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use crate::{
fbig::FBig,
repr::{Context, Repr, Word},
round::Round,
};
use core::ops::{Mul, MulAssign, Neg};
use dashu_base::{Abs, Sign, Signed};
use dashu_int::IBig;
impl<R: Round, const B: Word> FBig<R, B> {
/// Get the sign of the number. Positive zero has a positive sign, negative zero has a
/// negative sign.
///
/// # Examples
///
/// ```
/// # use core::str::FromStr;
/// # use dashu_base::{ParseError, Sign};
/// # use dashu_float::DBig;
/// assert_eq!(DBig::ZERO.sign(), Sign::Positive);
/// assert_eq!(DBig::from_str("-1.234")?.sign(), Sign::Negative);
/// # Ok::<(), ParseError>(())
/// ```
#[inline]
pub const fn sign(&self) -> Sign {
self.repr.sign()
}
/// A number representing the sign of `self`.
///
/// * [FBig::ONE] if the number is positive (including `inf`)
/// * [FBig::ZERO] if the number is zero
/// * [FBig::NEG_ONE] if the number is negative (including `-inf`)
///
/// # Examples
/// ```
/// # use core::str::FromStr;
/// # use dashu_base::ParseError;
/// # use dashu_float::DBig;
/// assert_eq!(DBig::from_str("2.01")?.signum(), DBig::ONE);
/// assert_eq!(DBig::from_str("-1.234")?.signum(), DBig::NEG_ONE);
/// # Ok::<(), ParseError>(())
/// ```
pub const fn signum(&self) -> Self {
let significand = if self.repr.significand.is_zero() {
// distinguish infinities from signed zero; signum(±0) = +0
match self.repr.exponent {
isize::MAX => IBig::ONE,
isize::MIN => IBig::NEG_ONE,
_ => IBig::ZERO,
}
} else {
self.repr.significand.signum()
};
let repr = Repr {
significand,
exponent: 0,
};
Self::new(repr, Context::new(1))
}
}
impl<const B: Word> Neg for Repr<B> {
type Output = Self;
#[inline]
fn neg(self) -> Self::Output {
Repr::neg(self)
}
}
impl<R: Round, const B: Word> Neg for FBig<R, B> {
type Output = Self;
#[inline]
fn neg(mut self) -> Self::Output {
self.repr = self.repr.neg();
self
}
}
impl<R: Round, const B: Word> Neg for &FBig<R, B> {
type Output = FBig<R, B>;
#[inline]
fn neg(self) -> Self::Output {
self.clone().neg()
}
}
impl<R: Round, const B: Word> Abs for FBig<R, B> {
type Output = Self;
fn abs(mut self) -> Self::Output {
// flip -0 -> +0 and -inf -> +inf by toggling the special-value exponent;
// finite values take the absolute value of their significand.
if self.repr.significand.is_zero() {
if self.repr.exponent == -1 {
self.repr.exponent = 0;
} else if self.repr.exponent == isize::MIN {
self.repr.exponent = isize::MAX;
}
} else {
self.repr.significand = self.repr.significand.abs();
}
self
}
}
impl<R: Round, const B: Word> Mul<FBig<R, B>> for Sign {
type Output = FBig<R, B>;
#[inline]
fn mul(self, rhs: FBig<R, B>) -> Self::Output {
match self {
Sign::Positive => rhs,
Sign::Negative => -rhs,
}
}
}
impl<R: Round, const B: Word> Mul<Sign> for FBig<R, B> {
type Output = FBig<R, B>;
#[inline]
fn mul(self, rhs: Sign) -> Self::Output {
match rhs {
Sign::Positive => self,
Sign::Negative => -self,
}
}
}
impl<R: Round, const B: Word> MulAssign<Sign> for FBig<R, B> {
#[inline]
fn mul_assign(&mut self, rhs: Sign) {
if rhs == Sign::Negative {
self.repr = self.repr.clone().neg();
}
}
}
impl<R: Round, const B: Word> Signed for FBig<R, B> {
#[inline]
fn sign(&self) -> Sign {
self.repr.sign()
}
}