amxmodx/public/amtl/am-float.h

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2014-09-18 17:29:58 +00:00
// vim: set sts=8 ts=2 sw=2 tw=99 et:
//
// Copyright (C) 2013, David Anderson and AlliedModders LLC
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of AlliedModders LLC nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
#ifndef _include_amtl_float_h_
#define _include_amtl_float_h_
#include <math.h>
#include <float.h>
namespace ke {
static const uint32_t kFloat32ExponentMask = 0x7F800000;
static const uint64_t kFloat64ExponentMask = 0x7FFF000000000000ULL;
struct float32_bits
{
static const uint32_t kExponentMask = kFloat32ExponentMask;
typedef uint32_t Bits;
union layout {
uint32_t bits;
float value;
};
static layout to_layout(float value) {
layout impl;
impl.value = value;
return impl;
}
};
struct float64_bits
{
static const uint64_t kExponentMask = kFloat64ExponentMask;
typedef uint64_t Bits;
union layout {
uint64_t bits;
float value;
};
static layout to_layout(float value) {
layout impl;
impl.value = value;
return impl;
}
};
template <typename T>
struct float_bits;
template <>
struct float_bits<float> : public float32_bits {};
template <>
struct float_bits<double> : public float64_bits {};
template <typename T>
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static inline bool
IsNaN(T v)
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{
#ifdef _MSC_VER
return !!_isnan(v);
#else
return isnan(v);
#endif
}
template <typename T> static inline bool
IsInfinite(T value)
{
typedef float_bits<T> Properties;
typedef typename Properties::Bits Bits;
Bits bits = Properties::to_layout(value).bits;
return (bits & Properties::kExponentMask) == Properties::kExponentMask;
};
// Performs the operation (x % y) where x and y are floating-point values.
//
// To compute a floating point modulus, this function returns "r", where r
// satisfies the following equation:
//
// x = (I * y) + r
//
// Where I is an integer <= x, and r is a value less than y. If no such
// integer I exists, the result is NaN.
//
// If x or y are NaN, the result is NaN.
// If x is +/-Infinity, the result is NaN.
// If y is 0, the result is NaN (as a divide by zero is implied).
//
// If y is Infinity, then r = x (and I = 0).
// If x is +/-0, then r = +/-0.
template <typename T> static inline T
FloatModulo(T left, T right)
{
#if defined(KE_WINDOWS)
// Windows fmod() does not follow the contract above, in that:
// 42 % Infinity => NaN, instead of 42, and
// -0 % -N => 0, instead of -0.
if ((!IsInfinite(left) && IsInfinite(right)) ||
(left == 0 && !IsInfinite(right)))
{
return left;
}
#endif
return fmod(left, right);
}
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} // namespace ke
#endif // _include_amtl_float_h_