Merge pull request #2 from OptoCloud/master

Increase accuracy and speed of TimeTag conversions
LucHeart · Jul 10, 2024 · c15e2f3 · c15e2f3
2 parents bc589bb + 410a09f
commit c15e2f3
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Showing 3 changed files with 61 additions and 21 deletions.
diff --git a/CoreOSC.Tests/TimetagTest.cs b/CoreOSC.Tests/TimetagTest.cs
@@ -8,12 +8,14 @@ public class TimetagTest
     [Fact]
     public void TestTimetag()
     {
-        var time = (ulong) 60 * 60 * 24 * 365 * 108;
-        time <<= 32;
-        time += (ulong)(Math.Pow(2, 32) / 2);
-        var date = Utils.TimeTagToDateTime(time);
+        ulong tag = 0;
 
-        Assert.Equal(DateTime.Parse("2007-12-06 00:00:00.500"), date);
+        tag |= (ulong)3424309443 << 32; // https://www.timeanddate.com/date/durationresult.html?d1=1&m1=1&y1=1900&d2=6&m2=7&y2=2008&h1=0&i1=0&s1=0&h2=5&i2=4&s2=3
+        tag |= (ulong)(0xFFFFFFFF / 10); // 100ms
+
+        var date = Utils.TimeTagToDateTime(tag);
+
+        Assert.Equal(DateTime.Parse("2008-7-06 05:04:03.100"), date);
     }
 
     [Fact]
@@ -29,5 +31,6 @@ public void TestDateTimeToTimetag()
         Assert.Equal(dt.Minute, dtBack.Minute);
         Assert.Equal(dt.Second, dtBack.Second);
         Assert.Equal(dt.Millisecond, dtBack.Millisecond);
+        Assert.Equal(dt.Microsecond, dtBack.Microsecond);
     }
 }
diff --git a/CoreOSC/TimeTag.cs b/CoreOSC/TimeTag.cs
@@ -4,22 +4,38 @@ namespace LucHeart.CoreOSC;
 
 public struct TimeTag
 {
+    public static TimeTag Immediate => new(1);
+
     public ulong Tag;
 
+    /// <summary>
+    /// Gets or sets the timestamp from a DateTime. DateTime has an accuracy down to 100 nanoseconds (100'000
+    /// picoseconds)
+    /// </summary>
     public DateTime Timestamp
     {
         get => Utils.TimeTagToDateTime(Tag);
         set => Tag = Utils.DateTimeToTimeTag(value);
     }
 
+    /// <summary>
+    /// Gets or sets the total seconds in the timestamp. the double precision number is multiplied by 2^32
+    /// giving an accuracy down to about 230 picoseconds ( 1/(2^32) of a second)
+    /// </summary>
+    public double Seconds
+    {
+        get => Utils.TimeTagToSeconds(Tag);
+        set => Tag = Utils.SecondsToTimeTag(value);
+    }
+
     /// <summary>
     /// Gets or sets the fraction of a second in the timestamp. the double precision number is multiplied by 2^32
     /// giving an accuracy down to about 230 picoseconds ( 1/(2^32) of a second)
     /// </summary>
     public double Fraction
     {
         get => Utils.TimeTagToFraction(Tag);
-        set => Tag = (Tag & 0xFFFFFFFF00000000) + (uint)(value * 0xFFFFFFFF);
+        set => Tag = Utils.SecondsToTimeTag(value);
     }
 
     public TimeTag(ulong value)

diff --git a/CoreOSC/Utils.cs b/CoreOSC/Utils.cs
@@ -4,36 +4,57 @@ namespace LucHeart.CoreOSC;
 
 public static class Utils
 {
+    private static readonly long EpochTicks = new DateTime(1900, 1, 1).Ticks;
+    private const uint OscTicksPerSecond = 0xFFFFFFFF;
+    private const double OscTicksPerDotNetTick = OscTicksPerSecond / (double)TimeSpan.TicksPerSecond; // 429.4967295
+
     public static DateTime TimeTagToDateTime(ulong val)
     {
         if (val == 1)
             return DateTime.Now;
 
-        var seconds = (uint)(val >> 32);
-        var time = DateTime.Parse("1900-01-01 00:00:00");
-        time = time.AddSeconds(seconds);
-        var fraction = TimeTagToFraction(val);
-        time = time.AddSeconds(fraction);
-        return time;
+        uint seconds = (uint)(val >> 32);
+        uint fraction = (uint)(val & 0xFFFFFFFF);
+
+        long secondsTicks = seconds * TimeSpan.TicksPerSecond;
+        long fractionTicks = (long)Math.Round(fraction / OscTicksPerDotNetTick); // We will loose accuracy in this conversion since there is about 430 OSC ticks per dotnet tick
+
+        return new DateTime(EpochTicks + secondsTicks + fractionTicks);
     }
 
-    public static double TimeTagToFraction(ulong val)
+    public static ulong DateTimeToTimeTag(DateTime value)
+    {
+        long ticks = value.Ticks - EpochTicks;
+        if (ticks < 0) return 0;
+
+        uint seconds = (uint)(ticks / TimeSpan.TicksPerSecond);
+        uint fractions = (uint)Math.Round((ticks - (seconds * TimeSpan.TicksPerSecond)) * OscTicksPerDotNetTick);
+
+        ulong secondTicks = (ulong)seconds << 32;
+        ulong fractionTicks = (ulong)fractions & 0xFFFFFFFF;
+
+        return secondTicks | fractionTicks;
+    }
+
+    public static double TimeTagToSeconds(ulong val)
     {
         if (val == 1)
             return 0.0;
 
-        var seconds = (uint)(val & 0x00000000FFFFFFFF);
-        var fraction = (double)seconds / 0xFFFFFFFF;
-        return fraction;
+        return (double)val / OscTicksPerSecond;
     }
 
-    public static ulong DateTimeToTimeTag(DateTime value)
+    public static ulong SecondsToTimeTag(double value)
     {
-        ulong seconds = (uint)(value - DateTime.Parse("1900-01-01 00:00:00.000")).TotalSeconds;
-        var fraction = (uint)Math.Ceiling(0xFFFFFFFF * ((double)value.Millisecond / 1000));
+        return (ulong)(value * OscTicksPerSecond);
+    }
+
+    public static double TimeTagToFraction(ulong val)
+    {
+        if (val == 1)
+            return 0.0;
 
-        var output = (seconds << 32) + fraction;
-        return output;
+        return (double)(val & 0xFFFFFFFF) / OscTicksPerSecond;
     }
 
     public static int AlignedStringLength(string val)