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52 lines
1.8 KiB
C
52 lines
1.8 KiB
C
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// 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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