diff options
Diffstat (limited to 'library/compiler-builtins/libm-test/src/f8_impl.rs')
| -rw-r--r-- | library/compiler-builtins/libm-test/src/f8_impl.rs | 505 |
1 files changed, 505 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm-test/src/f8_impl.rs b/library/compiler-builtins/libm-test/src/f8_impl.rs new file mode 100644 index 00000000000..905c7d7fde9 --- /dev/null +++ b/library/compiler-builtins/libm-test/src/f8_impl.rs @@ -0,0 +1,505 @@ +//! An IEEE-compliant 8-bit float type for testing purposes. + +use std::cmp::{self, Ordering}; +use std::{fmt, ops}; + +use crate::Float; + +/// Sometimes verifying float logic is easiest when all values can quickly be checked exhaustively +/// or by hand. +/// +/// IEEE-754 compliant type that includes a 1 bit sign, 4 bit exponent, and 3 bit significand. +/// Bias is -7. +/// +/// Based on <https://en.wikipedia.org/wiki/Minifloat#Example_8-bit_float_(1.4.3)>. +#[derive(Clone, Copy)] +#[repr(transparent)] +#[allow(non_camel_case_types)] +pub struct f8(u8); + +impl Float for f8 { + type Int = u8; + type SignedInt = i8; + + const ZERO: Self = Self(0b0_0000_000); + const NEG_ZERO: Self = Self(0b1_0000_000); + const ONE: Self = Self(0b0_0111_000); + const NEG_ONE: Self = Self(0b1_0111_000); + const MAX: Self = Self(0b0_1110_111); + const MIN: Self = Self(0b1_1110_111); + const INFINITY: Self = Self(0b0_1111_000); + const NEG_INFINITY: Self = Self(0b1_1111_000); + const NAN: Self = Self(0b0_1111_100); + const NEG_NAN: Self = Self(0b1_1111_100); + const MIN_POSITIVE_NORMAL: Self = Self(1 << Self::SIG_BITS); + // FIXME: incorrect values + const EPSILON: Self = Self::ZERO; + const PI: Self = Self::ZERO; + const NEG_PI: Self = Self::ZERO; + const FRAC_PI_2: Self = Self::ZERO; + + const BITS: u32 = 8; + const SIG_BITS: u32 = 3; + const SIGN_MASK: Self::Int = 0b1_0000_000; + const SIG_MASK: Self::Int = 0b0_0000_111; + const EXP_MASK: Self::Int = 0b0_1111_000; + const IMPLICIT_BIT: Self::Int = 0b0_0001_000; + + fn to_bits(self) -> Self::Int { + self.0 + } + + fn to_bits_signed(self) -> Self::SignedInt { + self.0 as i8 + } + + fn is_nan(self) -> bool { + self.0 & Self::EXP_MASK == Self::EXP_MASK && self.0 & Self::SIG_MASK != 0 + } + + fn is_infinite(self) -> bool { + self.0 & Self::EXP_MASK == Self::EXP_MASK && self.0 & Self::SIG_MASK == 0 + } + + fn is_sign_negative(self) -> bool { + self.0 & Self::SIGN_MASK != 0 + } + + fn from_bits(a: Self::Int) -> Self { + Self(a) + } + + fn abs(self) -> Self { + libm::generic::fabs(self) + } + + fn copysign(self, other: Self) -> Self { + libm::generic::copysign(self, other) + } + + fn fma(self, _y: Self, _z: Self) -> Self { + unimplemented!() + } + + fn normalize(_significand: Self::Int) -> (i32, Self::Int) { + unimplemented!