add std.hash.uint32

This is handy if you have a u32 and want a u32 and don't want to take a
detour through many layers of abstraction elsewhere in the std.hash
namespace.
Copied from https://nullprogram.com/blog/2018/07/31/

1 files changed, 14 insertions, 0 deletions

diff --git a/lib/std/hash.zig b/lib/std/hash.zig
index 5c85b38d55..eca7a70159 100644
--- a/lib/std/hash.zig
+++ b/lib/std/hash.zig
@@ -36,6 +36,20 @@ const xxhash = @import("hash/xxhash.zig");
 pub const XxHash64 = xxhash.XxHash64;
 pub const XxHash32 = xxhash.XxHash32;
 
+/// This is handy if you have a u32 and want a u32 and don't want to take a
+/// detour through many layers of abstraction elsewhere in the std.hash
+/// namespace.
+/// Copied from https://nullprogram.com/blog/2018/07/31/
+pub fn uint32(input: u32) u32 {
+    var x: u32 = input;
+    x ^= x >> 16;
+    x *%= 0x7feb352d;
+    x ^= x >> 15;
+    x *%= 0x846ca68b;
+    x ^= x >> 16;
+    return x;
+}
+
 test {
     _ = adler;
     _ = auto_hash;