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//===-- Bit representation of x86 long double numbers -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_UTILS_FPUTIL_LONG_DOUBLE_BITS_X86_H
#define LLVM_LIBC_UTILS_FPUTIL_LONG_DOUBLE_BITS_X86_H
#include "utils/FPUtil/FPBits.h"
#include <stdint.h>
namespace __llvm_libc {
namespace fputil {
template <> struct MantissaWidth<long double> {
static constexpr unsigned value = 63;
};
template <unsigned Width> struct Padding;
// i386 padding.
template <> struct Padding<4> { static constexpr unsigned Value = 16; };
// x86_64 padding.
template <> struct Padding<8> { static constexpr unsigned Value = 48; };
template <> struct __attribute__((packed)) FPBits<long double> {
using UIntType = __uint128_t;
static constexpr int exponentBias = 0x3FFF;
static constexpr int maxExponent = 0x7FFF;
UIntType mantissa : MantissaWidth<long double>::value;
uint8_t implicitBit : 1;
uint16_t exponent : ExponentWidth<long double>::value;
uint8_t sign : 1;
uint64_t padding : Padding<sizeof(uintptr_t)>::Value;
template <typename XType,
cpp::EnableIfType<cpp::IsSame<long double, XType>::Value, int> = 0>
explicit FPBits<long double>(XType x) {
*this = *reinterpret_cast<FPBits<long double> *>(&x);
}
operator long double() { return *reinterpret_cast<long double *>(this); }
int getExponent() const {
if (exponent == 0)
return int(1) - exponentBias;
return int(exponent) - exponentBias;
}
bool isZero() const {
return exponent == 0 && mantissa == 0 && implicitBit == 0;
}
bool isInf() const {
return exponent == maxExponent && mantissa == 0 && implicitBit == 1;
}
bool isNaN() const {
if (exponent == maxExponent) {
return (implicitBit == 0) || mantissa != 0;
} else if (exponent != 0) {
return implicitBit == 0;
}
return false;
}
bool isInfOrNaN() const {
return (exponent == maxExponent) || (exponent != 0 && implicitBit == 0);
}
// Methods below this are used by tests.
template <typename XType,
cpp::EnableIfType<cpp::IsSame<UIntType, XType>::Value, int> = 0>
explicit FPBits<long double>(XType x) {
// The last 4 bytes of v are ignored in case of i386.
*this = *reinterpret_cast<FPBits<long double> *>(&x);
}
UIntType bitsAsUInt() const {
// We cannot just return the bits as is as it will lead to reading
// out of bounds in case of i386. So, we first copy the wider value
// before returning the value. This makes the last 4 bytes are always
// zero in case i386.
UIntType result = UIntType(0);
*reinterpret_cast<FPBits<long double> *>(&result) = *this;
return result;
}
static FPBits<long double> zero() { return FPBits<long double>(0.0l); }
static FPBits<long double> negZero() {
FPBits<long double> bits(0.0l);
bits.sign = 1;
return bits;
}
static FPBits<long double> inf() {
FPBits<long double> bits(0.0l);
bits.exponent = maxExponent;
bits.implicitBit = 1;
return bits;
}
static FPBits<long double> negInf() {
FPBits<long double> bits(0.0l);
bits.exponent = maxExponent;
bits.implicitBit = 1;
bits.sign = 1;
return bits;
}
static long double buildNaN(UIntType v) {
FPBits<long double> bits(0.0l);
bits.exponent = maxExponent;
bits.implicitBit = 1;
bits.mantissa = v;
return bits;
}
};
static_assert(
sizeof(FPBits<long double>) == sizeof(long double),
"Internal long double representation does not match the machine format.");
} // namespace fputil
} // namespace __llvm_libc
#endif // LLVM_LIBC_UTILS_FPUTIL_LONG_DOUBLE_BITS_X86_H
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