jcmaster.c

   1 /*
   2  * jcmaster.c
   3  *
   4  * Copyright (C) 1991-1997, Thomas G. Lane.
   5  * Modified 2003-2011 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 /*
  47  * Compute JPEG image dimensions and related values.
  48  * NOTE: this is exported for possible use by application.
  49  * Hence it mustn't do anything that can't be done twice.
  50  */
  51
  52 GLOBAL(void)
  53 jpeg_calc_jpeg_dimensions (j_compress_ptr cinfo)
  54 /* Do computations that are needed before master selection phase */
  55 {
  56 #ifdef DCT_SCALING_SUPPORTED
  57
  58   /* Sanity check on input image dimensions to prevent overflow in
  59    * following calculation.
  60    * We do check jpeg_width and jpeg_height in initial_setup below,
  61    * but image_width and image_height can come from arbitrary data,
  62    * and we need some space for multiplication by block_size.
  63    */
  64   if (((long) cinfo->image_width >> 24) || ((long) cinfo->image_height >> 24))
  65     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
  66
  67   /* Compute actual JPEG image dimensions and DCT scaling choices. */
  68   if (cinfo->scale_num >= cinfo->scale_denom * cinfo->block_size) {
  69     /* Provide block_size/1 scaling */
  70     cinfo->jpeg_width = cinfo->image_width * cinfo->block_size;
  71     cinfo->jpeg_height = cinfo->image_height * cinfo->block_size;
  72     cinfo->min_DCT_h_scaled_size = 1;
  73     cinfo->min_DCT_v_scaled_size = 1;
  74   } else if (cinfo->scale_num * 2 >= cinfo->scale_denom * cinfo->block_size) {
  75     /* Provide block_size/2 scaling */
  76     cinfo->jpeg_width = (JDIMENSION)
  77       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 2L);
  78     cinfo->jpeg_height = (JDIMENSION)
  79       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 2L);
  80     cinfo->min_DCT_h_scaled_size = 2;
  81     cinfo->min_DCT_v_scaled_size = 2;
  82   } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * cinfo->block_size) {
  83     /* Provide block_size/3 scaling */
  84     cinfo->jpeg_width = (JDIMENSION)
  85       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 3L);
  86     cinfo->jpeg_height = (JDIMENSION)
  87       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 3L);
  88     cinfo->min_DCT_h_scaled_size = 3;
  89     cinfo->min_DCT_v_scaled_size = 3;
  90   } else if (cinfo->scale_num * 4 >= cinfo->scale_denom * cinfo->block_size) {
  91     /* Provide block_size/4 scaling */
  92     cinfo->jpeg_width = (JDIMENSION)
  93       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 4L);
  94     cinfo->jpeg_height = (JDIMENSION)
  95       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 4L);
  96     cinfo->min_DCT_h_scaled_size = 4;
  97     cinfo->min_DCT_v_scaled_size = 4;
  98   } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * cinfo->block_size) {
  99     /* Provide block_size/5 scaling */
 100     cinfo->jpeg_width = (JDIMENSION)
 101       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 5L);
 102     cinfo->jpeg_height = (JDIMENSION)
 103       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 5L);
 104     cinfo->min_DCT_h_scaled_size = 5;
 105     cinfo->min_DCT_v_scaled_size = 5;
 106   } else if (cinfo->scale_num * 6 >= cinfo->scale_denom * cinfo->block_size) {
 107     /* Provide block_size/6 scaling */
 108     cinfo->jpeg_width = (JDIMENSION)
 109       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 6L);
 110     cinfo->jpeg_height = (JDIMENSION)
 111       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 6L);
 112     cinfo->min_DCT_h_scaled_size = 6;
 113     cinfo->min_DCT_v_scaled_size = 6;
 114   } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * cinfo->block_size) {
 115     /* Provide block_size/7 scaling */
 116     cinfo->jpeg_width = (JDIMENSION)
 117       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 7L);
 118     cinfo->jpeg_height = (JDIMENSION)
 119       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 7L);
 120     cinfo->min_DCT_h_scaled_size = 7;
 121     cinfo->min_DCT_v_scaled_size = 7;
