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// Copyright © 2026 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::Float;
use core::cmp::Ordering::{self, *};
use malachite_base::num::basic::floats::PrimitiveFloat;
use malachite_base::num::basic::traits::{Infinity, NaN, NegativeInfinity, NegativeZero, Zero};
use malachite_base::num::conversion::traits::IntegerMantissaAndExponent;
use malachite_base::rounding_modes::RoundingMode;
impl Float {
/// Converts a primitive float to a [`Float`]. If the [`Float`] is nonzero and finite, it has
/// the specified precision. If rounding is needed, the specified rounding mode is used. An
/// [`Ordering`] is also returned, indicating whether the returned value is less than, equal to,
/// or greater than the original value. (Although a NaN is not comparable to any [`Float`],
/// converting a NaN to a NaN will also return `Equal`, indicating an exact conversion.)
///
/// If you're only using `Nearest`, try using [`Float::from_primitive_float_prec`] instead.
///
/// This function does not overflow or underflow.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `max(prec, x.sci_exponent().abs())`.
///
/// # Panics
/// Panics if `prec` is zero, or if `rm` is exact and the primitive float cannot be exactly
/// represented with the specified precision.
///
/// # Examples
/// See [here](super::from_primitive_float#from_primitive_float_prec_round).
#[inline]
pub fn from_primitive_float_prec_round<T: PrimitiveFloat>(
x: T,
prec: u64,
rm: RoundingMode,
) -> (Self, Ordering) {
assert_ne!(prec, 0);
if x.is_nan() {
(Self::NAN, Equal)
} else if !x.is_finite() {
if x.is_sign_positive() {
(Self::INFINITY, Equal)
} else {
(Self::NEGATIVE_INFINITY, Equal)
}
} else if x == T::ZERO {
if x.is_sign_positive() {
(Self::ZERO, Equal)
} else {
(Self::NEGATIVE_ZERO, Equal)
}
} else {
let (m, e) = x.integer_mantissa_and_exponent();
if x.is_sign_positive() {
let (f, o) = Self::from_unsigned_prec_round(m, prec, rm);
(f << e, o)
} else {
let (abs, o) = Self::from_unsigned_prec_round(m, prec, -rm);
(-(abs << e), o.reverse())
}
}
}
/// Converts a primitive float to a [`Float`]. If the [`Float`] is nonzero and finite, it has
/// the specified precision. An [`Ordering`] is also returned, indicating whether the returned
/// value is less than, equal to, or greater than the original value. (Although a NaN is not
/// comparable to any [`Float`], converting a NaN to a NaN will also return `Equal`, indicating
/// an exact conversion.)
///
/// Rounding may occur, in which case `Nearest` is used by default. To specify a rounding mode
/// as well as a precision, try [`Float::from_primitive_float_prec_round`].
///
/// This function does not overflow or underflow.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `max(prec, x.sci_exponent().abs())`.
///
/// # Panics
/// Panics if `prec` is zero.
///
/// # Examples
/// See [here](super::from_primitive_float#from_primitive_float_prec).
#[inline]
pub fn from_primitive_float_prec<T: PrimitiveFloat>(x: T, prec: u64) -> (Self, Ordering) {
assert_ne!(prec, 0);
if x.is_nan() {
(Self::NAN, Equal)
} else if !x.is_finite() {
if x.is_sign_positive() {
(Self::INFINITY, Equal)
} else {
(Self::NEGATIVE_INFINITY, Equal)
}
} else if x == T::ZERO {
if x.is_sign_positive() {
(Self::ZERO, Equal)
} else {
(Self::NEGATIVE_ZERO, Equal)
}
} else {
let (m, e) = x.integer_mantissa_and_exponent();
if x.is_sign_positive() {
let (f, o) = Self::from_unsigned_prec(m, prec);
(f << e, o)
} else {
let (abs, o) = Self::from_unsigned_prec(m, prec);
(-(abs << e), o.reverse())
}
}
}
}
macro_rules! impl_from_primitive_float {
($t: ident) => {
impl From<$t> for Float {
/// Converts a primitive float to a [`Float`].
///
/// If the primitive float is finite and nonzero, the precision of the [`Float`] is the
/// minimum possible precision to represent the primitive float exactly. If you want to
/// specify a different precision, try [`Float::from_primitive_float_prec`]. This may
/// require rounding, which uses `Nearest` by default. To specify a rounding mode as
/// well as a precision, try [`Float::from_primitive_float_prec_round`].
///
/// This function does not overflow or underflow.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `x.sci_exponent().abs()`.
///
/// # Examples
/// See [here](super::from_primitive_float#from).
#[inline]
fn from(x: $t) -> Float {
if x.is_nan() {
Float::NAN
} else if !x.is_finite() {
if x.is_sign_positive() {
Float::INFINITY
} else {
Float::NEGATIVE_INFINITY
}
} else if x == 0.0 {
if x.is_sign_positive() {
Float::ZERO
} else {
Float::NEGATIVE_ZERO
}
} else {
let (m, e) = x.integer_mantissa_and_exponent();
let abs = Float::from(m) << e;
if x.is_sign_positive() { abs } else { -abs }
}
}
}
};
}
apply_to_primitive_floats!(impl_from_primitive_float);