text: /*
   * 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.
   */
  
  /*
   * TIFF Library.
   *
   * Predictor Tag Support (used by multiple codecs).
   */
  #include "tiffiop.h"
  #include "tif_predict.h"
  
  #define	PredictorState(tif)	((TIFFPredictorState*) (tif)->tif_data)
  
  static int horAcc8(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int horAcc16(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int horAcc32(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int swabHorAcc16(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int swabHorAcc32(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int horDiff8(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int horDiff16(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int horDiff32(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int swabHorDiff16(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int swabHorDiff32(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int fpAcc(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int fpDiff(TIFF* tif, uint8* cp0, tmsize_t cc);
  static int PredictorDecodeRow(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s);
  static int PredictorDecodeTile(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s);
  static int PredictorEncodeRow(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s);
  static int PredictorEncodeTile(TIFF* tif, uint8* bp0, tmsize_t cc0, uint16 s);
  
  static int
  PredictorSetup(TIFF* tif)
  {
  	static const char module[] = "PredictorSetup";
  
  	TIFFPredictorState* sp = PredictorState(tif);
  	TIFFDirectory* td = &tif->tif_dir;
  
  	switch (sp->predictor)		/* no differencing */
  	{
  		case PREDICTOR_NONE:
  			return 1;
  		case PREDICTOR_HORIZONTAL:
  			if (td->td_bitspersample != 8
  			    && td->td_bitspersample != 16
  			    && td->td_bitspersample != 32) {
  				TIFFErrorExt(tif->tif_clientdata, module,
  				    "Horizontal differencing \"Predictor\" not supported with %d-bit samples",
  				    td->td_bitspersample);
  				return 0;
  			}
  			break;
  		case PREDICTOR_FLOATINGPOINT:
  			if (td->td_sampleformat != SAMPLEFORMAT_IEEEFP) {
  				TIFFErrorExt(tif->tif_clientdata, module,
  				    "Floating point \"Predictor\" not supported with %d data format",
  				    td->td_sampleformat);
  				return 0;
  			}
                          if (td->td_bitspersample != 16
                              && td->td_bitspersample != 24
                              && td->td_bitspersample != 32
                              && td->td_bitspersample != 64) { /* Should 64 be allowed? */
                                  TIFFErrorExt(tif->tif_clientdata, module,
                                               "Floating point \"Predictor\" not supported with %d-bit samples",
                                               td->td_bitspersample);
  				return 0;
                              }
  			break;
  		default:
  			TIFFErrorExt(tif->tif_clientdata, module,
  			    "\"Predictor\" value %d not supported",
  			    sp->predictor);
  			return 0;
  	}
  	sp->stride = (td->td_planarconfig == PLANARCONFIG_CONTIG ?
  	    td->td_samplesperpixel : 1);
  	/*
  	 * Calculate the scanline/tile-width size in bytes.
  	 */
  	if (isTiled(tif))
  		sp->rowsize = TIFFTileRowSize(tif);
  	else
  		sp->rowsize = TIFFScanlineSize(tif);
  	if (sp->rowsize == 0)
  		return 0;
  
  	return 1;
  }
  
  static int
  PredictorSetupDecode(TIFF* tif)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  	TIFFDirectory* td = &tif->tif_dir;
  
  	/* Note: when PredictorSetup() fails, the effets of setupdecode() */
  	/* will not be "cancelled" so setupdecode() might be robust to */
  	/* be called several times. */
  	if (!(*sp->setupdecode)(tif) || !PredictorSetup(tif))
  		return 0;
  
  	if (sp->predictor == 2) {
  		switch (td->td_bitspersample) {
  			case 8:  sp->decodepfunc = horAcc8; break;
  			case 16: sp->decodepfunc = horAcc16; break;
  			case 32: sp->decodepfunc = horAcc32; break;
  		}
  		/*
  		 * Override default decoding method with one that does the
  		 * predictor stuff.
  		 */
                  if( tif->tif_decoderow != PredictorDecodeRow )
                  {
                      sp->decoderow = tif->tif_decoderow;
                      tif->tif_decoderow = PredictorDecodeRow;
                      sp->decodestrip = tif->tif_decodestrip;
                      tif->tif_decodestrip = PredictorDecodeTile;
                      sp->decodetile = tif->tif_decodetile;
                      tif->tif_decodetile = PredictorDecodeTile;
                  }
  
