diff options
| -rw-r--r-- | library/compiler-builtins/libm/src/math/support/hex_float.rs | 183 | ||||
| -rw-r--r-- | library/compiler-builtins/libm/src/math/support/mod.rs | 2 |
2 files changed, 181 insertions, 4 deletions
diff --git a/library/compiler-builtins/libm/src/math/support/hex_float.rs b/library/compiler-builtins/libm/src/math/support/hex_float.rs index 6eb1bd67a99..da41622f296 100644 --- a/library/compiler-builtins/libm/src/math/support/hex_float.rs +++ b/library/compiler-builtins/libm/src/math/support/hex_float.rs @@ -2,7 +2,9 @@ #![allow(dead_code)] // FIXME: remove once this gets used -use super::{f32_from_bits, f64_from_bits}; +use core::fmt; + +use super::{Float, f32_from_bits, f64_from_bits}; /// Construct a 16-bit float from hex float representation (C-style) #[cfg(f16_enabled)] @@ -42,7 +44,7 @@ pub const fn parse_any(s: &str, bits: u32, sig_bits: u32) -> u128 { Parsed::Finite { neg, sig, exp } => (neg, sig, exp), Parsed::Infinite { neg } => return ((neg as u128) << (bits - 1)) | exp_mask, Parsed::Nan { neg } => { - return ((neg as u128) << (bits - 1)) | exp_mask | 1 << (sig_bits - 1); + return ((neg as u128) << (bits - 1)) | exp_mask | (1 << (sig_bits - 1)); } }; @@ -206,8 +208,107 @@ const fn u128_ilog2(v: u128) -> u32 { u128::BITS - 1 - v.leading_zeros() } +/// Format a floating point number as its IEEE hex (`%a`) representation. +pub struct Hexf<F>(pub F); + +// Adapted from https://github.com/ericseppanen/hexfloat2/blob/a5c27932f0ff/src/format.rs +fn fmt_any_hex<F: Float>(x: &F, f: &mut fmt::Formatter<'_>) -> fmt::Result { + if x.is_sign_negative() { + write!(f, "-")?; + } + + if x.is_nan() { + return write!(f, "NaN"); + } else if x.is_infinite() { + return write!(f, "inf"); + } else if *x == F::ZERO { + return write!(f, "0x0p+0"); + } + + let mut exponent = x.exp_unbiased(); + let sig = x.to_bits() & F::SIG_MASK; + + let bias = F::EXP_BIAS as i32; + // The mantissa MSB needs to be shifted up to the nearest nibble. + let mshift = (4 - (F::SIG_BITS % 4)) % 4; + let sig = sig << mshift; + // The width is rounded up to the nearest char (4 bits) + let mwidth = (F::SIG_BITS as usize + 3) / 4; + let leading = if exponent == -bias { + // subnormal number means we shift our output by 1 bit. + exponent += 1; + "0." + } else { + "1." + }; + + write!(f, "0x{leading}{sig:0mwidth$x}p{exponent:+}") +} + +#[cfg(f16_enabled)] +impl fmt::LowerHex for Hexf<f16> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt_any_hex(&self.0, f) + } +} + +impl fmt::LowerHex for Hexf<f32> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt_any_hex(&self.0, f) + } +} + +impl fmt::LowerHex for Hexf<f64> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt_any_hex(&self.0, f) + } +} + +#[cfg(f128_enabled)] +impl fmt::LowerHex for Hexf<f128> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt_any_hex(&self.0, f) + } +} + +impl fmt::LowerHex for Hexf<i32> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::LowerHex::fmt(&self.0, f) + } +} + +impl<T1, T2> fmt::LowerHex for Hexf<(T1, T2)> +where + T1: Copy, + T2: Copy, + Hexf<T1>: fmt::LowerHex, + Hexf<T2>: fmt::LowerHex, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "({:x}, {:x})", Hexf(self.0.0), Hexf(self.0.1)) + } +} + +impl<T> fmt::Debug for Hexf<T> +where + Hexf<T>: fmt::LowerHex, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::LowerHex::fmt(self, f) + } +} + +impl<T> fmt::Display for Hexf<T> +where + Hexf<T>: fmt::LowerHex, +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::LowerHex::fmt(self, f) + } +} + #[cfg(test)] -mod tests { +mod parse_tests { extern crate std; use std::{format, println}; @@ -666,3 +767,79 @@ mod tests_panicking { #[cfg(f128_enabled)] f128_tests!