diff options
Diffstat (limited to 'library')
| -rw-r--r-- | library/core/src/num/f128.rs | 640 | ||||
| -rw-r--r-- | library/core/src/num/f16.rs | 612 | ||||
| -rw-r--r-- | library/std/src/f128.rs | 30 | ||||
| -rw-r--r-- | library/std/src/f16.rs | 29 |
4 files changed, 1309 insertions, 2 deletions
diff --git a/library/core/src/num/f128.rs b/library/core/src/num/f128.rs index 490d7bd504d..58ed98c888c 100644 --- a/library/core/src/num/f128.rs +++ b/library/core/src/num/f128.rs @@ -11,6 +11,7 @@ #![unstable(feature = "f128", issue = "116909")] +use crate::convert::FloatToInt; use crate::mem; /// Basic mathematical constants. @@ -220,12 +221,50 @@ impl f128 { #[unstable(feature = "f128", issue = "116909")] pub const MAX_10_EXP: i32 = 4_932; + /// Not a Number (NaN). + /// + /// Note that IEEE 754 doesn't define just a single NaN value; + /// a plethora of bit patterns are considered to be NaN. + /// Furthermore, the standard makes a difference + /// between a "signaling" and a "quiet" NaN, + /// and allows inspecting its "payload" (the unspecified bits in the bit pattern). + /// This constant isn't guaranteed to equal to any specific NaN bitpattern, + /// and the stability of its representation over Rust versions + /// and target platforms isn't guaranteed. + #[cfg(not(bootstrap))] + #[allow(clippy::eq_op)] + #[rustc_diagnostic_item = "f128_nan"] + #[unstable(feature = "f128", issue = "116909")] + pub const NAN: f128 = 0.0_f128 / 0.0_f128; + + /// Infinity (∞). + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + pub const INFINITY: f128 = 1.0_f128 / 0.0_f128; + + /// Negative infinity (−∞). + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + pub const NEG_INFINITY: f128 = -1.0_f128 / 0.0_f128; + + /// Sign bit + #[cfg(not(bootstrap))] + pub(crate) const SIGN_MASK: u128 = 0x8000_0000_0000_0000_0000_0000_0000_0000; + + /// Minimum representable positive value (min subnormal) + #[cfg(not(bootstrap))] + const TINY_BITS: u128 = 0x1; + + /// Minimum representable negative value (min negative subnormal) + #[cfg(not(bootstrap))] + const NEG_TINY_BITS: u128 = Self::TINY_BITS | Self::SIGN_MASK; + /// Returns `true` if this value is NaN. /// /// ``` /// #![feature(f128)] /// # // FIXME(f16_f128): remove when `unordtf2` is available - /// # #[cfg(target_arch = "x86_64", target_os = "linux")] { + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { /// /// let nan = f128::NAN; /// let f = 7.0_f128; @@ -243,6 +282,78 @@ impl f128 { self != self } + // FIXME(#50145): `abs` is publicly unavailable in core due to + // concerns about portability, so this implementation is for + // private use internally. + #[inline] + #[cfg(not(bootstrap))] + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + pub(crate) const fn abs_private(self) -> f128 { + // SAFETY: This transmutation is fine. Probably. For the reasons std is using it. + unsafe { + mem::transmute::<u128, f128>(mem::transmute::<f128, u128>(self) & !Self::SIGN_MASK) + } + } + + /// Returns `true` if this value is positive infinity or negative infinity, and + /// `false` otherwise. + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let f = 7.0f128; + /// let inf = f128::INFINITY; + /// let neg_inf = f128::NEG_INFINITY; + /// let nan = f128::NAN; + /// + /// assert!(!f.is_infinite()); + /// assert!(!nan.is_infinite()); + /// + /// assert!(inf.is_infinite()); + /// assert!(neg_inf.is_infinite()); + /// # } + /// ``` + #[inline] + #[must_use] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + pub const fn is_infinite(self) -> bool { + (self == f128::INFINITY) | (self == f128::NEG_INFINITY) + } + + /// Returns `true` if this number is neither infinite nor NaN. + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `lttf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let f = 7.0f128; + /// let inf: f128 = f128::INFINITY; + /// let neg_inf: f128 = f128::NEG_INFINITY; + /// let nan: f128 = f128::NAN; + /// + /// assert!(f.is_finite()); + /// + /// assert!(!nan.is_finite()); + /// assert!(!inf.is_finite()); + /// assert!(!neg_inf.is_finite()); + /// # } + /// ``` + #[inline] + #[must_use] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + pub const fn is_finite(self) -> bool { + // There's no need to handle NaN separately: if self is NaN, + // the comparison is not true, exactly as desired. + self.abs_private() < Self::INFINITY + } + /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with /// positive sign bit and positive infinity. Note that IEEE 754 doesn't assign any /// meaning to the sign bit in case of a NaN, and as Rust doesn't guarantee that @@ -292,6 +403,222 @@ impl f128 { (self.to_bits() & (1 << 127)) != 0 } + /// Returns the least number greater than `self`. + /// + /// Let `TINY` be the smallest representable positive `f128`. Then, + /// - if `self.is_nan()`, this returns `self`; + /// - if `self` is [`NEG_INFINITY`], this returns [`MIN`]; + /// - if `self` is `-TINY`, this returns -0.0; + /// - if `self` is -0.0 or +0.0, this returns `TINY`; + /// - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`]; + /// - otherwise the unique least value greater than `self` is returned. + /// + /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x` + /// is finite `x == x.next_up().next_down()` also holds. + /// + /// ```rust + /// #![feature(f128)] + /// #![feature(float_next_up_down)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// // f128::EPSILON is the difference between 1.0 and the next number up. + /// assert_eq!