source: sasmodels/sasmodels/kernel_header.c @ 1557a1e

#ifdef __OPENCL_VERSION__
# define USE_OPENCL
#elif defined(_OPENMP)
# define USE_OPENMP
#endif

// If opencl is not available, then we are compiling a C function
// Note: if using a C++ compiler, then define kernel as extern "C"
#ifdef USE_OPENCL
   typedef int int32_t;
#  if defined(USE_SINCOS)
#    define SINCOS(angle,svar,cvar) svar=sincos(angle,&cvar)
#  else
#    define SINCOS(angle,svar,cvar) do {const double _t_=angle; svar=sin(_t_);cvar=cos(_t_);} while (0)
#  endif
   // OpenCL only has type generic math
   #define erff erf
   #define erfcf erfc
#else // !USE_OPENCL
// Use SAS_DOUBLE to force the use of double even for float kernels
#  define SAS_DOUBLE dou ## ble
#  ifdef __cplusplus
      #include <cstdio>
      #include <cmath>
      using namespace std;
      #if defined(_MSC_VER)
         #include <limits>
         #include <float.h>
         #define kernel extern "C" __declspec( dllexport )
         inline double trunc(double x) { return x>=0?floor(x):-floor(-x); }
         inline double fmin(double x, double y) { return x>y ? y : x; }
         inline double fmax(double x, double y) { return x<y ? y : x; }
         #define isnan(x) _isnan(x)
         #define isinf(x) (!_finite(x))
         #define isfinite(x) _finite(x)
         #define NAN (std::numeric_limits<double>::quiet_NaN()) // non-signalling NaN
         #define INFINITY (std::numeric_limits<double>::infinity())
         #define NEED_ERF
         #define NEED_EXPM1
         #define NEED_TGAMMA
     #else
         #define kernel extern "C"
         #include <cstdint>
     #endif
     inline void SINCOS(double angle, double &svar, double &cvar) { svar=sin(angle); cvar=cos(angle); }
#  else // !__cplusplus
     #include <inttypes.h>  // C99 guarantees that int32_t types is here
     #include <stdio.h>
     #if defined(__TINYC__)
         typedef int int32_t;
         #include <math.h>
         // TODO: test isnan
         inline double _isnan(double x) { return x != x; } // hope this doesn't optimize away!
         #undef isnan
         #define isnan(x) _isnan(x)
         // Defeat the double->float conversion since we don't have tgmath
         inline SAS_DOUBLE trunc(SAS_DOUBLE x) { return x>=0?floor(x):-floor(-x); }
         inline SAS_DOUBLE fmin(SAS_DOUBLE x, SAS_DOUBLE y) { return x>y ? y : x; }
         inline SAS_DOUBLE fmax(SAS_DOUBLE x, SAS_DOUBLE y) { return x<y ? y : x; }
         #define NEED_ERF
         #define NEED_EXPM1
         #define NEED_TGAMMA
     #else
         #include <tgmath.h> // C99 type-generic math, so sin(float) => sinf
     #endif
     // MSVC doesn't support C99, so no need for dllexport on C99 branch
     #define kernel
     #define SINCOS(angle,svar,cvar) do {const double _t_=angle; svar=sin(_t_);cvar=cos(_t_);} while (0)
#  endif  // !__cplusplus
#  define global
#  define local
#  define constant const
// OpenCL powr(a,b) = C99 pow(a,b), b >= 0
// OpenCL pown(a,b) = C99 pow(a,b), b integer
#  define powr(a,b) pow(a,b)
#  define pown(a,b) pow(a,b)
#endif // !USE_OPENCL

#if defined(NEED_EXPM1)
   static SAS_DOUBLE expm1(SAS_DOUBLE x_in) {
      double x = (double)x_in;  // go back to float for single precision kernels
      // Adapted from the cephes math library.
      // Copyright 1984 - 1992 by Stephen L. Moshier
      if (x != x || x == 0.0) {
         return x; // NaN and +/- 0
      } else if (x < -0.5 || x > 0.5) {
         return exp(x) - 1.0;
      } else {
         const double xsq = x*x;
         const double p = (((
            +1.2617719307481059087798E-4)*xsq
            +3.0299440770744196129956E-2)*xsq
            +9.9999999999999999991025E-1);
         const double q = ((((
            +3.0019850513866445504159E-6)*xsq
            +2.5244834034968410419224E-3)*xsq
            +2.2726554820815502876593E-1)*xsq
            +2.0000000000000000000897E0);
         double r = x * p;
         r =  r / (q - r);
         return r+r;
       }
   }
#endif

// Standard mathematical constants:
//   M_E, M_LOG2E, M_LOG10E, M_LN2, M_LN10, M_PI, M_PI_2=pi/2, M_PI_4=pi/4,
//   M_1_PI=1/pi, M_2_PI=2/pi, M_2_SQRTPI=2/sqrt(pi), SQRT2, SQRT1_2=sqrt(1/2)
// OpenCL defines M_constant_F for float constants, and nothing if double
// is not enabled on the card, which is why these constants may be missing
#ifndef M_PI
#  define M_PI 3.141592653589793
#endif
#ifndef M_PI_2
#  define M_PI_2 1.570796326794897
#endif
#ifndef M_PI_4
#  define M_PI_4 0.7853981633974483
#endif
#ifndef M_E
#  define M_E 2.718281828459045091
#endif

// Non-standard function library
// pi/180, used for converting between degrees and radians
// 4/3 pi for computing sphere volumes
// square and cube for computing squares and cubes
#ifndef M_PI_180
#  define M_PI_180 0.017453292519943295
#endif
#ifndef M_4PI_3
#  define M_4PI_3 4.18879020478639
#endif
inline double square(double x) { return x*x; }
inline double cube(double x) { return x*x*x; }
inline double sinc(double x) { return x==0 ? 1.0 : sin(x)/x; }