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tif_packbits.c

/* $Id: tif_packbits.c,v 1.13 2006/02/07 11:03:29 dron 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 %d 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 %d 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: */

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