generic/lib/math/clc_nextafter.cl

#include <clc/clc.h>
#include "../clcmacro.h"

// This file provides OpenCL C implementations of nextafter for
// targets that don't support the clang builtin.

#define AS_TYPE(x) as_##x

#define NEXTAFTER(FLOAT_TYPE, UINT_TYPE, INT_TYPE)                      \
_CLC_OVERLOAD _CLC_DEF FLOAT_TYPE __clc_nextafter(FLOAT_TYPE x, FLOAT_TYPE y) { \
  const UINT_TYPE sign_bit                                        \
   = (UINT_TYPE)1 << (sizeof(INT_TYPE) * 8 - 1);                  \
  const UINT_TYPE sign_bit_mask = sign_bit - 1;                   \
  INT_TYPE ix = AS_TYPE(INT_TYPE)(x);                             \
  INT_TYPE ax = ix & sign_bit_mask;                               \
  INT_TYPE mx = sign_bit - ix;                                    \
  mx = ix < 0 ? mx : ix;                                          \
  INT_TYPE iy = AS_TYPE(INT_TYPE)(y);                             \
  INT_TYPE ay = iy & sign_bit_mask;                               \
  INT_TYPE my = sign_bit - iy;                                    \
  my = iy < 0 ? my : iy;                                          \
  INT_TYPE t = mx + (mx < my ? 1 : -1);                           \
  INT_TYPE r = sign_bit - t;                                      \
  r = t < 0 ? r : t;                                              \
  r = isnan(x) ? ix : r;                                          \
  r = isnan(y) ? iy : r;                                          \
  r = ((ax | ay) == 0 | ix == iy) ? iy : r;                       \
  return AS_TYPE(FLOAT_TYPE)(r);                                  \
}

NEXTAFTER(float, uint, int)
_CLC_BINARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, float, __clc_nextafter, float, float)

#ifdef cl_khr_fp64
#pragma OPENCL EXTENSION cl_khr_fp64 : enable

NEXTAFTER(double, ulong, long)
_CLC_BINARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, __clc_nextafter, double, double)
#endif

#ifdef cl_khr_fp16
#pragma OPENCL EXTENSION cl_khr_fp16 : enable

NEXTAFTER(half, ushort, short)
_CLC_BINARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, half, __clc_nextafter, half, half)
#endif