add f16

Author: usamoi

build.rs

@@ -4,4 +4,8 @@ fn main() {
     ac.emit_expression_cfg("1f64.total_cmp(&2f64)", "has_total_cmp"); // 1.62
 
     autocfg::rerun_path("build.rs");
+
+    // FIXME: use autocfg to emit it
+    println!("cargo:rustc-cfg=has_f16");
+    println!("cargo:rustc-check-cfg=cfg(has_f16)");
 }

src/bounds.rs

@@ -1,3 +1,5 @@
+#[cfg(has_f16)]
+use core::f16;
 use core::num::Wrapping;
 use core::{f32, f64};
 use core::{i128, i16, i32, i64, i8, isize};
@@ -77,7 +79,10 @@ impl<T: Bounded> Bounded for Wrapping<T> {
     }
 }
 
+#[cfg(has_f16)]
+bounded_impl!(f16, f16::MIN, f16::MAX);
 bounded_impl!(f32, f32::MIN, f32::MAX);
+bounded_impl!(f64, f64::MIN, f64::MAX);
 
 macro_rules! for_each_tuple_ {
     ( $m:ident !! ) => (
@@ -110,7 +115,6 @@ macro_rules! bounded_tuple {
 }
 
 for_each_tuple!(bounded_tuple);
-bounded_impl!(f64, f64::MIN, f64::MAX);
 
 #[test]
 fn wrapping_bounded() {

src/cast.rs

@@ -1,3 +1,5 @@
+#[cfg(has_f16)]
+use core::f16;
 use core::mem::size_of;
 use core::num::Wrapping;
 use core::{f32, f64};
@@ -101,6 +103,15 @@ pub trait ToPrimitive {
         self.to_u64().map(From::from)
     }
 
+    /// Converts the value of `self` to an `f16`. Overflows may map to positive
+    /// or negative inifinity, otherwise `None` is returned if the value cannot
+    /// be represented by an `f16`.
+    #[cfg(has_f16)]
+    #[inline]
+    fn to_f16(&self) -> Option<f16> {
+        self.to_f64().as_ref().and_then(ToPrimitive::to_f16)
+    }
+
     /// Converts the value of `self` to an `f32`. Overflows may map to positive
     /// or negative inifinity, otherwise `None` is returned if the value cannot
     /// be represented by an `f32`.
@@ -177,6 +188,11 @@ macro_rules! impl_to_primitive_int {
                 fn to_u128 -> u128;
             }
 
+            #[cfg(has_f16)]
+            #[inline]
+            fn to_f16(&self) -> Option<f16> {
+                Some(*self as f16)
+            }
             #[inline]
             fn to_f32(&self) -> Option<f32> {
                 Some(*self as f32)
@@ -247,6 +263,11 @@ macro_rules! impl_to_primitive_uint {
                 fn to_u128 -> u128;
             }
 
+            #[cfg(has_f16)]
+            #[inline]
+            fn to_f16(&self) -> Option<f16> {
+                Some(*self as f16)
+            }
             #[inline]
             fn to_f32(&self) -> Option<f32> {
                 Some(*self as f32)
@@ -267,8 +288,9 @@ impl_to_primitive_uint!(u64);
 impl_to_primitive_uint!(u128);
 
 macro_rules! impl_to_primitive_float_to_float {
-    ($SrcT:ident : $( fn $method:ident -> $DstT:ident ; )*) => {$(
+    ($SrcT:ident : $( $(#[$cfg:meta])* fn $method:ident -> $DstT:ident ; )*) => {$(
         #[inline]
+        $(#[$cfg])*
         fn $method(&self) -> Option<$DstT> {
             // We can safely cast all values, whether NaN, +-inf, or finite.
             // Finite values that are reducing size may saturate to +-inf.
@@ -364,13 +386,17 @@ macro_rules! impl_to_primitive_float {
             }
 
             impl_to_primitive_float_to_float! { $T:
+                #[cfg(has_f16)]
+                fn to_f16 -> f16;
                 fn to_f32 -> f32;
                 fn to_f64 -> f64;
             }
         }
     };
 }
 
+#[cfg(has_f16)]
+impl_to_primitive_float!(f16);
 impl_to_primitive_float!(f32);
 impl_to_primitive_float!(f64);
 
@@ -469,6 +495,14 @@ pub trait FromPrimitive: Sized {
         n.to_u64().and_then(FromPrimitive::from_u64)
     }
 
