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