(1.0f128.next_up(), 1.0 + f128::EPSILON); + /// // But not for most numbers. + /// assert!(0.1f128.next_up() < 0.1 + f128::EPSILON); + /// assert_eq!(4611686018427387904f128.next_up(), 4611686018427387904.000000000000001); + /// # } + /// ``` + /// + /// [`NEG_INFINITY`]: Self::NEG_INFINITY + /// [`INFINITY`]: Self::INFINITY + /// [`MIN`]: Self::MIN + /// [`MAX`]: Self::MAX + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + // #[unstable(feature = "float_next_up_down", issue = "91399")] + pub fn next_up(self) -> Self { + // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing + // denormals to zero. This is in general unsound and unsupported, but here + // we do our best to still produce the correct result on such targets. + let bits = self.to_bits(); + if self.is_nan() || bits == Self::INFINITY.to_bits() { + return self; + } + + let abs = bits & !Self::SIGN_MASK; + let next_bits = if abs == 0 { + Self::TINY_BITS + } else if bits == abs { + bits + 1 + } else { + bits - 1 + }; + Self::from_bits(next_bits) + } + + /// Returns the greatest number less than `self`. + /// + /// Let `TINY` be the smallest representable positive `f128`. Then, + /// - if `self.is_nan()`, this returns `self`; + /// - if `self` is [`INFINITY`], this returns [`MAX`]; + /// - if `self` is `TINY`, this returns 0.0; + /// - if `self` is -0.0 or +0.0, this returns `-TINY`; + /// - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`]; + /// - otherwise the unique greatest value less than `self` is returned. + /// + /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x` + /// is finite `x == x.next_down().next_up()` also holds. + /// + /// ```rust + /// #![feature(f128)] + /// #![feature(float_next_up_down)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let x = 1.0f128; + /// // Clamp value into range [0, 1). + /// let clamped = x.clamp(0.0, 1.0f128.next_down()); + /// assert!(clamped < 1.0); + /// assert_eq!(clamped.next_up(), 1.0); + /// # } + /// ``` + /// + /// [`NEG_INFINITY`]: Self::NEG_INFINITY + /// [`INFINITY`]: Self::INFINITY + /// [`MIN`]: Self::MIN + /// [`MAX`]: Self::MAX + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + // #[unstable(feature = "float_next_up_down", issue = "91399")] + pub fn next_down(self) -> Self { + // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing + // denormals to zero. This is in general unsound and unsupported, but here + // we do our best to still produce the correct result on such targets. + let bits = self.to_bits(); + if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() { + return self; + } + + let abs = bits & !Self::SIGN_MASK; + let next_bits = if abs == 0 { + Self::NEG_TINY_BITS + } else if bits == abs { + bits - 1 + } else { + bits + 1 + }; + Self::from_bits(next_bits) + } + + /// Takes the reciprocal (inverse) of a number, `1/x`. + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let x = 2.0_f128; + /// let abs_difference = (x.recip() - (1.0 / x)).abs(); + /// + /// assert!(abs_difference <= f128::EPSILON); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn recip(self) -> Self { + 1.0 / self + } + + /// Converts radians to degrees. + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let angle = std::f128::consts::PI; + /// + /// let abs_difference = (angle.to_degrees() - 180.0).abs(); + /// assert!(abs_difference <= f128::EPSILON); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_degrees(self) -> Self { + // Use a literal for better precision. + const PIS_IN_180: f128 = 57.2957795130823208767981548141051703324054724665643215491602_f128; + self * PIS_IN_180 + } + + /// Converts degrees to radians. + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let angle = 180.0f128; + /// + /// let abs_difference = (angle.to_radians() - std::f128::consts::PI).abs(); + /// + /// assert!(abs_difference <= 1e-30); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_radians(self) -> f128 { + // Use a literal for better precision. + const RADS_PER_DEG: f128 = + 0.0174532925199432957692369076848861271344287188854172545609719_f128; + self * RADS_PER_DEG + } + + /// Rounds toward zero and converts to any primitive integer type, + /// assuming that the value is finite and fits in that type. + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `float*itf` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let value = 4.6_f128; + /// let rounded = unsafe { value.to_int_unchecked::<u16>() }; + /// assert_eq!(rounded, 4); + /// + /// let value = -128.9_f128; + /// let rounded = unsafe { value.to_int_unchecked::<i8>() }; + /// assert_eq!