Move FastRandom to LegacyRandom in osu.Game project

osu.Game.Rulesets.Catch/Beatmaps/CatchBeatmapProcessor.cs

@@ -5,10 +5,10 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using osu.Game.Beatmaps;
-using osu.Game.Rulesets.Catch.MathUtils;
 using osu.Game.Rulesets.Catch.Objects;
 using osu.Game.Rulesets.Catch.UI;
 using osu.Game.Rulesets.Objects.Types;
+using osu.Game.Utils;
 
 namespace osu.Game.Rulesets.Catch.Beatmaps
 {
@@ -46,7 +46,7 @@ namespace osu.Game.Rulesets.Catch.Beatmaps
 
         public void ApplyPositionOffsets(IBeatmap beatmap)
         {
-            var rng = new FastRandom(RNG_SEED);
+            var rng = new LegacyRandom(RNG_SEED);
 
             float? lastPosition = null;
             double lastStartTime = 0;
@@ -98,7 +98,7 @@ namespace osu.Game.Rulesets.Catch.Beatmaps
             initialiseHyperDash(beatmap);
         }
 
-        private static void applyHardRockOffset(CatchHitObject hitObject, ref float? lastPosition, ref double lastStartTime, FastRandom rng)
+        private static void applyHardRockOffset(CatchHitObject hitObject, ref float? lastPosition, ref double lastStartTime, LegacyRandom rng)
         {
             float offsetPosition = hitObject.OriginalX;
             double startTime = hitObject.StartTime;
@@ -146,7 +146,7 @@ namespace osu.Game.Rulesets.Catch.Beatmaps
         /// <param name="position">The position which the offset should be applied to.</param>
         /// <param name="maxOffset">The maximum offset, cannot exceed 20px.</param>
         /// <param name="rng">The random number generator.</param>
-        private static void applyRandomOffset(ref float position, double maxOffset, FastRandom rng)
+        private static void applyRandomOffset(ref float position, double maxOffset, LegacyRandom rng)
         {
             bool right = rng.NextBool();
             float rand = Math.Min(20, (float)rng.Next(0, Math.Max(0, maxOffset)));

osu.Game.Rulesets.Mania/Beatmaps/ManiaBeatmapConverter.cs

@@ -11,8 +11,8 @@ using osu.Game.Beatmaps;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Mania.Beatmaps.Patterns;
-using osu.Game.Rulesets.Mania.MathUtils;
 using osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy;
+using osu.Game.Utils;
 using osuTK;
 
 namespace osu.Game.Rulesets.Mania.Beatmaps
@@ -31,7 +31,7 @@ namespace osu.Game.Rulesets.Mania.Beatmaps
         private readonly int originalTargetColumns;
 
         // Internal for testing purposes
-        internal FastRandom Random { get; private set; }
+        internal LegacyRandom Random { get; private set; }
 
         private Pattern lastPattern = new Pattern();
 
@@ -84,7 +84,7 @@ namespace osu.Game.Rulesets.Mania.Beatmaps
             IBeatmapDifficultyInfo difficulty = original.Difficulty;
 
             int seed = (int)MathF.Round(difficulty.DrainRate + difficulty.CircleSize) * 20 + (int)(difficulty.OverallDifficulty * 41.2) + (int)MathF.Round(difficulty.ApproachRate);
-            Random = new FastRandom(seed);
+            Random = new LegacyRandom(seed);
 
             return base.ConvertBeatmap(original, cancellationToken);
         }
@@ -227,7 +227,7 @@ namespace osu.Game.Rulesets.Mania.Beatmaps
         /// </summary>
         private class SpecificBeatmapPatternGenerator : Patterns.Legacy.PatternGenerator
         {
-            public SpecificBeatmapPatternGenerator(FastRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
+            public SpecificBeatmapPatternGenerator(LegacyRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
                 : base(random, hitObject, beatmap, previousPattern, originalBeatmap)
             {
             }

osu.Game.Rulesets.Mania/Beatmaps/Patterns/Legacy/DistanceObjectPatternGenerator.cs

@@ -8,12 +8,12 @@ using System.Linq;
 using osu.Framework.Extensions.EnumExtensions;
 using osu.Game.Audio;
 using osu.Game.Beatmaps;
-using osu.Game.Rulesets.Mania.MathUtils;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Mania.Objects;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Beatmaps.Formats;
+using osu.Game.Utils;
 
 namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
 {
@@ -34,7 +34,7 @@ namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
 
         private PatternType convertType;
 
