Merge pull request #10 from drhurdle/bug/calculation_error_in_xoroshiro128plus

Fixed calculation issue in xoroshiro128plus algorithm

Author: dylan

HeavyCore/Common/Utilities/Random.swift

@@ -23,7 +23,7 @@ public struct PRNG {
         mutating func next() -> UInt {
             let s0: UInt = state[0]
             var s1 = state[1]
-            let result = s0 &* s1
+            let result = s0 &+ s1
 
             s1 ^= s0
             state[0] = rotateLeft(s0, b: 55) ^ s1 ^ (s1 << 14)

Playgrounds/Core.playground/Pages/Random.xcplaygroundpage/Contents.swift

@@ -95,4 +95,21 @@ sameSeedCheck // Expected to be true
 "** EXPECT TO BE TRUE **"
 diffSeedCheck // Expected to be true
 
+
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
+x.nextUInt(0, max: 1)
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