(rounded, i8::MIN); + /// # } + /// ``` + /// + /// # Safety + /// + /// The value must: + /// + /// * Not be `NaN` + /// * Not be infinite + /// * Be representable in the return type `Int`, after truncating off its fractional part + #[inline] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub unsafe fn to_int_unchecked<Int>(self) -> Int + where + Self: FloatToInt<Int>, + { + // SAFETY: the caller must uphold the safety contract for + // `FloatToInt::to_int_unchecked`. + unsafe { FloatToInt::<Int>::to_int_unchecked(self) } + } + /// Raw transmutation to `u128`. /// /// This is currently identical to `transmute::<f128, u128>(self)` on all platforms. @@ -367,4 +694,315 @@ impl f128 { // Stability concerns. unsafe { mem::transmute(v) } } + + /// Return the memory representation of this floating point number as a byte array in + /// big-endian (network) byte order. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// + /// let bytes = 12.5f128.to_be_bytes(); + /// assert_eq!( + /// bytes, + /// [0x40, 0x02, 0x90, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00] + /// ); + /// ``` + #[inline] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_be_bytes(self) -> [u8; 16] { + self.to_bits().to_be_bytes() + } + + /// Return the memory representation of this floating point number as a byte array in + /// little-endian byte order. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// + /// let bytes = 12.5f128.to_le_bytes(); + /// assert_eq!( + /// bytes, + /// [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x90, 0x02, 0x40] + /// ); + /// ``` + #[inline] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_le_bytes(self) -> [u8; 16] { + self.to_bits().to_le_bytes() + } + + /// Return the memory representation of this floating point number as a byte array in + /// native byte order. + /// + /// As the target platform's native endianness is used, portable code + /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead. + /// + /// [`to_be_bytes`]: f128::to_be_bytes + /// [`to_le_bytes`]: f128::to_le_bytes + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// + /// let bytes = 12.5f128.to_ne_bytes(); + /// assert_eq!( + /// bytes, + /// if cfg!(target_endian = "big") { + /// [0x40, 0x02, 0x90, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00] + /// } else { + /// [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x90, 0x02, 0x40] + /// } + /// ); + /// ``` + #[inline] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_ne_bytes(self) -> [u8; 16] { + self.to_bits().to_ne_bytes() + } + + /// Create a floating point value from its representation as a byte array in big endian. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let value = f128::from_be_bytes( + /// [0x40, 0x02, 0x90, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00] + /// ); + /// assert_eq!(value, 12.5); + /// # } + /// ``` + #[inline] + #[must_use] + #[unstable(feature = "f128", issue = "116909")] + pub fn from_be_bytes(bytes: [u8; 16]) -> Self { + Self::from_bits(u128::from_be_bytes(bytes)) + } + + /// Create a floating point value from its representation as a byte array in little endian. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let value = f128::from_le_bytes( + /// [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x90, 0x02, 0x40] + /// ); + /// assert_eq!(value, 12.5); + /// # } + /// ``` + #[inline] + #[must_use] + #[unstable(feature = "f128", issue = "116909")] + pub fn from_le_bytes(bytes: [u8; 16]) -> Self { + Self::from_bits(u128::from_le_bytes(bytes)) + } + + /// Create a floating point value from its representation as a byte array in native endian. + /// + /// As the target platform's native endianness is used, portable code + /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as + /// appropriate instead. + /// + /// [`from_be_bytes`]: f128::from_be_bytes + /// [`from_le_bytes`]: f128::from_le_bytes + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `eqtf2` is available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let value = f128::from_ne_bytes(if cfg!(target_endian = "big") { + /// [0x40, 0x02, 0x90, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00] + /// } else { + /// [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + /// 0x00, 0x00, 0x00, 0x00, 0x00, 0x90, 0x02, 0x40] + /// }); + /// assert_eq!