 122   } else if (cinfo->scale_num * 8 >= cinfo->scale_denom * cinfo->block_size) {
 123     /* Provide block_size/8 scaling */
 124     cinfo->jpeg_width = (JDIMENSION)
 125       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 8L);
 126     cinfo->jpeg_height = (JDIMENSION)
 127       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 8L);
 128     cinfo->min_DCT_h_scaled_size = 8;
 129     cinfo->min_DCT_v_scaled_size = 8;
 130   } else if (cinfo->scale_num * 9 >= cinfo->scale_denom * cinfo->block_size) {
 131     /* Provide block_size/9 scaling */
 132     cinfo->jpeg_width = (JDIMENSION)
 133       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 9L);
 134     cinfo->jpeg_height = (JDIMENSION)
 135       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 9L);
 136     cinfo->min_DCT_h_scaled_size = 9;
 137     cinfo->min_DCT_v_scaled_size = 9;
 138   } else if (cinfo->scale_num * 10 >= cinfo->scale_denom * cinfo->block_size) {
 139     /* Provide block_size/10 scaling */
 140     cinfo->jpeg_width = (JDIMENSION)
 141       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 10L);
 142     cinfo->jpeg_height = (JDIMENSION)
 143       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 10L);
 144     cinfo->min_DCT_h_scaled_size = 10;
 145     cinfo->min_DCT_v_scaled_size = 10;
 146   } else if (cinfo->scale_num * 11 >= cinfo->scale_denom * cinfo->block_size) {
 147     /* Provide block_size/11 scaling */
 148     cinfo->jpeg_width = (JDIMENSION)
 149       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 11L);
 150     cinfo->jpeg_height = (JDIMENSION)
 151       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 11L);
 152     cinfo->min_DCT_h_scaled_size = 11;
 153     cinfo->min_DCT_v_scaled_size = 11;
 154   } else if (cinfo->scale_num * 12 >= cinfo->scale_denom * cinfo->block_size) {
 155     /* Provide block_size/12 scaling */
 156     cinfo->jpeg_width = (JDIMENSION)
 157       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 12L);
 158     cinfo->jpeg_height = (JDIMENSION)
 159       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 12L);
 160     cinfo->min_DCT_h_scaled_size = 12;
 161     cinfo->min_DCT_v_scaled_size = 12;
 162   } else if (cinfo->scale_num * 13 >= cinfo->scale_denom * cinfo->block_size) {
 163     /* Provide block_size/13 scaling */
 164     cinfo->jpeg_width = (JDIMENSION)
 165       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 13L);
 166     cinfo->jpeg_height = (JDIMENSION)
 167       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 13L);
 168     cinfo->min_DCT_h_scaled_size = 13;
 169     cinfo->min_DCT_v_scaled_size = 13;
 170   } else if (cinfo->scale_num * 14 >= cinfo->scale_denom * cinfo->block_size) {
 171     /* Provide block_size/14 scaling */
 172     cinfo->jpeg_width = (JDIMENSION)
 173       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 14L);
 174     cinfo->jpeg_height = (JDIMENSION)
 175       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 14L);
 176     cinfo->min_DCT_h_scaled_size = 14;
 177     cinfo->min_DCT_v_scaled_size = 14;
 178   } else if (cinfo->scale_num * 15 >= cinfo->scale_denom * cinfo->block_size) {
 179     /* Provide block_size/15 scaling */
 180     cinfo->jpeg_width = (JDIMENSION)
 181       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 15L);
 182     cinfo->jpeg_height = (JDIMENSION)
 183       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 15L);
 184     cinfo->min_DCT_h_scaled_size = 15;
 185     cinfo->min_DCT_v_scaled_size = 15;
 186   } else {
 187     /* Provide block_size/16 scaling */
 188     cinfo->jpeg_width = (JDIMENSION)
 189       jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 16L);
 190     cinfo->jpeg_height = (JDIMENSION)
 191       jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 16L);
 192     cinfo->min_DCT_h_scaled_size = 16;
 193     cinfo->min_DCT_v_scaled_size = 16;
 194   }
 195
 196 #else /* !DCT_SCALING_SUPPORTED */
 197
 198   /* Hardwire it to "no scaling" */
 199   cinfo->jpeg_width = cinfo->image_width;
 200   cinfo->jpeg_height = cinfo->image_height;
 201   cinfo->min_DCT_h_scaled_size = DCTSIZE;
