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/******************************************************************************
* $Id: gdalchecksum.cpp,v 1.5 2005/04/04 15:24:16 fwarmerdam Exp $
*
* Project: GDAL
* Purpose: Compute simple checksum for a region of image data.
* Author: Frank Warmerdam, warmerdam@pobox.com
*
******************************************************************************
* Copyright (c) 2003, Frank Warmerdam
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
******************************************************************************
*
* $Log: gdalchecksum.cpp,v $
* Revision 1.5 2005/04/04 15:24:16 fwarmerdam
* added CPL_STDCALL to some functions
*
* Revision 1.4 2004/12/30 20:40:54 fwarmerdam
* Added documentation.
*
* Revision 1.3 2003/05/02 16:02:06 dron
* Memory leak fixed.
*
* Revision 1.2 2003/03/13 16:47:20 warmerda
* fixed bug in non-complex case
*
* Revision 1.1 2003/03/02 03:56:21 warmerda
* New
*
*/
#include "gdal_alg.h"
#include "cpl_conv.h"
CPL_CVSID("$Id: gdalchecksum.cpp,v 1.5 2005/04/04 15:24:16 fwarmerdam Exp $");
/************************************************************************/
/* GDALChecksumImage() */
/************************************************************************/
/**
* Compute checksum for image region.
*
* Computes a 16bit (0-65535) checksum from a region of raster data on a GDAL
* supported band. Floating point data is converted to 32bit integer
* so decimal portions of such raster data will not affect the checksum.
* Real and Imaginary components of complex bands influence the result.
*
* @param hBand the raster band to read from.
* @param nXOff pixel offset of window to read.
* @param nYOff line offset of window to read.
* @param nXSize pixel size of window to read.
* @param nYSize line size of window to read.
*
* @return Checksum value.
*/
int CPL_STDCALL
GDALChecksumImage( GDALRasterBandH hBand,
int nXOff, int nYOff, int nXSize, int nYSize )
{
const static int anPrimes[11] =
{ 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43 };
int iLine, i, nChecksum = 0, iPrime = 0, nCount;
int *panLineData;
int bComplex = GDALDataTypeIsComplex( GDALGetRasterDataType( hBand ) );
panLineData = (GInt32 *) CPLMalloc(nXSize * sizeof(GInt32) * 2);
for( iLine = nYOff; iLine < nYOff + nYSize; iLine++ )
{
if( bComplex )
{
GDALRasterIO( hBand, GF_Read, nXOff, iLine, nXSize, 1,
panLineData, nXSize, 1, GDT_CInt32, 0, 0 );
nCount = nXSize * 2;
}
else
{
GDALRasterIO( hBand, GF_Read, nXOff, iLine, nXSize, 1,
panLineData, nXSize, 1, GDT_Int32, 0, 0 );
nCount = nXSize;
}
for( i = 0; i < nCount; i++ )
{
nChecksum += (panLineData[i] % anPrimes[iPrime++]);
if( iPrime > 10 )
iPrime = 0;
nChecksum &= 0xffff;
}
}
CPLFree( panLineData );
return nChecksum;
}
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