compiler/libjpeg/main/jdinput.c

   1 /*
   2     $Id$
   3 */
   4
   5 /*
   6  * jdinput.c
   7  *
   8  * Copyright (C) 1991-1998, Thomas G. Lane.
   9  * This file is part of the Independent JPEG Group's software.
  10  * For conditions of distribution and use, see the accompanying README file.
  11  *
  12  * This file contains input control logic for the JPEG decompressor.
  13  * These routines are concerned with controlling the decompressor's input
  14  * processing (marker reading and coefficient/difference decoding).
  15  * The actual input reading is done in jdmarker.c, jdhuff.c, jdphuff.c,
  16  * and jdlhuff.c.
  17  */
  18
  19 #define JPEG_INTERNALS
  20 #include "jinclude.h"
  21 #include "jpeglib.h"
  22
  23
  24 /* Private state */
  25
  26 typedef struct {
  27   struct jpeg_input_controller pub; /* public fields */
  28
  29   boolean inheaders;            /* TRUE until first SOS is reached */
  30 } my_input_controller;
  31
  32 typedef my_input_controller * my_inputctl_ptr;
  33
  34
  35 /* Forward declarations */
  36 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
  37
  38
  39 /*
  40  * Routines to calculate various quantities related to the size of the image.
  41  */
  42
  43 LOCAL(void)
  44 initial_setup (j_decompress_ptr cinfo)
  45 /* Called once, when first SOS marker is reached */
  46 {
  47   int ci;
  48   jpeg_component_info *compptr;
  49
  50   /* Make sure image isn't bigger than I can handle */
  51   if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
  52       (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
  53     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
  54
  55   if (cinfo->process == JPROC_LOSSLESS) {
  56     /* If precision > compiled-in value, we must downscale */
  57     if (cinfo->data_precision > BITS_IN_JSAMPLE)
  58       WARNMS2(cinfo, JWRN_MUST_DOWNSCALE,
  59               cinfo->data_precision, BITS_IN_JSAMPLE);
  60   }
  61   else {  /* Lossy processes */
  62     /* For now, precision must match compiled-in value... */
  63     if (cinfo->data_precision != BITS_IN_JSAMPLE)
  64       ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
  65   }
  66
  67   /* Check that number of components won't exceed internal array sizes */
  68   if (cinfo->num_components > MAX_COMPONENTS)
  69     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
  70              MAX_COMPONENTS);
  71
  72   /* Compute maximum sampling factors; check factor validity */
  73   cinfo->max_h_samp_factor = 1;
  74   cinfo->max_v_samp_factor = 1;
  75   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  76        ci++, compptr++) {
  77     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
  78         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
  79       ERREXIT(cinfo, JERR_BAD_SAMPLING);
  80     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
  81                                    compptr->h_samp_factor);
  82     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
  83                                    compptr->v_samp_factor);
  84   }
  85
  86   /* We initialize codec_data_unit and min_codec_data_unit to data_unit.
  87    * In the full decompressor, this will be overridden by jdmaster.c;
  88    * but in the transcoder, jdmaster.c is not used, so we must do it here.
  89    */
  90   cinfo->min_codec_data_unit = cinfo->data_unit;
  91
  92   /* Compute dimensions of components */
  93   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  94        ci++, compptr++) {
  95     compptr->codec_data_unit = cinfo->data_unit;
  96     /* Size in data units */
  97     compptr->width_in_data_units = (JDIMENSION)
  98       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
  99                     (long) (cinfo->max_h_samp_factor * cinfo->data_unit));
 100     compptr->height_in_data_units = (JDIMENSION)
 101       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
 102                     (long) (cinfo->max_v_samp_factor * cinfo->data_unit));
 103     /* downsampled_width and downsampled_height will also be overridden by
 104      * jdmaster.c if we are doing full decompression.  The transcoder library
 105      * doesn't use these values, but the calling application might.