-        public DistanceObjectPatternGenerator(FastRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
+        public DistanceObjectPatternGenerator(LegacyRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
             : base(random, hitObject, beatmap, previousPattern, originalBeatmap)
         {
             convertType = PatternType.None;

osu.Game.Rulesets.Mania/Beatmaps/Patterns/Legacy/EndTimeObjectPatternGenerator.cs

@@ -2,13 +2,13 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
-using osu.Game.Rulesets.Mania.MathUtils;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
 using System.Linq;
 using osu.Game.Audio;
 using osu.Game.Beatmaps;
 using osu.Game.Rulesets.Mania.Objects;
+using osu.Game.Utils;
 
 namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
 {
@@ -17,7 +17,7 @@ namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
         private readonly int endTime;
         private readonly PatternType convertType;
 
-        public EndTimeObjectPatternGenerator(FastRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
+        public EndTimeObjectPatternGenerator(LegacyRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
             : base(random, hitObject, beatmap, previousPattern, originalBeatmap)
         {
             endTime = (int)((HitObject as IHasDuration)?.EndTime ?? 0);

osu.Game.Rulesets.Mania/Beatmaps/Patterns/Legacy/HitObjectPatternGenerator.cs

@@ -9,11 +9,11 @@ using osuTK;
 using osu.Game.Audio;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.ControlPoints;
-using osu.Game.Rulesets.Mania.MathUtils;
 using osu.Game.Rulesets.Mania.Objects;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Framework.Extensions.IEnumerableExtensions;
+using osu.Game.Utils;
 
 namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
 {
@@ -23,7 +23,7 @@ namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
 
         private readonly PatternType convertType;
 
-        public HitObjectPatternGenerator(FastRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, double previousTime, Vector2 previousPosition, double density,
+        public HitObjectPatternGenerator(LegacyRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, double previousTime, Vector2 previousPosition, double density,
                                          PatternType lastStair, IBeatmap originalBeatmap)
             : base(random, hitObject, beatmap, previousPattern, originalBeatmap)
         {

osu.Game.Rulesets.Mania/Beatmaps/Patterns/Legacy/PatternGenerator.cs

@@ -5,8 +5,8 @@ using System;
 using System.Linq;
 using JetBrains.Annotations;
 using osu.Game.Beatmaps;
-using osu.Game.Rulesets.Mania.MathUtils;
 using osu.Game.Rulesets.Objects;
+using osu.Game.Utils;
 
 namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
 {
@@ -23,14 +23,14 @@ namespace osu.Game.Rulesets.Mania.Beatmaps.Patterns.Legacy
         /// <summary>
         /// The random number generator to use.
         /// </summary>
-        protected readonly FastRandom Random;
+        protected readonly LegacyRandom Random;
 
         /// <summary>
         /// The beatmap which <see cref="HitObject"/> is being converted from.
         /// </summary>
         protected readonly IBeatmap OriginalBeatmap;
 
-        protected PatternGenerator(FastRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
+        protected PatternGenerator(LegacyRandom random, HitObject hitObject, ManiaBeatmap beatmap, Pattern previousPattern, IBeatmap originalBeatmap)
             : base(hitObject, beatmap, previousPattern)
         {
             if (random == null) throw new ArgumentNullException(nameof(random));