  		/*
  		 * If the data is horizontally differenced 16-bit data that
  		 * requires byte-swapping, then it must be byte swapped before
  		 * the accumulation step.  We do this with a special-purpose
  		 * routine and override the normal post decoding logic that
  		 * the library setup when the directory was read.
  		 */
  		if (tif->tif_flags & TIFF_SWAB) {
  			if (sp->decodepfunc == horAcc16) {
  				sp->decodepfunc = swabHorAcc16;
  				tif->tif_postdecode = _TIFFNoPostDecode;
              } else if (sp->decodepfunc == horAcc32) {
  				sp->decodepfunc = swabHorAcc32;
  				tif->tif_postdecode = _TIFFNoPostDecode;
              }
  		}
  	}
  
  	else if (sp->predictor == 3) {
  		sp->decodepfunc = fpAcc;
  		/*
  		 * Override default decoding method with one that does the
  		 * predictor stuff.
  		 */
                  if( tif->tif_decoderow != PredictorDecodeRow )
                  {
                      sp->decoderow = tif->tif_decoderow;
                      tif->tif_decoderow = PredictorDecodeRow;
                      sp->decodestrip = tif->tif_decodestrip;
                      tif->tif_decodestrip = PredictorDecodeTile;
                      sp->decodetile = tif->tif_decodetile;
                      tif->tif_decodetile = PredictorDecodeTile;
                  }
  		/*
  		 * The data should not be swapped outside of the floating
  		 * point predictor, the accumulation routine should return
  		 * byres in the native order.
  		 */
  		if (tif->tif_flags & TIFF_SWAB) {
  			tif->tif_postdecode = _TIFFNoPostDecode;
  		}
  		/*
  		 * Allocate buffer to keep the decoded bytes before
  		 * rearranging in the right order
  		 */
  	}
  
  	return 1;
  }
  
  static int
  PredictorSetupEncode(TIFF* tif)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  	TIFFDirectory* td = &tif->tif_dir;
  
  	if (!(*sp->setupencode)(tif) || !PredictorSetup(tif))
  		return 0;
  
  	if (sp->predictor == 2) {
  		switch (td->td_bitspersample) {
  			case 8:  sp->encodepfunc = horDiff8; break;
  			case 16: sp->encodepfunc = horDiff16; break;
  			case 32: sp->encodepfunc = horDiff32; break;
  		}
  		/*
  		 * Override default encoding method with one that does the
  		 * predictor stuff.
  		 */
                  if( tif->tif_encoderow != PredictorEncodeRow )
                  {
                      sp->encoderow = tif->tif_encoderow;
                      tif->tif_encoderow = PredictorEncodeRow;
                      sp->encodestrip = tif->tif_encodestrip;
                      tif->tif_encodestrip = PredictorEncodeTile;
                      sp->encodetile = tif->tif_encodetile;
                      tif->tif_encodetile = PredictorEncodeTile;
                  }
  
                  /*
                   * If the data is horizontally differenced 16-bit data that
                   * requires byte-swapping, then it must be byte swapped after
                   * the differentiation step.  We do this with a special-purpose
                   * routine and override the normal post decoding logic that
                   * the library setup when the directory was read.
                   */
                  if (tif->tif_flags & TIFF_SWAB) {
                      if (sp->encodepfunc == horDiff16) {
                              sp->encodepfunc = swabHorDiff16;
                              tif->tif_postdecode = _TIFFNoPostDecode;
                      } else if (sp->encodepfunc == horDiff32) {
                              sp->encodepfunc = swabHorDiff32;
                              tif->tif_postdecode = _TIFFNoPostDecode;
                      }
                  }
          }
  
