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51 lines
1.8 KiB
51 lines
1.8 KiB
// Copyright 2017 The Chromium Authors. All rights reserved. |
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// Use of this source code is governed by a BSD-style license that can be |
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// found in the LICENSE file. |
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#ifndef BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_ |
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#define BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_ |
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#include <cassert> |
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#include <limits> |
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#include <type_traits> |
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#include "base/numerics/safe_conversions_impl.h" |
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namespace base { |
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namespace internal { |
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// Fast saturation to a destination type. |
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template <typename Dst, typename Src> |
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struct SaturateFastAsmOp { |
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static const bool is_supported = |
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std::is_signed<Src>::value && std::is_integral<Dst>::value && |
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std::is_integral<Src>::value && |
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IntegerBitsPlusSign<Src>::value <= IntegerBitsPlusSign<int32_t>::value && |
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IntegerBitsPlusSign<Dst>::value <= IntegerBitsPlusSign<int32_t>::value && |
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!IsTypeInRangeForNumericType<Dst, Src>::value; |
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__attribute__((always_inline)) static Dst Do(Src value) { |
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int32_t src = value; |
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typename std::conditional<std::is_signed<Dst>::value, int32_t, |
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uint32_t>::type result; |
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if (std::is_signed<Dst>::value) { |
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asm("ssat %[dst], %[shift], %[src]" |
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: [dst] "=r"(result) |
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: [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value <= 32 |
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? IntegerBitsPlusSign<Dst>::value |
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: 32)); |
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} else { |
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asm("usat %[dst], %[shift], %[src]" |
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: [dst] "=r"(result) |
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: [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value < 32 |
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? IntegerBitsPlusSign<Dst>::value |
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: 31)); |
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} |
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return static_cast<Dst>(result); |
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} |
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}; |
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} // namespace internal |
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} // namespace base |
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#endif // BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_
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