   master = (my_master_ptr)
 584       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 585                                   SIZEOF(my_decomp_master));
 586   cinfo->master = (struct jpeg_decomp_master *) master;
 587   master->pub.prepare_for_output_pass = prepare_for_output_pass;
 588   master->pub.finish_output_pass = finish_output_pass;
 589
 590   master->pub.is_dummy_pass = FALSE;
 591
 592   master_selection(cinfo);
 593 }