(value, 12.5); + /// # } + /// ``` + #[inline] + #[must_use] + #[unstable(feature = "f128", issue = "116909")] + pub fn from_ne_bytes(bytes: [u8; 16]) -> Self { + Self::from_bits(u128::from_ne_bytes(bytes)) + } + + /// Return the ordering between `self` and `other`. + /// + /// Unlike the standard partial comparison between floating point numbers, + /// this comparison always produces an ordering in accordance to + /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision) + /// floating point standard. The values are ordered in the following sequence: + /// + /// - negative quiet NaN + /// - negative signaling NaN + /// - negative infinity + /// - negative numbers + /// - negative subnormal numbers + /// - negative zero + /// - positive zero + /// - positive subnormal numbers + /// - positive numbers + /// - positive infinity + /// - positive signaling NaN + /// - positive quiet NaN. + /// + /// The ordering established by this function does not always agree with the + /// [`PartialOrd`] and [`PartialEq`] implementations of `f128`. For example, + /// they consider negative and positive zero equal, while `total_cmp` + /// doesn't. + /// + /// The interpretation of the signaling NaN bit follows the definition in + /// the IEEE 754 standard, which may not match the interpretation by some of + /// the older, non-conformant (e.g. MIPS) hardware implementations. + /// + /// # Example + /// + /// ``` + /// #![feature(f128)] + /// + /// struct GoodBoy { + /// name: &'static str, + /// weight: f128, + /// } + /// + /// let mut bois = vec![ + /// GoodBoy { name: "Pucci", weight: 0.1 }, + /// GoodBoy { name: "Woofer", weight: 99.0 }, + /// GoodBoy { name: "Yapper", weight: 10.0 }, + /// GoodBoy { name: "Chonk", weight: f128::INFINITY }, + /// GoodBoy { name: "Abs. Unit", weight: f128::NAN }, + /// GoodBoy { name: "Floaty", weight: -5.0 }, + /// ]; + /// + /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight)); + /// + /// // `f128::NAN` could be positive or negative, which will affect the sort order. + /// if f128::NAN.is_sign_negative() { + /// bois.into_iter().map(|b| b.weight) + /// .zip([f128::NAN, -5.0, 0.1, 10.0, 99.0, f128::INFINITY].iter()) + /// .for_each(|(a, b)| assert_eq!(a.to_bits(), b.to_bits())) + /// } else { + /// bois.into_iter().map(|b| b.weight) + /// .zip([-5.0, 0.1, 10.0, 99.0, f128::INFINITY, f128::NAN].iter()) + /// .for_each(|(a, b)| assert_eq!(a.to_bits(), b.to_bits())) + /// } + /// ``` + #[inline] + #[must_use] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + pub fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering { + let mut left = self.to_bits() as i128; + let mut right = other.to_bits() as i128; + + // In case of negatives, flip all the bits except the sign + // to achieve a similar layout as two's complement integers + // + // Why does this work? IEEE 754 floats consist of three fields: + // Sign bit, exponent and mantissa. The set of exponent and mantissa + // fields as a whole have the property that their bitwise order is + // equal to the numeric magnitude where the magnitude is defined. + // The magnitude is not normally defined on NaN values, but + // IEEE 754 totalOrder defines the NaN values also to follow the + // bitwise order. This leads to order explained in the doc comment. + // However, the representation of magnitude is the same for negative + // and positive numbers – only the sign bit is different. + // To easily compare the floats as signed integers, we need to + // flip the exponent and mantissa bits in case of negative numbers. + // We effectively convert the numbers to "two's complement" form. + // + // To do the flipping, we construct a mask and XOR against it. + // We branchlessly calculate an "all-ones except for the sign bit" + // mask from negative-signed values: right shifting sign-extends + // the integer, so we "fill" the mask with sign bits, and then + // convert to unsigned to push one more zero bit. + // On positive values, the mask is all zeros, so it's a no-op. + left ^= (((left >> 127) as u128) >> 1) as i128; + right ^= (((right >> 127) as u128) >> 1) as i128; + + left.cmp(&right) + } + + /// Restrict a value to a certain interval unless it is NaN. + /// + /// Returns `max` if `self` is greater than `max`, and `min` if `self` is + /// less than `min`. Otherwise this returns `self`. + /// + /// Note that this function returns NaN if the initial value was NaN as + /// well. + /// + /// # Panics + /// + /// Panics if `min > max`, `min` is NaN, or `max` is NaN. + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// # // FIXME(f16_f128): remove when `{eq,gt,unord}tf` are available + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// assert!((-3.0f128).clamp(-2.0, 1.0) == -2.0); + /// assert!((0.0f128).clamp(-2.0, 1.0) == 0.0); + /// assert!((2.0f128).clamp(-2.0, 1.0) == 1.0); + /// assert!((f128::NAN).clamp(-2.0, 1.0).is_nan()); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn clamp(mut self, min: f128, max: f128) -> f128 { + assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}"); + if self < min { + self = min; + } + if self > max { + self = max; + } + self + } } diff --git a/library/core/src/num/f16.rs b/library/core/src/num/f16.rs index 4b0c25fcce9..3c58b0af9c2 100644 --- a/library/core/src/num/f16.rs +++ b/library/core/src/num/f16.rs @@ -11,6 +11,7 @@ #![unstable(feature = "f16", issue = "116909")] +use crate::convert::FloatToInt; use crate::mem; /// Basic mathematical constants. @@ -215,11 +216,49 @@ impl f16 { #[unstable(feature = "f16", issue = "116909")] pub const MAX_10_EXP: i32 = 4; + /// Not a Number (NaN). + /// + /// Note that IEEE 754 doesn't define just a single NaN value; + /// a plethora of bit patterns are considered to be