⚡️ Drop infinite loop for explicit loop (#507)

dubzzz · Jan 8, 2023 · bb69be5 · bb69be5
1 parent 2dd7280
commit bb69be5
Showing 1 changed file with 21 additions and 17 deletions.
diff --git a/src/distribution/internals/UnsafeUniformIntDistributionInternal.ts b/src/distribution/internals/UnsafeUniformIntDistributionInternal.ts
@@ -11,13 +11,11 @@ export function unsafeUniformIntDistributionInternal(rangeSize: number, rng: Ran
   // Range provided by the RandomGenerator is large enough
   if (rangeSize <= NumValues) {
     const MaxAllowed = NumValues - (NumValues % rangeSize);
-    while (true) {
-      const out = rng.unsafeNext();
-      const deltaV = out - MinRng;
-      if (deltaV < MaxAllowed) {
-        return deltaV % rangeSize; // Warning: we expect NumValues <= 2**32, so diff too
-      }
+    let deltaV = rng.unsafeNext() - MinRng;
+    while (deltaV >= MaxAllowed) {
+      deltaV = rng.unsafeNext() - MinRng;
     }
+    return deltaV % rangeSize; // Warning: we expect NumValues <= 2**32, so diff too
   }
 
   // Compute number of iterations required to have enough random
@@ -30,16 +28,22 @@ export function unsafeUniformIntDistributionInternal(rangeSize: number, rng: Ran
   }
   const MaxAcceptedRandom = rangeSize * Math.floor((1 * FinalNumValues) / rangeSize);
 
-  while (true) {
-    // Aggregate mutiple calls to next() into a single random value
-    let value = 0;
-    for (let num = 0; num !== NumIterations; ++num) {
-      const out = rng.unsafeNext();
-      value = NumValues * value + (out - MinRng); // Warning: we overflow may when diff > max_safe (eg: =max_safe-min_safe+1)
-    }
-    if (value < MaxAcceptedRandom) {
-      const inDiff = value - rangeSize * Math.floor((1 * value) / rangeSize);
-      return inDiff;
-    }
+  let largeDeltaV = unsafeComputeValue(rng, NumIterations, NumValues, MinRng);
+  while (largeDeltaV >= MaxAcceptedRandom) {
+    largeDeltaV = unsafeComputeValue(rng, NumIterations, NumValues, MinRng);
+  }
+  const inDiff = largeDeltaV - rangeSize * Math.floor((1 * largeDeltaV) / rangeSize);
+  return inDiff;
+}
+
+/**
+ * Aggregate multiple calls to next() into a single random value
+ */
+function unsafeComputeValue(rng: RandomGenerator, NumIterations: number, NumValues: number, MinRng: number): number {
+  let value = 0;
+  for (let num = 0; num !== NumIterations; ++num) {
+    const out = rng.unsafeNext();
+    value = NumValues * value + (out - MinRng); // Warning: we overflow may when diff > max_safe (eg: =max_safe-min_safe+1)
   }
+  return value;
 }