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

// Use SAS_DOUBLE to force the use of double even for float kernels
#define SAS_DOUBLE dou ## ble

// 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

   #define USE_GPU
   #define pglobal global
   #define pconstant constant

   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
   // Intel CPU on Mac gives strange values for erf(); on the verified
   // platforms (intel, nvidia, amd), the cephes erf() is significantly
   // faster than that available in the native OpenCL.
   #define NEED_ERF
   // OpenCL only has type generic math
   #define expf exp
   #ifndef NEED_ERF
   #  define erff erf
   #  define erfcf erfc
   #endif

#elif defined(USE_CUDA)

   #define USE_GPU
   #define local __shared__
   #define pglobal
   #define constant __constant__
   #define pconstant const
   #define kernel extern "C" __global__

   // 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)
   //typedef int int32_t;
   #if defined(USE_SINCOS)
   #  define SINCOS(angle,svar,cvar) sincos(angle,&svar,&cvar)
   #else
   #  define SINCOS(angle,svar,cvar) do {const double _t_=angle; svar=sin(_t_);cvar=cos(_t_);} while (0)
   #endif

#else // !USE_OPENCL && !USE_CUDA

   #define local
   #define pglobal
   #define constant const
   #define pconstant const

   #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: check isnan is correct
         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
         #define NEED_CBRT
         // expf missing from windows?
         #define expf exp
     #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
   // 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_CBRT)
   #define cbrt(_x) pow(_x, 0.33333333333333333333333)
#endif

#if defined(NEED_EXPM1)
   // TODO: precision is a half digit lower than numpy on mac in [1e-7, 0.5]
   // Run "explore/precision.py sas_expm1" to see this (may have to fiddle
   // the xrange for log to see the complete range).
   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
#ifndef M_SQRT1_2
#  define M_SQRT1_2 0.70710678118654746
#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 sas_sinx_x(double x) { return x==0 ? 1.0 : sin(x)/x; }

// CRUFT: support old style models with orientation received qx, qy and angles

// To rotate from the canonical position to theta, phi, psi, first rotate by
// psi about the major axis, oriented along z, which is a rotation in the
// detector plane xy. Next rotate by theta about the y axis, aligning the major
// axis in the xz plane. Finally, rotate by phi in the detector plane xy.
// To compute the scattering, undo these rotations in reverse order:
//     rotate in xy by -phi, rotate in xz by -theta, rotate in xy by -psi
// The returned q is the length of the q vector and (xhat, yhat, zhat) is a unit
// vector in the q direction.
// To change between counterclockwise and clockwise rotation, change the
// sign of phi and psi.

#if 1
//think cos(theta) should be sin(theta) in new coords, RKH 11Jan2017
#define ORIENT_SYMMETRIC(qx, qy, theta, phi, q, sn, cn) do { \
    SINCOS(phi*M_PI_180, sn, cn); \
    q = sqrt(qx*qx + qy*qy); \
    cn  = (q==0. ? 1.0 : (cn*qx + sn*qy)/q * sin(theta*M_PI_180));  \
    sn = sqrt(1 - cn*cn); \
    } while (0)
#else
// SasView 3.x definition of orientation
#define ORIENT_SYMMETRIC(qx, qy, theta, phi, q, sn, cn) do { \
    SINCOS(theta*M_PI_180, sn, cn); \
    q = sqrt(qx*qx + qy*qy);\
    cn = (q==0. ? 1.0 : (cn*cos(phi*M_PI_180)*qx + sn*qy)/q); \
    sn = sqrt(1 - cn*cn); \
    } while (0)
#endif

#if 1
#define ORIENT_ASYMMETRIC(qx, qy, theta, phi, psi, q, xhat, yhat, zhat) do { \
    q = sqrt(qx*qx + qy*qy); \
    const double qxhat = qx/q; \
    const double qyhat = qy/q; \
    double sin_theta, cos_theta; \
    double sin_phi, cos_phi; \
    double sin_psi, cos_psi; \
    SINCOS(theta*M_PI_180, sin_theta, cos_theta); \
    SINCOS(phi*M_PI_180, sin_phi, cos_phi); \
    SINCOS(psi*M_PI_180, sin_psi, cos_psi); \
    xhat = qxhat*(-sin_phi*sin_psi + cos_theta*cos_phi*cos_psi) \
         + qyhat*( cos_phi*sin_psi + cos_theta*sin_phi*cos_psi); \
    yhat = qxhat*(-sin_phi*cos_psi - cos_theta*cos_phi*sin_psi) \
         + qyhat*( cos_phi*cos_psi - cos_theta*sin_phi*sin_psi); \
    zhat = qxhat*(-sin_theta*cos_phi) \
         + qyhat*(-sin_theta*sin_phi); \
    } while (0)
#else
// SasView 3.x definition of orientation
#define ORIENT_ASYMMETRIC(qx, qy, theta, phi, psi, q, cos_alpha, cos_mu, cos_nu) do { \
    q = sqrt(qx*qx + qy*qy); \
    const double qxhat = qx/q; \
    const double qyhat = qy/q; \
    double sin_theta, cos_theta; \
    double sin_phi, cos_phi; \
    double sin_psi, cos_psi; \
    SINCOS(theta*M_PI_180, sin_theta, cos_theta); \
    SINCOS(phi*M_PI_180, sin_phi, cos_phi); \
    SINCOS(psi*M_PI_180, sin_psi, cos_psi); \
    cos_alpha = cos_theta*cos_phi*qxhat + sin_theta*qyhat; \
    cos_mu = (-sin_theta*cos_psi*cos_phi - sin_psi*sin_phi)*qxhat + cos_theta*cos_psi*qyhat; \
    cos_nu = (-cos_phi*sin_psi*sin_theta + sin_phi*cos_psi)*qxhat + sin_psi*cos_theta*qyhat; \
    } while (0)
#endif
