src/jpeg/jdinput.c

   1 /*
   2  * jdinput.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 input control logic for the JPEG decompressor.
   9  * These routines are concerned with controlling the decompressor's input
  10  * processing (marker reading and coefficient decoding).  The actual input
  11  * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
  12  */
  13
  14 #define JPEG_INTERNALS
  15 #include "jinclude.h"
  16 #include "jpeglib.h"
  17
  18 #if defined(__VISAGECPP__)
  19 /* Visual Age fixups for multiple declarations */
  20 #  define start_input_pass   start_input_pass2 /* already in jcmaint.c */
  21 #endif
  22
  23 /* Private state */
  24
  25 typedef struct {
  26   struct jpeg_input_controller pub; /* public fields */
  27
  28   boolean inheaders;            /* TRUE until first SOS is reached */
  29 } my_input_controller;
  30
  31 typedef my_input_controller * my_inputctl_ptr;
  32
  33
  34 /* Forward declarations */
  35 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
  36
  37
  38 /*
  39  * Routines to calculate various quantities related to the size of the image.
  40  */
  41
  42 LOCAL(void)
  43 initial_setup (j_decompress_ptr cinfo)
  44 /* Called once, when first SOS marker is reached */
  45 {
  46   int ci;
  47   jpeg_component_info *compptr;
  48
  49   /* Make sure image isn't bigger than I can handle */
  50   if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
  51       (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
  52     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
  53
  54   /* For now, precision must match compiled-in value... */
  55   if (cinfo->data_precision != BITS_IN_JSAMPLE)
  56     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
  57
  58   /* Check that number of components won't exceed internal array sizes */
  59   if (cinfo->num_components > MAX_COMPONENTS)
  60     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
  61              MAX_COMPONENTS);
  62
  63   /* Compute maximum sampling factors; check factor validity */
  64   cinfo->max_h_samp_factor = 1;
  65   cinfo->max_v_samp_factor = 1;
  66   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  67        ci++, compptr++) {
  68     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
  69         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
  70       ERREXIT(cinfo, JERR_BAD_SAMPLING);
  71     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
  72                                    compptr->h_samp_factor);
  73     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
  74                                    compptr->v_samp_factor);
  75   }
  76
  77   /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
  78    * In the full decompressor, this will be overridden by jdmaster.c;
  79    * but in the transcoder, jdmaster.c is not used, so we must do it here.
  80    */
  81   cinfo->min_DCT_scaled_size = DCTSIZE;
  82
  83   /* Compute dimensions of components */
  84   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  85        ci++, compptr++) {
  86     compptr->DCT_scaled_size = DCTSIZE;
  87     /* Size in DCT blocks */
  88     compptr->width_in_blocks = (JDIMENSION)
  89       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
  90                     (long) (cinfo->max_h_samp_factor * DCTSIZE));
  91     compptr->height_in_blocks = (JDIMENSION)
  92       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
  93                     (long) (cinfo->max_v_samp_factor * DCTSIZE));
  94     /* downsampled_width and downsampled_height will also be overridden by
  95      * jdmaster.c if we are doing full decompression.  The transcoder library
  96      * doesn't use these values, but the calling application might.
  97      */
  98     /* Size in samples */
  99     compptr->downsampled_width = (JDIMENSION)
 100       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
 101                     (long) cinfo->max_h_samp_factor);
 102     compptr->downsampled_height = (JDIMENSION)
 103       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
 104                     (long) cinfo->max_v_samp_factor);
 105     /* Mark component needed, until color conversion says otherwise */
 106     compptr->component_needed = TRUE;
 107     /* Mark no quantization table yet saved for component */
 108     compptr->quant_table = NULL;
 109   }
 110
 111   /* Compute number of fully interleaved MCU rows. */
 112   cinfo->total_iMCU_rows = (JDIMENSION)
 113     jdiv_round_up((long) cinfo->image_height,
 114                   (long) (cinfo->max_v_samp_factor*DCTSIZE));
 115
 116   /* Decide whether file contains multiple scans */
 117   if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
 118     cinfo->inputctl->has_multiple_scans = TRUE;
 119   else
 120     cinfo->inputctl->has_multiple_scans = FALSE;
 121 }
 122
 123
 124 LOCAL(void)
 125 per_scan_setup (j_decompress_ptr cinfo)
 126 /* Do computations that are needed before processing a JPEG scan */
 127 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
 128 {
 129   int ci, mcublks, tmp;
 130   jpeg_component_info *compptr;
 131
 132   if (cinfo->comps_in_scan == 1) {
 133
 134     /* Noninterleaved (single-component) scan */
 135     compptr = cinfo->cur_comp_info[0];
 136
 137     /* Overall image size in MCUs */
 138     cinfo->MCUs_per_row = compptr->width_in_blocks;
 139     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
 140
 141     /* For noninterleaved scan, always one block per MCU */
 142     compptr->MCU_width = 1;
 143     compptr->MCU_height = 1;
 144     compptr->MCU_blocks = 1;
 145     compptr->MCU_sample_width = compptr->DCT_scaled_size;
 146     compptr->last_col_width = 1;
 147     /* For noninterleaved scans, it is convenient to define last_row_height
 148      * as the number of block rows present in the last iMCU row.
