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Introduce a trait constant for the minimum positive normal value

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This commit is contained in:
Trevor Gross 2025-02-10 08:17:57 +00:00
parent 2f0685a9a2
commit 35f5731d62
2 changed files with 10 additions and 0 deletions
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1
library/compiler-builtins/libm/crates/libm-test/src/f8_impl.rs
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@ -32,6 +32,7 @@ impl Float for f8 {
const INFINITY: Self = Self(0b0_1111_000);
const NEG_INFINITY: Self = Self(0b1_1111_000);
const NAN: Self = Self(0b0_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;

9
library/compiler-builtins/libm/src/math/support/float_traits.rs
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@ -41,6 +41,8 @@ pub trait Float:
const NEG_PI: Self;
const FRAC_PI_2: Self;
const MIN_POSITIVE_NORMAL: Self;
/// The bitwidth of the float type
const BITS: u32;
@ -200,6 +202,9 @@ macro_rules! float_impl {
const MIN: Self = $from_bits(Self::Int::MAX & !(1 << Self::SIG_BITS));
const EPSILON: Self = <$ty>::EPSILON;
// Exponent is a 1 in the LSB
const MIN_POSITIVE_NORMAL: Self = $from_bits(1 << Self::SIG_BITS);
const PI: Self = core::$ty::consts::PI;
const NEG_PI: Self = -Self::PI;
const FRAC_PI_2: Self = core::$ty::consts::FRAC_PI_2;
@ -358,6 +363,7 @@ mod tests {
// results for zero and subnormals.
assert_eq!(f16::ZERO.exp_unbiased(), -15);
assert_eq!(f16::from_bits(0x1).exp_unbiased(), -15);
assert_eq!(f16::MIN_POSITIVE, f16::MIN_POSITIVE_NORMAL);
// `from_parts`
assert_biteq!(f16::from_parts(true, f16::EXP_BIAS, 0), -1.0f16);
@ -383,6 +389,7 @@ mod tests {
// results for zero and subnormals.
assert_eq!(f32::ZERO.exp_unbiased(), -127);
assert_eq!(f32::from_bits(0x1).exp_unbiased(), -127);
assert_eq!(f32::MIN_POSITIVE, f32::MIN_POSITIVE_NORMAL);
// `from_parts`
assert_biteq!(f32::from_parts(true, f32::EXP_BIAS, 0), -1.0f32);
@ -409,6 +416,7 @@ mod tests {
// results for zero and subnormals.
assert_eq!(f64::ZERO.exp_unbiased(), -1023);
assert_eq!(f64::from_bits(0x1).exp_unbiased(), -1023);
assert_eq!(f64::MIN_POSITIVE, f64::MIN_POSITIVE_NORMAL);
// `from_parts`
assert_biteq!(f64::from_parts(true, f64::EXP_BIAS, 0), -1.0f64);
@ -436,6 +444,7 @@ mod tests {
// results for zero and subnormals.
assert_eq!(f128::ZERO.exp_unbiased(), -16383);
assert_eq!(f128::from_bits(0x1).exp_unbiased(), -16383);
assert_eq!(f128::MIN_POSITIVE, f128::MIN_POSITIVE_NORMAL);
// `from_parts`
assert_biteq!(f128::from_parts(true, f128::EXP_BIAS, 0), -1.0f128);