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