() + } +} + +impl f8 { + pub const ALL_LEN: usize = 240; + + /// All non-infinite non-NaN values of `f8` + pub const ALL: [Self; Self::ALL_LEN] = [ + // -m*2^7 + Self(0b1_1110_111), // -240 + Self(0b1_1110_110), + Self(0b1_1110_101), + Self(0b1_1110_100), + Self(0b1_1110_011), + Self(0b1_1110_010), + Self(0b1_1110_001), + Self(0b1_1110_000), // -128 + // -m*2^6 + Self(0b1_1101_111), // -120 + Self(0b1_1101_110), + Self(0b1_1101_101), + Self(0b1_1101_100), + Self(0b1_1101_011), + Self(0b1_1101_010), + Self(0b1_1101_001), + Self(0b1_1101_000), // -64 + // -m*2^5 + Self(0b1_1100_111), // -60 + Self(0b1_1100_110), + Self(0b1_1100_101), + Self(0b1_1100_100), + Self(0b1_1100_011), + Self(0b1_1100_010), + Self(0b1_1100_001), + Self(0b1_1100_000), // -32 + // -m*2^4 + Self(0b1_1011_111), // -30 + Self(0b1_1011_110), + Self(0b1_1011_101), + Self(0b1_1011_100), + Self(0b1_1011_011), + Self(0b1_1011_010), + Self(0b1_1011_001), + Self(0b1_1011_000), // -16 + // -m*2^3 + Self(0b1_1010_111), // -15 + Self(0b1_1010_110), + Self(0b1_1010_101), + Self(0b1_1010_100), + Self(0b1_1010_011), + Self(0b1_1010_010), + Self(0b1_1010_001), + Self(0b1_1010_000), // -8 + // -m*2^2 + Self(0b1_1001_111), // -7.5 + Self(0b1_1001_110), + Self(0b1_1001_101), + Self(0b1_1001_100), + Self(0b1_1001_011), + Self(0b1_1001_010), + Self(0b1_1001_001), + Self(0b1_1001_000), // -4 + // -m*2^1 + Self(0b1_1000_111), // -3.75 + Self(0b1_1000_110), + Self(0b1_1000_101), + Self(0b1_1000_100), + Self(0b1_1000_011), + Self(0b1_1000_010), + Self(0b1_1000_001), + Self(0b1_1000_000), // -2 + // -m*2^0 + Self(0b1_0111_111), // -1.875 + Self(0b1_0111_110), + Self(0b1_0111_101), + Self(0b1_0111_100), + Self(0b1_0111_011), + Self(0b1_0111_010), + Self(0b1_0111_001), + Self(0b1_0111_000), // -1 + // -m*2^-1 + Self(0b1_0110_111), // −0.9375 + Self(0b1_0110_110), + Self(0b1_0110_101), + Self(0b1_0110_100), + Self(0b1_0110_011), + Self(0b1_0110_010), + Self(0b1_0110_001), + Self(0b1_0110_000), // -0.5 + // -m*2^-2 + Self(0b1_0101_111), // −0.46875 + Self(0b1_0101_110), + Self(0b1_0101_101), + Self(0b1_0101_100), + Self(0b1_0101_011), + Self(0b1_0101_010), + Self(0b1_0101_001), + Self(0b1_0101_000), // -0.25 + // -m*2^-3 + Self(0b1_0100_111), // −0.234375 + Self(0b1_0100_110), + Self(0b1_0100_101), + Self(0b1_0100_100), + Self(0b1_0100_011), + Self(0b1_0100_010), + Self(0b1_0100_001), + Self(0b1_0100_000), // -0.125 + // -m*2^-4 + Self(0b1_0011_111), // −0.1171875 + Self(0b1_0011_110), + Self(0b1_0011_101), + Self(0b1_0011_100), + Self(0b1_0011_011), + Self(0b1_0011_010), + Self(0b1_0011_001), + Self(0b1_0011_000), // −0.0625 + // -m*2^-5 + Self(0b1_0010_111), // −0.05859375 + Self(0b1_0010_110), + Self(0b1_0010_101), + Self(0b1_0010_100), + Self(0b1_0010_011), + Self(0b1_0010_010), + Self(0b1_0010_001), + Self(0b1_0010_000), // −0.03125 + // -m*2^-6 + Self(0b1_0001_111), // −0.029296875 + Self(0b1_0001_110), + Self(0b1_0001_101), + Self(0b1_0001_100), + Self(0b1_0001_011), + Self(0b1_0001_010), + Self(0b1_0001_001), + Self(0b1_0001_000), // −0.015625 + // -m*2^-7 subnormal numbers + Self(0b1_0000_111), // −0.013671875 + Self(0b1_0000_110), + Self(0b1_0000_101), + Self(0b1_0000_100), + Self(0b1_0000_011), + Self(0b1_0000_010), + Self(0b1_0000_001), // −0.001953125 + // Zeroes + Self(0b1_0000_000), // -0.0 + Self(0b0_0000_000), // 0.0 + // m*2^-7 // subnormal numbers + Self(0b0_0000_001), + Self(0b0_0000_010), + Self(0b0_0000_011), + Self(0b0_0000_100), + Self(0b0_0000_101), + Self(0b0_0000_110), + Self(0b0_0000_111), // 0.013671875 + // m*2^-6 + Self(0b0_0001_000), // 0.015625 + Self(0b0_0001_001), + Self(0b0_0001_010), + Self(0b0_0001_011), + Self(0b0_0001_100), + Self(0b0_0001_101), + Self(0b0_0001_110), + Self(0b0_0001_111), // 0.029296875 + // m*2^-5 + Self(0b0_0010_000), // 0.03125 + Self(0b0_0010_001), + Self(0b0_0010_010), + Self(0b0_0010_011), + Self(0b0_0010_100), + Self(0b0_0010_101), + Self(0b0_0010_110), + Self(0b0_0010_111), // 0.05859375 + // m*2^-4 + Self(0b0_0011_000), // 0.0625 + Self(0b0_0011_001), + Self(0b0_0011_010), + Self(0b0_0011_011), + Self(0b0_0011_100), + Self(0b0_0011_101), + Self(0b0_0011_110), + Self(0b0_0011_111), // 0.1171875 + // m*2^-3 + Self(0b0_0100_000), // 0.125 + Self(0b0_0100_001), + Self(0b0_0100_010), + Self(0b0_0100_011), + Self(0b0_0100_100), + Self(0b0_0100_101), + Self(0b0_0100_110), + Self(0b0_0100_111), // 0.234375 + // m*2^-2 + Self(0b0_0101_000), // 0.25 + Self(0b0_0101_001), + Self(0b0_0101_010), + Self(0b0_0101_011), + Self(0b0_0101_100), + Self(0b0_0101_101), + Self(0b0_0101_110), + Self(0b0_0101_111), // 0.46875 + // m*2^-1 + Self(0b0_0110_000), // 0.5 + Self(0b0_0110_001), + Self(0b0_0110_010), + Self(0b0_0110_011), + Self(0b0_0110_100), + Self(0b0_0110_101), + Self(0b0_0110_110), + Self(0b0_0110_111), // 0.9375 + // m*2^0 + Self(0b0_0111_000), // 1 + Self(0b0_0111_001), + Self(0b0_0111_010), + Self(0b0_0111_011), + Self(0b0_0111_100), + Self(0b0_0111_101), + Self(0b0_0111_110), + Self(0b0_0111_111), // 1.875 + // m*2^1 + Self(0b0_1000_000), // 2 + Self(0b0_1000_001), + Self(0b0_1000_010), + Self(0b0_1000_011), + Self(0b0_1000_100), + Self(0b0_1000_101), + Self(0b0_1000_110), + Self(0b0_1000_111), // 3.75 + // m*2^2 + Self(0b0_1001_000), // 4 + Self(0b0_1001_001), + Self(0b0_1001_010), + Self(0b0_1001_011), + Self(0b0_1001_100), + Self(0b0_1001_101), + Self(0b0_1001_110), + Self(0b0_1001_111), // 7.5 + // m*2^3 + Self(0b0_1010_000), // 8 + Self(0b0_1010_001), + Self(0b0_1010_010), + Self(0b0_1010_011), + Self(0b0_1010_100), + Self(0b0_1010_101), + Self(0b0_1010_110), + Self(0b0_1010_111), // 15 + // m*2^4 + Self(0b0_1011_000), // 16 + Self(0b0_1011_001), + Self(0b0_1011_010), + Self(0b0_1011_011), + Self(0b0_1011_100), + Self(0b0_1011_101), + Self(0b0_1011_110), + Self(0b0_1011_111), // 30 + // m*2^5 + Self(0b0_1100_000), // 32 + Self(0b0_1100_001), + Self(0b0_1100_010), + Self(0b0_1100_011), + Self(0b0_1100_100), + Self(0b0_1100_101), + Self(0b0_1100_110), + Self(0b0_1100_111), // 60 + // m*2^6 + Self(0b0_1101_000), // 64 + Self(0b0_1101_001), + Self(0b0_1101_010), + Self(0b0_1101_011), + Self(0b0_1101_100), + Self(0b0_1101_101), + Self(0b0_1101_110), + Self(0b0_1101_111), // 120 + // m*2^7 + Self(0b0_1110_000), // 128 + Self(0b0_1110_001), + Self(0b0_1110_010), + Self(0b0_1110_011), + Self(0b0_1110_100), + Self(0b0_1110_101), + Self(0b0_1110_110), + Self(0b0_1110_111), // 240 + ]; +} + +impl ops::Add for f8 { + type Output = Self; + fn add(self, _rhs: Self) -> Self::Output { + unimplemented!