libs/jpeg/jcmaster.c

   1 /*
   2  * jcmaster.c
   3  *
   4  * Copyright (C) 1991-1997, Thomas G. Lane.
   5  * Modified 2003-2020 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 compressor.
  10  * These routines are concerned with parameter validation, initial setup,
  11  * and inter-pass control (determining the number of passes and the work
  12  * to be done in each pass).
  13  */
  14
  15 #define JPEG_INTERNALS
  16 #include "jinclude.h"
  17 #include "jpeglib.h"
  18
  19
  20 /* Private state */
  21
  22 typedef enum {
  23         main_pass,              /* input data, also do first output step */
  24         huff_opt_pass,          /* Huffman code optimization pass */
  25         output_pass             /* data output pass */
  26 } c_pass_type;
  27
  28 typedef struct {
  29   struct jpeg_comp_master pub;  /* public fields */
  30
  31   c_pass_type pass_type;        /* the type of the current pass */
  32
  33   int pass_number;              /* # of passes completed */
  34   int total_passes;             /* total # of passes needed */
  35
  36   int scan_number;              /* current index in scan_info[] */
  37 } my_comp_master;
  38
  39 typedef my_comp_master * my_master_ptr;
  40
  41
  42 /*
  43  * Support routines that do various essential calculations.
  44  */
  45
  46 LOCAL(void)
  47 initial_setup (j_compress_ptr cinfo)
  48 /* Do computations that are needed before master selection phase */
  49 {
  50   int ci, ssize;
  51   jpeg_component_info *compptr;
  52
  53   /* Sanity check on block_size */
  54   if (cinfo->block_size < 1 || cinfo->block_size > 16)
  55     ERREXIT2(cinfo, JERR_BAD_DCTSIZE, cinfo->block_size, cinfo->block_size);
  56
  57   /* Derive natural_order from block_size */
  58   switch (cinfo->block_size) {
  59   case 2: cinfo->natural_order = jpeg_natural_order2; break;
  60   case 3: cinfo->natural_order = jpeg_natural_order3; break;
  61   case 4: cinfo->natural_order = jpeg_natural_order4; break;
  62   case 5: cinfo->natural_order = jpeg_natural_order5; break;
  63   case 6: cinfo->natural_order = jpeg_natural_order6; break;
  64   case 7: cinfo->natural_order = jpeg_natural_order7; break;
  65   default: cinfo->natural_order = jpeg_natural_order;
  66   }
  67
  68   /* Derive lim_Se from block_size */
  69   cinfo->lim_Se = cinfo->block_size < DCTSIZE ?
  70     cinfo->block_size * cinfo->block_size - 1 : DCTSIZE2-1;
  71
  72   /* Sanity check on image dimensions */
  73   if (cinfo->jpeg_height <= 0 || cinfo->jpeg_width <= 0 ||
  74       cinfo->num_components <= 0)
  75     ERREXIT(cinfo, JERR_EMPTY_IMAGE);
  76
  77   /* Make sure image isn't bigger than I can handle */
  78   if ((long) cinfo->jpeg_height > (long) JPEG_MAX_DIMENSION ||
  79       (long) cinfo->jpeg_width > (long) JPEG_MAX_DIMENSION)
  80     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
  81
  82   /* Only 8 to 12 bits data precision are supported for DCT based JPEG */
  83   if (cinfo->data_precision < 8 || cinfo->data_precision > 12)
  84     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
  85
  86   /* Check that number of components won't exceed internal array sizes */
  87   if (cinfo->num_components > MAX_COMPONENTS)
  88     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
  89              MAX_COMPONENTS);
  90
  91   /* Compute maximum sampling factors; check factor validity */
  92   cinfo->max_h_samp_factor = 1;
  93   cinfo->max_v_samp_factor = 1;
  94   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  95        ci++, compptr++) {
  96     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
  97         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
  98       ERREXIT(cinfo, JERR_BAD_SAMPLING);
  99     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
 100                                    compptr->h_samp_factor);
 101     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
 102                                    compptr->v_samp_factor);
 103   }
 104
 105   /* Compute dimensions of components */
 106   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 107        ci++, compptr++) {
 108     /* Fill in the correct component_index value; don't rely on application */
 109     compptr->component_index = ci;
 110     /* In selecting the actual DCT scaling for each component, we try to
 111      * scale down the chroma components via DCT scaling rather than downsampling.
