| // Copyright 2017 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_NUMERICS_CLAMPED_MATH_IMPL_H_ |
| #define BASE_NUMERICS_CLAMPED_MATH_IMPL_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include <climits> |
| #include <cmath> |
| #include <cstdlib> |
| #include <limits> |
| #include <type_traits> |
| |
| #include "base/numerics/checked_math.h" |
| #include "base/numerics/safe_conversions.h" |
| #include "base/numerics/safe_math_shared_impl.h" |
| |
| namespace base { |
| namespace internal { |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedAddOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedAddOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename MaxExponentPromotion<T, U>::type; |
| template <typename V = result_type> |
| static V Do(T x, U y) { |
| // TODO(jschuh) Make this "constexpr if" once we're C++17. |
| if (ClampedAddFastOp<T, U>::is_supported) |
| return ClampedAddFastOp<T, U>::template Do<V>(x, y); |
| |
| V result; |
| return CheckedAddOp<T, U>::Do(x, y, &result) |
| ? result |
| // Prefer a compile-time constant (if we have one). |
| : GetMaxOrMin<V>(IsCompileTimeConstant(x) ? IsValueNegative(x) |
| : IsValueNegative(y)); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedSubOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedSubOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename MaxExponentPromotion<T, U>::type; |
| template <typename V = result_type> |
| static V Do(T x, U y) { |
| // TODO(jschuh) Make this "constexpr if" once we're C++17. |
| if (ClampedSubFastOp<T, U>::is_supported) |
| return ClampedSubFastOp<T, U>::template Do<V>(x, y); |
| |
| V result; |
| return CheckedSubOp<T, U>::Do(x, y, &result) |
| ? result |
| // Prefer a compile-time constant (if we have one). |
| : GetMaxOrMin<V>(IsCompileTimeConstant(x) ? IsValueNegative(x) |
| : !IsValueNegative(y)); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedMulOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedMulOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename MaxExponentPromotion<T, U>::type; |
| template <typename V = result_type> |
| static V Do(T x, U y) { |
| // TODO(jschuh) Make this "constexpr if" once we're C++17. |
| if (ClampedMulFastOp<T, U>::is_supported) |
| return ClampedMulFastOp<T, U>::template Do<V>(x, y); |
| |
| V result; |
| return CheckedMulOp<T, U>::Do(x, y, &result) |
| ? result |
| : GetMaxOrMin<V>(IsValueNegative(x) ^ IsValueNegative(y)); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedDivOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedDivOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename MaxExponentPromotion<T, U>::type; |
| template <typename V = result_type> |
| static V Do(T x, U y) { |
| V result = SaturationDefaultLimits<V>::NaN(); |
| return !x || CheckedDivOp<T, U>::Do(x, y, &result) |
| ? result |
| : GetMaxOrMin<V>(IsValueNegative(x) ^ IsValueNegative(y)); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedModOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedModOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename MaxExponentPromotion<T, U>::type; |
| template <typename V = result_type> |
| static V Do(T x, U y) { |
| V result; |
| return CheckedModOp<T, U>::Do(x, y, &result) ? result : x; |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedLshOp {}; |
| |
| // Left shift. Non-zero values saturate in the direction of the sign. A zero |
| // shifted by any value always results in zero. |
| // Note: This class template supports left shifting negative values. |
| template <typename T, typename U> |
| struct ClampedLshOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = T; |
| template <typename V = result_type> |
| static V Do(T x, U shift) { |
| static_assert(!std::is_signed<U>::value, "Shift value must be unsigned."); |
| V result = x; |
| return (shift < std::numeric_limits<T>::digits && |
| CheckedMulOp<T, T>::Do(x, T(1) << shift, &result)) |
| ? result |