  	else if (sp->predictor == 3) {
  		sp->encodepfunc = fpDiff;
  		/*
  		 * Override default encoding method with one that does the
  		 * predictor stuff.
  		 */
                  if( tif->tif_encoderow != PredictorEncodeRow )
                  {
                      sp->encoderow = tif->tif_encoderow;
                      tif->tif_encoderow = PredictorEncodeRow;
                      sp->encodestrip = tif->tif_encodestrip;
                      tif->tif_encodestrip = PredictorEncodeTile;
                      sp->encodetile = tif->tif_encodetile;
                      tif->tif_encodetile = PredictorEncodeTile;
                  }
  	}
  
  	return 1;
  }
  
  #define REPEAT4(n, op)		\
      switch (n) {		\
      default: { \
          tmsize_t i; for (i = n-4; i > 0; i--) { op; } }  /*-fallthrough*/  \
      case 4:  op; /*-fallthrough*/ \
      case 3:  op; /*-fallthrough*/ \
      case 2:  op; /*-fallthrough*/ \
      case 1:  op; /*-fallthrough*/ \
      case 0:  ;			\
      }
  
  /* Remarks related to C standard compliance in all below functions : */
  /* - to avoid any undefined behaviour, we only operate on unsigned types */
  /*   since the behaviour of "overflows" is defined (wrap over) */
  /* - when storing into the byte stream, we explicitly mask with 0xff so */
  /*   as to make icc -check=conversions happy (not necessary by the standard) */
  
  TIFF_NOSANITIZE_UNSIGNED_INT_OVERFLOW
  static int
  horAcc8(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	tmsize_t stride = PredictorState(tif)->stride;
  
  	unsigned char* cp = (unsigned char*) cp0;
      if((cc%stride)!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "horAcc8",
                       "%s", "(cc%stride)!=0");
          return 0;
      }
  
  	if (cc > stride) {
  		/*
  		 * Pipeline the most common cases.
  		 */
  		if (stride == 3)  {
  			unsigned int cr = cp[0];
  			unsigned int cg = cp[1];
  			unsigned int cb = cp[2];
  			cc -= 3;
  			cp += 3;
  			while (cc>0) {
  				cp[0] = (unsigned char) ((cr += cp[0]) & 0xff);
  				cp[1] = (unsigned char) ((cg += cp[1]) & 0xff);
  				cp[2] = (unsigned char) ((cb += cp[2]) & 0xff);
  				cc -= 3;
  				cp += 3;
  			}
  		} else if (stride == 4)  {
  			unsigned int cr = cp[0];
  			unsigned int cg = cp[1];
  			unsigned int cb = cp[2];
  			unsigned int ca = cp[3];
  			cc -= 4;
  			cp += 4;
  			while (cc>0) {
  				cp[0] = (unsigned char) ((cr += cp[0]) & 0xff);
  				cp[1] = (unsigned char) ((cg += cp[1]) & 0xff);
  				cp[2] = (unsigned char) ((cb += cp[2]) & 0xff);
  				cp[3] = (unsigned char) ((ca += cp[3]) & 0xff);
  				cc -= 4;
  				cp += 4;
  			}
  		} else  {
  			cc -= stride;
  			do {
  				REPEAT4(stride, cp[stride] =
  					(unsigned char) ((cp[stride] + *cp) & 0xff); cp++)
  				cc -= stride;
  			} while (cc>0);
  		}
  	}
  	return 1;
  }
  
  static int
  swabHorAcc16(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	uint16* wp = (uint16*) cp0;
  	tmsize_t wc = cc / 2;
  
          TIFFSwabArrayOfShort(wp, wc);
          return horAcc16(tif, cp0, cc);
  }
  
  TIFF_NOSANITIZE_UNSIGNED_INT_OVERFLOW
  static int
  horAcc16(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	tmsize_t stride = PredictorState(tif)->stride;
  	uint16* wp = (uint16*) cp0;
  	tmsize_t wc = cc / 2;
  
      if((cc%(2*stride))!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "horAcc16",
                       "%s", "cc%(2*stride))!=0");
          return 0;
      }
  
  	if (wc > stride) {
  		wc -= stride;
  		do {
  			REPEAT4(stride, wp[stride] = (uint16)(((unsigned int)wp[stride] + (unsigned int)wp[0]) & 0xffff); wp++)
  			wc -= stride;
  		} while (wc > 0);
  	}
  	return 1;
  }
  
  static int
  swabHorAcc32(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	uint32* wp = (uint32*) cp0;
  	tmsize_t wc = cc / 4;
  
