std::rand: Add an implementation of ISAAC64.

This is 2x faster on 64-bit computers at generating anything larger
than 32-bits.

It has been verified against the canonical C implementation from the
website of the creator of ISAAC64.

Also, move `Rng.next` to `Rng.next_u32` and add `Rng.next_u64` to
take full advantage of the wider word width; otherwise Isaac64 will
always be squeezed down into a u32 wasting half the entropy and
offering no advantage over the 32-bit variant.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstd/rt/task.rs b/src/libstd/rt/task.rs
index 2d1b57cebf5..48b894f51e0 100644
--- a/src/libstd/rt/task.rs
+++ b/src/libstd/rt/task.rs
@@ -509,7 +509,7 @@ mod test {
         do run_in_newsched_task() {
             use rand::{rng, Rng};
             let mut r = rng();
-            let _ = r.next();
+            let _ = r.next_u32();
         }
     }