 202   cinfo->min_DCT_v_scaled_size = DCTSIZE;
 203
 204 #endif /* DCT_SCALING_SUPPORTED */
 205 }
 206
 207
 208 LOCAL(void)
 209 jpeg_calc_trans_dimensions (j_compress_ptr cinfo)
 210 {
 211   if (cinfo->min_DCT_h_scaled_size != cinfo->min_DCT_v_scaled_size)
 212     ERREXIT2(cinfo, JERR_BAD_DCTSIZE,
 213              cinfo->min_DCT_h_scaled_size, cinfo->min_DCT_v_scaled_size);
 214
 215   cinfo->block_size = cinfo->min_DCT_h_scaled_size;
 216 }
 217
 218
 219 LOCAL(void)
 220 initial_setup (j_compress_ptr cinfo, boolean transcode_only)
 221 /* Do computations that are needed before master selection phase */
 222 {
 223   int ci, ssize;
 224   jpeg_component_info *compptr;
 225   long samplesperrow;
 226   JDIMENSION jd_samplesperrow;
 227
 228   if (transcode_only)
 229     jpeg_calc_trans_dimensions(cinfo);
 230   else
 231     jpeg_calc_jpeg_dimensions(cinfo);
 232
 233   /* Sanity check on block_size */
 234   if (cinfo->block_size < 1 || cinfo->block_size > 16)
 235     ERREXIT2(cinfo, JERR_BAD_DCTSIZE, cinfo->block_size, cinfo->block_size);
 236
 237   /* Derive natural_order from block_size */
 238   switch (cinfo->block_size) {
 239   case 2: cinfo->natural_order = jpeg_natural_order2; break;
 240   case 3: cinfo->natural_order = jpeg_natural_order3; break;
 241   case 4: cinfo->natural_order = jpeg_natural_order4; break;
 242   case 5: cinfo->natural_order = jpeg_natural_order5; break;
 243   case 6: cinfo->natural_order = jpeg_natural_order6; break;
 244   case 7: cinfo->natural_order = jpeg_natural_order7; break;
 245   default: cinfo->natural_order = jpeg_natural_order; break;
 246   }
 247
 248   /* Derive lim_Se from block_size */
 249   cinfo->lim_Se = cinfo->block_size < DCTSIZE ?
 250     cinfo->block_size * cinfo->block_size - 1 : DCTSIZE2-1;
 251
 252   /* Sanity check on image dimensions */
 253   if (cinfo->jpeg_height <= 0 || cinfo->jpeg_width <= 0 ||
 254       cinfo->num_components <= 0 || cinfo->input_components <= 0)
 255     ERREXIT(cinfo, JERR_EMPTY_IMAGE);
 256
 257   /* Make sure image isn't bigger than I can handle */
 258   if ((long) cinfo->jpeg_height > (long) JPEG_MAX_DIMENSION ||
 259       (long) cinfo->jpeg_width > (long) JPEG_MAX_DIMENSION)
 260     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
 261
 262   /* Width of an input scanline must be representable as JDIMENSION. */
 263   samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
 264   jd_samplesperrow = (JDIMENSION) samplesperrow;
 265   if ((long) jd_samplesperrow != samplesperrow)
 266     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 267
 268   /* For now, precision must match compiled-in value... */
 269   if (cinfo->data_precision != BITS_IN_JSAMPLE)
 270     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
 271
 272   /* Check that number of components won't exceed internal array sizes */
 273   if (cinfo->num_components > MAX_COMPONENTS)
 274     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
 275              MAX_COMPONENTS);
 276
 277   /* Compute maximum sampling factors; check factor validity */
 278   cinfo->max_h_samp_factor = 1;
 279   cinfo->max_v_samp_factor = 1;
 280   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 281        ci++, compptr++) {
 282     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
 283         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
 284       ERREXIT(cinfo, JERR_BAD_SAMPLING);
 285     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
 286                                    compptr->h_samp_factor);
 287     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
 288                                    compptr->v_samp_factor);
 289   }
 290
 291   /* Compute dimensions of components */
 292   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 293        ci++, compptr++) {
 294     /* Fill in the correct component_index value; don't rely on application */
 295     compptr->component_index = ci;
 296     /* In selecting the actual DCT scaling for each component, we try to
 297      * scale down the chroma components via DCT scaling rather than downsampling.
