1 files changed, 63 insertions, 0 deletions
diff --git a/src/mscorlib/src/System/Diagnostics/Debug.Windows.cs b/src/mscorlib/src/System/Diagnostics/Debug.Windows.cs
new file mode 100644
index 0000000000..095e9b6985
--- /dev/null
+++ b/src/mscorlib/src/System/Diagnostics/Debug.Windows.cs
@@ -0,0 +1,63 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Diagnostics
+{
+    public static partial class Debug
+    {
+        private static void ShowAssertDialog(string stackTrace, string message, string detailMessage)
+        {
+            if (Debugger.IsAttached)
+            {
+                Debugger.Break();
+            }
+            else
+            {
+                // In Core, we do not show a dialog.
+                // Fail in order to avoid anyone catching an exception and masking
+                // an assert failure.
+                var ex = new DebugAssertException(message, detailMessage, stackTrace);
+                Environment.FailFast(ex.Message, ex);
+            }
+        }
+
+        private static void WriteCore(string message)
+        {
+            // really huge messages mess up both VS and dbmon, so we chop it up into 
+            // reasonable chunks if it's too big. This is the number of characters 
+            // that OutputDebugstring chunks at.
+            const int WriteChunkLength = 4091;
+
+            // We don't want output from multiple threads to be interleaved.
+            lock (s_ForLock)
+            {
+                if (message == null || message.Length <= WriteChunkLength)
+                {
+                    WriteToDebugger(message);
+                }
+                else
+                {
+                    int offset;
+                    for (offset = 0; offset < message.Length - WriteChunkLength; offset += WriteChunkLength)
+                    {
+                        WriteToDebugger(message.Substring(offset, WriteChunkLength));
+                    }
+                    WriteToDebugger(message.Substring(offset));
+                }
+            }
+        }
+
+        private static void WriteToDebugger(string message)
+        {
+            if (Debugger.IsLogging())
+            {
+                Debugger.Log(0, null, message);
+            }
+            else
+            {
+                Interop.Kernel32.OutputDebugString(message ?? string.Empty);
+            }
+        }
+    }
+}