 112      * This saves time if the downsampler gets to use 1:1 scaling.
 113      * Note this code adapts subsampling ratios which are powers of 2.
 114      */
 115     ssize = 1;
 116 #ifdef DCT_SCALING_SUPPORTED
 117     if (! cinfo->raw_data_in)
 118       while (cinfo->min_DCT_h_scaled_size * ssize <=
 119              (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
 120              (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) ==
 121              0) {
 122         ssize = ssize * 2;
 123       }
 124 #endif
 125     compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
 126     ssize = 1;
 127 #ifdef DCT_SCALING_SUPPORTED
 128     if (! cinfo->raw_data_in)
 129       while (cinfo->min_DCT_v_scaled_size * ssize <=
 130              (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
 131              (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) ==
 132              0) {
 133         ssize = ssize * 2;
 134       }
 135 #endif
 136     compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
 137
 138     /* We don't support DCT ratios larger than 2. */
 139     if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
 140         compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
 141     else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
 142         compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
 143
 144     /* Size in DCT blocks */
 145     compptr->width_in_blocks = (JDIMENSION)
 146       jdiv_round_up((long) cinfo->jpeg_width * (long) compptr->h_samp_factor,
 147                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
 148     compptr->height_in_blocks = (JDIMENSION)
 149       jdiv_round_up((long) cinfo->jpeg_height * (long) compptr->v_samp_factor,
 150                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 151     /* Size in samples */
 152     compptr->downsampled_width = (JDIMENSION)
 153       jdiv_round_up((long) cinfo->jpeg_width *
 154                     (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
 155                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
 156     compptr->downsampled_height = (JDIMENSION)
 157       jdiv_round_up((long) cinfo->jpeg_height *
 158                     (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
 159                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 160     /* Don't need quantization scale after DCT,
 161      * until color conversion says otherwise.
 162      */
 163     compptr->component_needed = FALSE;
 164   }
 165
 166   /* Compute number of fully interleaved MCU rows (number of times that
 167    * main controller will call coefficient controller).
 168    */
 169   cinfo->total_iMCU_rows = (JDIMENSION)
 170     jdiv_round_up((long) cinfo->jpeg_height,
 171                   (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 172 }
 173
 174
 175 #ifdef C_MULTISCAN_FILES_SUPPORTED
 176
 177 LOCAL(void)
 178 validate_script (j_compress_ptr cinfo)
 179 /* Verify that the scan script in cinfo->scan_info[] is valid; also
 180  * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
 181  */
 182 {
 183   const jpeg_scan_info * scanptr;
 184   int scanno, ncomps, ci, coefi, thisi;
 185   int Ss, Se, Ah, Al;
 186   boolean component_sent[MAX_COMPONENTS];
 187 #ifdef C_PROGRESSIVE_SUPPORTED
 188   int * last_bitpos_ptr;
 189   int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
 190   /* -1 until that coefficient has been seen; then last Al for it */
 191 #endif
 192
 193   if (cinfo->num_scans <= 0)
 194     ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);
 195
 196   /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
 197    * for progressive JPEG, no scan can have this.
 198    */
 199   scanptr = cinfo->scan_info;
 200   if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
 201 #ifdef C_PROGRESSIVE_SUPPORTED
 202     cinfo->progressive_mode = TRUE;
 203     last_bitpos_ptr = & last_bitpos[0][0];
 204     for (ci = 0; ci < cinfo->num_components; ci++)
 205       for (coefi = 0; coefi < DCTSIZE2; coefi++)
 206         *last_bitpos_ptr++ = -1;
 207 #else
 208     ERREXIT(cinfo, JERR_NOT_COMPILED);
 209 #endif
 210   } else {
 211     cinfo->progressive_mode = FALSE;
 212     for (ci = 0; ci < cinfo->num_components; ci++)
 213       component_sent[ci] = FALSE;
 214   }
 215
 216   for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
 217     /* Validate component indexes */
 218     ncomps = scanptr->comps_in_scan;
 219     if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
 220       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
 221     for (ci = 0; ci < ncomps; ci++) {
 222       thisi = scanptr->component_index[ci];
 223       if (thisi < 0 || thisi >= cinfo->num_components)
 224         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 225       /* Components must appear in SOF order within each scan */
 226       if (ci > 0 && thisi <= scanptr->component_index[ci-1])
 227         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 228     }
 229     /* Validate progression parameters */
 230     Ss = scanptr->Ss;
 231     Se = scanptr->Se;
 232     Ah = scanptr->Ah;
 233     Al = scanptr->Al;
 234     if (cinfo->progressive_mode) {
 235 #ifdef C_PROGRESSIVE_SUPPORTED
 236       /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
 237        * seems wrong: the upper bound ought to depend on data precision.
