1 files changed, 31 insertions, 0 deletions
diff --git a/csharp/ProtocolBuffers/CodedInputStream.cs b/csharp/ProtocolBuffers/CodedInputStream.cs
new file mode 100644
index 00000000..66dae52c
--- /dev/null
+++ b/csharp/ProtocolBuffers/CodedInputStream.cs
@@ -0,0 +1,31 @@
+
+namespace Google.ProtocolBuffers {
+  public sealed class CodedInputStream {
+
+    /// <summary>
+    /// Decode a 32-bit value with ZigZag encoding.
+    /// </summary>
+    /// <remarks>
+    /// ZigZag encodes signed integers into values that can be efficiently
+    /// encoded with varint.  (Otherwise, negative values must be 
+    /// sign-extended to 64 bits to be varint encoded, thus always taking
+    /// 10 bytes on the wire.)
+    /// </remarks>
+    public static int DecodeZigZag32(uint n) {
+      return (int)(n >> 1) ^ -(int)(n & 1);
+    }
+
+    /// <summary>
+    /// Decode a 32-bit value with ZigZag encoding.
+    /// </summary>
+    /// <remarks>
+    /// ZigZag encodes signed integers into values that can be efficiently
+    /// encoded with varint.  (Otherwise, negative values must be 
+    /// sign-extended to 64 bits to be varint encoded, thus always taking
+    /// 10 bytes on the wire.)
+    /// </remarks>
+    public static long DecodeZigZag64(ulong n) {
+      return (long)(n >> 1) ^ -(long)(n & 1);
+    }
+  }
+}