() + } +} + +impl ops::Sub for f8 { + type Output = Self; + fn sub(self, _rhs: Self) -> Self::Output { + unimplemented!() + } +} +impl ops::Mul for f8 { + type Output = Self; + fn mul(self, _rhs: Self) -> Self::Output { + unimplemented!() + } +} +impl ops::Div for f8 { + type Output = Self; + fn div(self, _rhs: Self) -> Self::Output { + unimplemented!() + } +} + +impl ops::Neg for f8 { + type Output = Self; + fn neg(self) -> Self::Output { + Self(self.0 ^ Self::SIGN_MASK) + } +} + +impl ops::Rem for f8 { + type Output = Self; + fn rem(self, _rhs: Self) -> Self::Output { + unimplemented!() + } +} + +impl ops::AddAssign for f8 { + fn add_assign(&mut self, _rhs: Self) { + unimplemented!() + } +} + +impl ops::SubAssign for f8 { + fn sub_assign(&mut self, _rhs: Self) { + unimplemented!() + } +} + +impl ops::MulAssign for f8 { + fn mul_assign(&mut self, _rhs: Self) { + unimplemented!() + } +} + +impl cmp::PartialEq for f8 { + fn eq(&self, other: &Self) -> bool { + if self.is_nan() || other.is_nan() { + false + } else if self.abs().to_bits() | other.abs().to_bits() == 0 { + true + } else { + self.0 == other.0 + } + } +} +impl cmp::PartialOrd for f8 { + fn partial_cmp(&self, other: &Self) -> Option<Ordering> { + let inf_rep = f8::EXP_MASK; + + let a_abs = self.abs().to_bits(); + let b_abs = other.abs().to_bits(); + + // If either a or b is NaN, they are unordered. + if a_abs > inf_rep || b_abs > inf_rep { + return None; + } + + // If a and b are both zeros, they are equal. + if a_abs | b_abs == 0 { + return Some(Ordering::Equal); + } + + let a_srep = self.to_bits_signed(); + let b_srep = other.to_bits_signed(); + let res = a_srep.cmp(&b_srep); + + if a_srep & b_srep >= 0 { + // If at least one of a and b is positive, we get the same result comparing + // a and b as signed integers as we would with a fp_ting-point compare. + Some(res) + } else { + // Otherwise, both are negative, so we need to flip the sense of the + // comparison to get the correct result. + Some(res.reverse()) + } + } +} +impl fmt::Display for f8 { + fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result { + unimplemented!() + } +} + +impl fmt::Debug for f8 { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Binary::fmt(self, f) + } +} + +impl fmt::Binary for f8 { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let v = self.0; + write!( + f, + "0b{:b}_{:04b}_{:03b}", + v >> 7, + (v & Self::EXP_MASK) >> Self::SIG_BITS, + v & Self::SIG_MASK + ) + } +} + +impl fmt::LowerHex for f8 { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.0.fmt(f) + } +} + +pub const fn hf8(s: &str) -> f8 { + let Ok(bits) = libm::support::hex_float::parse_hex_exact(s, 8, 3) else { + panic!() + }; + f8(bits as u8) +} |