use core::mem; use core::ops; use super::int::Int; pub mod conv; pub mod cmp; pub mod add; pub mod pow; pub mod sub; pub mod mul; pub mod div; /// Trait for some basic operations on floats pub trait Float: Copy + PartialEq + PartialOrd + ops::AddAssign + ops::MulAssign + ops::Add + ops::Sub + ops::Div + ops::Rem + { /// A uint of the same with as the float type Int: Int; const ZERO: Self; const ONE: Self; /// The bitwidth of the float type const BITS: u32; /// The bitwidth of the significand const SIGNIFICAND_BITS: u32; /// The bitwidth of the exponent const EXPONENT_BITS: u32 = Self::BITS - Self::SIGNIFICAND_BITS - 1; /// The maximum value of the exponent const EXPONENT_MAX: u32 = (1 << Self::EXPONENT_BITS) - 1; /// The exponent bias value const EXPONENT_BIAS: u32 = Self::EXPONENT_MAX >> 1; /// A mask for the sign bit const SIGN_MASK: Self::Int; /// A mask for the significand const SIGNIFICAND_MASK: Self::Int; // The implicit bit of the float format const IMPLICIT_BIT: Self::Int; /// A mask for the exponent const EXPONENT_MASK: Self::Int; /// Returns `self` transmuted to `Self::Int` fn repr(self) -> Self::Int; #[cfg(test)] /// Checks if two floats have the same bit representation. *Except* for NaNs! NaN can be /// represented in multiple different ways. This method returns `true` if two NaNs are /// compared. fn eq_repr(self, rhs: Self) -> bool; /// Returns a `Self::Int` transmuted back to `Self` fn from_repr(a: Self::Int) -> Self; /// Constructs a `Self` from its parts. Inputs are treated as bits and shifted into position. fn from_parts(sign: bool, exponent: Self::Int, significand: Self::Int) -> Self; /// Returns (normalized exponent, normalized significand) fn normalize(significand: Self::Int) -> (i32, Self::Int); } // FIXME: Some of this can be removed if RFC Issue #1424 is resolved // https://github.com/rust-lang/rfcs/issues/1424 macro_rules! float_impl { ($ty:ident, $ity:ident, $bits:expr, $significand_bits:expr) => { impl Float for $ty { type Int = $ity; const ZERO: Self = 0.0; const ONE: Self = 1.0; const BITS: u32 = $bits; const SIGNIFICAND_BITS: u32 = $significand_bits; const SIGN_MASK: Self::Int = 1 << (Self::BITS - 1); const SIGNIFICAND_MASK: Self::Int = (1 << Self::SIGNIFICAND_BITS) - 1; const IMPLICIT_BIT: Self::Int = 1 << Self::SIGNIFICAND_BITS; const EXPONENT_MASK: Self::Int = !(Self::SIGN_MASK | Self::SIGNIFICAND_MASK); fn repr(self) -> Self::Int { unsafe { mem::transmute(self) } } #[cfg(test)] fn eq_repr(self, rhs: Self) -> bool { if self.is_nan() && rhs.is_nan() { true } else { self.repr() == rhs.repr() } } fn from_repr(a: Self::Int) -> Self { unsafe { mem::transmute(a) } } fn from_parts(sign: bool, exponent: Self::Int, significand: Self::Int) -> Self { Self::from_repr(((sign as Self::Int) << (Self::BITS - 1)) | ((exponent << Self::SIGNIFICAND_BITS) & Self::EXPONENT_MASK) | (significand & Self::SIGNIFICAND_MASK)) } fn normalize(significand: Self::Int) -> (i32, Self::Int) { let shift = significand.leading_zeros() .wrapping_sub((Self::Int::ONE << Self::SIGNIFICAND_BITS).leading_zeros()); (1i32.wrapping_sub(shift as i32), significand << shift as Self::Int) } } } } float_impl!(f32, u32, 32, 23); float_impl!(f64, u64, 64, 52);