jrdjfif.c

EVM板JPEG实现,Texas Instruments TMS320C54x EVM JPEG

   {
/*    ERREXIT(cinfo->emethods, "Bogus SOF length"); */
      send_command(ERR12);
      receive_command();
      exit();
   }

  cinfo->comp_info = (jpeg_component_info *) (*cinfo->emethods->alloc_small)
			(cinfo->num_components * SIZEOF(jpeg_component_info));
  
  for (ci = 0; ci < cinfo->num_components; ci++) {
    compptr = &cinfo->comp_info[ci];
    compptr->component_index = ci;
    compptr->component_id = JGETC(cinfo);
    c = JGETC(cinfo);
    compptr->h_samp_factor = (c >> 4) & 15;
    compptr->v_samp_factor = (c     ) & 15;
    compptr->quant_tbl_no  = JGETC(cinfo);
      
/*    TRACEMS4(cinfo->emethods, 1, "    Component %d: %dhx%dv q=%d",
	     compptr->component_id, compptr->h_samp_factor,
        compptr->v_samp_factor, compptr->quant_tbl_no); */
  }
}


LOCAL void
get_sos (decompress_info_ptr cinfo)
/* Process a SOS marker */
{
  INT32 length;
  int i, ci, n, c, cc;
  jpeg_component_info * compptr;
  
  length = get_2bytes(cinfo);
  
  n = JGETC(cinfo);  /* Number of components */
  cinfo->comps_in_scan = n;
  length -= 3;
  
  if (length != (n * 2 + 3) || n < 1 || n > MAX_COMPS_IN_SCAN)
   {
/*    ERREXIT(cinfo->emethods, "Bogus SOS length"); */
      send_command(ERR12);
      receive_command();
      exit();
   }

/*  TRACEMS1(cinfo->emethods, 1, "Start Of Scan: %d components", n); */
  
  for (i = 0; i < n; i++) {
    cc = JGETC(cinfo);
    c = JGETC(cinfo);
    length -= 2;
    
    for (ci = 0; ci < cinfo->num_components; ci++)
      if (cc == cinfo->comp_info[ci].component_id)
	break;
    
    if (ci >= cinfo->num_components)
   {
/*      ERREXIT(cinfo->emethods, "Invalid component number in SOS"); */
      send_command(ERR12);
      receive_command();
      exit();
   }
    
    compptr = &cinfo->comp_info[ci];
    cinfo->cur_comp_info[i] = compptr;
    compptr->dc_tbl_no = (c >> 4) & 15;
    compptr->ac_tbl_no = (c     ) & 15;
    
/*    TRACEMS3(cinfo->emethods, 1, "    c%d: [dc=%d ac=%d]", cc,
        compptr->dc_tbl_no, compptr->ac_tbl_no); */
  }
  
  while (length > 0) {
    (void) JGETC(cinfo);
    length--;
  }
}


LOCAL void
get_soi (decompress_info_ptr cinfo)
/* Process an SOI marker */
{
  int i;
  
/*  TRACEMS(cinfo->emethods, 1, "Start of Image"); */

  /* Reset all parameters that are defined to be reset by SOI */

  for (i = 0; i < NUM_ARITH_TBLS; i++) {
    cinfo->arith_dc_L[i] = 0;
    cinfo->arith_dc_U[i] = 1;
    cinfo->arith_ac_K[i] = 5;
  }
  cinfo->restart_interval = 0;

  cinfo->density_unit = 0;	/* set default JFIF APP0 values */
  cinfo->X_density = 1;
  cinfo->Y_density = 1;

  cinfo->CCIR601_sampling = FALSE; /* Assume non-CCIR sampling */
}


LOCAL int
next_marker (decompress_info_ptr cinfo)
/* Find the next JPEG marker */
/* Note that the output might not be a valid marker code, */
/* but it will never be 0 or FF */
{
  int c, nbytes;

  nbytes = 0;
  do {
    do {			/* skip any non-FF bytes */
      nbytes++;
      c = JGETC(cinfo);
    } while (c != 0xFF);
    do {			/* skip any duplicate FFs */
      /* we don't increment nbytes here since extra FFs are legal */
      c = JGETC(cinfo);
    } while (c == 0xFF);
  } while (c == 0);		/* repeat if it was a stuffed FF/00 */

  if (nbytes != 1)
/*    WARNMS2(cinfo->emethods,
	    "Corrupt JPEG data: %d extraneous bytes before marker 0x%02x",
       nbytes-1, c); */
		 send_command(ERR13);

  return c;
}


LOCAL JPEG_MARKER
process_tables (decompress_info_ptr cinfo)
/* Scan and process JPEG markers that can appear in any order */
/* Return when an SOI, EOI, SOFn, or SOS is found */
{
  int c;

  while (TRUE) {
    c = next_marker(cinfo);
      