 298      * This saves time if the downsampler gets to use 1:1 scaling.
 299      * Note this code adapts subsampling ratios which are powers of 2.
 300      */
 301     ssize = 1;
 302 #ifdef DCT_SCALING_SUPPORTED
 303     while (cinfo->min_DCT_h_scaled_size * ssize <=
 304            (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
 305            (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
 306       ssize = ssize * 2;
 307     }
 308 #endif
 309     compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
 310     ssize = 1;
 311 #ifdef DCT_SCALING_SUPPORTED
 312     while (cinfo->min_DCT_v_scaled_size * ssize <=
 313            (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
 314            (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
 315       ssize = ssize * 2;
 316     }
 317 #endif
 318     compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
 319
 320     /* We don't support DCT ratios larger than 2. */
 321     if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
 322         compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
 323     else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
 324         compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
 325
 326     /* Size in DCT blocks */
 327     compptr->width_in_blocks = (JDIMENSION)
 328       jdiv_round_up((long) cinfo->jpeg_width * (long) compptr->h_samp_factor,
 329                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
 330     compptr->height_in_blocks = (JDIMENSION)
 331       jdiv_round_up((long) cinfo->jpeg_height * (long) compptr->v_samp_factor,
 332                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 333     /* Size in samples */
 334     compptr->downsampled_width = (JDIMENSION)
 335       jdiv_round_up((long) cinfo->jpeg_width *
 336                     (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
 337                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
 338     compptr->downsampled_height = (JDIMENSION)
 339       jdiv_round_up((long) cinfo->jpeg_height *
 340                     (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
 341                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 342     /* Mark component needed (this flag isn't actually used for compression) */
 343     compptr->component_needed = TRUE;
 344   }
 345
 346   /* Compute number of fully interleaved MCU rows (number of times that
 347    * main controller will call coefficient controller).
 348    */
 349   cinfo->total_iMCU_rows = (JDIMENSION)
 350     jdiv_round_up((long) cinfo->jpeg_height,
 351                   (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 352 }
 353
 354
 355 #ifdef C_MULTISCAN_FILES_SUPPORTED
 356
 357 LOCAL(void)
 358 validate_script (j_compress_ptr cinfo)
 359 /* Verify that the scan script in cinfo->scan_info[] is valid; also
 360  * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
 361  */
 362 {
 363   const jpeg_scan_info * scanptr;
 364   int scanno, ncomps, ci, coefi, thisi;
 365   int Ss, Se, Ah, Al;
 366   boolean component_sent[MAX_COMPONENTS];
 367 #ifdef C_PROGRESSIVE_SUPPORTED
 368   int * last_bitpos_ptr;
 369   int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
 370   /* -1 until that coefficient has been seen; then last Al for it */
 371 #endif
 372
 373   if (cinfo->num_scans <= 0)
 374     ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);
 375
 376   /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
 377    * for progressive JPEG, no scan can have this.
 378    */
 379   scanptr = cinfo->scan_info;
 380   if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
 381 #ifdef C_PROGRESSIVE_SUPPORTED
 382     cinfo->progressive_mode = TRUE;
 383     last_bitpos_ptr = & last_bitpos[0][0];
 384     for (ci = 0; ci < cinfo->num_components; ci++)
 385       for (coefi = 0; coefi < DCTSIZE2; coefi++)
 386         *last_bitpos_ptr++ = -1;
 387 #else
 388     ERREXIT(cinfo, JERR_NOT_COMPILED);
 389 #endif
 390   } else {
 391     cinfo->progressive_mode = FALSE;
 392     for (ci = 0; ci < cinfo->num_components; ci++)
 393       component_sent[ci] = FALSE;
 394   }
 395
 396   for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
 397     /* Validate component indexes */
 398     ncomps = scanptr->comps_in_scan;
 399     if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
 400       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
 401     for (ci = 0; ci < ncomps; ci++) {
 402       thisi = scanptr->component_index[ci];
 403       if (thisi < 0 || thisi >= cinfo->num_components)
 404         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 405       /* Components must appear in SOF order within each scan */
 406       if (ci > 0 && thisi <= scanptr->component_index[ci-1])
 407         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 408     }
 409     /* Validate progression parameters */
 410     Ss = scanptr->Ss;
 411     Se = scanptr->Se;
 412     Ah = scanptr->Ah;
 413     Al = scanptr->Al;
 414     if (cinfo->progressive_mode) {
 415 #ifdef C_PROGRESSIVE_SUPPORTED
 416       /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
 417        * seems wrong: the upper bound ought to depend on data precision.
