Implement Standard for SIMD integer types

Author: pitdicker

src/distributions/integer.rs

@@ -12,6 +12,8 @@
 
 use {Rng};
 use distributions::{Distribution, Standard};
+#[cfg(feature="simd_support")]
+use core::simd::*;
 
 impl Distribution<u8> for Standard {
     #[inline]
@@ -84,6 +86,39 @@ impl_int_from_uint! { i64, u64 }
 #[cfg(feature = "i128_support")] impl_int_from_uint! { i128, u128 }
 impl_int_from_uint! { isize, usize }
 
+#[cfg(feature="simd_support")]
+macro_rules! simd_impl {
+    ($bits:expr,) => {};
+    ($bits:expr, $ty:ty, $($ty_more:ty,)*) => {
+        simd_impl!($bits, $($ty_more,)*);
+
+        impl Distribution<$ty> for Standard {
+            #[inline]
+            fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> $ty {
+                let mut vec = Default::default();
+                unsafe {
+                    let ptr = &mut vec;
+                    let b_ptr = &mut *(ptr as *mut $ty as *mut [u8; $bits/8]);
+                    rng.fill_bytes(b_ptr);
+                }
+                vec
+            }
+        }
+    }
+}
+
+#[cfg(feature="simd_support")]
+simd_impl!(16, u8x2, i8x2,);
+#[cfg(feature="simd_support")]
+simd_impl!(32, u8x4, i8x4, u16x2, i16x2,);
+#[cfg(feature="simd_support")]
+simd_impl!(64, u8x8, i8x8, u16x4, i16x4, u32x2, i32x2,);
+#[cfg(feature="simd_support")]
+simd_impl!(128, u8x16, i8x16, u16x8, i16x8, u32x4, i32x4, u64x2, i64x2,);
+#[cfg(feature="simd_support")]
+simd_impl!(256, u8x32, i8x32, u16x16, i16x16, u32x8, i32x8, u64x4, i64x4,);
+#[cfg(feature="simd_support")]
+simd_impl!(512, u8x64, i8x64, u16x32, i16x32, u32x16, i32x16, u64x8, i64x8,);
 
 #[cfg(test)]
 mod tests {