 106      */
 107     /* Size in samples */
 108     compptr->downsampled_width = (JDIMENSION)
 109       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
 110                     (long) cinfo->max_h_samp_factor);
 111     compptr->downsampled_height = (JDIMENSION)
 112       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
 113                     (long) cinfo->max_v_samp_factor);
 114     /* Mark component needed, until color conversion says otherwise */
 115     compptr->component_needed = TRUE;
 116     /* Mark no quantization table yet saved for component */
 117     compptr->quant_table = NULL;
 118   }
 119
 120   /* Compute number of fully interleaved MCU rows. */
 121   cinfo->total_iMCU_rows = (JDIMENSION)
 122     jdiv_round_up((long) cinfo->image_height,
 123                   (long) (cinfo->max_v_samp_factor*cinfo->data_unit));
 124
 125   /* Decide whether file contains multiple scans */
 126   if (cinfo->comps_in_scan < cinfo->num_components ||
 127       cinfo->process == JPROC_PROGRESSIVE)
 128     cinfo->inputctl->has_multiple_scans = TRUE;
 129   else
 130     cinfo->inputctl->has_multiple_scans = FALSE;
 131 }
 132
 133
 134 LOCAL(void)
 135 per_scan_setup (j_decompress_ptr cinfo)
 136 /* Do computations that are needed before processing a JPEG scan */
 137 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
 138 {
 139   int ci, mcublks, tmp;
 140   jpeg_component_info *compptr;
 141
 142   if (cinfo->comps_in_scan == 1) {
 143
 144     /* Noninterleaved (single-component) scan */
 145     compptr = cinfo->cur_comp_info[0];
 146
 147     /* Overall image size in MCUs */
 148     cinfo->MCUs_per_row = compptr->width_in_data_units;
 149     cinfo->MCU_rows_in_scan = compptr->height_in_data_units;
 150
 151     /* For noninterleaved scan, always one data unit per MCU */
 152     compptr->MCU_width = 1;
 153     compptr->MCU_height = 1;
 154     compptr->MCU_data_units = 1;
 155     compptr->MCU_sample_width = compptr->codec_data_unit;
 156     compptr->last_col_width = 1;
 157     /* For noninterleaved scans, it is convenient to define last_row_height
 158      * as the number of data unit rows present in the last iMCU row.
 159      */
 160     tmp = (int) (compptr->height_in_data_units % compptr->v_samp_factor);
 161     if (tmp == 0) tmp = compptr->v_samp_factor;
 162     compptr->last_row_height = tmp;
 163
 164     /* Prepare array describing MCU composition */
 165     cinfo->data_units_in_MCU = 1;
 166     cinfo->MCU_membership[0] = 0;
 167
 168   } else {
 169
 170     /* Interleaved (multi-component) scan */
 171     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
 172       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
 173                MAX_COMPS_IN_SCAN);
 174
 175     /* Overall image size in MCUs */
 176     cinfo->MCUs_per_row = (JDIMENSION)
 177       jdiv_round_up((long) cinfo->image_width,
 178                     (long) (cinfo->max_h_samp_factor*cinfo->data_unit));
 179     cinfo->MCU_rows_in_scan = (JDIMENSION)
 180       jdiv_round_up((long) cinfo->image_height,
 181                     (long) (cinfo->max_v_samp_factor*cinfo->data_unit));
 182
 183     cinfo->data_units_in_MCU = 0;
 184
 185     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 186       compptr = cinfo->cur_comp_info[ci];
 187       /* Sampling factors give # of data units of component in each MCU */
 188       compptr->MCU_width = compptr->h_samp_factor;
 189       compptr->MCU_height = compptr->v_samp_factor;
 190       compptr->MCU_data_units = compptr->MCU_width * compptr->MCU_height;
 191       compptr->MCU_sample_width = compptr->MCU_width * compptr->codec_data_unit;
 192       /* Figure number of non-dummy data units in last MCU column & row */
 193       tmp = (int) (compptr->width_in_data_units % compptr->MCU_width);
 194       if (tmp == 0) tmp = compptr->MCU_width;
 195       compptr->last_col_width = tmp;
 196       tmp = (int) (compptr->height_in_data_units % compptr->MCU_height);
 197       if (tmp == 0) tmp = compptr->MCU_height;
 198       compptr->last_row_height = tmp;
 199       /* Prepare array describing MCU composition */
 200       mcublks = compptr->MCU_data_units;
 201       if (cinfo->data_units_in_MCU + mcublks > D_MAX_DATA_UNITS_IN_MCU)
 202         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
 203       while (mcublks-- > 0) {
 204         cinfo->MCU_membership[cinfo->data_units_in_MCU++] = ci;
 205       }
 206     }
 207
 208   }
 209 }
 210
 211
 212 /*
 213  * Initialize the input modules to read a scan of compressed data.
 214  * The first call to this is done by jdmaster.c after initializing
 215  * the entire decompressor (during jpeg_start_decompress).
 216  * Subsequent calls come from consume_markers, below.
