tif_next.c

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/*
 * 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 <precomp.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);      op_offset++; break;  \
    }                   \
}
 
#define LITERALROW  0x00
#define LITERALSPAN 0x40
#define WHITE       ((1<<2)-1)
 
static int
NeXTDecode(TIFF* tif, uint8* buf, tmsize_t occ, uint16 s)
{
    static const char module[] = "NeXTDecode";
    unsigned char *bp, *op;
    tmsize_t cc;
    uint8* row;
    tmsize_t scanline, n;
 
    (void) s;
    /*
     * Each scanline is assumed to start off as all
     * white (we assume a PhotometricInterpretation
     * of ``min-is-black'').
     */
    for (op = (unsigned char*) buf, cc = occ; cc-- > 0;)
        *op++ = 0xff;
 
    bp = (unsigned char *)tif->tif_rawcp;
    cc = tif->tif_rawcc;
    scanline = tif->tif_scanlinesize;
    if (occ % scanline)
    {
        TIFFErrorExt(tif->tif_clientdata, module, "Fractional scanlines cannot be read");
        return (0);
    }
    for (row = buf; cc > 0 && 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: {
            tmsize_t off;
            /*
             * The scanline has a literal span that begins at some
             * offset.
             */
            if( cc < 4 )
                goto bad;
            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: {
            uint32 npixels = 0, grey;
            tmsize_t op_offset = 0;
            uint32 imagewidth = tif->tif_dir.td_imagewidth;
            if( isTiled(tif) )
                imagewidth = tif->tif_dir.td_tilewidth;
 
            /*
             * 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 = (uint32)((n>>6) & 0x3);
                n &= 0x3f;
                /*
                 * Ensure the run does not exceed the scanline
                 * bounds, potentially resulting in a security
                 * issue.
                 */
                while (n-- > 0 && npixels < imagewidth && op_offset < scanline)
                    SETPIXEL(op, grey);
                if (npixels >= imagewidth)
                    break;
                if (op_offset >= scanline ) {
                    TIFFErrorExt(tif->tif_clientdata, module, "Invalid data for scanline %ld",
                        (long) tif->tif_row);
                    return (0);
                }
                if (cc == 0)
                    goto bad;
                n = *bp++;
                cc--;
            }
            break;
        }
        }
    }
    tif->tif_rawcp = (uint8*) bp;
    tif->tif_rawcc = cc;
    return (1);
bad:
    TIFFErrorExt(tif->tif_clientdata, module, "Not enough data for scanline %ld",
        (long) tif->tif_row);
    return (0);
}
 
static int
NeXTPreDecode(TIFF* tif, uint16 s)
{
    static const char module[] = "NeXTPreDecode";
    TIFFDirectory *td = &tif->tif_dir;
    (void)s;
 
    if( td->td_bitspersample != 2 )
    {
        TIFFErrorExt(tif->tif_clientdata, module, "Unsupported BitsPerSample = %d",
                     td->td_bitspersample);
        return (0);
    }
    return (1);
}
    
int
TIFFInitNeXT(TIFF* tif, int scheme)
{
    (void) scheme;
    tif->tif_predecode = NeXTPreDecode;  
    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: */
/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 8
 * fill-column: 78
 * End:
 */