NaN. + /// Furthermore, the standard makes a difference + /// between a "signaling" and a "quiet" NaN, + /// and allows inspecting its "payload" (the unspecified bits in the bit pattern). + /// This constant isn't guaranteed to equal to any specific NaN bitpattern, + /// and the stability of its representation over Rust versions + /// and target platforms isn't guaranteed. + #[cfg(not(bootstrap))] + #[allow(clippy::eq_op)] + #[rustc_diagnostic_item = "f16_nan"] + #[unstable(feature = "f16", issue = "116909")] + pub const NAN: f16 = 0.0_f16 / 0.0_f16; + + /// Infinity (∞). + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + pub const INFINITY: f16 = 1.0_f16 / 0.0_f16; + + /// Negative infinity (−∞). + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + pub const NEG_INFINITY: f16 = -1.0_f16 / 0.0_f16; + + /// Sign bit + #[cfg(not(bootstrap))] + const SIGN_MASK: u16 = 0x8000; + + /// Minimum representable positive value (min subnormal) + #[cfg(not(bootstrap))] + const TINY_BITS: u16 = 0x1; + + /// Minimum representable negative value (min negative subnormal) + #[cfg(not(bootstrap))] + const NEG_TINY_BITS: u16 = Self::TINY_BITS | Self::SIGN_MASK; + /// Returns `true` if this value is NaN. /// /// ``` /// #![feature(f16)] - /// # #[cfg(target_arch = "x86_64")] { // FIXME(f16_f128): remove when ABI bugs are fixed + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 /// /// let nan = f16::NAN; /// let f = 7.0_f16; @@ -237,6 +276,74 @@ impl f16 { self != self } + // FIXMxE(#50145): `abs` is publicly unavailable in core due to + // concerns about portability, so this implementation is for + // private use internally. + #[inline] + #[cfg(not(bootstrap))] + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + pub(crate) const fn abs_private(self) -> f16 { + // SAFETY: This transmutation is fine. Probably. For the reasons std is using it. + unsafe { mem::transmute::<u16, f16>(mem::transmute::<f16, u16>(self) & !Self::SIGN_MASK) } + } + + /// Returns `true` if this value is positive infinity or negative infinity, and + /// `false` otherwise. + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 + /// + /// let f = 7.0f16; + /// let inf = f16::INFINITY; + /// let neg_inf = f16::NEG_INFINITY; + /// let nan = f16::NAN; + /// + /// assert!(!f.is_infinite()); + /// assert!(!nan.is_infinite()); + /// + /// assert!(inf.is_infinite()); + /// assert!(neg_inf.is_infinite()); + /// # } + /// ``` + #[inline] + #[must_use] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + pub const fn is_infinite(self) -> bool { + (self == f16::INFINITY) | (self == f16::NEG_INFINITY) + } + + /// Returns `true` if this number is neither infinite nor NaN. + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 + /// + /// let f = 7.0f16; + /// let inf: f16 = f16::INFINITY; + /// let neg_inf: f16 = f16::NEG_INFINITY; + /// let nan: f16 = f16::NAN; + /// + /// assert!(f.is_finite()); + /// + /// assert!(!nan.is_finite()); + /// assert!(!inf.is_finite()); + /// assert!(!neg_inf.is_finite()); + /// # } + /// ``` + #[inline] + #[must_use] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + #[rustc_const_unstable(feature = "const_float_classify", issue = "72505")] + pub const fn is_finite(self) -> bool { + // There's no need to handle NaN separately: if self is NaN, + // the comparison is not true, exactly as desired. + self.abs_private() < Self::INFINITY + } + /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with /// positive sign bit and positive infinity. Note that IEEE 754 doesn't assign any /// meaning to the sign bit in case of a NaN, and as Rust doesn't guarantee that @@ -286,6 +393,220 @@ impl f16 { (self.to_bits() & (1 << 15)) != 0 } + /// Returns the least number greater than `self`. + /// + /// Let `TINY` be the smallest representable positive `f16`. Then, + /// - if `self.is_nan()`, this returns `self`; + /// - if `self` is [`NEG_INFINITY`], this returns [`MIN`]; + /// - if `self` is `-TINY`, this returns -0.0; + /// - if `self` is -0.0 or +0.0, this returns `TINY`; + /// - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`]; + /// - otherwise the unique least value greater than `self` is returned. + /// + /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x` + /// is finite `x == x.next_up().next_down()` also holds. + /// + /// ```rust + /// #![feature(f16)] + /// #![feature(float_next_up_down)] + /// # // FIXME(f16_f128): ABI issues on MSVC + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// // f16::EPSILON is the difference between 1.0 and the next number up. + /// assert_eq!(1.0f16.next_up(), 1.0 + f16::EPSILON); + /// // But not for most numbers. + /// assert!(0.1f16.next_up() < 0.1 + f16::EPSILON); + /// assert_eq!