          TIFFSwabArrayOfLong(wp, wc);
  	return horAcc32(tif, cp0, cc);
  }
  
  TIFF_NOSANITIZE_UNSIGNED_INT_OVERFLOW
  static int
  horAcc32(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	tmsize_t stride = PredictorState(tif)->stride;
  	uint32* wp = (uint32*) cp0;
  	tmsize_t wc = cc / 4;
  
      if((cc%(4*stride))!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "horAcc32",
                       "%s", "cc%(4*stride))!=0");
          return 0;
      }
  
  	if (wc > stride) {
  		wc -= stride;
  		do {
  			REPEAT4(stride, wp[stride] += wp[0]; wp++)
  			wc -= stride;
  		} while (wc > 0);
  	}
  	return 1;
  }
  
  /*
   * Floating point predictor accumulation routine.
   */
  static int
  fpAcc(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	tmsize_t stride = PredictorState(tif)->stride;
  	uint32 bps = tif->tif_dir.td_bitspersample / 8;
  	tmsize_t wc = cc / bps;
  	tmsize_t count = cc;
  	uint8 *cp = (uint8 *) cp0;
  	uint8 *tmp;
  
      if(cc%(bps*stride)!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "fpAcc",
                       "%s", "cc%(bps*stride))!=0");
          return 0;
      }
  
      tmp = (uint8 *)_TIFFmalloc(cc);
  	if (!tmp)
  		return 0;
  
  	while (count > stride) {
  		REPEAT4(stride, cp[stride] =
                          (unsigned char) ((cp[stride] + cp[0]) & 0xff); cp++)
  		count -= stride;
  	}
  
  	_TIFFmemcpy(tmp, cp0, cc);
  	cp = (uint8 *) cp0;
  	for (count = 0; count < wc; count++) {
  		uint32 byte;
  		for (byte = 0; byte < bps; byte++) {
  			#if WORDS_BIGENDIAN
  			cp[bps * count + byte] = tmp[byte * wc + count];
  			#else
  			cp[bps * count + byte] =
  				tmp[(bps - byte - 1) * wc + count];
  			#endif
  		}
  	}
  	_TIFFfree(tmp);
      return 1;
  }
  
  /*
   * Decode a scanline and apply the predictor routine.
   */
  static int
  PredictorDecodeRow(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s)
  {
  	TIFFPredictorState *sp = PredictorState(tif);
  
  	assert(sp != NULL);
  	assert(sp->decoderow != NULL);
  	assert(sp->decodepfunc != NULL);  
  
  	if ((*sp->decoderow)(tif, op0, occ0, s)) {
  		return (*sp->decodepfunc)(tif, op0, occ0);
  	} else
  		return 0;
  }
  
  /*
   * Decode a tile/strip and apply the predictor routine.
   * Note that horizontal differencing must be done on a
   * row-by-row basis.  The width of a "row" has already
   * been calculated at pre-decode time according to the
   * strip/tile dimensions.
   */
  static int
  PredictorDecodeTile(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s)
  {
  	TIFFPredictorState *sp = PredictorState(tif);
  
  	assert(sp != NULL);
  	assert(sp->decodetile != NULL);
  
  	if ((*sp->decodetile)(tif, op0, occ0, s)) {
  		tmsize_t rowsize = sp->rowsize;
  		assert(rowsize > 0);
  		if((occ0%rowsize) !=0)
          {
              TIFFErrorExt(tif->tif_clientdata, "PredictorDecodeTile",
                           "%s", "occ0%rowsize != 0");
              return 0;
          }
  		assert(sp->decodepfunc != NULL);
  		while (occ0 > 0) {
  			if( !(*sp->decodepfunc)(tif, op0, rowsize) )
                  return 0;
  			occ0 -= rowsize;
  			op0 += rowsize;
  		}
  		return 1;
  	} else
  		return 0;
  }
  
