From 64fcebf4e53dc0e5782eaee3753ba3a789e5761a Mon Sep 17 00:00:00 2001
From: a dinosaur <dino@a-dinosaur.com>
Date: Sun, 1 Sep 2024 05:11:48 +1000
Subject: [PATCH] simpler range mask calculation

---
 Sources/Voxelotl/Random/RandomRange.swift | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/Sources/Voxelotl/Random/RandomRange.swift b/Sources/Voxelotl/Random/RandomRange.swift
index 1352213..de89e48 100644
--- a/Sources/Voxelotl/Random/RandomRange.swift
+++ b/Sources/Voxelotl/Random/RandomRange.swift
@@ -65,21 +65,9 @@ public extension RandomProvider where Output: UnsignedInteger {
   }
 
   mutating func nextModless(in bound: Output) -> Output {
-    func pow2MaskFrom(range num: Output) -> Output {
-      if num & (num - 1) == 0 {
-        return num - 1
-      }
-      var result: Output = 1
-      for _ in 0..<Output.bitWidth {
-        if result >= num {
-          return result - 1
-        }
-        result <<= 1
-      }
-      return .max
-    }
+    let shift = bound.leadingZeroBitCount
+    let mask = Output.max &>> shift
 
-    let mask = pow2MaskFrom(range: bound)
     var result: Output
     repeat {
       result = next() & mask