 418        * Perhaps they really meant 0..N+1 for N-bit precision.
 419        * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
 420        * out-of-range reconstructed DC values during the first DC scan,
 421        * which might cause problems for some decoders.
 422        */
 423 #if BITS_IN_JSAMPLE == 8
 424 #define MAX_AH_AL 10
 425 #else
 426 #define MAX_AH_AL 13
 427 #endif
 428       if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
 429           Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
 430         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 431       if (Ss == 0) {
 432         if (Se != 0)            /* DC and AC together not OK */
 433           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 434       } else {
 435         if (ncomps != 1)        /* AC scans must be for only one component */
 436           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 437       }
 438       for (ci = 0; ci < ncomps; ci++) {
 439         last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
 440         if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
 441           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 442         for (coefi = Ss; coefi <= Se; coefi++) {
 443           if (last_bitpos_ptr[coefi] < 0) {
 444             /* first scan of this coefficient */
 445             if (Ah != 0)
 446               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 447           } else {
 448             /* not first scan */
 449             if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
 450               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 451           }
 452           last_bitpos_ptr[coefi] = Al;
 453         }
 454       }
 455 #endif
 456     } else {
 457       /* For sequential JPEG, all progression parameters must be these: */
 458       if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
 459         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
 460       /* Make sure components are not sent twice */
 461       for (ci = 0; ci < ncomps; ci++) {
 462         thisi = scanptr->component_index[ci];
 463         if (component_sent[thisi])
 464           ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
 465         component_sent[thisi] = TRUE;
 466       }
 467     }
 468   }
 469
 470   /* Now verify that everything got sent. */
 471   if (cinfo->progressive_mode) {
 472 #ifdef C_PROGRESSIVE_SUPPORTED
 473     /* For progressive mode, we only check that at least some DC data
 474      * got sent for each component; the spec does not require that all bits
 475      * of all coefficients be transmitted.  Would it be wiser to enforce
 476      * transmission of all coefficient bits??
 477      */
 478     for (ci = 0; ci < cinfo->num_components; ci++) {
 479       if (last_bitpos[ci][0] < 0)
 480         ERREXIT(cinfo, JERR_MISSING_DATA);
 481     }
 482 #endif
 483   } else {
 484     for (ci = 0; ci < cinfo->num_components; ci++) {
 485       if (! component_sent[ci])
 486         ERREXIT(cinfo, JERR_MISSING_DATA);
 487     }
 488   }
 489 }
 490
 491
 492 LOCAL(void)
 493 reduce_script (j_compress_ptr cinfo)
 494 /* Adapt scan script for use with reduced block size;
 495  * assume that script has been validated before.
 496  */
 497 {
 498   jpeg_scan_info * scanptr;
 499   int idxout, idxin;
 500
 501   /* Circumvent const declaration for this function */
 502   scanptr = (jpeg_scan_info *) cinfo->scan_info;
 503   idxout = 0;
 504
 505   for (idxin = 0; idxin < cinfo->num_scans; idxin++) {
 506     /* After skipping, idxout becomes smaller than idxin */
 507     if (idxin != idxout)
 508       /* Copy rest of data;
 509        * note we stay in given chunk of allocated memory.
