S.R.CS.Unsafe: Add 'IntPtr ByteOffset<T>(ref T origin, ref T target)' (#12895)

1 files changed, 31 insertions, 0 deletions

diff --git a/src/System.Runtime.CompilerServices.Unsafe/tests/UnsafeTests.cs b/src/System.Runtime.CompilerServices.Unsafe/tests/UnsafeTests.cs
index 2a90b63525..1385fbe442 100644
--- a/src/System.Runtime.CompilerServices.Unsafe/tests/UnsafeTests.cs
+++ b/src/System.Runtime.CompilerServices.Unsafe/tests/UnsafeTests.cs
@@ -387,6 +387,37 @@ namespace System.Runtime.CompilerServices
             Assert.IsType(typeof(Object), Unsafe.As<string>(o));
         }
 
+        [Fact]
+        public static void ByteOffsetArray()
+        {
+            var a = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7 };
+
+            Assert.Equal(new IntPtr(0), Unsafe.ByteOffset(ref a[0], ref a[0]));
+            Assert.Equal(new IntPtr(1), Unsafe.ByteOffset(ref a[0], ref a[1]));
+            Assert.Equal(new IntPtr(-1), Unsafe.ByteOffset(ref a[1], ref a[0]));
+            Assert.Equal(new IntPtr(2), Unsafe.ByteOffset(ref a[0], ref a[2]));
+            Assert.Equal(new IntPtr(-2), Unsafe.ByteOffset(ref a[2], ref a[0]));
+            Assert.Equal(new IntPtr(3), Unsafe.ByteOffset(ref a[0], ref a[3]));
+            Assert.Equal(new IntPtr(4), Unsafe.ByteOffset(ref a[0], ref a[4]));
+            Assert.Equal(new IntPtr(5), Unsafe.ByteOffset(ref a[0], ref a[5]));
+            Assert.Equal(new IntPtr(6), Unsafe.ByteOffset(ref a[0], ref a[6]));
+            Assert.Equal(new IntPtr(7), Unsafe.ByteOffset(ref a[0], ref a[7]));
+        }
+        
+        [Fact]
+        public static void ByteOffsetStackByte4()
+        {
+            var byte4 = new Byte4();
+
+            Assert.Equal(new IntPtr(0), Unsafe.ByteOffset(ref byte4.B0, ref byte4.B0));
+            Assert.Equal(new IntPtr(1), Unsafe.ByteOffset(ref byte4.B0, ref byte4.B1));
+            Assert.Equal(new IntPtr(-1), Unsafe.ByteOffset(ref byte4.B1, ref byte4.B0));
+            Assert.Equal(new IntPtr(2), Unsafe.ByteOffset(ref byte4.B0, ref byte4.B2));
+            Assert.Equal(new IntPtr(-2), Unsafe.ByteOffset(ref byte4.B2, ref byte4.B0));
+            Assert.Equal(new IntPtr(3), Unsafe.ByteOffset(ref byte4.B0, ref byte4.B3));
+            Assert.Equal(new IntPtr(-3), Unsafe.ByteOffset(ref byte4.B3, ref byte4.B0));
+        }
+
         // Active Issue: https://github.com/dotnet/coreclr/issues/6505
         // These tests require C# compiler with support for ref returns and locals
 #if false