math_ex.h

//----------------------------------------------------------------------------//
//                                                                            //
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//----------------------------------------------------------------------------//
 
#ifndef OZZ_OZZ_BASE_MATHS_MATH_EX_H_
#define OZZ_OZZ_BASE_MATHS_MATH_EX_H_
 
#include <cassert>
#include <cmath>
 
#include "ozz/base/platform.h"
 
namespace ozz {
namespace math {
 
// Returns the linear interpolation of _a and _b with coefficient _f.
// _f is not limited to range [0,1].
OZZ_INLINE float Lerp(float _a, float _b, float _f) {
  return (_b - _a) * _f + _a;
}
 
// Returns the minimum of _a and _b. Comparison's based on operator <.
template <typename _Ty>
OZZ_INLINE _Ty Min(_Ty _a, _Ty _b) {
  return (_a < _b) ? _a : _b;
}
 
// Returns the maximum of _a and _b. Comparison's based on operator <.
template <typename _Ty>
OZZ_INLINE _Ty Max(_Ty _a, _Ty _b) {
  return (_b < _a) ? _a : _b;
}
 
// Clamps _x between _a and _b. Comparison's based on operator <.
// Result is unknown if _a is not less or equal to _b.
template <typename _Ty>
OZZ_INLINE _Ty Clamp(_Ty _a, _Ty _x, _Ty _b) {
  const _Ty min = _x < _b ? _x : _b;
  return min < _a ? _a : min;
}
 
// Implements int selection, avoiding branching.
OZZ_INLINE int Select(bool _b, int _true, int _false) {
  return _false ^ (-static_cast<int>(_b) & (_true ^ _false));
}
 
// Implements float selection, avoiding branching.
OZZ_INLINE float Select(bool _b, float _true, float _false) {
  union {
    float f;
    int32_t i;
  } t = {_true};
  union {
    float f;
    int32_t i;
  } f = {_false};
  union {
    int32_t i;
    float f;
  } r = {f.i ^ (-static_cast<int32_t>(_b) & (t.i ^ f.i))};
  return r.f;
}
 
// Implements pointer selection, avoiding branching.
template <typename _Ty>
OZZ_INLINE _Ty* Select(bool _b, _Ty* _true, _Ty* _false) {
  union {
    _Ty* p;
    intptr_t i;
  } t = {_true};
  union {
    _Ty* p;
    intptr_t i;
  } f = {_false};
  union {
    intptr_t i;
    _Ty* p;
  } r = {f.i ^ (-static_cast<intptr_t>(_b) & (t.i ^ f.i))};
  return r.p;
}
 
// Implements const pointer selection, avoiding branching.
template <typename _Ty>
OZZ_INLINE const _Ty* Select(bool _b, const _Ty* _true, const _Ty* _false) {
  union {
    const _Ty* p;
    intptr_t i;
  } t = {_true};
  union {
    const _Ty* p;
    intptr_t i;
  } f = {_false};
  union {
    intptr_t i;
    const _Ty* p;
  } r = {f.i ^ (-static_cast<intptr_t>(_b) & (t.i ^ f.i))};
  return r.p;
}
 
}  // namespace math
}  // namespace ozz
#endif  // OZZ_OZZ_BASE_MATHS_MATH_EX_H_