 149      */
 150     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
 151     if (tmp == 0) tmp = compptr->v_samp_factor;
 152     compptr->last_row_height = tmp;
 153
 154     /* Prepare array describing MCU composition */
 155     cinfo->blocks_in_MCU = 1;
 156     cinfo->MCU_membership[0] = 0;
 157
 158   } else {
 159
 160     /* Interleaved (multi-component) scan */
 161     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
 162       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
 163                MAX_COMPS_IN_SCAN);
 164
 165     /* Overall image size in MCUs */
 166     cinfo->MCUs_per_row = (JDIMENSION)
 167       jdiv_round_up((long) cinfo->image_width,
 168                     (long) (cinfo->max_h_samp_factor*DCTSIZE));
 169     cinfo->MCU_rows_in_scan = (JDIMENSION)
 170       jdiv_round_up((long) cinfo->image_height,
 171                     (long) (cinfo->max_v_samp_factor*DCTSIZE));
 172
 173     cinfo->blocks_in_MCU = 0;
 174
 175     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 176       compptr = cinfo->cur_comp_info[ci];
 177       /* Sampling factors give # of blocks of component in each MCU */
 178       compptr->MCU_width = compptr->h_samp_factor;
 179       compptr->MCU_height = compptr->v_samp_factor;
 180       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
 181       compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
 182       /* Figure number of non-dummy blocks in last MCU column & row */
 183       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
 184       if (tmp == 0) tmp = compptr->MCU_width;
 185       compptr->last_col_width = tmp;
 186       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
 187       if (tmp == 0) tmp = compptr->MCU_height;
 188       compptr->last_row_height = tmp;
 189       /* Prepare array describing MCU composition */
 190       mcublks = compptr->MCU_blocks;
 191       if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
 192         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
 193       while (mcublks-- > 0) {
 194         cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
 195       }
 196     }
 197
 198   }
 199 }
 200
 201
 202 /*
 203  * Save away a copy of the Q-table referenced by each component present
 204  * in the current scan, unless already saved during a prior scan.
 205  *
 206  * In a multiple-scan JPEG file, the encoder could assign different components
 207  * the same Q-table slot number, but change table definitions between scans
 208  * so that each component uses a different Q-table.  (The IJG encoder is not
 209  * currently capable of doing this, but other encoders might.)  Since we want
 210  * to be able to dequantize all the components at the end of the file, this
 211  * means that we have to save away the table actually used for each component.
 212  * We do this by copying the table at the start of the first scan containing
 213  * the component.
 214  * The JPEG spec prohibits the encoder from changing the contents of a Q-table
 215  * slot between scans of a component using that slot.  If the encoder does so
 216  * anyway, this decoder will simply use the Q-table values that were current
 217  * at the start of the first scan for the component.
 218  *
 219  * The decompressor output side looks only at the saved quant tables,
 220  * not at the current Q-table slots.
 221  */
 222
 223 LOCAL(void)
 224 latch_quant_tables (j_decompress_ptr cinfo)
 225 {
 226   int ci, qtblno;
 227   jpeg_component_info *compptr;
 228   JQUANT_TBL * qtbl;
 229
 230   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 231     compptr = cinfo->cur_comp_info[ci];
 232     /* No work if we already saved Q-table for this component */
 233     if (compptr->quant_table != NULL)
 234       continue;
 235     /* Make sure specified quantization table is present */
 236     qtblno = compptr->quant_tbl_no;
 237     if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
 238         cinfo->quant_tbl_ptrs[qtblno] == NULL)
 239       ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
 240     /* OK, save away the quantization table */
 241     qtbl = (JQUANT_TBL *)
 242       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 243                                   SIZEOF(JQUANT_TBL));
 244     MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
 245     compptr->quant_table = qtbl;
 246   }
 247 }
 248
 249
 250 /*
 251  * Initialize the input modules to read a scan of compressed data.
 252  * The first call to this is done by jdmaster.c after initializing
 253  * the entire decompressor (during jpeg_start_decompress).
 254  * Subsequent calls come from consume_markers, below.
