chore: improve accuracy of thread sleep in emu thread

src/util.zig

@@ -6,3 +6,30 @@ pub fn sext(comptime bits: comptime_int, value: u32) u32 {
 
     return @bitCast(u32, @bitCast(i32, value << amount) >> amount);
 }
+
+pub const FpsAverage = struct {
+    const Self = @This();
+
+    total: u64,
+    sample_count: u64,
+
+    pub fn init() Self {
+        return .{ .total = 0, .sample_count = 0 };
+    }
+
+    pub fn add(self: *Self, sample: u64) void {
+        if (self.sample_count == 1000) return self.reset(sample);
+
+        self.total += sample;
+        self.sample_count += 1;
+    }
+
+    pub fn calc(self: *const Self) u64 {
+        return self.total / self.sample_count;
+    }
+
+    fn reset(self: *Self, sample: u64) void {
+        self.total = sample;
+        self.sample_count = 1;
+    }
+};