(4356f16.next_up(), 4360.0); + /// # } + /// ``` + /// + /// [`NEG_INFINITY`]: Self::NEG_INFINITY + /// [`INFINITY`]: Self::INFINITY + /// [`MIN`]: Self::MIN + /// [`MAX`]: Self::MAX + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + // #[unstable(feature = "float_next_up_down", issue = "91399")] + pub fn next_up(self) -> Self { + // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing + // denormals to zero. This is in general unsound and unsupported, but here + // we do our best to still produce the correct result on such targets. + let bits = self.to_bits(); + if self.is_nan() || bits == Self::INFINITY.to_bits() { + return self; + } + + let abs = bits & !Self::SIGN_MASK; + let next_bits = if abs == 0 { + Self::TINY_BITS + } else if bits == abs { + bits + 1 + } else { + bits - 1 + }; + Self::from_bits(next_bits) + } + + /// Returns the greatest number less than `self`. + /// + /// Let `TINY` be the smallest representable positive `f16`. Then, + /// - if `self.is_nan()`, this returns `self`; + /// - if `self` is [`INFINITY`], this returns [`MAX`]; + /// - if `self` is `TINY`, this returns 0.0; + /// - if `self` is -0.0 or +0.0, this returns `-TINY`; + /// - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`]; + /// - otherwise the unique greatest value less than `self` is returned. + /// + /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x` + /// is finite `x == x.next_down().next_up()` also holds. + /// + /// ```rust + /// #![feature(f16)] + /// #![feature(float_next_up_down)] + /// # // FIXME(f16_f128): ABI issues on MSVC + /// # #[cfg(all(target_arch = "x86_64", target_os = "linux"))] { + /// + /// let x = 1.0f16; + /// // Clamp value into range [0, 1). + /// let clamped = x.clamp(0.0, 1.0f16.next_down()); + /// assert!(clamped < 1.0); + /// assert_eq!(clamped.next_up(), 1.0); + /// # } + /// ``` + /// + /// [`NEG_INFINITY`]: Self::NEG_INFINITY + /// [`INFINITY`]: Self::INFINITY + /// [`MIN`]: Self::MIN + /// [`MAX`]: Self::MAX + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + // #[unstable(feature = "float_next_up_down", issue = "91399")] + pub fn next_down(self) -> Self { + // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing + // denormals to zero. This is in general unsound and unsupported, but here + // we do our best to still produce the correct result on such targets. + let bits = self.to_bits(); + if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() { + return self; + } + + let abs = bits & !Self::SIGN_MASK; + let next_bits = if abs == 0 { + Self::NEG_TINY_BITS + } else if bits == abs { + bits - 1 + } else { + bits + 1 + }; + Self::from_bits(next_bits) + } + + /// Takes the reciprocal (inverse) of a number, `1/x`. + /// + /// ``` + /// #![feature(f16)] + /// # // FIXME(f16_f128): remove when `extendhfsf2` and `truncsfhf2` are available + /// # #[cfg(target_os = "linux")] { + /// + /// let x = 2.0_f16; + /// let abs_difference = (x.recip() - (1.0 / x)).abs(); + /// + /// assert!(abs_difference <= f16::EPSILON); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn recip(self) -> Self { + 1.0 / self + } + + /// Converts radians to degrees. + /// + /// ``` + /// #![feature(f16)] + /// # // FIXME(f16_f128): remove when `extendhfsf2` and `truncsfhf2` are available + /// # #[cfg(target_os = "linux")] { + /// + /// let angle = std::f16::consts::PI; + /// + /// let abs_difference = (angle.to_degrees() - 180.0).abs(); + /// assert!(abs_difference <= 0.5); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_degrees(self) -> Self { + // Use a literal for better precision. + const PIS_IN_180: f16 = 57.2957795130823208767981548141051703_f16; + self * PIS_IN_180 + } + + /// Converts degrees to radians. + /// + /// ``` + /// #![feature(f16)] + /// # // FIXME(f16_f128): remove when `extendhfsf2` and `truncsfhf2` are available + /// # #[cfg(target_os = "linux")] { + /// + /// let angle = 180.0f16; + /// + /// let abs_difference = (angle.to_radians() - std::f16::consts::PI).abs(); + /// + /// assert!(abs_difference <= 0.01); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_radians(self) -> f16 { + // Use a literal for better precision. + const RADS_PER_DEG: f16 = 0.017453292519943295769236907684886_f16; + self * RADS_PER_DEG + } + + /// Rounds toward zero and converts to any primitive integer type, + /// assuming that the value is finite and fits in that type. + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 + /// + /// let value = 4.6_f16; + /// let rounded = unsafe { value.to_int_unchecked::<u16>() }; + /// assert_eq!(rounded, 4); + /// + /// let value = -128.9_f16; + /// let rounded = unsafe { value.to_int_unchecked::<i8>() }; + /// assert_eq!(rounded, i8::MIN); + /// # } + /// ``` + /// + /// # Safety + /// + /// The value must: + /// + /// * Not be `NaN` + /// * Not be infinite + /// * Be representable in the return type `Int`, after truncating off its fractional part + #[inline] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub unsafe fn to_int_unchecked<Int>(self) -> Int + where + Self: FloatToInt<Int>, + { + // SAFETY: the caller must uphold the safety contract for + // `FloatToInt::to_int_unchecked`. + unsafe { FloatToInt::<Int>::to_int_unchecked(self) } + } + /// Raw transmutation to `u16`. /// /// This is currently identical to `transmute::<f16, u16>(self)` on all platforms. @@ -362,4 +683,293 @@ impl f16 { // Stability concerns. unsafe { mem::transmute(v) } } + + /// Return the memory representation of this floating point number as a byte array in + /// big-endian (network) byte order. