tif_next.c

Go to the documentation of this file.

/* $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: */