src/jpeg/jcmaster.c

   1 /*
   2  * jcmaster.c
   3  *
   4  * Copyright (C) 1991-1997, Thomas G. Lane.
   5  * This file is part of the Independent JPEG Group's software.
   6  * For conditions of distribution and use, see the accompanying README file.
   7  *
   8  * This file contains master control logic for the JPEG compressor.
   9  * These routines are concerned with parameter validation, initial setup,
  10  * and inter-pass control (determining the number of passes and the work
  11  * to be done in each pass).
  12  */
  13
  14 #define JPEG_INTERNALS
  15 #include "jinclude.h"
  16 #include "jpeglib.h"
  17
  18
  19 /* Private state */
  20
  21 typedef enum {
  22         main_pass,              /* input data, also do first output step */
  23         huff_opt_pass,          /* Huffman code optimization pass */
  24         output_pass             /* data output pass */
  25 } c_pass_type;
  26
  27 typedef struct {
  28   struct jpeg_comp_master pub;  /* public fields */
  29
  30   c_pass_type pass_type;        /* the type of the current pass */
  31
  32   int pass_number;              /* # of passes completed */
  33   int total_passes;             /* total # of passes needed */
  34
  35   int scan_number;              /* current index in scan_info[] */
  36 } my_comp_master;
  37
  38 typedef my_comp_master * my_master_ptr;
  39
  40
  41 /*
  42  * Support routines that do various essential calculations.
  43  */
  44
  45 LOCAL(void)
  46 initial_setup (j_compress_ptr cinfo)
  47 /* Do computations that are needed before master selection phase */
  48 {
  49   int ci;
  50   jpeg_component_info *compptr;
  51   long samplesperrow;
  52   JDIMENSION jd_samplesperrow;
  53
  54   /* Sanity check on image dimensions */
  55   if (cinfo->image_height <= 0 || cinfo->image_width <= 0
  56       || cinfo->num_components <= 0 || cinfo->input_components <= 0)
  57     ERREXIT(cinfo, JERR_EMPTY_IMAGE);
  58
  59   /* Make sure image isn't bigger than I can handle */
  60   if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
  61       (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
  62     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
  63
  64   /* Width of an input scanline must be representable as JDIMENSION. */
  65   samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
  66   jd_samplesperrow = (JDIMENSION) samplesperrow;
  67   if ((long) jd_samplesperrow != samplesperrow)
  68     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
  69
  70   /* For now, precision must match compiled-in value... */
  71   if (cinfo->data_precision != BITS_IN_JSAMPLE)
  72     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
  73
  74   /* Check that number of components won't exceed internal array sizes */
  75   if (cinfo->num_components > MAX_COMPONENTS)
  76     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
  77              MAX_COMPONENTS);
  78
  79   /* Compute maximum sampling factors; check factor validity */
  80   cinfo->max_h_samp_factor = 1;
  81   cinfo->max_v_samp_factor = 1;
  82   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  83        ci++, compptr++) {
  84     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
  85         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
  86       ERREXIT(cinfo, JERR_BAD_SAMPLING);
  87     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
  88                                    compptr->h_samp_factor);
  89     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
  90                                    compptr->v_samp_factor);
  91   }
  92
  93   /* Compute dimensions of components */
  94   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  95        ci++, compptr++) {
  96     /* Fill in the correct component_index value; don't rely on application */
  97     compptr->component_index = ci;
  98     /* For compression, we never do DCT scaling. */
  99     compptr->DCT_scaled_size = DCTSIZE;
 100     /* Size in DCT blocks */
 101     compptr->width_in_blocks = (JDIMENSION)
 102       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
 103                     (long) (cinfo->max_h_samp_factor * DCTSIZE));
 104     compptr->height_in_blocks = (JDIMENSION)
 105       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
 106                     (long) (cinfo->max_v_samp_factor * DCTSIZE));
 107     /* Size in samples */
 108     compptr->downsampled_width = (JDIMENSION)
 109       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
 110                     (long) cinfo->max_h_samp_factor);
 111     compptr->downsampled_height = (JDIMENSION)
 112       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
 113                     (long) cinfo->max_v_samp_factor);
 114     /* Mark component needed (this flag isn't actually used for compression) */
 115     compptr->component_needed = TRUE;
 116   }
 117
 118   /* Compute number of fully interleaved MCU rows (number of times that
 119    * main controller will call coefficient controller).