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// + /// let bytes = 12.5f16.to_be_bytes(); + /// assert_eq!(bytes, [0x4a, 0x40]); + /// ``` + #[inline] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_be_bytes(self) -> [u8; 2] { + self.to_bits().to_be_bytes() + } + + /// Return the memory representation of this floating point number as a byte array in + /// little-endian byte order. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// + /// let bytes = 12.5f16.to_le_bytes(); + /// assert_eq!(bytes, [0x40, 0x4a]); + /// ``` + #[inline] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_le_bytes(self) -> [u8; 2] { + self.to_bits().to_le_bytes() + } + + /// Return the memory representation of this floating point number as a byte array in + /// native byte order. + /// + /// As the target platform's native endianness is used, portable code + /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead. + /// + /// [`to_be_bytes`]: f16::to_be_bytes + /// [`to_le_bytes`]: f16::to_le_bytes + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// + /// let bytes = 12.5f16.to_ne_bytes(); + /// assert_eq!( + /// bytes, + /// if cfg!(target_endian = "big") { + /// [0x4a, 0x40] + /// } else { + /// [0x40, 0x4a] + /// } + /// ); + /// ``` + #[inline] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "this returns the result of the operation, without modifying the original"] + pub fn to_ne_bytes(self) -> [u8; 2] { + self.to_bits().to_ne_bytes() + } + + /// Create a floating point value from its representation as a byte array in big endian. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 + /// + /// let value = f16::from_be_bytes([0x4a, 0x40]); + /// assert_eq!(value, 12.5); + /// # } + /// ``` + #[inline] + #[must_use] + #[unstable(feature = "f16", issue = "116909")] + pub fn from_be_bytes(bytes: [u8; 2]) -> Self { + Self::from_bits(u16::from_be_bytes(bytes)) + } + + /// Create a floating point value from its representation as a byte array in little endian. + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 + /// + /// let value = f16::from_le_bytes([0x40, 0x4a]); + /// assert_eq!(value, 12.5); + /// # } + /// ``` + #[inline] + #[must_use] + #[unstable(feature = "f16", issue = "116909")] + pub fn from_le_bytes(bytes: [u8; 2]) -> Self { + Self::from_bits(u16::from_le_bytes(bytes)) + } + + /// Create a floating point value from its representation as a byte array in native endian. + /// + /// As the target platform's native endianness is used, portable code + /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as + /// appropriate instead. + /// + /// [`from_be_bytes`]: f16::from_be_bytes + /// [`from_le_bytes`]: f16::from_le_bytes + /// + /// See [`from_bits`](Self::from_bits) for some discussion of the + /// portability of this operation (there are almost no issues). + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 + /// + /// let value = f16::from_ne_bytes(if cfg!(target_endian = "big") { + /// [0x4a, 0x40] + /// } else { + /// [0x40, 0x4a] + /// }); + /// assert_eq!(value, 12.5); + /// # } + /// ``` + #[inline] + #[must_use] + #[unstable(feature = "f16", issue = "116909")] + pub fn from_ne_bytes(bytes: [u8; 2]) -> Self { + Self::from_bits(u16::from_ne_bytes(bytes)) + } + + /// Return the ordering between `self` and `other`. + /// + /// Unlike the standard partial comparison between floating point numbers, + /// this comparison always produces an ordering in accordance to + /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision) + /// floating point standard. The values are ordered in the following sequence: + /// + /// - negative quiet NaN + /// - negative signaling NaN + /// - negative infinity + /// - negative numbers + /// - negative subnormal numbers + /// - negative zero + /// - positive zero + /// - positive subnormal numbers + /// - positive numbers + /// - positive infinity + /// - positive signaling NaN + /// - positive quiet NaN. + /// + /// The ordering established by this function does not always agree with the + /// [`PartialOrd`] and [`PartialEq`] implementations of `f16`. For example, + /// they consider negative and positive zero equal, while `total_cmp` + /// doesn't. + /// + /// The interpretation of the signaling NaN bit follows the definition in + /// the IEEE 754 standard, which may not match the interpretation by some of + /// the older, non-conformant (e.g. MIPS) hardware implementations. + /// + /// # Example + /// + /// ``` + /// #![feature(f16)] + /// + /// struct GoodBoy { + /// name: &'static str, + /// weight: f16, + /// } + /// + /// let mut bois = vec![ + /// GoodBoy { name: "Pucci", weight: 0.1 }, + /// GoodBoy { name: "Woofer", weight: 99.0 }, + /// GoodBoy { name: "Yapper", weight: 10.0 }, + /// GoodBoy { name: "Chonk", weight: f16::INFINITY }, + /// GoodBoy { name: "Abs. Unit", weight: f16::NAN }, + /// GoodBoy { name: "Floaty", weight: -5.0 }, + /// ]; + /// + /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight)); + /// + /// // `f16::NAN` could be positive or negative, which will affect the sort order. + /// if f16::NAN.is_sign_negative() { + /// bois.into_iter().map(|b| b.weight) + /// .zip([f16::NAN, -5.0, 0.1, 10.0, 99.0, f16::INFINITY].iter()) + /// .for_each(|(a, b)| assert_eq!