Tolerance to avoid potential precision issues (#288)

Equality comparison of floating point numbers. Possible loss of precision while rounding values.

Author: Meowchestra

BardMusicPlayer.Script/BasicSharp/Interpreter.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Threading.Tasks;
@@ -286,8 +287,9 @@ private void Goto()
 
     private void If()
     {
+        const float tolerance = 0.0001f; // define a small tolerance value
         // check if argument is equal to 0
-        var result = Expr().BinOp(new Value(0), Token.Equal).Real == 1;
+        var result = Math.Abs(Expr().BinOp(new Value(0), Token.Equal).Real - 1) < tolerance;
 
         Match(Token.Then);
         GetNextToken();
@@ -411,8 +413,9 @@ private void For()
                     loopsteps.Add(var, step);
             }
         }
-
-        if (vars[var].BinOp(v, Token.More).Real == 1)
+        
+        const float tolerance = 0.0001f; // define a small tolerance value
+        if (Math.Abs(vars[var].BinOp(v, Token.More).Real - 1) < tolerance)
         {
             while (true)
             {
@@ -447,7 +450,8 @@ private void Next()
 
     private void Assert()
     {
-        var result = Expr().BinOp(new Value(0), Token.Equal).Real == 1;
+        const float tolerance = 0.0001f; // define a small tolerance value
+        var result = Math.Abs(Expr().BinOp(new Value(0), Token.Equal).Real - 1) < tolerance;
 
         if (result)
         {

BardMusicPlayer.Script/BasicSharp/Value.cs

@@ -68,6 +68,7 @@ public readonly Value UnaryOp(Token tok)
     public readonly Value BinOp(Value b, Token tok)
     {
         var a = this;
+        const float tolerance = 0.0001f; // define a small tolerance value
         if (a.Type != b.Type)
         {
             // promote one value to higher type
@@ -82,9 +83,9 @@ public readonly Value BinOp(Value b, Token tok)
             case Token.Plus:
                 return a.Type == ValueType.Real ? new Value(a.Real + b.Real) : new Value(a.String + b.String);
             case Token.Equal:
-                return a.Type == ValueType.Real ? new Value(a.Real == b.Real ? 1 : 0) : new Value(a.String == b.String ? 1 : 0);
+                return a.Type == ValueType.Real ? new Value(Math.Abs(a.Real - b.Real) < tolerance ? 1 : 0) : new Value(a.String == b.String ? 1 : 0);
             case Token.NotEqual:
-                return a.Type == ValueType.Real ? new Value(a.Real == b.Real ? 0 : 1) : new Value(a.String == b.String ? 0 : 1);
+                return a.Type == ValueType.Real ? new Value(Math.Abs(a.Real - b.Real) < tolerance ? 0 : 1) : new Value(a.String == b.String ? 0 : 1);
             default:
             {
                 if (a.Type == ValueType.String)

BardMusicPlayer.Transmogrify/Song/Importers/GuitarPro/GP6File.cs

@@ -22,8 +22,8 @@ public sealed class GP6File : GPFile
     public static int totalLength;
     public static int lengthPassed;
 
-    private readonly byte[] udata; //uncompressed data
-
+    private readonly byte[] udata;   //uncompressed data
+    const float tolerance = 0.0001f; // define a small tolerance value
     //public List<Track> tracks;
     public GP6File(byte[] _data)
     {
@@ -441,15 +441,15 @@ public static Beat transferBeat(Node node, int index, Voice voice)
 
             if (hasWhammy)
             {
-                if (whammyBarMiddleOffset1 == -1.0f)
+                if (Math.Abs(whammyBarMiddleOffset1 - (-1.0f)) < tolerance)
                 {
                     whammyBarMiddleOffset1 = whammyBarOriginOffset +
                                              (whammyBarDestinationOffset - whammyBarOriginOffset) / 2.0f;
                     whammyBarMiddleValue =
                         whammyBarOriginValue + (whammyBarDestinationValue - whammyBarOriginValue) / 2.0f;
                 }
 
-                if (whammyBarMiddleOffset2 == -1.0f) whammyBarMiddleOffset2 = whammyBarMiddleOffset1;
+                if (Math.Abs(whammyBarMiddleOffset2 - (-1.0f)) < tolerance) whammyBarMiddleOffset2 = whammyBarMiddleOffset1;
                 beat.effect.tremoloBar = new BendEffect
                 {
                     type = BendType.none, //Not defined in GP6
@@ -674,13 +674,13 @@ public static Note transferNote(Node node, int index, Beat beat, int velocity, G
 
             if (hasBendEffect)
             {
-                if (bendMidOff1 == -1.0f)
+                if (Math.Abs(bendMidOff1 - (-1.0f)) < tolerance)
                 {
                     bendMidOff1 = bendOrigOff + (bendDestOff - bendOrigOff) / 2.0f;
                     bendMidVal  = bendOrigVal + (bendDestVal - bendOrigVal) / 2.0f;
                 }
 
-                if (bendMidOff2 == -1.0f) bendMidOff2 = bendMidOff1;
+                if (Math.Abs(bendMidOff2 - (-1.0f)) < tolerance) bendMidOff2 = bendMidOff1;
 
                 bendEffect.points.Add(new BendPoint(0.0f, bendOrigVal));
                 bendEffect.points.Add(new BendPoint(bendOrigOff, bendOrigVal));
@@ -697,7 +697,7 @@ public static Note transferNote(Node node, int index, Beat beat, int velocity, G
                 note.effect.bend = bendEffect;
             }
 
-            if (harmonicFret != -1)
+            if (Math.Abs(harmonicFret - (-1)) > tolerance)
             {
                 switch (harmonicType)
                 {

BardMusicPlayer.Transmogrify/Song/Importers/GuitarPro/Native/NativeFormat.cs

@@ -398,8 +398,9 @@ public List<Note> retrieveNotes(GuitarPro.Track track, int[] tuning, Track myTra
 
                             if (last != null)
                             {
-                                note.fret = last.fret; //For GP3 & GP4
-                                if (last.harmonic != note.harmonic || last.harmonicFret != note.harmonicFret
+                                note.fret = last.fret;           //For GP3 & GP4
+                                const float tolerance = 0.0001f; // define a small tolerance value
+                                if (last.harmonic != note.harmonic || Math.Abs(last.harmonicFret - note.harmonicFret) > tolerance
                                    )
                                     dontAddNote = false;
 
@@ -759,7 +760,8 @@ public static List<Tempo> retrieveTempos(GPFile file)
                     position = pos
                 };
                 pos += flipDuration(mh.timeSignature.denominator) * mh.timeSignature.numerator;
-                if (oldTempo != t.value) tempos.Add(t);
+                const float tolerance = 0.0001f; // define a small tolerance value
+                if (Math.Abs(oldTempo - t.value) > tolerance) tempos.Add(t);
                 oldTempo = t.value;
             }
         }

BardMusicPlayer/UI_Classic/Classic_Siren.cs

@@ -183,7 +183,8 @@ private void Siren_PlaybackTimeChanged(double currentTime, double endTime, int a
         Siren_VoiceCount.Content = activeVoices.ToString();
 
         TimeSpan t;
-        if (Siren_Position.Maximum != endTime)
+        const float tolerance = 0.0001f;                            // define a small tolerance value
+        if (Math.Abs(Siren_Position.Maximum - endTime) > tolerance) // use tolerance to compare values
         {
             Siren_Position.Maximum   = endTime;
             t                        = TimeSpan.FromMilliseconds(endTime);