 217  */
 218
 219 METHODDEF(void)
 220 start_input_pass (j_decompress_ptr cinfo)
 221 {
 222   per_scan_setup(cinfo);
 223   (*cinfo->codec->start_input_pass) (cinfo);
 224   cinfo->inputctl->consume_input = cinfo->codec->consume_data;
 225 }
 226
 227
 228 /*
 229  * Finish up after inputting a compressed-data scan.
 230  * This is called by the coefficient controller after it's read all
 231  * the expected data of the scan.
 232  */
 233
 234 METHODDEF(void)
 235 finish_input_pass (j_decompress_ptr cinfo)
 236 {
 237   cinfo->inputctl->consume_input = consume_markers;
 238 }
 239
 240
 241 /*
 242  * Read JPEG markers before, between, or after compressed-data scans.
 243  * Change state as necessary when a new scan is reached.
 244  * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
 245  *
 246  * The consume_input method pointer points either here or to the
 247  * coefficient controller's consume_data routine, depending on whether
 248  * we are reading a compressed data segment or inter-segment markers.
 249  */
 250
 251 METHODDEF(int)
 252 consume_markers (j_decompress_ptr cinfo)
 253 {
 254   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
 255   int val;
 256
 257   if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
 258     return JPEG_REACHED_EOI;
 259
 260   val = (*cinfo->marker->read_markers) (cinfo);
 261
 262   switch (val) {
 263   case JPEG_REACHED_SOS:        /* Found SOS */
 264     if (inputctl->inheaders) {  /* 1st SOS */
 265       initial_setup(cinfo);
 266       /*
 267        * Initialize the decompression codec.  We need to do this here so that
 268        * any codec-specific fields and function pointers are available to
 269        * the rest of the library.
 270        */
 271       jinit_d_codec(cinfo);
 272       inputctl->inheaders = FALSE;
 273       /* Note: start_input_pass must be called by jdmaster.c
 274        * before any more input can be consumed.  jdapimin.c is
 275        * responsible for enforcing this sequencing.
 276        */
 277     } else {                    /* 2nd or later SOS marker */
 278       if (! inputctl->pub.has_multiple_scans)
 279         ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
 280       start_input_pass(cinfo);
 281     }
 282     break;
 283   case JPEG_REACHED_EOI:        /* Found EOI */
 284     inputctl->pub.eoi_reached = TRUE;
 285     if (inputctl->inheaders) {  /* Tables-only datastream, apparently */
 286       if (cinfo->marker->saw_SOF)
 287         ERREXIT(cinfo, JERR_SOF_NO_SOS);
 288     } else {
 289       /* Prevent infinite loop in coef ctlr's decompress_data routine
 290        * if user set output_scan_number larger than number of scans.
 291        */
 292       if (cinfo->output_scan_number > cinfo->input_scan_number)
 293         cinfo->output_scan_number = cinfo->input_scan_number;
 294     }
 295     break;
 296   case JPEG_SUSPENDED:
 297     break;
 298   }
 299
 300   return val;
 301 }
 302
 303
 304 /*
 305  * Reset state to begin a fresh datastream.
 306  */
 307
 308 METHODDEF(void)
 309 reset_input_controller (j_decompress_ptr cinfo)
 310 {
 311   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
 312
 313   inputctl->pub.consume_input = consume_markers;
 314   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
 315   inputctl->pub.eoi_reached = FALSE;
 316   inputctl->inheaders = TRUE;
 317   /* Reset other modules */
 318   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
 319   (*cinfo->marker->reset_marker_reader) (cinfo);
 320   /* Reset progression state -- would be cleaner if entropy decoder did this */
 321   cinfo->coef_bits = NULL;
 322 }
 323
 324
 325 /*
 326  * Initialize the input controller module.
 327  * This is called only once, when the decompression object is created.
 328  */
 329
 330 JGLOBAL(void)
 331 jinit_input_controller (j_decompress_ptr cinfo)
 332 {
 333   my_inputctl_ptr inputctl;
 334
 335   /* Create subobject in permanent pool */
 336   inputctl = (my_inputctl_ptr)
 337     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
 338                                 SIZEOF(my_input_controller));
 339   cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
 340   /* Initialize method pointers */
 341   inputctl->pub.consume_input = consume_markers;
 342   inputctl->pub.reset_input_controller = reset_input_controller;
 343   inputctl->pub.start_input_pass = start_input_pass;
 344   inputctl->pub.finish_input_pass = finish_input_pass;
 345   /* Initialize state: can't use reset_input_controller since we don't
 346    * want to try to reset other modules yet.
 347    */
 348   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
 349   inputctl->pub.eoi_reached = FALSE;
 350   inputctl->inheaders = TRUE;
 351 }