src/ieee754.rs

   1 use crate::f16::F16;
   2
   3 mod sealed {
   4     use crate::f16::F16;
   5
   6     pub trait Sealed {}
   7     impl Sealed for F16 {}
   8     impl Sealed for f32 {}
   9     impl Sealed for f64 {}
  10 }
  11
  12 pub trait FloatEncoding: sealed::Sealed + Copy + 'static + Send + Sync {
  13     type BitsType;
  14     type SignedBitsType;
  15     const EXPONENT_BIAS_UNSIGNED: Self::BitsType;
  16     const EXPONENT_BIAS_SIGNED: Self::SignedBitsType;
  17     const SIGN_FIELD_WIDTH: Self::BitsType;
  18     const EXPONENT_FIELD_WIDTH: Self::BitsType;
  19     const MANTISSA_FIELD_WIDTH: Self::BitsType;
  20     const SIGN_FIELD_SHIFT: Self::BitsType;
  21     const EXPONENT_FIELD_SHIFT: Self::BitsType;
  22     const MANTISSA_FIELD_SHIFT: Self::BitsType;
  23     const SIGN_FIELD_MASK: Self::BitsType;
  24     const EXPONENT_FIELD_MASK: Self::BitsType;
  25     const MANTISSA_FIELD_MASK: Self::BitsType;
  26     const IMPLICIT_MANTISSA_BIT: Self::BitsType;
  27     const ZERO_SUBNORMAL_EXPONENT: Self::BitsType;
  28     const NAN_INFINITY_EXPONENT: Self::BitsType;
  29     const INFINITY_BITS: Self::BitsType;
  30     const NAN_BITS: Self::BitsType;
  31 }
  32
  33 macro_rules! impl_float_encoding {
  34     (
  35         impl FloatEncoding for $float:ident {
  36             type BitsType = $bits_type:ident;
  37             type SignedBitsType = $signed_bits_type:ident;
  38             const EXPONENT_FIELD_WIDTH: u32 = $exponent_field_width:literal;
  39             const MANTISSA_FIELD_WIDTH: u32 = $mantissa_field_width:literal;
  40         }
  41     ) => {
  42         impl FloatEncoding for $float {
  43             type BitsType = $bits_type;
  44             type SignedBitsType = $signed_bits_type;
  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         type BitsType = u16;
  73         type SignedBitsType = i16;
  74         const EXPONENT_FIELD_WIDTH: u32 = 5;
  75         const MANTISSA_FIELD_WIDTH: u32 = 10;
  76     }
  77 }
  78
  79 impl_float_encoding! {
  80     impl FloatEncoding for f32 {
  81         type BitsType = u32;
  82         type SignedBitsType = i32;
  83         const EXPONENT_FIELD_WIDTH: u32 = 8;
  84         const MANTISSA_FIELD_WIDTH: u32 = 23;
  85     }
  86 }
  87
  88 impl_float_encoding! {
  89     impl FloatEncoding for f64 {
  90         type BitsType = u64;
  91         type SignedBitsType = i64;
  92         const EXPONENT_FIELD_WIDTH: u32 = 11;
  93         const MANTISSA_FIELD_WIDTH: u32 = 52;
  94     }
  95 }