osu.Game.Rulesets.Mania/MathUtils/FastRandom.cs

@@ -1,95 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-using System;
-
-namespace osu.Game.Rulesets.Mania.MathUtils
-{
-    /// <summary>
-    /// A PRNG specified in http://heliosphan.org/fastrandom.html.
-    /// </summary>
-    internal class FastRandom
-    {
-        private const double int_to_real = 1.0 / (int.MaxValue + 1.0);
-        private const uint int_mask = 0x7FFFFFFF;
-        private const uint y = 842502087;
-        private const uint z = 3579807591;
-        private const uint w = 273326509;
-
-        internal uint X { get; private set; }
-        internal uint Y { get; private set; } = y;
-        internal uint Z { get; private set; } = z;
-        internal uint W { get; private set; } = w;
-
-        public FastRandom(int seed)
-        {
-            X = (uint)seed;
-        }
-
-        public FastRandom()
-            : this(Environment.TickCount)
-        {
-        }
-
-        /// <summary>
-        /// Generates a random unsigned integer within the range [<see cref="uint.MinValue"/>, <see cref="uint.MaxValue"/>).
-        /// </summary>
-        /// <returns>The random value.</returns>
-        public uint NextUInt()
-        {
-            uint t = X ^ (X << 11);
-            X = Y;
-            Y = Z;
-            Z = W;
-            return W = W ^ (W >> 19) ^ t ^ (t >> 8);
-        }
-
-        /// <summary>
-        /// Generates a random integer value within the range [0, <see cref="int.MaxValue"/>).
-        /// </summary>
-        /// <returns>The random value.</returns>
-        public int Next() => (int)(int_mask & NextUInt());
-
-        /// <summary>
-        /// Generates a random integer value within the range [0, <paramref name="upperBound"/>).
-        /// </summary>
-        /// <param name="upperBound">The upper bound.</param>
-        /// <returns>The random value.</returns>
-        public int Next(int upperBound) => (int)(NextDouble() * upperBound);
-
-        /// <summary>
-        /// Generates a random integer value within the range [<paramref name="lowerBound"/>, <paramref name="upperBound"/>).
-        /// </summary>
-        /// <param name="lowerBound">The lower bound of the range.</param>
-        /// <param name="upperBound">The upper bound of the range.</param>
-        /// <returns>The random value.</returns>
-        public int Next(int lowerBound, int upperBound) => (int)(lowerBound + NextDouble() * (upperBound - lowerBound));
-
-        /// <summary>
-        /// Generates a random double value within the range [0, 1).
-        /// </summary>
-        /// <returns>The random value.</returns>
-        public double NextDouble() => int_to_real * Next();
-
-        private uint bitBuffer;
-        private int bitIndex = 32;
-
-        /// <summary>
-        /// Generates a reandom boolean value. Cached such that a random value is only generated once in every 32 calls.
-        /// </summary>
-        /// <returns>The random value.</returns>
-        public bool NextBool()
-        {
-            if (bitIndex == 32)
-            {
-                bitBuffer = NextUInt();
-                bitIndex = 1;
-
-                return (bitBuffer & 1) == 1;
-            }
-
-            bitIndex++;
-            return ((bitBuffer >>= 1) & 1) == 1;
-        }
-    }
-}

osu.Game/Utils/LegacyRandom.cs

@@ -2,27 +2,36 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using osu.Framework.Utils;
 
-namespace osu.Game.Rulesets.Catch.MathUtils
+namespace osu.Game.Utils
 {
     /// <summary>
     /// A PRNG specified in http://heliosphan.org/fastrandom.html.
+    /// Should only be used to match legacy behaviour. See <see cref="RNG"/> for a newer alternative.
     /// </summary>
-    public class FastRandom
+    /// <remarks>
+    /// Known in osu-stable code as `FastRandom`.
+    /// </remarks>
+    public class LegacyRandom
     {
         private const double int_to_real = 1.0 / (int.MaxValue + 1.0);
         private const uint int_mask = 0x7FFFFFFF;
-        private const uint y_initial = 842502087;
+        private const uint y = 842502087;
-        private const uint z_initial = 3579807591;
+        private const uint z = 3579807591;
-        private const uint w_initial = 273326509;
+        private const uint w = 273326509;
-        private uint x, y = y_initial, z = z_initial, w = w_initial;
 
-        public FastRandom(int seed)
+        public uint X { get; private set; }
+        public uint Y { get; private set; } = y;
+        public uint Z { get; private set; } = z;
+        public uint W { get; private set; } = w;
+
+        public LegacyRandom(int seed)
         {
-            x = (uint)seed;
+            X = (uint)seed;
         }
 
-        public FastRandom()
+        public LegacyRandom()
             : this(Environment.TickCount)
         {
         }
@@ -33,11 +42,11 @@ namespace osu.Game.Rulesets.Catch.MathUtils
         /// <returns>The random value.</returns>
         public uint NextUInt()
         {
-            uint t = x ^ (x << 11);
+            uint t = X ^ (X << 11);
-            x = y;
+            X = Y;
-            y = z;
+            Y = Z;
-            z = w;
+            Z = W;
-            return w = w ^ (w >> 19) ^ t ^ (t >> 8);
+            return W = W ^ (W >> 19) ^ t ^ (t >> 8);
         }
 
         /// <summary>