+    /// Converts a `f16` to return an optional value of this type. If the
+    /// value cannot be represented by this type, then `None` is returned.
+    #[cfg(has_f16)]
+    #[inline]
+    fn from_f16(n: f16) -> Option<Self> {
+        FromPrimitive::from_f64(n as f64)
+    }
+
     /// Converts a `f32` to return an optional value of this type. If the
     /// value cannot be represented by this type, then `None` is returned.
     #[inline]
@@ -545,6 +579,11 @@ macro_rules! impl_from_primitive {
                 n.$to_ty()
             }
 
+            #[cfg(has_f16)]
+            #[inline]
+            fn from_f16(n: f16) -> Option<$T> {
+                n.$to_ty()
+            }
             #[inline]
             fn from_f32(n: f32) -> Option<$T> {
                 n.$to_ty()
@@ -569,6 +608,8 @@ impl_from_primitive!(u16, to_u16);
 impl_from_primitive!(u32, to_u32);
 impl_from_primitive!(u64, to_u64);
 impl_from_primitive!(u128, to_u128);
+#[cfg(has_f16)]
+impl_from_primitive!(f16, to_f16);
 impl_from_primitive!(f32, to_f32);
 impl_from_primitive!(f64, to_f64);
 
@@ -598,6 +639,8 @@ impl<T: ToPrimitive> ToPrimitive for Wrapping<T> {
         fn to_u64 -> u64;
         fn to_u128 -> u128;
 
+        #[cfg(has_f16)]
+        fn to_f16 -> f16;
         fn to_f32 -> f32;
         fn to_f64 -> f64;
     }
@@ -629,6 +672,8 @@ impl<T: FromPrimitive> FromPrimitive for Wrapping<T> {
         fn from_u64(u64);
         fn from_u128(u128);
 
+        #[cfg(has_f16)]
+        fn from_f16(f16);
         fn from_f32(f32);
         fn from_f64(f64);
     }
@@ -692,6 +737,8 @@ impl_num_cast!(i32, to_i32);
 impl_num_cast!(i64, to_i64);
 impl_num_cast!(i128, to_i128);
 impl_num_cast!(isize, to_isize);
+#[cfg(has_f16)]
+impl_num_cast!(f16, to_f16);
 impl_num_cast!(f32, to_f32);
 impl_num_cast!(f64, to_f64);
 
@@ -742,29 +789,31 @@ macro_rules! impl_as_primitive {
             #[inline] fn as_(self) -> $U { self as $U }
         }
     };
-    (@ $T: ty => { $( $U: ty ),* } ) => {$(
-        impl_as_primitive!(@ $T => impl $U);
+    (@ $T: ty => { $( $(#[$cfg:meta])* $U: ty ),* } ) => {$(
+        impl_as_primitive!(@ $T => $(#[$cfg])* impl $U);
     )*};
-    ($T: ty => { $( $U: ty ),* } ) => {
-        impl_as_primitive!(@ $T => { $( $U ),* });
+    ($T: ty => { $( $(#[$cfg:meta])* $U: ty ),* } ) => {
+        impl_as_primitive!(@ $T => { $( $(#[$cfg])* $U ),* });
         impl_as_primitive!(@ $T => { u8, u16, u32, u64, u128, usize });
         impl_as_primitive!(@ $T => { i8, i16, i32, i64, i128, isize });
     };
 }
 
-impl_as_primitive!(u8 => { char, f32, f64 });
-impl_as_primitive!(i8 => { f32, f64 });
-impl_as_primitive!(u16 => { f32, f64 });
-impl_as_primitive!(i16 => { f32, f64 });
-impl_as_primitive!(u32 => { f32, f64 });
-impl_as_primitive!(i32 => { f32, f64 });
-impl_as_primitive!(u64 => { f32, f64 });
-impl_as_primitive!(i64 => { f32, f64 });
-impl_as_primitive!(u128 => { f32, f64 });
-impl_as_primitive!(i128 => { f32, f64 });
-impl_as_primitive!(usize => { f32, f64 });
-impl_as_primitive!(isize => { f32, f64 });
-impl_as_primitive!(f32 => { f32, f64 });
-impl_as_primitive!(f64 => { f32, f64 });
+impl_as_primitive!(u8 => { char, #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(i8 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(u16 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(i16 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(u32 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(i32 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(u64 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(i64 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(u128 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(i128 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(usize => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(isize => { #[cfg(has_f16)] f16, f32, f64 });
+#[cfg(has_f16)]
+impl_as_primitive!(f16 => { f16, f32, f64 });
+impl_as_primitive!(f32 => { #[cfg(has_f16)] f16, f32, f64 });
+impl_as_primitive!(f64 => { #[cfg(has_f16)] f16, f32, f64 });
 impl_as_primitive!(char => { char });
 impl_as_primitive!(bool => {});