  TIFF_NOSANITIZE_UNSIGNED_INT_OVERFLOW
  static int
  horDiff8(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  	tmsize_t stride = sp->stride;
  	unsigned char* cp = (unsigned char*) cp0;
  
      if((cc%stride)!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "horDiff8",
                       "%s", "(cc%stride)!=0");
          return 0;
      }
  
  	if (cc > stride) {
  		cc -= stride;
  		/*
  		 * Pipeline the most common cases.
  		 */
  		if (stride == 3) {
  			unsigned int r1, g1, b1;
  			unsigned int r2 = cp[0];
  			unsigned int g2 = cp[1];
  			unsigned  int b2 = cp[2];
  			do {
  				r1 = cp[3]; cp[3] = (unsigned char)((r1-r2)&0xff); r2 = r1;
  				g1 = cp[4]; cp[4] = (unsigned char)((g1-g2)&0xff); g2 = g1;
  				b1 = cp[5]; cp[5] = (unsigned char)((b1-b2)&0xff); b2 = b1;
  				cp += 3;
  			} while ((cc -= 3) > 0);
  		} else if (stride == 4) {
  			unsigned int r1, g1, b1, a1;
  			unsigned int r2 = cp[0];
  			unsigned int g2 = cp[1];
  			unsigned int b2 = cp[2];
  			unsigned int a2 = cp[3];
  			do {
  				r1 = cp[4]; cp[4] = (unsigned char)((r1-r2)&0xff); r2 = r1;
  				g1 = cp[5]; cp[5] = (unsigned char)((g1-g2)&0xff); g2 = g1;
  				b1 = cp[6]; cp[6] = (unsigned char)((b1-b2)&0xff); b2 = b1;
  				a1 = cp[7]; cp[7] = (unsigned char)((a1-a2)&0xff); a2 = a1;
  				cp += 4;
  			} while ((cc -= 4) > 0);
  		} else {
  			cp += cc - 1;
  			do {
  				REPEAT4(stride, cp[stride] = (unsigned char)((cp[stride] - cp[0])&0xff); cp--)
  			} while ((cc -= stride) > 0);
  		}
  	}
  	return 1;
  }
  
  TIFF_NOSANITIZE_UNSIGNED_INT_OVERFLOW
  static int
  horDiff16(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  	tmsize_t stride = sp->stride;
  	uint16 *wp = (uint16*) cp0;
  	tmsize_t wc = cc/2;
  
      if((cc%(2*stride))!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "horDiff8",
                       "%s", "(cc%(2*stride))!=0");
          return 0;
      }
  
  	if (wc > stride) {
  		wc -= stride;
  		wp += wc - 1;
  		do {
  			REPEAT4(stride, wp[stride] = (uint16)(((unsigned int)wp[stride] - (unsigned int)wp[0]) & 0xffff); wp--)
  			wc -= stride;
  		} while (wc > 0);
  	}
  	return 1;
  }
  
  static int
  swabHorDiff16(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
      uint16* wp = (uint16*) cp0;
      tmsize_t wc = cc / 2;
  
      if( !horDiff16(tif, cp0, cc) )
          return 0;
  
      TIFFSwabArrayOfShort(wp, wc);
      return 1;
  }
  
  TIFF_NOSANITIZE_UNSIGNED_INT_OVERFLOW
  static int
  horDiff32(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  	tmsize_t stride = sp->stride;
  	uint32 *wp = (uint32*) cp0;
  	tmsize_t wc = cc/4;
  
      if((cc%(4*stride))!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "horDiff32",
                       "%s", "(cc%(4*stride))!=0");
          return 0;
      }
  
  	if (wc > stride) {
  		wc -= stride;
  		wp += wc - 1;
  		do {
  			REPEAT4(stride, wp[stride] -= wp[0]; wp--)
  			wc -= stride;
  		} while (wc > 0);
  	}
  	return 1;
  }
  
  static int
  swabHorDiff32(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
      uint32* wp = (uint32*) cp0;
      tmsize_t wc = cc / 4;
  
      if( !horDiff32(tif, cp0, cc) )
          return 0;
  
