text: /* $Id: tif_strip.c,v 1.2 2006/02/21 05:55:31 bean Exp $ */
  
  /*
   * Copyright (c) 1991-1997 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.
   *
   * Strip-organized Image Support Routines.
   */
  #include "tiffiop.h"
  
  static uint32
  summarize(TIFF* tif, size_t summand1, size_t summand2, const char* where)
  {
  	/*
  	 * XXX: We are using casting to uint32 here, bacause sizeof(size_t)
  	 * may be larger than sizeof(uint32) on 64-bit architectures.
  	 */
  	uint32	bytes = summand1 + summand2;
  
  	if (bytes - summand1 != summand2) {
  		TIFFErrorExt(tif->tif_clientdata, tif->tif_name, "Integer overflow in %s", where);
  		bytes = 0;
  	}
  
  	return (bytes);
  }
  
  static uint32
  multiply(TIFF* tif, size_t nmemb, size_t elem_size, const char* where)
  {
  	uint32	bytes = nmemb * elem_size;
  
  	if (elem_size && bytes / elem_size != nmemb) {
  		TIFFErrorExt(tif->tif_clientdata, tif->tif_name, "Integer overflow in %s", where);
  		bytes = 0;
  	}
  
  	return (bytes);
  }
  
  /*
   * Compute which strip a (row,sample) value is in.
   */
  tstrip_t
  TIFFComputeStrip(TIFF* tif, uint32 row, tsample_t sample)
  {
  	TIFFDirectory *td = &tif->tif_dir;
  	tstrip_t strip;
  
  	strip = row / td->td_rowsperstrip;
  	if (td->td_planarconfig == PLANARCONFIG_SEPARATE) {
  		if (sample >= td->td_samplesperpixel) {
  			TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
  			    "%lu: Sample out of range, max %lu",
  			    (unsigned long) sample, (unsigned long) td->td_samplesperpixel);
  			return ((tstrip_t) 0);
  		}
  		strip += sample*td->td_stripsperimage;
  	}
  	return (strip);
  }
  
  /*
   * Compute how many strips are in an image.
   */
  tstrip_t
  TIFFNumberOfStrips(TIFF* tif)
  {
  	TIFFDirectory *td = &tif->tif_dir;
  	tstrip_t nstrips;
  
  	nstrips = (td->td_rowsperstrip == (uint32) -1 ? 1 :
  	     TIFFhowmany(td->td_imagelength, td->td_rowsperstrip));
  	if (td->td_planarconfig == PLANARCONFIG_SEPARATE)
  		nstrips = multiply(tif, nstrips, td->td_samplesperpixel,
  				   "TIFFNumberOfStrips");
  	return (nstrips);
  }
  
  /*
   * Compute the # bytes in a variable height, row-aligned strip.
   */
  tsize_t
  TIFFVStripSize(TIFF* tif, uint32 nrows)
  {
  	TIFFDirectory *td = &tif->tif_dir;
  
  	if (nrows == (uint32) -1)
  		nrows = td->td_imagelength;
  	if (td->td_planarconfig == PLANARCONFIG_CONTIG &&
  	    td->td_photometric == PHOTOMETRIC_YCBCR &&
  	    !isUpSampled(tif)) {
  		/*
  		 * Packed YCbCr data contain one Cb+Cr for every
  		 * HorizontalSampling*VerticalSampling Y values.
  		 * Must also roundup width and height when calculating
  		 * since images that are not a multiple of the
  		 * horizontal/vertical subsampling area include
  		 * YCbCr data for the extended image.
  		 */
                  uint16 ycbcrsubsampling[2];
                  tsize_t w, scanline, samplingarea;
  
                  TIFFGetField( tif, TIFFTAG_YCBCRSUBSAMPLING, 
                                ycbcrsubsampling + 0, 
                                ycbcrsubsampling + 1 );
  
  		samplingarea = ycbcrsubsampling[0]*ycbcrsubsampling[1];
  		if (samplingarea == 0) {
  			TIFFErrorExt(tif->tif_clientdata, tif->tif_name, "Invalid YCbCr subsampling");
  			return 0;
  		}
  
  		w = TIFFroundup(td->td_imagewidth, ycbcrsubsampling[0]);
  		scanline = TIFFhowmany8(multiply(tif, w, td->td_bitspersample,
  						 "TIFFVStripSize"));
  		nrows = TIFFroundup(nrows, ycbcrsubsampling[1]);
  		/* NB: don't need TIFFhowmany here 'cuz everything is rounded */
  		scanline = multiply(tif, nrows, scanline, "TIFFVStripSize");
  		return ((tsize_t)
  		    summarize(tif, scanline,
  			      multiply(tif, 2, scanline / samplingarea,
  				       "TIFFVStripSize"), "TIFFVStripSize"));
  	} else
  		return ((tsize_t) multiply(tif, nrows, TIFFScanlineSize(tif),
  					   "TIFFVStripSize"));
  }
  
