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// 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_SAFE_CONVERSIONS_ARM_IMPL_H_
#define BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_
#include <cassert>
#include <limits>
#include <type_traits>
#include "base/numerics/safe_conversions_impl.h"
namespace base {
namespace internal {
// Fast saturation to a destination type.
template <typename Dst, typename Src>
struct SaturateFastAsmOp {
static constexpr bool is_supported =
std::is_signed<Src>::value && std::is_integral<Dst>::value &&
std::is_integral<Src>::value &&
IntegerBitsPlusSign<Src>::value <= IntegerBitsPlusSign<int32_t>::value &&
IntegerBitsPlusSign<Dst>::value <= IntegerBitsPlusSign<int32_t>::value &&
!IsTypeInRangeForNumericType<Dst, Src>::value;
__attribute__((always_inline)) static Dst Do(Src value) {
int32_t src = value;
typename std::conditional<std::is_signed<Dst>::value, int32_t,
uint32_t>::type result;
if (std::is_signed<Dst>::value) {
asm("ssat %[dst], %[shift], %[src]"
: [dst] "=r"(result)
: [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value <= 32
? IntegerBitsPlusSign<Dst>::value
: 32));
} else {
asm("usat %[dst], %[shift], %[src]"
: [dst] "=r"(result)
: [src] "r"(src), [shift] "n"(IntegerBitsPlusSign<Dst>::value < 32
? IntegerBitsPlusSign<Dst>::value
: 31));
}
return static_cast<Dst>(result);
}
};
} // namespace internal
} // namespace base
#endif // BASE_NUMERICS_SAFE_CONVERSIONS_ARM_IMPL_H_