      TIFFSwabArrayOfLong(wp, wc);
      return 1;
  }
  
  /*
   * Floating point predictor differencing routine.
   */
  TIFF_NOSANITIZE_UNSIGNED_INT_OVERFLOW
  static int
  fpDiff(TIFF* tif, uint8* cp0, tmsize_t cc)
  {
  	tmsize_t stride = PredictorState(tif)->stride;
  	uint32 bps = tif->tif_dir.td_bitspersample / 8;
  	tmsize_t wc = cc / bps;
  	tmsize_t count;
  	uint8 *cp = (uint8 *) cp0;
  	uint8 *tmp;
  
      if((cc%(bps*stride))!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "fpDiff",
                       "%s", "(cc%(bps*stride))!=0");
          return 0;
      }
  
      tmp = (uint8 *)_TIFFmalloc(cc);
  	if (!tmp)
  		return 0;
  
  	_TIFFmemcpy(tmp, cp0, cc);
  	for (count = 0; count < wc; count++) {
  		uint32 byte;
  		for (byte = 0; byte < bps; byte++) {
  			#if WORDS_BIGENDIAN
  			cp[byte * wc + count] = tmp[bps * count + byte];
  			#else
  			cp[(bps - byte - 1) * wc + count] =
  				tmp[bps * count + byte];
  			#endif
  		}
  	}
  	_TIFFfree(tmp);
  
  	cp = (uint8 *) cp0;
  	cp += cc - stride - 1;
  	for (count = cc; count > stride; count -= stride)
  		REPEAT4(stride, cp[stride] = (unsigned char)((cp[stride] - cp[0])&0xff); cp--)
      return 1;
  }
  
  static int
  PredictorEncodeRow(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
  {
  	TIFFPredictorState *sp = PredictorState(tif);
  
  	assert(sp != NULL);
  	assert(sp->encodepfunc != NULL);
  	assert(sp->encoderow != NULL);
  
  	/* XXX horizontal differencing alters user's data XXX */
  	if( !(*sp->encodepfunc)(tif, bp, cc) )
          return 0;
  	return (*sp->encoderow)(tif, bp, cc, s);
  }
  
  static int
  PredictorEncodeTile(TIFF* tif, uint8* bp0, tmsize_t cc0, uint16 s)
  {
  	static const char module[] = "PredictorEncodeTile";
  	TIFFPredictorState *sp = PredictorState(tif);
          uint8 *working_copy;
  	tmsize_t cc = cc0, rowsize;
  	unsigned char* bp;
          int result_code;
  
  	assert(sp != NULL);
  	assert(sp->encodepfunc != NULL);
  	assert(sp->encodetile != NULL);
  
          /* 
           * Do predictor manipulation in a working buffer to avoid altering
           * the callers buffer. http://trac.osgeo.org/gdal/ticket/1965
           */
          working_copy = (uint8*) _TIFFmalloc(cc0);
          if( working_copy == NULL )
          {
              TIFFErrorExt(tif->tif_clientdata, module, 
                           "Out of memory allocating " TIFF_SSIZE_FORMAT " byte temp buffer.",
                           cc0 );
              return 0;
          }
          memcpy( working_copy, bp0, cc0 );
          bp = working_copy;
  
  	rowsize = sp->rowsize;
  	assert(rowsize > 0);
  	if((cc0%rowsize)!=0)
      {
          TIFFErrorExt(tif->tif_clientdata, "PredictorEncodeTile",
                       "%s", "(cc0%rowsize)!=0");
          _TIFFfree( working_copy );
          return 0;
      }
  	while (cc > 0) {
  		(*sp->encodepfunc)(tif, bp, rowsize);
  		cc -= rowsize;
  		bp += rowsize;
  	}
  	result_code = (*sp->encodetile)(tif, working_copy, cc0, s);
  