 120    */
 121   cinfo->total_iMCU_rows = (JDIMENSION)
 122     jdiv_round_up((long) cinfo->image_height,
 123                   (long) (cinfo->max_v_samp_factor*DCTSIZE));
 124 }
 125
 126
 127 #ifdef C_MULTISCAN_FILES_SUPPORTED
 128
 129 LOCAL(void)
 130 validate_script (j_compress_ptr cinfo)
 131 /* Verify that the scan script in cinfo->scan_info[] is valid; also
 132  * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
 133  */
 134 {
 135   const jpeg_scan_info * scanptr;
 136   int scanno, ncomps, ci, coefi, thisi;
 137   int Ss, Se, Ah, Al;
 138   boolean component_sent[MAX_COMPONENTS];
 139 #ifdef C_PROGRESSIVE_SUPPORTED
 140   int * last_bitpos_ptr;
 141   int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
 142   /* -1 until that coefficient has been seen; then last Al for it */
 143 #endif
 144
 145   if (cinfo->num_scans <= 0)
 146     ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);
 147
 148   /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
 149    * for progressive JPEG, no scan can have this.
 150    */
 151   scanptr = cinfo->scan_info;
 152   if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
 153 #ifdef C_PROGRESSIVE_SUPPORTED
 154     cinfo->progressive_mode = TRUE;
 155     last_bitpos_ptr = & last_bitpos[0][0];
 156     for (ci = 0; ci < cinfo->num_components; ci++)
 157       for (coefi = 0; coefi < DCTSIZE2; coefi++)
 158         *last_bitpos_ptr++ = -1;
 159 #else
 160     ERREXIT(cinfo, JERR_NOT_COMPILED);
 161 #endif
 162   } else {
 163     cinfo->progressive_mode = FALSE;
 164     for (ci = 0; ci < cinfo->num_components; ci++)
 165       component_sent[ci] = FALSE;
 166   }
 167
 168   for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
 169     /* Validate component indexes */
 170     ncomps = scanptr->comps_in_scan;
 171     if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
 172       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
 173     for (ci = 0; ci < ncomps; ci++) {
 174       thisi = scanptr->component_index[ci];
 175       if (thisi < 0 || thisi >= cinfo->num_components)
 176         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 177       /* Components must appear in SOF order within each scan */
 178       if (ci > 0 && thisi <= scanptr->component_index[ci-1])
 179         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 180     }
 181     /* Validate progression parameters */
 182     Ss = scanptr->Ss;
 183     Se = scanptr->Se;
 184     Ah = scanptr->Ah;
 185     Al = scanptr->Al;
 186     if (cinfo->progressive_mode) {
 187 #ifdef C_PROGRESSIVE_SUPPORTED
 188       /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
 189        * seems wrong: the upper bound ought to depend on data precision.
 190        * Perhaps they really meant 0..N+1 for N-bit precision.
 191        * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
 192        * out-of-range reconstructed DC values during the first DC scan,
 193        * which might cause problems for some decoders.
 194        */
 195 #if BITS_IN_JSAMPLE == 8
 196 #define MAX_AH_AL 10
 197 #else
 198 #define MAX_AH_AL 13
 199 #endif
 200       if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
 201           Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
 202         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 203       if (Ss == 0) {
 204         if (Se != 0)            /* DC and AC together not OK */
 205           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 206       } else {
 207         if (ncomps != 1)        /* AC scans must be for only one component */
 208           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 209       }
 210       for (ci = 0; ci < ncomps; ci++) {
 211         last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
 212         if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
 213           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 214         for (coefi = Ss; coefi <= Se; coefi++) {
 215           if (last_bitpos_ptr[coefi] < 0) {
 216             /* first scan of this coefficient */
 217             if (Ah != 0)
 218               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 219           } else {
 220             /* not first scan */
 221             if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
 222               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 223           }
 224           last_bitpos_ptr[coefi] = Al;
 225         }
 226       }
 227 #endif
 228     } else {
 229       /* For sequential JPEG, all progression parameters must be these: */
 230       if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
 231         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 232       /* Make sure components are not sent twice */
 233       for (ci = 0; ci < ncomps; ci++) {
 234         thisi = scanptr->component_index[ci];
 235         if (component_sent[thisi])
 236           ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 237         component_sent[thisi] = TRUE;
 238       }
 239     }
 240   }
 241
 242   /* Now verify that everything got sent. */
 243   if (cinfo->progressive_mode) {
 244 #ifdef C_PROGRESSIVE_SUPPORTED
 245     /* For progressive mode, we only check that at least some DC data
 246      * got sent for each component; the spec does not require that all bits
 247      * of all coefficients be transmitted.  Would it be wiser to enforce
 248      * transmission of all coefficient bits??
