From ed896d976d081c8042ef18e9ac79b840f3d432b3 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Fri, 21 Oct 2022 05:12:32 -0300
Subject: [PATCH] chore: change implementation of rotr

---
 src/util.zig | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/util.zig b/src/util.zig
index a68e78a..f116c39 100644
--- a/src/util.zig
+++ b/src/util.zig
@@ -9,11 +9,12 @@ pub inline fn sext(comptime bits: comptime_int, value: u32) u32 {
 }
 
 /// See https://godbolt.org/z/W3en9Eche
-pub inline fn rotr(comptime T: type, value: T, r: anytype) T {
-    comptime std.debug.assert(@typeInfo(T).Int.signedness == .unsigned);
-    const ar = @truncate(Log2Int(T), r);
+pub inline fn rotr(comptime T: type, x: T, r: anytype) T {
+    if (@typeInfo(T).Int.signedness == .signed)
+        @compileError("cannot rotate signed integer");
 
-    return value >> ar | value << @truncate(Log2Int(T), @typeInfo(T).Int.bits - @as(T, ar));
+    const ar = @intCast(Log2Int(T), @mod(r, @typeInfo(T).Int.bits));
+    return x >> ar | x << (1 +% ~ar);
 }
 
 pub const FpsAverage = struct {