 238        * Perhaps they really meant 0..N+1 for N-bit precision.
 239        * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
 240        * out-of-range reconstructed DC values during the first DC scan,
 241        * which might cause problems for some decoders.
 242        */
 243       if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
 244           Ah < 0 || Ah > (cinfo->data_precision > 8 ? 13 : 10) ||
 245           Al < 0 || Al > (cinfo->data_precision > 8 ? 13 : 10))
 246         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 247       if (Ss == 0) {
 248         if (Se != 0)            /* DC and AC together not OK */
 249           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 250       } else {
 251         if (ncomps != 1)        /* AC scans must be for only one component */
 252           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 253       }
 254       for (ci = 0; ci < ncomps; ci++) {
 255         last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
 256         if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
 257           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 258         for (coefi = Ss; coefi <= Se; coefi++) {
 259           if (last_bitpos_ptr[coefi] < 0) {
 260             /* first scan of this coefficient */
 261             if (Ah != 0)
 262               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 263           } else {
 264             /* not first scan */
 265             if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
 266               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 267           }
 268           last_bitpos_ptr[coefi] = Al;
 269         }
 270       }
 271 #endif
 272     } else {
 273       /* For sequential JPEG, all progression parameters must be these: */
 274       if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
 275         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 276       /* Make sure components are not sent twice */
 277       for (ci = 0; ci < ncomps; ci++) {
 278         thisi = scanptr->component_index[ci];
 279         if (component_sent[thisi])
 280           ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 281         component_sent[thisi] = TRUE;
 282       }
 283     }
 284   }
 285
 286   /* Now verify that everything got sent. */
 287   if (cinfo->progressive_mode) {
 288 #ifdef C_PROGRESSIVE_SUPPORTED
 289     /* For progressive mode, we only check that at least some DC data
 290      * got sent for each component; the spec does not require that all bits
 291      * of all coefficients be transmitted.  Would it be wiser to enforce
 292      * transmission of all coefficient bits??
 293      */
 294     for (ci = 0; ci < cinfo->num_components; ci++) {
 295       if (last_bitpos[ci][0] < 0)
 296         ERREXIT(cinfo, JERR_MISSING_DATA);
 297     }
 298 #endif
 299   } else {
 300     for (ci = 0; ci < cinfo->num_components; ci++) {
 301       if (! component_sent[ci])
 302         ERREXIT(cinfo, JERR_MISSING_DATA);
 303     }
 304   }
 305 }
 306
 307
 308 LOCAL(void)
 309 reduce_script (j_compress_ptr cinfo)
 310 /* Adapt scan script for use with reduced block size;
 311  * assume that script has been validated before.
 312  */
 313 {
 314   jpeg_scan_info * scanptr;
 315   int idxout, idxin;
 316
 317   /* Circumvent const declaration for this function */
 318   scanptr = (jpeg_scan_info *) cinfo->scan_info;
 319   idxout = 0;
 320
 321   for (idxin = 0; idxin < cinfo->num_scans; idxin++) {
 322     /* After skipping, idxout becomes smaller than idxin */
 323     if (idxin != idxout)
 324       /* Copy rest of data;
 325        * note we stay in given chunk of allocated memory.
