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