/* $Id: tif_thunder.c,v 1.12 2011-04-02 20:54:09 bfriesen 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"
#include <assert.h>
#ifdef THUNDER_SUPPORT
/*
 * TIFF Library.
 *
 * ThunderScan 4-bit Compression Algorithm Support
 */

/*
 * ThunderScan uses an encoding scheme designed for
 * 4-bit pixel values.  Data is encoded in bytes, with
 * each byte split into a 2-bit code word and a 6-bit
 * data value.  The encoding gives raw data, runs of
 * pixels, or pixel values encoded as a delta from the
 * previous pixel value.  For the latter, either 2-bit
 * or 3-bit delta values are used, with the deltas packed
 * into a single byte.
 */
#define	THUNDER_DATA		0x3f	/* mask for 6-bit data */
#define	THUNDER_CODE		0xc0	/* mask for 2-bit code word */
/* code values */
#define	THUNDER_RUN		0x00	/* run of pixels w/ encoded count */
#define	THUNDER_2BITDELTAS	0x40	/* 3 pixels w/ encoded 2-bit deltas */
#define	    DELTA2_SKIP		2	/* skip code for 2-bit deltas */
#define	THUNDER_3BITDELTAS	0x80	/* 2 pixels w/ encoded 3-bit deltas */
#define	    DELTA3_SKIP		4	/* skip code for 3-bit deltas */
#define	THUNDER_RAW		0xc0	/* raw data encoded */

static const int twobitdeltas[4] = { 0, 1, 0, -1 };
static const int threebitdeltas[8] = { 0, 1, 2, 3, 0, -3, -2, -1 };

#define	SETPIXEL(op, v) {                     \
    lastpixel = (v) & 0xf;                \
        if ( npixels < maxpixels )         \
        {                                     \
      if (npixels++ & 1)                  \
        *op++ |= lastpixel;               \
      else                                \
        op[0] = (uint8) (lastpixel << 4); \
        }                                     \
}

static int
ThunderSetupDecode(TIFF* tif)
{
    static const char module[] = "ThunderSetupDecode";

        if( tif->tif_dir.td_bitspersample != 4 )
        {
                TIFFErrorExt(tif->tif_clientdata, module,
                             "Wrong bitspersample value (%d), Thunder decoder only supports 4bits per sample.",
                             (int) tif->tif_dir.td_bitspersample );
                return 0;
        }


    return (1);
}

static int
ThunderDecode(TIFF* tif, uint8* op, tmsize_t maxpixels)
{
    static const char module[] = "ThunderDecode";
    register unsigned char *bp;
    register tmsize_t cc;
    unsigned int lastpixel;
    tmsize_t npixels;

    bp = (unsigned char *)tif->tif_rawcp;
    cc = tif->tif_rawcc;
    lastpixel = 0;
    npixels = 0;
    while (cc > 0 && npixels < maxpixels) {
        int n, delta;

        n = *bp++, cc--;
        switch (n & THUNDER_CODE) {
        case THUNDER_RUN:		/* pixel run */
            /*
             * Replicate the last pixel n times,
             * where n is the lower-order 6 bits.
             */
            if (npixels & 1) {
                op[0] |= lastpixel;
                lastpixel = *op++; npixels++; n--;
            } else
                lastpixel |= lastpixel << 4;
            npixels += n;
            if (npixels < maxpixels) {
                for (; n > 0; n -= 2)
                    *op++ = (uint8) lastpixel;
            }
            if (n == -1)
                *--op &= 0xf0;
            lastpixel &= 0xf;
            break;
        case THUNDER_2BITDELTAS:	/* 2-bit deltas */
            if ((delta = ((n >> 4) & 3)) != DELTA2_SKIP)
                SETPIXEL(op, lastpixel + twobitdeltas[delta]);
            if ((delta = ((n >> 2) & 3)) != DELTA2_SKIP)
                SETPIXEL(op, lastpixel + twobitdeltas[delta]);
            if ((delta = (n & 3)) != DELTA2_SKIP)
                SETPIXEL(op, lastpixel + twobitdeltas[delta]);
            break;
        case THUNDER_3BITDELTAS:	/* 3-bit deltas */
            if ((delta = ((n >> 3) & 7)) != DELTA3_SKIP)
                SETPIXEL(op, lastpixel + threebitdeltas[delta]);
            if ((delta = (n & 7)) != DELTA3_SKIP)
                SETPIXEL(op, lastpixel + threebitdeltas[delta]);
            break;
        case THUNDER_RAW:		/* raw data */
            SETPIXEL(op, n);
            break;
        }
    }
    tif->tif_rawcp = (uint8*) bp;
    tif->tif_rawcc = cc;
    if (npixels != maxpixels) {
#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
        TIFFErrorExt(tif->tif_clientdata, module,
                 "%s data at scanline %lu (%I64u != %I64u)",
                 npixels < maxpixels ? "Not enough" : "Too much",
                 (unsigned long) tif->tif_row,
                 (unsigned __int64) npixels,
                 (unsigned __int64) maxpixels);
#else
        TIFFErrorExt(tif->tif_clientdata, module,
                 "%s data at scanline %lu (%llu != %llu)",
                 npixels < maxpixels ? "Not enough" : "Too much",
                 (unsigned long) tif->tif_row,
                 (unsigned long long) npixels,
                 (unsigned long long) maxpixels);
#endif
        return (0);
    }

        return (1);
}

static int
ThunderDecodeRow(TIFF* tif, uint8* buf, tmsize_t occ, uint16 s)
{
    static const char module[] = "ThunderDecodeRow";
    uint8* row = buf;

    (void) s;
    if (occ % tif->tif_scanlinesize)
    {
        TIFFErrorExt(tif->tif_clientdata, module, "Fractional scanlines cannot be read");
        return (0);
    }
    while (occ > 0) {
        if (!ThunderDecode(tif, row, tif->tif_dir.td_imagewidth))
            return (0);
        occ -= tif->tif_scanlinesize;
        row += tif->tif_scanlinesize;
    }
    return (1);
}

int
TIFFInitThunderScan(TIFF* tif, int scheme)
{
    (void) scheme;

        tif->tif_setupdecode = ThunderSetupDecode;
    tif->tif_decoderow = ThunderDecodeRow;
    tif->tif_decodestrip = ThunderDecodeRow;
    return (1);
}
#endif /* THUNDER_SUPPORT */

/* vim: set ts=8 sts=8 sw=8 noet: */
/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 8
 * fill-column: 78
 * End:
 */