(); } + +#[cfg(test)] +mod print_tests { + extern crate std; + use std::string::ToString; + + use super::*; + + #[test] + #[cfg(f16_enabled)] + fn test_f16() { + use std::format; + // Exhaustively check that `f16` roundtrips. + for x in 0..=u16::MAX { + let f = f16::from_bits(x); + let s = format!("{}", Hexf(f)); + let from_s = hf16(&s); + + if f.is_nan() && from_s.is_nan() { + continue; + } + + assert_eq!( + f.to_bits(), + from_s.to_bits(), + "{f:?} formatted as {s} but parsed as {from_s:?}" + ); + } + } + + #[test] + fn spot_checks() { + assert_eq!(Hexf(f32::MAX).to_string(), "0x1.fffffep+127"); + assert_eq!(Hexf(f64::MAX).to_string(), "0x1.fffffffffffffp+1023"); + + assert_eq!(Hexf(f32::MIN).to_string(), "-0x1.fffffep+127"); + assert_eq!(Hexf(f64::MIN).to_string(), "-0x1.fffffffffffffp+1023"); + + assert_eq!(Hexf(f32::ZERO).to_string(), "0x0p+0"); + assert_eq!(Hexf(f64::ZERO).to_string(), "0x0p+0"); + + assert_eq!(Hexf(f32::NEG_ZERO).to_string(), "-0x0p+0"); + assert_eq!(Hexf(f64::NEG_ZERO).to_string(), "-0x0p+0"); + + assert_eq!(Hexf(f32::NAN).to_string(), "NaN"); + assert_eq!(Hexf(f64::NAN).to_string(), "NaN"); + + assert_eq!(Hexf(f32::INFINITY).to_string(), "inf"); + assert_eq!(Hexf(f64::INFINITY).to_string(), "inf"); + + assert_eq!(Hexf(f32::NEG_INFINITY).to_string(), "-inf"); + assert_eq!(Hexf(f64::NEG_INFINITY).to_string(), "-inf"); + + #[cfg(f16_enabled)] + { + assert_eq!(Hexf(f16::MAX).to_string(), "0x1.ffcp+15"); + assert_eq!(Hexf(f16::MIN).to_string(), "-0x1.ffcp+15"); + assert_eq!(Hexf(f16::ZERO).to_string(), "0x0p+0"); + assert_eq!(Hexf(f16::NEG_ZERO).to_string(), "-0x0p+0"); + assert_eq!(Hexf(f16::NAN).to_string(), "NaN"); + assert_eq!(Hexf(f16::INFINITY).to_string(), "inf"); + assert_eq!(Hexf(f16::NEG_INFINITY).to_string(), "-inf"); + } + + #[cfg(f128_enabled)] + { + assert_eq!(Hexf(f128::MAX).to_string(), "0x1.ffffffffffffffffffffffffffffp+16383"); + assert_eq!(Hexf(f128::MIN).to_string(), "-0x1.ffffffffffffffffffffffffffffp+16383"); + assert_eq!(Hexf(f128::ZERO).to_string(), "0x0p+0"); + assert_eq!(Hexf(f128::NEG_ZERO).to_string(), "-0x0p+0"); + assert_eq!(Hexf(f128::NAN).to_string(), "NaN"); + assert_eq!(Hexf(f128::INFINITY).to_string(), "inf"); + assert_eq!(Hexf(f128::NEG_INFINITY).to_string(), "-inf"); + } + } +} diff --git a/library/compiler-builtins/libm/src/math/support/mod.rs b/library/compiler-builtins/libm/src/math/support/mod.rs index b82a2ea0540..d471c5b7013 100644 --- a/library/compiler-builtins/libm/src/math/support/mod.rs +++ b/library/compiler-builtins/libm/src/math/support/mod.rs @@ -13,7 +13,7 @@ pub use hex_float::hf16; #[cfg(f128_enabled)] pub use hex_float::hf128; #[allow(unused_imports)] -pub use hex_float::{hf32, hf64}; +pub use hex_float::{Hexf, hf32, hf64}; pub use int_traits::{CastFrom, CastInto, DInt, HInt, Int, MinInt}; /// Hint to the compiler that the current path is cold. |