/* $Id: tif_packbits.c,v 1.5 2005/11/19 16:02:59 malaterre 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 = _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 )
                        {
                            TIFFWarning(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)
                        {
                            TIFFWarning(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) {
    TIFFError(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 */