 510        */
 511       scanptr[idxout] = scanptr[idxin];
 512     if (scanptr[idxout].Ss > cinfo->lim_Se)
 513       /* Entire scan out of range - skip this entry */
 514       continue;
 515     if (scanptr[idxout].Se > cinfo->lim_Se)
 516       /* Limit scan to end of block */
 517       scanptr[idxout].Se = cinfo->lim_Se;
 518     idxout++;
 519   }
 520
 521   cinfo->num_scans = idxout;
 522 }
 523
 524 #endif /* C_MULTISCAN_FILES_SUPPORTED */
 525
 526
 527 LOCAL(void)
 528 select_scan_parameters (j_compress_ptr cinfo)
 529 /* Set up the scan parameters for the current scan */
 530 {
 531   int ci;
 532
 533 #ifdef C_MULTISCAN_FILES_SUPPORTED
 534   if (cinfo->scan_info != NULL) {
 535     /* Prepare for current scan --- the script is already validated */
 536     my_master_ptr master = (my_master_ptr) cinfo->master;
 537     const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;
 538
 539     cinfo->comps_in_scan = scanptr->comps_in_scan;
 540     for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
 541       cinfo->cur_comp_info[ci] =
 542         &cinfo->comp_info[scanptr->component_index[ci]];
 543     }
 544     if (cinfo->progressive_mode) {
 545       cinfo->Ss = scanptr->Ss;
 546       cinfo->Se = scanptr->Se;
 547       cinfo->Ah = scanptr->Ah;
 548       cinfo->Al = scanptr->Al;
 549       return;
 550     }
 551   }
 552   else
 553 #endif
 554   {
 555     /* Prepare for single sequential-JPEG scan containing all components */
 556     if (cinfo->num_components > MAX_COMPS_IN_SCAN)
 557       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
 558                MAX_COMPS_IN_SCAN);
 559     cinfo->comps_in_scan = cinfo->num_components;
 560     for (ci = 0; ci < cinfo->num_components; ci++) {
 561       cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
 562     }
 563   }
 564   cinfo->Ss = 0;
 565   cinfo->Se = cinfo->block_size * cinfo->block_size - 1;
 566   cinfo->Ah = 0;
 567   cinfo->Al = 0;
 568 }
 569
 570
 571 LOCAL(void)
 572 per_scan_setup (j_compress_ptr cinfo)
 573 /* Do computations that are needed before processing a JPEG scan */
 574 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
 575 {
 576   int ci, mcublks, tmp;
 577   jpeg_component_info *compptr;
 578
 579   if (cinfo->comps_in_scan == 1) {
 580
 581     /* Noninterleaved (single-component) scan */
 582     compptr = cinfo->cur_comp_info[0];
 583
 584     /* Overall image size in MCUs */
 585     cinfo->MCUs_per_row = compptr->width_in_blocks;
 586     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
 587
 588     /* For noninterleaved scan, always one block per MCU */
 589     compptr->MCU_width = 1;
 590     compptr->MCU_height = 1;
 591     compptr->MCU_blocks = 1;
 592     compptr->MCU_sample_width = compptr->DCT_h_scaled_size;
 593     compptr->last_col_width = 1;
 594     /* For noninterleaved scans, it is convenient to define last_row_height
 595      * as the number of block rows present in the last iMCU row.
 596      */
 597     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
 598     if (tmp == 0) tmp = compptr->v_samp_factor;
 599     compptr->last_row_height = tmp;
 600
 601     /* Prepare array describing MCU composition */
 602     cinfo->blocks_in_MCU = 1;
 603     cinfo->MCU_membership[0] = 0;
 604
 605   } else {
 606
 607     /* Interleaved (multi-component) scan */
 608     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
 609       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
 610                MAX_COMPS_IN_SCAN);
 611
 612     /* Overall image size in MCUs */
 613     cinfo->MCUs_per_row = (JDIMENSION)
 614       jdiv_round_up((long) cinfo->jpeg_width,
 615                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
 616     cinfo->MCU_rows_in_scan = (JDIMENSION)
 617       jdiv_round_up((long) cinfo->jpeg_height,
 618                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
 619
 620     cinfo->blocks_in_MCU = 0;
 621
 622     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 623       compptr = cinfo->cur_comp_info[ci];
 624       /* Sampling factors give # of blocks of component in each MCU */
 625       compptr->MCU_width = compptr->h_samp_factor;
 626       compptr->MCU_height = compptr->v_samp_factor;
 627       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
 628       compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;
 629       /* Figure number of non-dummy blocks in last MCU column & row */
 630       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
 631       if (tmp == 0) tmp = compptr->MCU_width;
 632       compptr->last_col_width = tmp;
 633       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
 634       if (tmp == 0) tmp = compptr->MCU_height;
 635       compptr->last_row_height = tmp;
 636       /* Prepare array describing MCU composition */
 637       mcublks = compptr->MCU_blocks;
 638       if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
 639         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
 640       while (mcublks-- > 0) {
 641         cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
 642       }
 643     }
 644
 645   }
 646
 647   /* Convert restart specified in rows to actual MCU count. */
 648   /* Note that count must fit in 16 bits, so we provide limiting. */
 649   if (cinfo->restart_in_rows > 0) {
 650     long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
 651     cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
 652   }
 653 }
 654
 655
 656 /*
 657  * Per-pass setup.
