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tif_next.c

/* $Id: tif_next.c,v 1.6 2005/12/21 12:23:13 joris Exp $ */

/*
 * Copyright (c) 1988-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

#include "tiffiop.h"
#ifdef NEXT_SUPPORT
/*
 * TIFF Library.
 *
 * NeXT 2-bit Grey Scale Compression Algorithm Support
 */

#define SETPIXEL(op, v) {                 \
      switch (npixels++ & 3) {            \
      case 0:     op[0]  = (unsigned char) ((v) << 6); break;     \
      case 1:     op[0] |= (v) << 4; break;     \
      case 2:     op[0] |= (v) << 2; break;     \
      case 3:     *op++ |= (v);        break;   \
      }                             \
}

#define LITERALROW      0x00
#define LITERALSPAN     0x40
#define WHITE     ((1<<2)-1)

static int
NeXTDecode(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
      register unsigned char *bp, *op;
      register tsize_t cc;
      register int n;
      tidata_t row;
      tsize_t scanline;

      (void) s;
      /*
       * Each scanline is assumed to start off as all
       * white (we assume a PhotometricInterpretation
       * of ``min-is-black'').
       */
      for (op = buf, cc = occ; cc-- > 0;)
            *op++ = 0xff;

      bp = (unsigned char *)tif->tif_rawcp;
      cc = tif->tif_rawcc;
      scanline = tif->tif_scanlinesize;
      for (row = buf; (long)occ > 0; occ -= scanline, row += scanline) {
            n = *bp++, cc--;
            switch (n) {
            case LITERALROW:
                  /*
                   * The entire scanline is given as literal values.
                   */
                  if (cc < scanline)
                        goto bad;
                  _TIFFmemcpy(row, bp, scanline);
                  bp += scanline;
                  cc -= scanline;
                  break;
            case LITERALSPAN: {
                  int off;
                  /*
                   * The scanline has a literal span
                   * that begins at some offset.
                   */
                  off = (bp[0] * 256) + bp[1];
                  n = (bp[2] * 256) + bp[3];
                  if (cc < 4+n || off+n > scanline)
                        goto bad;
                  _TIFFmemcpy(row+off, bp+4, n);
                  bp += 4+n;
                  cc -= 4+n;
                  break;
            }
            default: {
                  register int npixels = 0, grey;
                  unsigned long imagewidth = tif->tif_dir.td_imagewidth;

                  /*
                   * The scanline is composed of a sequence
                   * of constant color ``runs''.  We shift
                   * into ``run mode'' and interpret bytes
                   * as codes of the form <color><npixels>
                   * until we've filled the scanline.
                   */
                  op = row;
                  for (;;) {
                        grey = (n>>6) & 0x3;
                        n &= 0x3f;
                        while (n-- > 0)
                              SETPIXEL(op, grey);
                        if (npixels >= (int) imagewidth)
                              break;
                        if (cc == 0)
                              goto bad;
                        n = *bp++, cc--;
                  }
                  break;
            }
            }
      }
      tif->tif_rawcp = (tidata_t) bp;
      tif->tif_rawcc = cc;
      return (1);
bad:
      TIFFErrorExt(tif->tif_clientdata, tif->tif_name, "NeXTDecode: Not enough data for scanline %ld",
          (long) tif->tif_row);
      return (0);
}

int
TIFFInitNeXT(TIFF* tif, int scheme)
{
      (void) scheme;
      tif->tif_decoderow = NeXTDecode;
      tif->tif_decodestrip = NeXTDecode;
      tif->tif_decodetile = NeXTDecode;
      return (1);
}
#endif /* NEXT_SUPPORT */

/* vim: set ts=8 sts=8 sw=8 noet: */

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