src/ieee754.rs

   1 use crate::{
   2     f16::F16,
   3     scalar::Scalar,
   4     traits::{Float, Make},
   5 };
   6
   7 mod sealed {
   8     use crate::f16::F16;
   9
  10     pub trait Sealed {}
  11     impl Sealed for F16 {}
  12     impl Sealed for f32 {}
  13     impl Sealed for f64 {}
  14 }
  15
  16 pub trait FloatEncoding:
  17     sealed::Sealed + Copy + 'static + Send + Sync + Float + Make<Context = Scalar>
  18 {
  19     const EXPONENT_BIAS_UNSIGNED: Self::BitsType;
  20     const EXPONENT_BIAS_SIGNED: Self::SignedBitsType;
  21     const SIGN_FIELD_WIDTH: Self::BitsType;
  22     const EXPONENT_FIELD_WIDTH: Self::BitsType;
  23     const MANTISSA_FIELD_WIDTH: Self::BitsType;
  24     const SIGN_FIELD_SHIFT: Self::BitsType;
  25     const EXPONENT_FIELD_SHIFT: Self::BitsType;
  26     const MANTISSA_FIELD_SHIFT: Self::BitsType;
  27     const SIGN_FIELD_MASK: Self::BitsType;
  28     const EXPONENT_FIELD_MASK: Self::BitsType;
  29     const MANTISSA_FIELD_MASK: Self::BitsType;
  30     const IMPLICIT_MANTISSA_BIT: Self::BitsType;
  31     const ZERO_SUBNORMAL_EXPONENT: Self::BitsType;
  32     const NAN_INFINITY_EXPONENT: Self::BitsType;
  33     const INFINITY_BITS: Self::BitsType;
  34     const NAN_BITS: Self::BitsType;
  35 }
  36
  37 macro_rules! impl_float_encoding {
  38     (
  39         impl FloatEncoding for $float:ident {
  40             const EXPONENT_FIELD_WIDTH: u32 = $exponent_field_width:literal;
  41             const MANTISSA_FIELD_WIDTH: u32 = $mantissa_field_width:literal;
  42         }
  43     ) => {
  44         impl FloatEncoding for $float {
  45             const EXPONENT_BIAS_UNSIGNED: Self::BitsType =
  46                 (1 << (Self::EXPONENT_FIELD_WIDTH - 1)) - 1;
  47             const EXPONENT_BIAS_SIGNED: Self::SignedBitsType = Self::EXPONENT_BIAS_UNSIGNED as _;
  48             const SIGN_FIELD_WIDTH: Self::BitsType = 1;
  49             const EXPONENT_FIELD_WIDTH: Self::BitsType = $exponent_field_width;
  50             const MANTISSA_FIELD_WIDTH: Self::BitsType = $mantissa_field_width;
  51             const SIGN_FIELD_SHIFT: Self::BitsType =
  52                 Self::EXPONENT_FIELD_SHIFT + Self::EXPONENT_FIELD_WIDTH;
  53             const EXPONENT_FIELD_SHIFT: Self::BitsType = Self::MANTISSA_FIELD_WIDTH;
  54             const MANTISSA_FIELD_SHIFT: Self::BitsType = 0;
  55             const SIGN_FIELD_MASK: Self::BitsType = 1 << Self::SIGN_FIELD_SHIFT;
  56             const EXPONENT_FIELD_MASK: Self::BitsType =
  57                 ((1 << Self::EXPONENT_FIELD_WIDTH) - 1) << Self::EXPONENT_FIELD_SHIFT;
  58             const MANTISSA_FIELD_MASK: Self::BitsType = (1 << Self::MANTISSA_FIELD_WIDTH) - 1;
  59             const IMPLICIT_MANTISSA_BIT: Self::BitsType = 1 << Self::MANTISSA_FIELD_WIDTH;
  60             const ZERO_SUBNORMAL_EXPONENT: Self::BitsType = 0;
  61             const NAN_INFINITY_EXPONENT: Self::BitsType = (1 << Self::EXPONENT_FIELD_WIDTH) - 1;
  62             const INFINITY_BITS: Self::BitsType =
  63                 Self::NAN_INFINITY_EXPONENT << Self::EXPONENT_FIELD_SHIFT;
  64             const NAN_BITS: Self::BitsType =
  65                 Self::INFINITY_BITS | (1 << (Self::MANTISSA_FIELD_WIDTH - 1));
  66         }
  67     };
  68 }
  69
  70 impl_float_encoding! {
  71     impl FloatEncoding for F16 {
  72         const EXPONENT_FIELD_WIDTH: u32 = 5;
  73         const MANTISSA_FIELD_WIDTH: u32 = 10;
  74     }
  75 }
  76
  77 impl_float_encoding! {
  78     impl FloatEncoding for f32 {
  79         const EXPONENT_FIELD_WIDTH: u32 = 8;
  80         const MANTISSA_FIELD_WIDTH: u32 = 23;
  81     }
  82 }
  83
  84 impl_float_encoding! {
  85     impl FloatEncoding for f64 {
  86         const EXPONENT_FIELD_WIDTH: u32 = 11;
  87         const MANTISSA_FIELD_WIDTH: u32 = 52;
  88     }
  89 }