 658  * This is called at the beginning of each pass.  We determine which modules
 659  * will be active during this pass and give them appropriate start_pass calls.
 660  * We also set is_last_pass to indicate whether any more passes will be
 661  * required.
 662  */
 663
 664 METHODDEF(void)
 665 prepare_for_pass (j_compress_ptr cinfo)
 666 {
 667   my_master_ptr master = (my_master_ptr) cinfo->master;
 668
 669   switch (master->pass_type) {
 670   case main_pass:
 671     /* Initial pass: will collect input data, and do either Huffman
 672      * optimization or data output for the first scan.
 673      */
 674     select_scan_parameters(cinfo);
 675     per_scan_setup(cinfo);
 676     if (! cinfo->raw_data_in) {
 677       (*cinfo->cconvert->start_pass) (cinfo);
 678       (*cinfo->downsample->start_pass) (cinfo);
 679       (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
 680     }
 681     (*cinfo->fdct->start_pass) (cinfo);
 682     (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
 683     (*cinfo->coef->start_pass) (cinfo,
 684                                 (master->total_passes > 1 ?
 685                                  JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 686     (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 687     if (cinfo->optimize_coding) {
 688       /* No immediate data output; postpone writing frame/scan headers */
 689       master->pub.call_pass_startup = FALSE;
 690     } else {
 691       /* Will write frame/scan headers at first jpeg_write_scanlines call */
 692       master->pub.call_pass_startup = TRUE;
 693     }
 694     break;
 695 #ifdef ENTROPY_OPT_SUPPORTED
 696   case huff_opt_pass:
 697     /* Do Huffman optimization for a scan after the first one. */
 698     select_scan_parameters(cinfo);
 699     per_scan_setup(cinfo);
 700     if (cinfo->Ss != 0 || cinfo->Ah == 0) {
 701       (*cinfo->entropy->start_pass) (cinfo, TRUE);
 702       (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
 703       master->pub.call_pass_startup = FALSE;
 704       break;
 705     }
 706     /* Special case: Huffman DC refinement scans need no Huffman table
 707      * and therefore we can skip the optimization pass for them.
 708      */
 709     master->pass_type = output_pass;
 710     master->pass_number++;
 711     /*FALLTHROUGH*/
 712 #endif
 713   case output_pass:
 714     /* Do a data-output pass. */
 715     /* We need not repeat per-scan setup if prior optimization pass did it. */
 716     if (! cinfo->optimize_coding) {
 717       select_scan_parameters(cinfo);
 718       per_scan_setup(cinfo);
 719     }
 720     (*cinfo->entropy->start_pass) (cinfo, FALSE);
 721     (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
 722     /* We emit frame/scan headers now */
 723     if (master->scan_number == 0)
 724       (*cinfo->marker->write_frame_header) (cinfo);
 725     (*cinfo->marker->write_scan_header) (cinfo);
 726     master->pub.call_pass_startup = FALSE;
 727     break;
 728   default:
 729     ERREXIT(cinfo, JERR_NOT_COMPILED);
 730   }
 731
 732   master->pub.is_last_pass = (master->pass_number == master->total_passes-1);
 733
 734   /* Set up progress monitor's pass info if present */
 735   if (cinfo->progress != NULL) {
 736     cinfo->progress->completed_passes = master->pass_number;
 737     cinfo->progress->total_passes = master->total_passes;
 738   }
 739 }
 740
 741
 742 /*
 743  * Special start-of-pass hook.