    switch (c) {
    case M_SOF0:
    case M_SOF1:
    case M_SOF2:
    case M_SOF3:
    case M_SOF5:
    case M_SOF6:
    case M_SOF7:
    case M_JPG:
    case M_SOF9:
    case M_SOF10:
    case M_SOF11:
    case M_SOF13:
    case M_SOF14:
    case M_SOF15:
    case M_SOI:
    case M_EOI:
    case M_SOS:
      return ((JPEG_MARKER) c);
      
    case M_DHT:
      get_dht(cinfo);
      break;
      
    case M_DAC:
      get_dac(cinfo);
      break;
      
    case M_DQT:
      get_dqt(cinfo);
      break;
      
    case M_DRI:
      get_dri(cinfo);
      break;
      
    case M_APP0:
      get_app0(cinfo);
      break;

    case M_RST0:		/* these are all parameterless */
    case M_RST1:
    case M_RST2:
    case M_RST3:
    case M_RST4:
    case M_RST5:
    case M_RST6:
    case M_RST7:
    case M_TEM:
/*      TRACEMS1(cinfo->emethods, 1, "Unexpected marker 0x%02x", c); */
      break;

    default:	/* must be DNL, DHP, EXP, APPn, JPGn, COM, or RESn */
      skip_variable(cinfo, c);
      break;
    }
  }
}



/*
 * Initialize and read the file header (everything through the SOF marker).
 */

METHODDEF void
read_file_header (decompress_info_ptr cinfo)
{
  int c;

  /* Demand an SOI marker at the start of the file --- otherwise it's
   * probably not a JPEG file at all.  If the user interface wants to support
   * nonstandard headers in front of the SOI, it must skip over them itself
   * before calling jpeg_decompress().
   */
  if (JGETC(cinfo) != 0xFF  ||  JGETC(cinfo) != M_SOI)
   {
/*    ERREXIT(cinfo->emethods, "Not a JPEG file"); */
      send_command(ERR12);
      receive_command();
      exit();
   }

  get_soi(cinfo);		/* OK, process SOI */

  /* Process markers until SOF */
  c = process_tables(cinfo);

  switch (c) {
  case M_SOF0:
  case M_SOF1:
    get_sof(cinfo, c);
    cinfo->arith_code = FALSE;
    break;
      
  case M_SOF9:
    get_sof(cinfo, c);
    cinfo->arith_code = TRUE;
    break;

  default:
/*    ERREXIT1(cinfo->emethods, "Unsupported SOF marker type 0x%02x", c); */
      send_command(ERR12);
      receive_command();
      exit();
    break;
  }

  /* Figure out what colorspace we have */
  /* (too bad the JPEG committee didn't provide a real way to specify this) */

  switch (cinfo->num_components) {
  case 1:
    cinfo->jpeg_color_space = CS_GRAYSCALE;
    break;

  case 3:
    /* if we saw a JFIF marker, leave it set to YCbCr; */
    /* also leave it alone if UI has provided a value */
    if (cinfo->jpeg_color_space == CS_UNKNOWN) {
      short cid0 = cinfo->comp_info[0].component_id;
      short cid1 = cinfo->comp_info[1].component_id;
      short cid2 = cinfo->comp_info[2].component_id;

      if (cid0 == 1 && cid1 == 2 && cid2 == 3)
	cinfo->jpeg_color_space = CS_YCbCr; /* assume it's JFIF w/out marker */
      else if (cid0 == 1 && cid1 == 4 && cid2 == 5)
	cinfo->jpeg_color_space = CS_YIQ; /* prototype's YIQ matrix */
      else {
/*   TRACEMS3(cinfo->emethods, 1,
		 "Unrecognized component IDs %d %d %d, assuming YCbCr",
       cid0, cid1, cid2); */
	cinfo->jpeg_color_space = CS_YCbCr;
      }
    }
    break;

  case 4:
    cinfo->jpeg_color_space = CS_CMYK;
    break;

  default:
    cinfo->jpeg_color_space = CS_UNKNOWN;
    break;
  }
}


/*
 * Read the start of a scan (everything through the SOS marker).
 * Return TRUE if find SOS, FALSE if find EOI.
 */

METHODDEF boolean
read_scan_header (decompress_info_ptr cinfo)
{
  int c;
  
  /* Process markers until SOS or EOI */
  c = process_tables(cinfo);
  
  switch (c) {
  case M_SOS:
    get_sos(cinfo);
    return TRUE;
    
  case M_EOI:
/*    TRACEMS(cinfo->emethods, 1, "End Of Image"); */
    return FALSE;

  default:
/*    ERREXIT1(cinfo->emethods, "Unexpected marker 0x%02x", c); */
      send_command(ERR12);
      receive_command();
      exit();
    break;
  }
  return FALSE;			/* keeps lint happy */
}


