Trait rustc_apfloat::ieee::Semantics

pub trait Semantics: Sized {
    const BITS: usize;
    const PRECISION: usize;
    const MAX_EXP: ExpInt;
    const MIN_EXP: ExpInt;
    const QNAN_BIT: usize;
    const QNAN_SIGNIFICAND: u128;
    fn from_bits(bits: u128) -> IeeeFloat<Self> { ... }
    fn to_bits(x: IeeeFloat<Self>) -> u128 { ... }
}

Represents floating point arithmetic semantics.

Associated Constants

const BITS: usize

Total number of bits in the in-memory format.

const PRECISION: usize

Number of bits in the significand. This includes the integer bit.

const MAX_EXP: ExpInt

The largest E such that 2^E is representable; this matches the definition of IEEE 754.

const MIN_EXP: ExpInt

The smallest E such that 2^E is a normalized number; this matches the definition of IEEE 754.

const QNAN_BIT: usize

The significand bit that marks NaN as quiet.

const QNAN_SIGNIFICAND: u128

The significand bitpattern to mark a NaN as quiet. NOTE: for X87DoubleExtended we need to set two bits instead of 2.

Provided methods

fn from_bits(bits: u128) -> IeeeFloat<Self>

fn to_bits(x: IeeeFloat<Self>) -> u128

Implementors

impl Semantics for DoubleS

const BITS: usize

const PRECISION: usize

const MAX_EXP: ExpInt

impl Semantics for HalfS

const BITS: usize

const PRECISION: usize

const MAX_EXP: ExpInt

impl Semantics for QuadS

const BITS: usize

const PRECISION: usize

const MAX_EXP: ExpInt

impl Semantics for SingleS

const BITS: usize

const PRECISION: usize

const MAX_EXP: ExpInt

impl Semantics for X87DoubleExtendedS

const QNAN_SIGNIFICAND: u128

For x87 extended precision, we want to make a NaN, not a pseudo-NaN. Maybe we should expose the ability to make pseudo-NaNs?

fn from_bits(bits: u128) -> IeeeFloat<Self>

Integer bit is explicit in this format. Intel hardware (387 and later) does not support these bit patterns: exponent = all 1’s, integer bit 0, significand 0 (“pseudoinfinity”) exponent = all 1’s, integer bit 0, significand nonzero (“pseudoNaN”) exponent = 0, integer bit 1 (“pseudodenormal”) exponent != 0 nor all 1’s, integer bit 0 (“unnormal”) At the moment, the first two are treated as NaNs, the second two as Normal.

const BITS: usize

const PRECISION: usize

const MAX_EXP: ExpInt

fn to_bits(x: IeeeFloat<Self>) -> u128

impl<F: Float> Semantics for FallbackExtendedS<F>

const BITS: usize

const PRECISION: usize

const MAX_EXP: ExpInt

impl<F: Float> Semantics for FallbackS<F>

const BITS: usize

const PRECISION: usize

const MAX_EXP: ExpInt

const MIN_EXP: ExpInt