| : (x ? GetMaxOrMin<V>(IsValueNegative(x)) : 0); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedRshOp {}; |
| |
| // Right shift. Negative values saturate to -1. Positive or 0 saturates to 0. |
| template <typename T, typename U> |
| struct ClampedRshOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = T; |
| template <typename V = result_type> |
| static V Do(T x, U shift) { |
| static_assert(!std::is_signed<U>::value, "Shift value must be unsigned."); |
| return shift < IntegerBitsPlusSign<T>::value |
| ? saturated_cast<V>(x >> shift) |
| // Signed right shift is odd, because it saturates to -1 or 0. |
| : as_unsigned(V(0)) - IsValueNegative(x); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedAndOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedAndOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename std::make_unsigned< |
| typename MaxExponentPromotion<T, U>::type>::type; |
| template <typename V> |
| static constexpr V Do(T x, U y) { |
| return static_cast<result_type>(x) & static_cast<result_type>(y); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedOrOp {}; |
| |
| // For simplicity we promote to unsigned integers. |
| template <typename T, typename U> |
| struct ClampedOrOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename std::make_unsigned< |
| typename MaxExponentPromotion<T, U>::type>::type; |
| template <typename V> |
| static constexpr V Do(T x, U y) { |
| return static_cast<result_type>(x) | static_cast<result_type>(y); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedXorOp {}; |
| |
| // For simplicity we support only unsigned integers. |
| template <typename T, typename U> |
| struct ClampedXorOp<T, |
| U, |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_integral<U>::value>::type> { |
| using result_type = typename std::make_unsigned< |
| typename MaxExponentPromotion<T, U>::type>::type; |
| template <typename V> |
| static constexpr V Do(T x, U y) { |
| return static_cast<result_type>(x) ^ static_cast<result_type>(y); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedMaxOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedMaxOp< |
| T, |
| U, |
| typename std::enable_if<std::is_arithmetic<T>::value && |
| std::is_arithmetic<U>::value>::type> { |
| using result_type = typename MaxExponentPromotion<T, U>::type; |
| template <typename V = result_type> |
| static constexpr V Do(T x, U y) { |
| return IsGreater<T, U>::Test(x, y) ? saturated_cast<V>(x) |
| : saturated_cast<V>(y); |
| } |
| }; |
| |
| template <typename T, typename U, class Enable = void> |
| struct ClampedMinOp {}; |
| |
| template <typename T, typename U> |
| struct ClampedMinOp< |
| T, |
| U, |
| typename std::enable_if<std::is_arithmetic<T>::value && |
| std::is_arithmetic<U>::value>::type> { |
| using result_type = typename LowestValuePromotion<T, U>::type; |
| template <typename V = result_type> |
| static constexpr V Do(T x, U y) { |
| return IsLess<T, U>::Test(x, y) ? saturated_cast<V>(x) |
| : saturated_cast<V>(y); |
| } |
| }; |
| |
| // This is just boilerplate that wraps the standard floating point arithmetic. |
| // A macro isn't the nicest solution, but it beats rewriting these repeatedly. |
| #define BASE_FLOAT_ARITHMETIC_OPS(NAME, OP) \ |
| template <typename T, typename U> \ |
| struct Clamped##NAME##Op< \ |
| T, U, \ |
| typename std::enable_if<std::is_floating_point<T>::value || \ |
| std::is_floating_point<U>::value>::type> { \ |
| using result_type = typename MaxExponentPromotion<T, U>::type; \ |
| template <typename V = result_type> \ |
| static constexpr V Do(T x, U y) { \ |
| return saturated_cast<V>(x OP y); \ |
| } \ |
| }; |
| |
| BASE_FLOAT_ARITHMETIC_OPS(Add, +) |
| BASE_FLOAT_ARITHMETIC_OPS(Sub, -) |
| BASE_FLOAT_ARITHMETIC_OPS(Mul, *) |
| BASE_FLOAT_ARITHMETIC_OPS(Div, /) |
| |
| #undef BASE_FLOAT_ARITHMETIC_OPS |
| |
| } // namespace internal |
| } // namespace base |
| |
| #endif // BASE_NUMERICS_CLAMPED_MATH_IMPL_H_ |