(a.to_bits(), b.to_bits())) + /// } else { + /// bois.into_iter().map(|b| b.weight) + /// .zip([-5.0, 0.1, 10.0, 99.0, f16::INFINITY, f16::NAN].iter()) + /// .for_each(|(a, b)| assert_eq!(a.to_bits(), b.to_bits())) + /// } + /// ``` + #[inline] + #[must_use] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + pub fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering { + let mut left = self.to_bits() as i16; + let mut right = other.to_bits() as i16; + + // In case of negatives, flip all the bits except the sign + // to achieve a similar layout as two's complement integers + // + // Why does this work? IEEE 754 floats consist of three fields: + // Sign bit, exponent and mantissa. The set of exponent and mantissa + // fields as a whole have the property that their bitwise order is + // equal to the numeric magnitude where the magnitude is defined. + // The magnitude is not normally defined on NaN values, but + // IEEE 754 totalOrder defines the NaN values also to follow the + // bitwise order. This leads to order explained in the doc comment. + // However, the representation of magnitude is the same for negative + // and positive numbers – only the sign bit is different. + // To easily compare the floats as signed integers, we need to + // flip the exponent and mantissa bits in case of negative numbers. + // We effectively convert the numbers to "two's complement" form. + // + // To do the flipping, we construct a mask and XOR against it. + // We branchlessly calculate an "all-ones except for the sign bit" + // mask from negative-signed values: right shifting sign-extends + // the integer, so we "fill" the mask with sign bits, and then + // convert to unsigned to push one more zero bit. + // On positive values, the mask is all zeros, so it's a no-op. + left ^= (((left >> 15) as u16) >> 1) as i16; + right ^= (((right >> 15) as u16) >> 1) as i16; + + left.cmp(&right) + } + + /// Restrict a value to a certain interval unless it is NaN. + /// + /// Returns `max` if `self` is greater than `max`, and `min` if `self` is + /// less than `min`. Otherwise this returns `self`. + /// + /// Note that this function returns NaN if the initial value was NaN as + /// well. + /// + /// # Panics + /// + /// Panics if `min > max`, `min` is NaN, or `max` is NaN. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(target_arch = "aarch64")] { // FIXME(f16_F128): rust-lang/rust#123885 + /// + /// assert!((-3.0f16).clamp(-2.0, 1.0) == -2.0); + /// assert!((0.0f16).clamp(-2.0, 1.0) == 0.0); + /// assert!((2.0f16).clamp(-2.0, 1.0) == 1.0); + /// assert!((f16::NAN).clamp(-2.0, 1.0).is_nan()); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn clamp(mut self, min: f16, max: f16) -> f16 { + assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}"); + if self < min { + self = min; + } + if self > max { + self = max; + } + self + } } diff --git a/library/std/src/f128.rs b/library/std/src/f128.rs index 491235a872e..0591c6f517b 100644 --- a/library/std/src/f128.rs +++ b/library/std/src/f128.rs @@ -32,4 +32,34 @@ impl f128 { pub fn powi(self, n: i32) -> f128 { unsafe { intrinsics::powif128(self, n) } } + + /// Computes the absolute value of `self`. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f128)] + /// # #[cfg(reliable_f128)] { // FIXME(f16_f128): reliable_f128 + /// + /// let x = 3.5_f128; + /// let y = -3.5_f128; + /// + /// assert_eq!(x.abs(), x); + /// assert_eq!(y.abs(), -y); + /// + /// assert!(f128::NAN.abs().is_nan()); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f128", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn abs(self) -> Self { + // FIXME(f16_f128): replace with `intrinsics::fabsf128` when available + // We don't do this now because LLVM has lowering bugs for f128 math. + Self::from_bits(self.to_bits() & !(1 << 127)) + } } diff --git a/library/std/src/f16.rs b/library/std/src/f16.rs index 1cb655ffabd..d4851862299 100644 --- a/library/std/src/f16.rs +++ b/library/std/src/f16.rs @@ -32,4 +32,33 @@ impl f16 { pub fn powi(self, n: i32) -> f16 { unsafe { intrinsics::powif16(self, n) } } + + /// Computes the absolute value of `self`. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #[cfg(reliable_f16)] { + /// + /// let x = 3.5_f16; + /// let y = -3.5_f16; + /// + /// assert_eq!(x.abs(), x); + /// assert_eq!(y.abs(), -y); + /// + /// assert!(f16::NAN.abs().is_nan()); + /// # } + /// ``` + #[inline] + #[cfg(not(bootstrap))] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn abs(self) -> Self { + // FIXME(f16_f128): replace with `intrinsics::fabsf16` when available + Self::from_bits(self.to_bits() & !(1 << 15)) + } } |