 326        */
 327       scanptr[idxout] = scanptr[idxin];
 328     if (scanptr[idxout].Ss > cinfo->lim_Se)
 329       /* Entire scan out of range - skip this entry */
 330       continue;
 331     if (scanptr[idxout].Se > cinfo->lim_Se)
 332       /* Limit scan to end of block */
 333       scanptr[idxout].Se = cinfo->lim_Se;
 334     idxout++;
 335   }
 336
 337   cinfo->num_scans = idxout;
 338 }
 339
 340 #endif /* C_MULTISCAN_FILES_SUPPORTED */
 341
 342
 343 LOCAL(void)
 344 select_scan_parameters (j_compress_ptr cinfo)
 345 /* Set up the scan parameters for the current scan */
 346 {
 347   int ci;
 348
 349 #ifdef C_MULTISCAN_FILES_SUPPORTED
 350   if (cinfo->scan_info != NULL) {
 351     /* Prepare for current scan --- the script is already validated */
 352     my_master_ptr master = (my_master_ptr) cinfo->master;
 353     const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;
 354
 355     cinfo->comps_in_scan = scanptr->comps_in_scan;
 356     for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
 357       cinfo->cur_comp_info[ci] =
 358         &cinfo->comp_info[scanptr->component_index[ci]];
 359     }
 360     if (cinfo->progressive_mode) {
 361       cinfo->Ss = scanptr->Ss;
 362       cinfo->Se = scanptr->Se;
 363       cinfo->Ah = scanptr->Ah;
 364       cinfo->Al = scanptr->Al;
 365       return;
 366     }
 367   }
 368   else
 369 #endif
 370   {
 371     /* Prepare for single sequential-JPEG scan containing all components */
 372     if (cinfo->num_components > MAX_COMPS_IN_SCAN)
 373       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
 374                MAX_COMPS_IN_SCAN);
 375     cinfo->comps_in_scan = cinfo->num_components;
 376     for (ci = 0; ci < cinfo->num_components; ci++) {
 377       cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
 378     }
 379   }
 380   cinfo->Ss = 0;
 381   cinfo->Se = cinfo->block_size * cinfo->block_size - 1;
 382   cinfo->Ah = 0;
 383   cinfo->Al = 0;
 384 }
 385
 386
 387 LOCAL(void)
 388 per_scan_setup (j_compress_ptr cinfo)
 389 /* Do computations that are needed before processing a JPEG scan */
 390 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
 391 {
 392   int ci, mcublks, tmp;
 393   jpeg_component_info *compptr;
 394
 395   if (cinfo->comps_in_scan == 1) {
 396
 397     /* Noninterleaved (single-component) scan */
 398     compptr = cinfo->cur_comp_info[0];
 399
 400     /* Overall image size in MCUs */
 401     cinfo->MCUs_per_row = compptr->width_in_blocks;
 402     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
 403
 404     /* For noninterleaved scan, always one block per MCU */
 405     compptr->MCU_width = 1;
 406     compptr->MCU_height = 1;
 407     compptr->MCU_blocks = 1;
 408     compptr->MCU_sample_width = compptr->DCT_h_scaled_size;
 409     compptr->last_col_width = 1;
 410     /* For noninterleaved scans, it is convenient to define last_row_height
 411      * as the number of block rows present in the last iMCU row.
 412      */
 413     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
 414     if (tmp == 0) tmp = compptr->v_samp_factor;
 415     compptr->last_row_height = tmp;
 416
 417     /* Prepare array describing MCU composition */
 418     cinfo->blocks_in_MCU = 1;
 419     cinfo->MCU_membership[0] = 0;
 420
 421   } else {
 422
 423     /* Interleaved (multi-component) scan */
 424     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
 425       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
 426                MAX_COMPS_IN_SCAN);
 427
 428     /* Overall image size in MCUs */
 429     cinfo->MCUs_per_row = (JDIMENSION)
 430       jdiv_round_up((long) cinfo->jpeg_width,
 431                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
 432     cinfo->MCU_rows_in_scan = cinfo->total_iMCU_rows;
 433
 434     cinfo->blocks_in_MCU = 0;
 435
 436     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 437       compptr = cinfo->cur_comp_info[ci];
 438       /* Sampling factors give # of blocks of component in each MCU */
 439       compptr->MCU_width = compptr->h_samp_factor;
 440       compptr->MCU_height = compptr->v_samp_factor;
 441       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
 442       compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;
 443       /* Figure number of non-dummy blocks in last MCU column & row */
 444       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
 445       if (tmp == 0) tmp = compptr->MCU_width;
 446       compptr->last_col_width = tmp;
 447       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
 448       if (tmp == 0) tmp = compptr->MCU_height;
 449       compptr->last_row_height = tmp;
 450       /* Prepare array describing MCU composition */
 451       mcublks = compptr->MCU_blocks;
 452       if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
 453         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
 454       while (mcublks-- > 0) {
 455         cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
 456       }
 457     }
 458
 459   }
 460
 461   /* Convert restart specified in rows to actual MCU count. */
 462   /* Note that count must fit in 16 bits, so we provide limiting. */
 463   if (cinfo->restart_in_rows > 0) {
 464     long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
 465     cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
 466   }
 467 }
 468
 469
 470 /*
 471  * Per-pass setup.