 249      */
 250     for (ci = 0; ci < cinfo->num_components; ci++) {
 251       if (last_bitpos[ci][0] < 0)
 252         ERREXIT(cinfo, JERR_MISSING_DATA);
 253     }
 254 #endif
 255   } else {
 256     for (ci = 0; ci < cinfo->num_components; ci++) {
 257       if (! component_sent[ci])
 258         ERREXIT(cinfo, JERR_MISSING_DATA);
 259     }
 260   }
 261 }
 262
 263 #endif /* C_MULTISCAN_FILES_SUPPORTED */
 264
 265
 266 LOCAL(void)
 267 select_scan_parameters (j_compress_ptr cinfo)
 268 /* Set up the scan parameters for the current scan */
 269 {
 270   int ci;
 271
 272 #ifdef C_MULTISCAN_FILES_SUPPORTED
 273   if (cinfo->scan_info != NULL) {
 274     /* Prepare for current scan --- the script is already validated */
 275     my_master_ptr master = (my_master_ptr) cinfo->master;
 276     const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;
 277
 278     cinfo->comps_in_scan = scanptr->comps_in_scan;
 279     for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
 280       cinfo->cur_comp_info[ci] =
 281         &cinfo->comp_info[scanptr->component_index[ci]];
 282     }
 283     cinfo->Ss = scanptr->Ss;
 284     cinfo->Se = scanptr->Se;
 285     cinfo->Ah = scanptr->Ah;
 286     cinfo->Al = scanptr->Al;
 287   }
 288   else
 289 #endif
 290   {
 291     /* Prepare for single sequential-JPEG scan containing all components */
 292     if (cinfo->num_components > MAX_COMPS_IN_SCAN)
 293       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
 294                MAX_COMPS_IN_SCAN);
 295     cinfo->comps_in_scan = cinfo->num_components;
 296     for (ci = 0; ci < cinfo->num_components; ci++) {
 297       cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
 298     }
 299     cinfo->Ss = 0;
 300     cinfo->Se = DCTSIZE2-1;
 301     cinfo->Ah = 0;
 302     cinfo->Al = 0;
 303   }
 304 }
 305
 306
 307 LOCAL(void)
 308 per_scan_setup (j_compress_ptr cinfo)
 309 /* Do computations that are needed before processing a JPEG scan */
 310 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
 311 {
 312   int ci, mcublks, tmp;
 313   jpeg_component_info *compptr;
 314
 315   if (cinfo->comps_in_scan == 1) {
 316
 317     /* Noninterleaved (single-component) scan */
 318     compptr = cinfo->cur_comp_info[0];
 319
 320     /* Overall image size in MCUs */
 321     cinfo->MCUs_per_row = compptr->width_in_blocks;
 322     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
 323
 324     /* For noninterleaved scan, always one block per MCU */
 325     compptr->MCU_width = 1;
 326     compptr->MCU_height = 1;
 327     compptr->MCU_blocks = 1;
 328     compptr->MCU_sample_width = DCTSIZE;
 329     compptr->last_col_width = 1;
 330     /* For noninterleaved scans, it is convenient to define last_row_height
 331      * as the number of block rows present in the last iMCU row.
