tif_packbits.c

Go to the documentation of this file.

/* $Id: tif_packbits.c,v 1.13.2.2 2010-06-08 18:50:42 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"
#ifdef PACKBITS_SUPPORT
/*
 * TIFF Library.
 *
 * PackBits Compression Algorithm Support
 */
#include <stdio.h>

static int
PackBitsPreEncode(TIFF* tif, tsample_t s)
{
    (void) s;

        if (!(tif->tif_data = (tidata_t)_TIFFmalloc(sizeof(tsize_t))))
        return (0);
    /*
     * Calculate the scanline/tile-width size in bytes.
     */
    if (isTiled(tif))
        *(tsize_t*)tif->tif_data = TIFFTileRowSize(tif);
    else
        *(tsize_t*)tif->tif_data = TIFFScanlineSize(tif);
    return (1);
}

static int
PackBitsPostEncode(TIFF* tif)
{
        if (tif->tif_data)
            _TIFFfree(tif->tif_data);
    return (1);
}

/*
 * NB: tidata is the type representing *(tidata_t);
 *     if tidata_t is made signed then this type must
 *     be adjusted accordingly.
 */
typedef unsigned char tidata;

/*
 * Encode a run of pixels.
 */
static int
PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
    unsigned char* bp = (unsigned char*) buf;
    tidata_t op, ep, lastliteral;
    long n, slop;
    int b;
    enum { BASE, LITERAL, RUN, LITERAL_RUN } state;

    (void) s;
    op = tif->tif_rawcp;
    ep = tif->tif_rawdata + tif->tif_rawdatasize;
    state = BASE;
    lastliteral = 0;
    while (cc > 0) {
        /*
         * Find the longest string of identical bytes.
         */
        b = *bp++, cc--, n = 1;
        for (; cc > 0 && b == *bp; cc--, bp++)
            n++;
    again:
        if (op + 2 >= ep) {     /* insure space for new data */
            /*
             * Be careful about writing the last
             * literal.  Must write up to that point
             * and then copy the remainder to the
             * front of the buffer.
             */
            if (state == LITERAL || state == LITERAL_RUN) {
                slop = op - lastliteral;
                tif->tif_rawcc += lastliteral - tif->tif_rawcp;
                if (!TIFFFlushData1(tif))
                    return (-1);
                op = tif->tif_rawcp;
                while (slop-- > 0)
                    *op++ = *lastliteral++;
                lastliteral = tif->tif_rawcp;
            } else {
                tif->tif_rawcc += op - tif->tif_rawcp;
                if (!TIFFFlushData1(tif))
                    return (-1);
                op = tif->tif_rawcp;
            }
        }
        switch (state) {
        case BASE:      /* initial state, set run/literal */
            if (n > 1) {
                state = RUN;
                if (n > 128) {
                    *op++ = (tidata) -127;
                    *op++ = (tidataval_t) b;
                    n -= 128;
                    goto again;
                }
                *op++ = (tidataval_t)(-(n-1));
                *op++ = (tidataval_t) b;
            } else {
                lastliteral = op;
                *op++ = 0;
                *op++ = (tidataval_t) b;
                state = LITERAL;
            }
            break;
        case LITERAL:       /* last object was literal string */
            if (n > 1) {
                state = LITERAL_RUN;
                if (n > 128) {
                    *op++ = (tidata) -127;
                    *op++ = (tidataval_t) b;
                    n -= 128;
                    goto again;
                }
                *op++ = (tidataval_t)(-(n-1));  /* encode run */
                *op++ = (tidataval_t) b;
            } else {            /* extend literal */
                if (++(*lastliteral) == 127)
                    state = BASE;
                *op++ = (tidataval_t) b;
            }
            break;
        case RUN:       /* last object was run */
            if (n > 1) {
                if (n > 128) {
                    *op++ = (tidata) -127;
                    *op++ = (tidataval_t) b;
                    n -= 128;
                    goto again;
                }
                *op++ = (tidataval_t)(-(n-1));
                *op++ = (tidataval_t) b;
            } else {
                lastliteral = op;
                *op++ = 0;
                *op++ = (tidataval_t) b;
                state = LITERAL;
            }
            break;
        case LITERAL_RUN:   /* literal followed by a run */
            /*
             * Check to see if previous run should
             * be converted to a literal, in which
             * case we convert literal-run-literal
             * to a single literal.
             */
            if (n == 1 && op[-2] == (tidata) -1 &&
                *lastliteral < 126) {
                state = (((*lastliteral) += 2) == 127 ?
                    BASE : LITERAL);
                op[-2] = op[-1];    /* replicate */
            } else
                state = RUN;
            goto again;
        }
    }
    tif->tif_rawcc += op - tif->tif_rawcp;
    tif->tif_rawcp = op;
    return (1);
}

/*
 * Encode a rectangular chunk of pixels.  We break it up
 * into row-sized pieces to insure that encoded runs do
 * not span rows.  Otherwise, there can be problems with
 * the decoder if data is read, for example, by scanlines
 * when it was encoded by strips.
 */
static int
PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
    tsize_t rowsize = *(tsize_t*)tif->tif_data;

    while ((long)cc > 0) {
        int chunk = rowsize;
        
        if( cc < chunk )
            chunk = cc;

        if (PackBitsEncode(tif, bp, chunk, s) < 0)
            return (-1);
        bp += chunk;
        cc -= chunk;
    }
    return (1);
}

static int
PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
{
    char *bp;
    tsize_t cc;
    long n;
    int b;

    (void) s;
    bp = (char*) tif->tif_rawcp;
    cc = tif->tif_rawcc;
    while (cc > 0 && (long)occ > 0) {
        n = (long) *bp++, cc--;
        /*
         * Watch out for compilers that
         * don't sign extend chars...
         */
        if (n >= 128)
            n -= 256;
        if (n < 0) {        /* replicate next byte -n+1 times */
            if (n == -128)  /* nop */
                continue;
                        n = -n + 1;
                        if( occ < n )
                        {
                            TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
                                        "PackBitsDecode: discarding %ld bytes "
                                        "to avoid buffer overrun",
                                        n - occ);
                            n = occ;
                        }
            occ -= n;
            b = *bp++, cc--;
            while (n-- > 0)
                *op++ = (tidataval_t) b;
        } else {        /* copy next n+1 bytes literally */
            if (occ < n + 1)
                        {
                            TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
                                        "PackBitsDecode: discarding %ld bytes "
                                        "to avoid buffer overrun",
                                        n - occ + 1);
                            n = occ - 1;
                        }
                        _TIFFmemcpy(op, bp, ++n);
            op += n; occ -= n;
            bp += n; cc -= n;
        }
    }
    tif->tif_rawcp = (tidata_t) bp;
    tif->tif_rawcc = cc;
    if (occ > 0) {
        TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
            "PackBitsDecode: Not enough data for scanline %ld",
            (long) tif->tif_row);
        return (0);
    }
    return (1);
}

int
TIFFInitPackBits(TIFF* tif, int scheme)
{
    (void) scheme;
    tif->tif_decoderow = PackBitsDecode;
    tif->tif_decodestrip = PackBitsDecode;
    tif->tif_decodetile = PackBitsDecode;
    tif->tif_preencode = PackBitsPreEncode;
        tif->tif_postencode = PackBitsPostEncode;
    tif->tif_encoderow = PackBitsEncode;
    tif->tif_encodestrip = PackBitsEncodeChunk;
    tif->tif_encodetile = PackBitsEncodeChunk;
    return (1);
}
#endif /* PACKBITS_SUPPORT */

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