 472  * This is called at the beginning of each pass.  We determine which modules
 473  * will be active during this pass and give them appropriate start_pass calls.
 474  * We also set is_last_pass to indicate whether any more passes will be
 475  * required.
 476  */
 477
 478 METHODDEF(void)
 479 prepare_for_pass (j_compress_ptr cinfo)
 480 {
 481   my_master_ptr master = (my_master_ptr) cinfo->master;
 482
 483   switch (master->pass_type) {
 484   case main_pass:
 485     /* Initial pass: will collect input data, and do either Huffman
 486      * optimization or data output for the first scan.
 487      */
 488     select_scan_parameters(cinfo);
 489     per_scan_setup(cinfo);
 490     if (! cinfo->raw_data_in) {
 491       (*cinfo->cconvert->start_pass) (cinfo);
 492       (*cinfo->downsample->start_pass) (cinfo);
 493       (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
 494     }
 495     (*cinfo->fdct->start_pass) (cinfo);
 496     (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
 497     (*cinfo->coef->start_pass) (cinfo,
 498                                 (master->total_passes > 1 ?
 499                                  JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 500     (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 501     if (cinfo->optimize_coding) {
 502       /* No immediate data output; postpone writing frame/scan headers */
 503       master->pub.call_pass_startup = FALSE;
 504     } else {
 505       /* Will write frame/scan headers at first jpeg_write_scanlines call */
 506       master->pub.call_pass_startup = TRUE;
 507     }
 508     break;
 509 #ifdef ENTROPY_OPT_SUPPORTED
 510   case huff_opt_pass:
 511     /* Do Huffman optimization for a scan after the first one. */
 512     select_scan_parameters(cinfo);
 513     per_scan_setup(cinfo);
 514     if (cinfo->Ss != 0 || cinfo->Ah == 0) {
 515       (*cinfo->entropy->start_pass) (cinfo, TRUE);
 516       (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
 517       master->pub.call_pass_startup = FALSE;
 518       break;
 519     }
 520     /* Special case: Huffman DC refinement scans need no Huffman table
 521      * and therefore we can skip the optimization pass for them.
 522      */
 523     master->pass_type = output_pass;
 524     master->pass_number++;
 525     /*FALLTHROUGH*/
 526 #endif
 527   case output_pass:
 528     /* Do a data-output pass. */
 529     /* We need not repeat per-scan setup if prior optimization pass did it. */
 530     if (! cinfo->optimize_coding) {
 531       select_scan_parameters(cinfo);
 532       per_scan_setup(cinfo);
 533     }
 534     (*cinfo->entropy->start_pass) (cinfo, FALSE);
 535     (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
 536     /* We emit frame/scan headers now */
 537     if (master->scan_number == 0)
 538       (*cinfo->marker->write_frame_header) (cinfo);
 539     (*cinfo->marker->write_scan_header) (cinfo);
 540     master->pub.call_pass_startup = FALSE;
 541     break;
 542   default:
 543     ERREXIT(cinfo, JERR_NOT_COMPILED);
 544   }
 545
 546   master->pub.is_last_pass = (master->pass_number == master->total_passes-1);
 547
 548   /* Set up progress monitor's pass info if present */
 549   if (cinfo->progress != NULL) {
 550     cinfo->progress->completed_passes = master->pass_number;
 551     cinfo->progress->total_passes = master->total_passes;
 552   }
 553 }
 554
 555
 556 /*
 557  * Special start-of-pass hook.
