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//===-- Floating-point manipulation functions -------------------*- 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
//
//===----------------------------------------------------------------------===//
#include "FPBits.h"
#include "NearestIntegerOperations.h"
#include "utils/CPP/TypeTraits.h"
#ifndef LLVM_LIBC_UTILS_FPUTIL_MANIPULATION_FUNCTIONS_H
#define LLVM_LIBC_UTILS_FPUTIL_MANIPULATION_FUNCTIONS_H
namespace __llvm_libc {
namespace fputil {
#if defined(__x86_64__) || defined(__i386__)
template <typename T> struct Standard754Type {
static constexpr bool Value =
cpp::IsSame<float, cpp::RemoveCVType<T>>::Value ||
cpp::IsSame<double, cpp::RemoveCVType<T>>::Value;
};
#else
template <typename T> struct Standard754Type {
static constexpr bool Value = cpp::IsFloatingPointType<T>::Value;
};
#endif
template <typename T> static inline T frexp_impl(FPBits<T> &bits, int &exp) {
exp = bits.getExponent() + 1;
static constexpr uint16_t resultExponent = FPBits<T>::exponentBias - 1;
bits.exponent = resultExponent;
return bits;
}
template <typename T, cpp::EnableIfType<Standard754Type<T>::Value, int> = 0>
static inline T frexp(T x, int &exp) {
FPBits<T> bits(x);
if (bits.isInfOrNaN())
return x;
if (bits.isZero()) {
exp = 0;
return x;
}
return frexp_impl(bits, exp);
}
#if defined(__x86_64__) || defined(__i386__)
static inline long double frexp(long double x, int &exp) {
FPBits<long double> bits(x);
if (bits.isInfOrNaN())
return x;
if (bits.isZero()) {
exp = 0;
return x;
}
if (bits.exponent != 0 || bits.implicitBit == 1)
return frexp_impl(bits, exp);
exp = bits.getExponent();
int shiftCount = 0;
uint64_t fullMantissa = *reinterpret_cast<uint64_t *>(&bits);
static constexpr uint64_t msBitMask = uint64_t(1) << 63;
for (; (fullMantissa & msBitMask) == uint64_t(0);
fullMantissa <<= 1, ++shiftCount) {
// This for loop will terminate as fullMantissa is != 0. If it were 0,
// then x will be NaN and handled before control reaches here.
// When the loop terminates, fullMantissa will represent the full mantissa
// of a normal long double value. That is, the implicit bit has the value
// of 1.
}
exp = exp - shiftCount + 1;
*reinterpret_cast<uint64_t *>(&bits) = fullMantissa;
bits.exponent = FPBits<long double>::exponentBias - 1;
return bits;
}
#endif
template <typename T,
cpp::EnableIfType<cpp::IsFloatingPointType<T>::Value, int> = 0>
static inline T modf(T x, T &iptr) {
FPBits<T> bits(x);
if (bits.isZero() || bits.isNaN()) {
iptr = x;
return x;
} else if (bits.isInf()) {
iptr = x;
return bits.sign ? FPBits<T>::negZero() : FPBits<T>::zero();
} else {
iptr = trunc(x);
if (x == iptr) {
// If x is already an integer value, then return zero with the right
// sign.
return bits.sign ? FPBits<T>::negZero() : FPBits<T>::zero();
} else {
return x - iptr;
}
}
}
template <typename T,
cpp::EnableIfType<cpp::IsFloatingPointType<T>::Value, int> = 0>
static inline T copysign(T x, T y) {
FPBits<T> xbits(x);
xbits.sign = FPBits<T>(y).sign;
return xbits;
}
template <typename T> static inline T logb_impl(const FPBits<T> &bits) {
return bits.getExponent();
}
template <typename T, cpp::EnableIfType<Standard754Type<T>::Value, int> = 0>
static inline T logb(T x) {
FPBits<T> bits(x);
if (bits.isZero()) {
// TODO(Floating point exception): Raise div-by-zero exception.
// TODO(errno): POSIX requires setting errno to ERANGE.
return FPBits<T>::negInf();
} else if (bits.isNaN()) {
return x;
} else if (bits.isInf()) {
// Return positive infinity.
return FPBits<T>::inf();
}
return logb_impl(bits);
}
#if defined(__x86_64__) || defined(__i386__)
static inline long double logb(long double x) {
FPBits<long double> bits(x);
if (bits.isZero()) {
// TODO(Floating point exception): Raise div-by-zero exception.
// TODO(errno): POSIX requires setting errno to ERANGE.
return FPBits<long double>::negInf();
} else if (bits.isNaN()) {
return x;
} else if (bits.isInf()) {
// Return positive infinity.
return FPBits<long double>::inf();
}
if (bits.exponent != 0 || bits.implicitBit == 1)
return logb_impl(bits);
int exp = bits.getExponent();
int shiftCount = 0;
uint64_t fullMantissa = *reinterpret_cast<uint64_t *>(&bits);
static constexpr uint64_t msBitMask = uint64_t(1) << 63;
for (; (fullMantissa & msBitMask) == uint64_t(0);
fullMantissa <<= 1, ++shiftCount) {
// This for loop will terminate as fullMantissa is != 0. If it were 0,
// then x will be NaN and handled before control reaches here.
// When the loop terminates, fullMantissa will represent the full mantissa
// of a normal long double value. That is, the implicit bit has the value
// of 1.
}
return exp - shiftCount;
}
#endif
} // namespace fputil
} // namespace __llvm_libc
#endif // LLVM_LIBC_UTILS_FPUTIL_MANIPULATION_FUNCTIONS_H
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