  
  /*
   * Compute the # bytes in a raw strip.
   */
  tsize_t
  TIFFRawStripSize(TIFF* tif, tstrip_t strip)
  {
  	TIFFDirectory* td = &tif->tif_dir;
  	tsize_t bytecount = td->td_stripbytecount[strip];
  
  	if (bytecount <= 0) {
  		TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
  			  "%lu: Invalid strip byte count, strip %lu",
  			  (unsigned long) bytecount, (unsigned long) strip);
  		bytecount = (tsize_t) -1;
  	}
  
  	return bytecount;
  }
  
  /*
   * Compute the # bytes in a (row-aligned) strip.
   *
   * Note that if RowsPerStrip is larger than the
   * recorded ImageLength, then the strip size is
   * truncated to reflect the actual space required
   * to hold the strip.
   */
  tsize_t
  TIFFStripSize(TIFF* tif)
  {
  	TIFFDirectory* td = &tif->tif_dir;
  	uint32 rps = td->td_rowsperstrip;
  	if (rps > td->td_imagelength)
  		rps = td->td_imagelength;
  	return (TIFFVStripSize(tif, rps));
  }
  
  /*
   * Compute a default strip size based on the image
   * characteristics and a requested value.  If the
   * request is <1 then we choose a strip size according
   * to certain heuristics.
   */
  uint32
  TIFFDefaultStripSize(TIFF* tif, uint32 request)
  {
  	return (*tif->tif_defstripsize)(tif, request);
  }
  
  uint32
  _TIFFDefaultStripSize(TIFF* tif, uint32 s)
  {
  	if ((int32) s < 1) {
  		/*
  		 * If RowsPerStrip is unspecified, try to break the
  		 * image up into strips that are approximately 8Kbytes.
  		 */
  		tsize_t scanline = TIFFScanlineSize(tif);
  		s = (uint32)(8*1024) / (scanline == 0 ? 1 : scanline);
  		if (s == 0)		/* very wide images */
  			s = 1;
  	}
  	return (s);
  }
  
  /*
   * Return the number of bytes to read/write in a call to
   * one of the scanline-oriented i/o routines.  Note that
   * this number may be 1/samples-per-pixel if data is
   * stored as separate planes.
   */
  tsize_t
  TIFFScanlineSize(TIFF* tif)
  {
  	TIFFDirectory *td = &tif->tif_dir;
  	tsize_t scanline;
  	
  	scanline = multiply (tif, td->td_bitspersample, td->td_imagewidth,
  			     "TIFFScanlineSize");
  	if (td->td_planarconfig == PLANARCONFIG_CONTIG)
  		scanline = multiply (tif, scanline, td->td_samplesperpixel,
  				     "TIFFScanlineSize");
  	return ((tsize_t) TIFFhowmany8(scanline));
  }
  
  /*
   * Return the number of bytes required to store a complete
   * decoded and packed raster scanline (as opposed to the
   * I/O size returned by TIFFScanlineSize which may be less
   * if data is store as separate planes).
   */
  tsize_t
  TIFFRasterScanlineSize(TIFF* tif)
  {
  	TIFFDirectory *td = &tif->tif_dir;
  	tsize_t scanline;
  	
  	scanline = multiply (tif, td->td_bitspersample, td->td_imagewidth,
  			     "TIFFRasterScanlineSize");
  	if (td->td_planarconfig == PLANARCONFIG_CONTIG) {
  		scanline = multiply (tif, scanline, td->td_samplesperpixel,
  				     "TIFFRasterScanlineSize");
  		return ((tsize_t) TIFFhowmany8(scanline));
  	} else
  		return ((tsize_t) multiply (tif, TIFFhowmany8(scanline),
  					    td->td_samplesperpixel,
  					    "TIFFRasterScanlineSize"));
  }
  
  /* vim: set ts=8 sts=8 sw=8 noet: */
  