          _TIFFfree( working_copy );
  
          return result_code;
  }
  
  #define	FIELD_PREDICTOR	(FIELD_CODEC+0)		/* XXX */
  
  static const TIFFField predictFields[] = {
      { TIFFTAG_PREDICTOR, 1, 1, TIFF_SHORT, 0, TIFF_SETGET_UINT16, TIFF_SETGET_UINT16, FIELD_PREDICTOR, FALSE, FALSE, "Predictor", NULL },
  };
  
  static int
  PredictorVSetField(TIFF* tif, uint32 tag, va_list ap)
  {
  	TIFFPredictorState *sp = PredictorState(tif);
  
  	assert(sp != NULL);
  	assert(sp->vsetparent != NULL);
  
  	switch (tag) {
  	case TIFFTAG_PREDICTOR:
  		sp->predictor = (uint16) va_arg(ap, uint16_vap);
  		TIFFSetFieldBit(tif, FIELD_PREDICTOR);
  		break;
  	default:
  		return (*sp->vsetparent)(tif, tag, ap);
  	}
  	tif->tif_flags |= TIFF_DIRTYDIRECT;
  	return 1;
  }
  
  static int
  PredictorVGetField(TIFF* tif, uint32 tag, va_list ap)
  {
  	TIFFPredictorState *sp = PredictorState(tif);
  
  	assert(sp != NULL);
  	assert(sp->vgetparent != NULL);
  
  	switch (tag) {
  	case TIFFTAG_PREDICTOR:
  		*va_arg(ap, uint16*) = (uint16)sp->predictor;
  		break;
  	default:
  		return (*sp->vgetparent)(tif, tag, ap);
  	}
  	return 1;
  }
  
  static void
  PredictorPrintDir(TIFF* tif, FILE* fd, long flags)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  
  	(void) flags;
  	if (TIFFFieldSet(tif,FIELD_PREDICTOR)) {
  		fprintf(fd, "  Predictor: ");
  		switch (sp->predictor) {
  			case 1: fprintf(fd, "none "); break;
  			case 2: fprintf(fd, "horizontal differencing "); break;
  			case 3: fprintf(fd, "floating point predictor "); break;
  		}
  		fprintf(fd, "%d (0x%x)\n", sp->predictor, sp->predictor);
  	}
  	if (sp->printdir)
  		(*sp->printdir)(tif, fd, flags);
  }
  
  int
  TIFFPredictorInit(TIFF* tif)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  
  	assert(sp != 0);
  
  	/*
  	 * Merge codec-specific tag information.
  	 */
  	if (!_TIFFMergeFields(tif, predictFields,
  			      TIFFArrayCount(predictFields))) {
  		TIFFErrorExt(tif->tif_clientdata, "TIFFPredictorInit",
  		    "Merging Predictor codec-specific tags failed");
  		return 0;
  	}
  
  	/*
  	 * Override parent get/set field methods.
  	 */
  	sp->vgetparent = tif->tif_tagmethods.vgetfield;
  	tif->tif_tagmethods.vgetfield =
              PredictorVGetField;/* hook for predictor tag */
  	sp->vsetparent = tif->tif_tagmethods.vsetfield;
  	tif->tif_tagmethods.vsetfield =
  	    PredictorVSetField;/* hook for predictor tag */
  	sp->printdir = tif->tif_tagmethods.printdir;
  	tif->tif_tagmethods.printdir =
              PredictorPrintDir;	/* hook for predictor tag */
  
  	sp->setupdecode = tif->tif_setupdecode;
  	tif->tif_setupdecode = PredictorSetupDecode;
  	sp->setupencode = tif->tif_setupencode;
  	tif->tif_setupencode = PredictorSetupEncode;
  
  	sp->predictor = 1;			/* default value */
  	sp->encodepfunc = NULL;			/* no predictor routine */
  	sp->decodepfunc = NULL;			/* no predictor routine */
  	return 1;
  }
  
  int
  TIFFPredictorCleanup(TIFF* tif)
  {
  	TIFFPredictorState* sp = PredictorState(tif);
  
  	assert(sp != 0);
  
  	tif->tif_tagmethods.vgetfield = sp->vgetparent;
  	tif->tif_tagmethods.vsetfield = sp->vsetparent;
  	tif->tif_tagmethods.printdir = sp->printdir;
  	tif->tif_setupdecode = sp->setupdecode;
  	tif->tif_setupencode = sp->setupencode;
  
  	return 1;
  }
  
  /* vim: set ts=8 sts=8 sw=8 noet: */
  /*
   * Local Variables:
   * mode: c
   * c-basic-offset: 8
   * fill-column: 78
   * End:
   */
  