[Insight-developers] Optimized floor implementation in itkBilateralImageFilter/itkBSplineInterpolationWeightFunction

[Lydia Ng]

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#include <iostream>
#include <math.h>

int BSplineFloor(double x)
{
#if defined mips || defined sparc || defined __ppc__
  return (int)((unsigned int)(x + 2147483648.0) - 2147483648U);
#elif defined i386 || defined _M_IX86
  unsigned int hilo[2];
  *((double *)hilo) = x + 103079215104.0;  // (2**(52-16))*1.5
  return (int)((hilo[1]<<16)|(hilo[0]>>16));
#else
  return int(floor(x));
#endif
}

int main ( int argc, char * argv[] )
{

  double inputValue = 6.9999985811165137;
  double outputValue1 = floor( inputValue );
  double outputValue2 = BSplineFloor( inputValue );

  std::cout << inputValue << std::endl;
  std::cout << outputValue1 << std::endl;
  std::cout << outputValue2 << std::endl;

  return 0;

}
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PROJECT(Floored)

#-----------------------
# Define executables
#-----------------------
ADD_EXECUTABLE( TestFastFloor TestFastFloor.cxx  )
TARGET_LINK_LIBRARIES( TestFastFloor )