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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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_SRC_SUPPORT_FPUTIL_MANIPULATION_FUNCTIONS_H
#define LLVM_LIBC_SRC_SUPPORT_FPUTIL_MANIPULATION_FUNCTIONS_H
#include "FPBits.h"
#include "NearestIntegerOperations.h"
#include "NormalFloat.h"
#include "PlatformDefs.h"
#include "src/__support/CPP/bit.h"
#include "src/__support/CPP/type_traits.h"
#include "src/__support/macros/attributes.h"
#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
#include <limits.h>
#include <math.h>
namespace __llvm_libc {
namespace fputil {
template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
LIBC_INLINE T frexp(T x, int &exp) {
FPBits<T> bits(x);
if (bits.is_inf_or_nan())
return x;
if (bits.is_zero()) {
exp = 0;
return x;
}
NormalFloat<T> normal(bits);
exp = normal.exponent + 1;
normal.exponent = -1;
return normal;
}
template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
LIBC_INLINE T modf(T x, T &iptr) {
FPBits<T> bits(x);
if (bits.is_zero() || bits.is_nan()) {
iptr = x;
return x;
} else if (bits.is_inf()) {
iptr = x;
return bits.get_sign() ? T(FPBits<T>::neg_zero()) : T(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.get_sign() ? T(FPBits<T>::neg_zero()) : T(FPBits<T>::zero());
} else {
return x - iptr;
}
}
}
template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
LIBC_INLINE T copysign(T x, T y) {
FPBits<T> xbits(x);
xbits.set_sign(FPBits<T>(y).get_sign());
return T(xbits);
}
template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
LIBC_INLINE int ilogb(T x) {
// TODO: Raise appropriate floating point exceptions and set errno to the
// an appropriate error value wherever relevant.
FPBits<T> bits(x);
if (bits.is_zero()) {
return FP_ILOGB0;
} else if (bits.is_nan()) {
return FP_ILOGBNAN;
} else if (bits.is_inf()) {
return INT_MAX;
}
NormalFloat<T> normal(bits);
// The C standard does not specify the return value when an exponent is
// out of int range. However, XSI conformance required that INT_MAX or
// INT_MIN are returned.
// NOTE: It is highly unlikely that exponent will be out of int range as
// the exponent is only 15 bits wide even for the 128-bit floating point
// format.
if (normal.exponent > INT_MAX)
return INT_MAX;
else if (normal.exponent < INT_MIN)
return INT_MIN;
else
return normal.exponent;
}
template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
LIBC_INLINE T logb(T x) {
FPBits<T> bits(x);
if (bits.is_zero()) {
// TODO(Floating point exception): Raise div-by-zero exception.
// TODO(errno): POSIX requires setting errno to ERANGE.
return T(FPBits<T>::neg_inf());
} else if (bits.is_nan()) {
return x;
} else if (bits.is_inf()) {
// Return positive infinity.
return T(FPBits<T>::inf());
}
NormalFloat<T> normal(bits);
return static_cast<T>(normal.exponent);
}
template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
LIBC_INLINE T ldexp(T x, int exp) {
if (LIBC_UNLIKELY(exp == 0))
return x;
FPBits<T> bits(x);
if (LIBC_UNLIKELY(bits.is_zero() || bits.is_inf_or_nan()))
return x;
// NormalFloat uses int32_t to store the true exponent value. We should ensure
// that adding |exp| to it does not lead to integer rollover. But, if |exp|
// value is larger the exponent range for type T, then we can return infinity
// early. Because the result of the ldexp operation can be a subnormal number,
// we need to accommodate the (mantissaWidht + 1) worth of shift in
// calculating the limit.
int exp_limit = FPBits<T>::MAX_EXPONENT + MantissaWidth<T>::VALUE + 1;
if (exp > exp_limit)
return bits.get_sign() ? T(FPBits<T>::neg_inf()) : T(FPBits<T>::inf());
// Similarly on the negative side we return zero early if |exp| is too small.
if (exp < -exp_limit)
return bits.get_sign() ? T(FPBits<T>::neg_zero()) : T(FPBits<T>::zero());
// For all other values, NormalFloat to T conversion handles it the right way.
NormalFloat<T> normal(bits);
normal.exponent += exp;
return normal;
}
template <typename T, cpp::enable_if_t<cpp::is_floating_point_v<T>, int> = 0>
LIBC_INLINE T nextafter(T from, T to) {
FPBits<T> from_bits(from);
if (from_bits.is_nan())
return from;
FPBits<T> to_bits(to);
if (to_bits.is_nan())
return to;
if (from == to)
return to;
using UIntType = typename FPBits<T>::UIntType;
UIntType int_val = from_bits.uintval();
UIntType sign_mask = (UIntType(1) << (sizeof(T) * 8 - 1));
if (from != T(0.0)) {
if ((from < to) == (from > T(0.0))) {
++int_val;
} else {
--int_val;
}
} else {
int_val = (to_bits.uintval() & sign_mask) + UIntType(1);
}
return cpp::bit_cast<T>(int_val);
// TODO: Raise floating point exceptions as required by the standard.
}
} // namespace fputil
} // namespace __llvm_libc
#ifdef SPECIAL_X86_LONG_DOUBLE
#include "x86_64/NextAfterLongDouble.h"
#endif // SPECIAL_X86_LONG_DOUBLE
#endif // LLVM_LIBC_SRC_SUPPORT_FPUTIL_MANIPULATION_FUNCTIONS_H
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