 744  * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
 745  * In single-pass processing, we need this hook because we don't want to
 746  * write frame/scan headers during jpeg_start_compress; we want to let the
 747  * application write COM markers etc. between jpeg_start_compress and the
 748  * jpeg_write_scanlines loop.
 749  * In multi-pass processing, this routine is not used.
 750  */
 751
 752 METHODDEF(void)
 753 pass_startup (j_compress_ptr cinfo)
 754 {
 755   cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
 756
 757   (*cinfo->marker->write_frame_header) (cinfo);
 758   (*cinfo->marker->write_scan_header) (cinfo);
 759 }
 760
 761
 762 /*
 763  * Finish up at end of pass.
 764  */
 765
 766 METHODDEF(void)
 767 finish_pass_master (j_compress_ptr cinfo)
 768 {
 769   my_master_ptr master = (my_master_ptr) cinfo->master;
 770
 771   /* The entropy coder always needs an end-of-pass call,
 772    * either to analyze statistics or to flush its output buffer.
 773    */
 774   (*cinfo->entropy->finish_pass) (cinfo);
 775
 776   /* Update state for next pass */
 777   switch (master->pass_type) {
 778   case main_pass:
 779     /* next pass is either output of scan 0 (after optimization)
 780      * or output of scan 1 (if no optimization).
 781      */
 782     master->pass_type = output_pass;
 783     if (! cinfo->optimize_coding)
 784       master->scan_number++;
 785     break;
 786   case huff_opt_pass:
 787     /* next pass is always output of current scan */
 788     master->pass_type = output_pass;
 789     break;
 790   case output_pass:
 791     /* next pass is either optimization or output of next scan */
 792     if (cinfo->optimize_coding)
 793       master->pass_type = huff_opt_pass;
 794     master->scan_number++;
 795     break;
 796   }
 797
 798   master->pass_number++;
 799 }
 800
 801
 802 /*
 803  * Initialize master compression control.
 804  */
 805
 806 GLOBAL(void)
 807 jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
 808 {
 809   my_master_ptr master;
 810
 811   master = (my_master_ptr)
 812       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 813                                   SIZEOF(my_comp_master));
 814   cinfo->master = (struct jpeg_comp_master *) master;
 815   master->pub.prepare_for_pass = prepare_for_pass;
 816   master->pub.pass_startup = pass_startup;
 817   master->pub.finish_pass = finish_pass_master;
 818   master->pub.is_last_pass = FALSE;
 819
 820   /* Validate parameters, determine derived values */
 821   initial_setup(cinfo, transcode_only);
 822
 823   if (cinfo->scan_info != NULL) {
 824 #ifdef C_MULTISCAN_FILES_SUPPORTED
 825     validate_script(cinfo);
 826     if (cinfo->block_size < DCTSIZE)
 827       reduce_script(cinfo);
 828 #else
 829     ERREXIT(cinfo, JERR_NOT_COMPILED);
 830 #endif
 831   } else {
 832     cinfo->progressive_mode = FALSE;
 833     cinfo->num_scans = 1;
 834   }
 835
 836   if ((cinfo->progressive_mode || cinfo->block_size < DCTSIZE) &&
 837       !cinfo->arith_code)                       /*  TEMPORARY HACK ??? */
 838     /* assume default tables no good for progressive or downscale mode */
 839     cinfo->optimize_coding = TRUE;
 840
 841   /* Initialize my private state */
 842   if (transcode_only) {
 843     /* no main pass in transcoding */
 844     if (cinfo->optimize_coding)
 845       master->pass_type = huff_opt_pass;
 846     else
 847       master->pass_type = output_pass;
 848   } else {
 849     /* for normal compression, first pass is always this type: */
 850     master->pass_type = main_pass;
 851   }
 852   master->scan_number = 0;
 853   master->pass_number = 0;
 854   if (cinfo->optimize_coding)
 855     master->total_passes = cinfo->num_scans * 2;
 856   else
 857     master->total_passes = cinfo->num_scans;
 858 }