/*
 * The entropy decoder calls this routine if it finds a marker other than
 * the restart marker it was expecting.  (This code is *not* used unless
 * a nonzero restart interval has been declared.)  The passed parameter is
 * the marker code actually found (might be anything, except 0 or FF).
 * The desired restart marker is that indicated by cinfo->next_restart_num.
 * This routine is supposed to apply whatever error recovery strategy seems
 * appropriate in order to position the input stream to the next data segment.
 * For some file formats (eg, TIFF) extra information such as tile boundary
 * pointers may be available to help in this decision.
 *
 * This implementation is substantially constrained by wanting to treat the
 * input as a data stream; this means we can't back up.  (For instance, we
 * generally can't fseek() if the input is a Unix pipe.)  Therefore, we have
 * only the following actions to work with:
 *   1. Do nothing, let the entropy decoder resume at next byte of file.
 *   2. Read forward until we find another marker, discarding intervening
 *      data.  (In theory we could look ahead within the current bufferload,
 *      without having to discard data if we don't find the desired marker.
 *      This idea is not implemented here, in part because it makes behavior
 *      dependent on buffer size and chance buffer-boundary positions.)
 *   3. Push back the passed marker (with JUNGETC).  This will cause the
 *      entropy decoder to process an empty data segment, inserting dummy
 *      zeroes, and then re-read the marker we pushed back.
 * #2 is appropriate if we think the desired marker lies ahead, while #3 is
 * appropriate if the found marker is a future restart marker (indicating
 * that we have missed the desired restart marker, probably because it got
 * corrupted).

 * We apply #2 or #3 if the found marker is a restart marker no more than
 * two counts behind or ahead of the expected one.  We also apply #2 if the
 * found marker is not a legal JPEG marker code (it's certainly bogus data).
 * If the found marker is a restart marker more than 2 counts away, we do #1
 * (too much risk that the marker is erroneous; with luck we will be able to
 * resync at some future point).
 * For any valid non-restart JPEG marker, we apply #3.  This keeps us from
 * overrunning the end of a scan.  An implementation limited to single-scan
 * files might find it better to apply #2 for markers other than EOI, since
 * any other marker would have to be bogus data in that case.
 */

METHODDEF void
resync_to_restart (decompress_info_ptr cinfo, int marker)
{
  int desired = cinfo->next_restart_num;
  int action = 1;

  /* Always put up a warning. */
/*  WARNMS2(cinfo->emethods,
	  "Corrupt JPEG data: found 0x%02x marker instead of RST%d",
     marker, desired); */
	  send_command(ERR13);
  /* Outer loop handles repeated decision after scanning forward. */
  for (;;) {
    if (marker < M_SOF0)
      action = 2;		/* invalid marker */
    else if (marker < M_RST0 || marker > M_RST7)
      action = 3;		/* valid non-restart marker */
    else {
      if (marker == (M_RST0 + ((desired+1) & 7)) ||
	  marker == (M_RST0 + ((desired+2) & 7)))
	action = 3;		/* one of the next two expected restarts */
      else if (marker == (M_RST0 + ((desired-1) & 7)) ||
	       marker == (M_RST0 + ((desired-2) & 7)))
	action = 2;		/* a prior restart, so advance */
      else
	action = 1;		/* desired restart or too far away */
    }
/*    TRACEMS2(cinfo->emethods, 4,
        "At marker 0x%02x, recovery action %d", marker, action); */
    switch (action) {
    case 1:
      /* Let entropy decoder resume processing. */
      return;
    case 2:
      /* Scan to the next marker, and repeat the decision loop. */
      marker = next_marker(cinfo);
      break;
    case 3:
      /* Put back this marker & return. */
      /* Entropy decoder will be forced to process an empty segment. */
      JUNGETC(marker, cinfo);
      JUNGETC(0xFF, cinfo);
      return;
    }
  }
}


/*
 * Finish up after a compressed scan (series of read_jpeg_data calls);
 * prepare for another read_scan_header call.
 */

METHODDEF void
read_scan_trailer (decompress_info_ptr cinfo)
{
  /* no work needed */
}


/*
 * Finish up at the end of the file.
 */

METHODDEF void
read_file_trailer (decompress_info_ptr cinfo)
{
  /* no work needed */
}


/*
 * The method selection routine for standard JPEG header reading.
 * Note that this must be called by the user interface before calling
 * jpeg_decompress.  When a non-JFIF file is to be decompressed (TIFF,
 * perhaps), the user interface must discover the file type and call
 * the appropriate method selection routine.
 */

GLOBAL void
jselrjfif (decompress_info_ptr cinfo)
{
  cinfo->methods->read_file_header = read_file_header;
  cinfo->methods->read_scan_header = read_scan_header;
  /* For JFIF/raw-JPEG format, the user interface supplies read_jpeg_data. */
#if 0
  cinfo->methods->read_jpeg_data = read_jpeg_data;
#endif
  cinfo->methods->resync_to_restart = resync_to_restart;
  cinfo->methods->read_scan_trailer = read_scan_trailer;
  cinfo->methods->read_file_trailer = read_file_trailer;
}

#endif /* JFIF_SUPPORTED */