 332      */
 333     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
 334     if (tmp == 0) tmp = compptr->v_samp_factor;
 335     compptr->last_row_height = tmp;
 336
 337     /* Prepare array describing MCU composition */
 338     cinfo->blocks_in_MCU = 1;
 339     cinfo->MCU_membership[0] = 0;
 340
 341   } else {
 342
 343     /* Interleaved (multi-component) scan */
 344     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
 345       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
 346                MAX_COMPS_IN_SCAN);
 347
 348     /* Overall image size in MCUs */
 349     cinfo->MCUs_per_row = (JDIMENSION)
 350       jdiv_round_up((long) cinfo->image_width,
 351                     (long) (cinfo->max_h_samp_factor*DCTSIZE));
 352     cinfo->MCU_rows_in_scan = (JDIMENSION)
 353       jdiv_round_up((long) cinfo->image_height,
 354                     (long) (cinfo->max_v_samp_factor*DCTSIZE));
 355
 356     cinfo->blocks_in_MCU = 0;
 357
 358     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 359       compptr = cinfo->cur_comp_info[ci];
 360       /* Sampling factors give # of blocks of component in each MCU */
 361       compptr->MCU_width = compptr->h_samp_factor;
 362       compptr->MCU_height = compptr->v_samp_factor;
 363       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
 364       compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
 365       /* Figure number of non-dummy blocks in last MCU column & row */
 366       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
 367       if (tmp == 0) tmp = compptr->MCU_width;
 368       compptr->last_col_width = tmp;
 369       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
 370       if (tmp == 0) tmp = compptr->MCU_height;
 371       compptr->last_row_height = tmp;
 372       /* Prepare array describing MCU composition */
 373       mcublks = compptr->MCU_blocks;
 374       if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
 375         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
 376       while (mcublks-- > 0) {
 377         cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
 378       }
 379     }
 380
 381   }
 382
 383   /* Convert restart specified in rows to actual MCU count. */
 384   /* Note that count must fit in 16 bits, so we provide limiting. */
 385   if (cinfo->restart_in_rows > 0) {
 386     long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
 387     cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
 388   }
 389 }
 390
 391
 392 /*
 393  * Per-pass setup.
 394  * This is called at the beginning of each pass.  We determine which modules
 395  * will be active during this pass and give them appropriate start_pass calls.
 396  * We also set is_last_pass to indicate whether any more passes will be
 397  * required.
 398  */
 399
 400 METHODDEF(void)
 401 prepare_for_pass (j_compress_ptr cinfo)
 402 {
 403   my_master_ptr master = (my_master_ptr) cinfo->master;
 404
 405   switch (master->pass_type) {
 406   case main_pass:
 407     /* Initial pass: will collect input data, and do either Huffman
 408      * optimization or data output for the first scan.
 409      */
 410     select_scan_parameters(cinfo);
 411     per_scan_setup(cinfo);
 412     if (! cinfo->raw_data_in) {
 413       (*cinfo->cconvert->start_pass) (cinfo);
 414       (*cinfo->downsample->start_pass) (cinfo);
 415       (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
 416     }
 417     (*cinfo->fdct->start_pass) (cinfo);
 418     (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
 419     (*cinfo->coef->start_pass) (cinfo,
 420                                 (master->total_passes > 1 ?
 421                                  JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 422     (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 423     if (cinfo->optimize_coding) {
 424       /* No immediate data output; postpone writing frame/scan headers */
 425       master->pub.call_pass_startup = FALSE;
 426     } else {
 427       /* Will write frame/scan headers at first jpeg_write_scanlines call */
 428       master->pub.call_pass_startup = TRUE;
 429     }
 430     break;
 431 #ifdef ENTROPY_OPT_SUPPORTED
 432   case huff_opt_pass:
 433     /* Do Huffman optimization for a scan after the first one. */
 434     select_scan_parameters(cinfo);
 435     per_scan_setup(cinfo);
 436     if (cinfo->Ss != 0 || cinfo->Ah == 0 || cinfo->arith_code) {
 437       (*cinfo->entropy->start_pass) (cinfo, TRUE);
 438       (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
 439       master->pub.call_pass_startup = FALSE;
 440       break;
 441     }
 442     /* Special case: Huffman DC refinement scans need no Huffman table
 443      * and therefore we can skip the optimization pass for them.
 444      */
 445     master->pass_type = output_pass;
 446     master->pass_number++;
 447     /*FALLTHROUGH*/
 448 #endif
 449   case output_pass:
 450     /* Do a data-output pass. */
 451     /* We need not repeat per-scan setup if prior optimization pass did it. */
 452     if (! cinfo->optimize_coding) {
 453       select_scan_parameters(cinfo);
 454       per_scan_setup(cinfo);
 455     }
 456     (*cinfo->entropy->start_pass) (cinfo, FALSE);
 457     (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
 458     /* We emit frame/scan headers now */
 459     if (master->scan_number == 0)
 460       (*cinfo->marker->write_frame_header) (cinfo);
 461     (*cinfo->marker->write_scan_header) (cinfo);
 462     master->pub.call_pass_startup = FALSE;
 463     break;
 464   default:
 465     ERREXIT(cinfo, JERR_NOT_COMPILED);
 466   }
 467
 468   master->pub.is_last_pass = (master->pass_number == master->total_passes-1);
 469
 470   /* Set up progress monitor's pass info if present */
 471   if (cinfo->progress != NULL) {
 472     cinfo->progress->completed_passes = master->pass_number;
 473     cinfo->progress->total_passes = master->total_passes;
 474   }
 475 }
 476
 477
 478 /*
 479  * Special start-of-pass hook.
