-

commit cbcd66ac57af0a7707b5d66001e523ca26bb4eee
Author: Rolf Bjarne Kvinge <[email protected]>
Date:   Mon Apr 4 14:47:20 2016 +0200

    [CoreMidi] Avoid the use of fixed buffers.
    
    The C# compiler generates a non-stable backing type for the
    fixed buffer, which means we don't control the public API 100%.
    
    It's may even change between executions of the same C# compiler,
    which means it breaks our api-diff already.
    
    Example diff:
    
    /Applications/Xcode73.app/Contents/Developer/usr/bin/make verify-reference-assemblies-ios -j8
    GEN      temp/native-64/Xamarin.iOS.xml
    GEN      temp/native-32/Xamarin.iOS.xml
    --- temp/native-32/Xamarin.iOS.xml	2016-04-04 05:58:43.000000000 -0400
    +++ temp/native-64/Xamarin.iOS.xml	2016-04-04 05:58:43.000000000 -0400
    @@ -164415,14 +164415,14 @@
               </class>
               <class name="MidiValueMap" type="struct" base="System.ValueType" sealed="true" charset="Ansi" layout="Sequential">
                 <fields>
    -              <field name="Value" attrib="6" fieldtype="CoreMidi.MidiValueMap+[Value]__FixedBuffer0">
    +              <field name="Value" attrib="6" fieldtype="CoreMidi.MidiValueMap+[Value]__FixedBuffer1">
                     <attributes>
                       <attribute name="System.Runtime.CompilerServices.FixedBufferAttribute" />
                     </attributes>
                   </field>
                 </fields>
                 <classes>
    -              <class name="&lt;Value&gt;__FixedBuffer0" type="struct" base="System.ValueType" sealed="true" charset="Ansi" layout="Sequential" pack="0" size="128">
    +              <class name="&lt;Value&gt;__FixedBuffer1" type="struct" base="System.ValueType" sealed="true" charset="Ansi" layout="Sequential" pack="0" size="128">
                     <attributes>
                       <attribute name="System.Runtime.CompilerServices.CompilerGeneratedAttribute" />
                       <attribute name="System.Runtime.CompilerServices.UnsafeValueTypeAttribute" />
    make[3]: *** [verify-reference-assemblies-ios] Error 1

diff --git a/src/CoreMidi/MidiThruConnectionParams.cs b/src/CoreMidi/MidiThruConnectionParams.cs
index 884693a..911cdcf 100644
--- a/src/CoreMidi/MidiThruConnectionParams.cs
+++ b/src/CoreMidi/MidiThruConnectionParams.cs
@@ -51,7 +51,7 @@ namespace XamCore.CoreMidi {
 
 	[StructLayout (LayoutKind.Sequential)]
 	public unsafe struct MidiValueMap {
-		public fixed byte Value[128];
+		public byte[] Value;
 	}
 
 	[StructLayout (LayoutKind.Sequential)]
@@ -253,7 +253,6 @@ namespace XamCore.CoreMidi {
 			// Put ourselves at the end of the static struct in case we need to fetch the dynamic part of the struct
 			IntPtr bufferEnd = IntPtr.Add (buffer, Marshal.SizeOf (typeof (MidiThruConnectionParamsStruct)));
 			var controlsSize = Marshal.SizeOf (typeof (MidiControlTransform));
-			var mapsSize = Marshal.SizeOf (typeof (MidiValueMap));
 
 			if (connectionParams.NumControlTransforms == 0)
 				Controls = null;
@@ -271,8 +270,11 @@ namespace XamCore.CoreMidi {
 				Maps = new MidiValueMap [connectionParams.NumMaps];
 				bufferEnd = IntPtr.Add (bufferEnd, controlsSize * connectionParams.NumControlTransforms);
 				unsafe { // Lets use memcpy to avoid a for loop
-					fixed (MidiValueMap* arrAddr = &Maps[0])
-						Runtime.memcpy ((IntPtr) arrAddr, bufferEnd, mapsSize * connectionParams.NumMaps);
+					for (int i = 0; i < connectionParams.NumMaps; i++) {
+						Maps [i].Value = new byte [128];
+						fixed (byte* arrAddr = &Maps[i].Value [0])
+							Runtime.memcpy ((IntPtr) arrAddr, bufferEnd, 128);
+					}
 				}
 			}
 		}
@@ -301,11 +303,10 @@ namespace XamCore.CoreMidi {
 
 			var paramsSize = Marshal.SizeOf (typeof (MidiThruConnectionParamsStruct));
 			var controlsSize = Marshal.SizeOf (typeof (MidiControlTransform));
-			var mapsSize = Marshal.SizeOf (typeof (MidiValueMap));
 			// Get the full size of the struct, static + dynamic parts
 			var fullSize = paramsSize +
 				(Controls == null ? 0 : controlsSize * Controls.Length) +
-				(Maps == null ? 0 : mapsSize * Maps.Length);
+				(Maps == null ? 0 : 128 * Maps.Length);
 			var buffer = Marshal.AllocHGlobal (fullSize);
 			var bufferEnd = IntPtr.Add (buffer, Marshal.SizeOf (typeof (MidiThruConnectionParamsStruct)));
 
@@ -324,8 +325,10 @@ namespace XamCore.CoreMidi {
 					// Set the destination buffer after controls arr if any
 					bufferEnd = IntPtr.Add (bufferEnd, controlsSize * connectionParams.NumControlTransforms);
 					unsafe { // Lets use memcpy to avoid a for loop
-						fixed (MidiValueMap* arrAddr = &Maps[0])
-							Runtime.memcpy (bufferEnd, (IntPtr) arrAddr, mapsSize * connectionParams.NumMaps);
+						for (int i = 0; i < connectionParams.NumMaps; i++) {
+							fixed (byte* arrAddr = &Maps[i].Value [0])
+								Runtime.memcpy (bufferEnd, (IntPtr) arrAddr, 128);
+						}
 					}
 				}