rtl: add CachePadded

src/rtl/cache_padded.zig

@@ -0,0 +1,18 @@
+const std = @import("std");
+
+/// Type padded to a cache line.
+pub fn CachePadded(comptime T: type) type {
+    return struct {
+        const cache_line = std.atomic.cache_line;
+        const value_size = @sizeOf(T);
+        const padded_size = std.mem.alignForward(usize, value_size, cache_line);
+        const pad = padded_size - value_size;
+
+        value: T align(cache_line),
+        _pad: [pad]u8 = undefined,
+
+        pub fn init(val: T) @This() {
+            return .{ .value = val };
+        }
+    };
+}