 480  * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
 481  * In single-pass processing, we need this hook because we don't want to
 482  * write frame/scan headers during jpeg_start_compress; we want to let the
 483  * application write COM markers etc. between jpeg_start_compress and the
 484  * jpeg_write_scanlines loop.
 485  * In multi-pass processing, this routine is not used.
 486  */
 487
 488 METHODDEF(void)
 489 pass_startup (j_compress_ptr cinfo)
 490 {
 491   cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
 492
 493   (*cinfo->marker->write_frame_header) (cinfo);
 494   (*cinfo->marker->write_scan_header) (cinfo);
 495 }
 496
 497
 498 /*
 499  * Finish up at end of pass.
 500  */
 501
 502 METHODDEF(void)
 503 finish_pass_master (j_compress_ptr cinfo)
 504 {
 505   my_master_ptr master = (my_master_ptr) cinfo->master;
 506
 507   /* The entropy coder always needs an end-of-pass call,
 508    * either to analyze statistics or to flush its output buffer.
 509    */
 510   (*cinfo->entropy->finish_pass) (cinfo);
 511
 512   /* Update state for next pass */
 513   switch (master->pass_type) {
 514   case main_pass:
 515     /* next pass is either output of scan 0 (after optimization)
 516      * or output of scan 1 (if no optimization).
 517      */
 518     master->pass_type = output_pass;
 519     if (! cinfo->optimize_coding)
 520       master->scan_number++;
 521     break;
 522   case huff_opt_pass:
 523     /* next pass is always output of current scan */
 524     master->pass_type = output_pass;
 525     break;
 526   case output_pass:
 527     /* next pass is either optimization or output of next scan */
 528     if (cinfo->optimize_coding)
 529       master->pass_type = huff_opt_pass;
 530     master->scan_number++;
 531     break;
 532   }
 533
 534   master->pass_number++;
 535 }
 536
 537
 538 /*
 539  * Initialize master compression control.
 540  */
 541
 542 GLOBAL(void)
 543 jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
 544 {
 545   my_master_ptr master;
 546
 547   master = (my_master_ptr)
 548       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 549                                   SIZEOF(my_comp_master));
 550   cinfo->master = (struct jpeg_comp_master *) master;
 551   master->pub.prepare_for_pass = prepare_for_pass;
 552   master->pub.pass_startup = pass_startup;
 553   master->pub.finish_pass = finish_pass_master;
 554   master->pub.is_last_pass = FALSE;
 555
 556   /* Validate parameters, determine derived values */
 557   initial_setup(cinfo);
 558
 559   if (cinfo->scan_info != NULL) {
 560 #ifdef C_MULTISCAN_FILES_SUPPORTED
 561     validate_script(cinfo);
 562 #else
 563     ERREXIT(cinfo, JERR_NOT_COMPILED);
 564 #endif
 565   } else {
 566     cinfo->progressive_mode = FALSE;
 567     cinfo->num_scans = 1;
 568   }
 569
 570   if (cinfo->progressive_mode)  /*  TEMPORARY HACK ??? */
 571     cinfo->optimize_coding = TRUE; /* assume default tables no good for progressive mode */
 572
 573   /* Initialize my private state */
 574   if (transcode_only) {
 575     /* no main pass in transcoding */
 576     if (cinfo->optimize_coding)
 577       master->pass_type = huff_opt_pass;
 578     else
 579       master->pass_type = output_pass;
 580   } else {
 581     /* for normal compression, first pass is always this type: */
 582     master->pass_type = main_pass;
 583   }
 584   master->scan_number = 0;
 585   master->pass_number = 0;
 586   if (cinfo->optimize_coding)
 587     master->total_passes = cinfo->num_scans * 2;
 588   else
 589     master->total_passes = cinfo->num_scans;
 590 }