 255  */
 256
 257 METHODDEF(void)
 258 start_input_pass (j_decompress_ptr cinfo)
 259 {
 260   per_scan_setup(cinfo);
 261   latch_quant_tables(cinfo);
 262   (*cinfo->entropy->start_pass) (cinfo);
 263   (*cinfo->coef->start_input_pass) (cinfo);
 264   cinfo->inputctl->consume_input = cinfo->coef->consume_data;
 265 }
 266
 267
 268 /*
 269  * Finish up after inputting a compressed-data scan.
 270  * This is called by the coefficient controller after it's read all
 271  * the expected data of the scan.
 272  */
 273
 274 METHODDEF(void)
 275 finish_input_pass (j_decompress_ptr cinfo)
 276 {
 277   cinfo->inputctl->consume_input = consume_markers;
 278 }
 279
 280
 281 /*
 282  * Read JPEG markers before, between, or after compressed-data scans.
 283  * Change state as necessary when a new scan is reached.
 284  * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
 285  *
 286  * The consume_input method pointer points either here or to the
 287  * coefficient controller's consume_data routine, depending on whether
 288  * we are reading a compressed data segment or inter-segment markers.
 289  */
 290
 291 METHODDEF(int)
 292 consume_markers (j_decompress_ptr cinfo)
 293 {
 294   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
 295   int val;
 296
 297   if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
 298     return JPEG_REACHED_EOI;
 299
 300   val = (*cinfo->marker->read_markers) (cinfo);
 301
 302   switch (val) {
 303   case JPEG_REACHED_SOS:        /* Found SOS */
 304     if (inputctl->inheaders) {  /* 1st SOS */
 305       initial_setup(cinfo);
 306       inputctl->inheaders = FALSE;
 307       /* Note: start_input_pass must be called by jdmaster.c
 308        * before any more input can be consumed.  jdapimin.c is
 309        * responsible for enforcing this sequencing.
 310        */
 311     } else {                    /* 2nd or later SOS marker */
 312       if (! inputctl->pub.has_multiple_scans)
 313         ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
 314       start_input_pass(cinfo);
 315     }
 316     break;
 317   case JPEG_REACHED_EOI:        /* Found EOI */
 318     inputctl->pub.eoi_reached = TRUE;
 319     if (inputctl->inheaders) {  /* Tables-only datastream, apparently */
 320       if (cinfo->marker->saw_SOF)
 321         ERREXIT(cinfo, JERR_SOF_NO_SOS);
 322     } else {
 323       /* Prevent infinite loop in coef ctlr's decompress_data routine
 324        * if user set output_scan_number larger than number of scans.
 325        */
 326       if (cinfo->output_scan_number > cinfo->input_scan_number)
 327         cinfo->output_scan_number = cinfo->input_scan_number;
 328     }
 329     break;
 330   case JPEG_SUSPENDED:
 331     break;
 332   }
 333
 334   return val;
 335 }
 336
 337
 338 /*
 339  * Reset state to begin a fresh datastream.
 340  */
 341
 342 METHODDEF(void)
 343 reset_input_controller (j_decompress_ptr cinfo)
 344 {
 345   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
 346
 347   inputctl->pub.consume_input = consume_markers;
 348   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
 349   inputctl->pub.eoi_reached = FALSE;
 350   inputctl->inheaders = TRUE;
 351   /* Reset other modules */
 352   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
 353   (*cinfo->marker->reset_marker_reader) (cinfo);
 354   /* Reset progression state -- would be cleaner if entropy decoder did this */
 355   cinfo->coef_bits = NULL;
 356 }
 357
 358
 359 /*
 360  * Initialize the input controller module.
 361  * This is called only once, when the decompression object is created.
 362  */
 363
 364 GLOBAL(void)
 365 jinit_input_controller (j_decompress_ptr cinfo)
 366 {
 367   my_inputctl_ptr inputctl;
 368
 369   /* Create subobject in permanent pool */
 370   inputctl = (my_inputctl_ptr)
 371     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
 372                                 SIZEOF(my_input_controller));
 373   cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
 374   /* Initialize method pointers */
 375   inputctl->pub.consume_input = consume_markers;
 376   inputctl->pub.reset_input_controller = reset_input_controller;
 377   inputctl->pub.start_input_pass = start_input_pass;
 378   inputctl->pub.finish_input_pass = finish_input_pass;
 379   /* Initialize state: can't use reset_input_controller since we don't
 380    * want to try to reset other modules yet.
 381    */
 382   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
 383   inputctl->pub.eoi_reached = FALSE;
 384   inputctl->inheaders = TRUE;
 385 }
 386
 387 #if defined(__VISAGECPP__)
 388 #  ifdef start_input_pass2
 389 #   undef start_input_pass2
 390 #  endif
 391 #endif