1 files changed, 52 insertions, 0 deletions
diff --git a/Crypto/src/util/io/PushbackStream.cs b/Crypto/src/util/io/PushbackStream.cs
new file mode 100644
index 000000000..954694259
--- /dev/null
+++ b/Crypto/src/util/io/PushbackStream.cs
@@ -0,0 +1,52 @@
+using System;
+using System.IO;
+
+using Org.BouncyCastle.Asn1.Utilities;
+
+namespace Org.BouncyCastle.Utilities.IO
+{
+ public class PushbackStream
+ : FilterStream
+ {
+ private int buf = -1;
+
+ public PushbackStream(
+ Stream s)
+ : base(s)
+ {
+ }
+
+ public override int ReadByte()
+ {
+ if (buf != -1)
+ {
+ int tmp = buf;
+ buf = -1;
+ return tmp;
+ }
+
+ return base.ReadByte();
+ }
+
+ public override int Read(byte[] buffer, int offset, int count)
+ {
+ if (buf != -1 && count > 0)
+ {
+ // TODO Can this case be made more efficient?
+ buffer[offset] = (byte) buf;
+ buf = -1;
+ return 1;
+ }
+
+ return base.Read(buffer, offset, count);
+ }
+
+ public virtual void Unread(int b)
+ {
+ if (buf != -1)
+ throw new InvalidOperationException("Can only push back one byte");
+
+ buf = b & 0xFF;
+ }
+ }
+}
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