 558  * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
 559  * In single-pass processing, we need this hook because we don't want to
 560  * write frame/scan headers during jpeg_start_compress; we want to let the
 561  * application write COM markers etc. between jpeg_start_compress and the
 562  * jpeg_write_scanlines loop.
 563  * In multi-pass processing, this routine is not used.
 564  */
 565
 566 METHODDEF(void)
 567 pass_startup (j_compress_ptr cinfo)
 568 {
 569   cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
 570
 571   (*cinfo->marker->write_frame_header) (cinfo);
 572   (*cinfo->marker->write_scan_header) (cinfo);
 573 }
 574
 575
 576 /*
 577  * Finish up at end of pass.
 578  */
 579
 580 METHODDEF(void)
 581 finish_pass_master (j_compress_ptr cinfo)
 582 {
 583   my_master_ptr master = (my_master_ptr) cinfo->master;
 584
 585   /* The entropy coder always needs an end-of-pass call,
 586    * either to analyze statistics or to flush its output buffer.
 587    */
 588   (*cinfo->entropy->finish_pass) (cinfo);
 589
 590   /* Update state for next pass */
 591   switch (master->pass_type) {
 592   case main_pass:
 593     /* next pass is either output of scan 0 (after optimization)
 594      * or output of scan 1 (if no optimization).
 595      */
 596     master->pass_type = output_pass;
 597     if (! cinfo->optimize_coding)
 598       master->scan_number++;
 599     break;
 600   case huff_opt_pass:
 601     /* next pass is always output of current scan */
 602     master->pass_type = output_pass;
 603     break;
 604   case output_pass:
 605     /* next pass is either optimization or output of next scan */
 606     if (cinfo->optimize_coding)
 607       master->pass_type = huff_opt_pass;
 608     master->scan_number++;
 609     break;
 610   }
 611
 612   master->pass_number++;
 613 }
 614
 615
 616 /*
 617  * Initialize master compression control.
 618  */
 619
 620 GLOBAL(void)
 621 jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
 622 {
 623   my_master_ptr master;
 624
 625   master = (my_master_ptr) (*cinfo->mem->alloc_small)
 626     ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_comp_master));
 627   cinfo->master = &master->pub;
 628   master->pub.prepare_for_pass = prepare_for_pass;
 629   master->pub.pass_startup = pass_startup;
 630   master->pub.finish_pass = finish_pass_master;
 631   master->pub.is_last_pass = FALSE;
 632
 633   /* Validate parameters, determine derived values */
 634   initial_setup(cinfo);
 635
 636   if (cinfo->scan_info != NULL) {
 637 #ifdef C_MULTISCAN_FILES_SUPPORTED
 638     validate_script(cinfo);
 639     if (cinfo->block_size < DCTSIZE)
 640       reduce_script(cinfo);
 641 #else
 642     ERREXIT(cinfo, JERR_NOT_COMPILED);
 643 #endif
 644   } else {
 645     cinfo->progressive_mode = FALSE;
 646     cinfo->num_scans = 1;
 647   }
 648
 649   if (cinfo->optimize_coding)
 650     cinfo->arith_code = FALSE; /* disable arithmetic coding */
 651   else if (! cinfo->arith_code &&
 652            (cinfo->progressive_mode ||
 653             (cinfo->block_size > 1 && cinfo->block_size < DCTSIZE)))
 654     /* TEMPORARY HACK ??? */
 655     /* assume default tables no good for progressive or reduced AC mode */
 656     cinfo->optimize_coding = TRUE; /* force Huffman optimization */
 657
 658   /* Initialize my private state */
 659   if (transcode_only) {
 660     /* no main pass in transcoding */
 661     if (cinfo->optimize_coding)
 662       master->pass_type = huff_opt_pass;
 663     else
 664       master->pass_type = output_pass;
 665   } else {
 666     /* for normal compression, first pass is always this type: */
 667     master->pass_type = main_pass;
 668   }
 669   master->scan_number = 0;
 670   master->pass_number = 0;
 671   if (cinfo->optimize_coding)
 672     master->total_passes = cinfo->num_scans * 2;
 673   else
 674     master->total_passes = cinfo->num_scans;
 675 }