From c66bf4c088638169e74e6911f6c6601614bce353 Mon Sep 17 00:00:00 2001
From: Wolfgang Thaller <wolfgang.thaller@gmx.net>
Date: Sun, 22 Apr 2018 14:07:52 +0200
Subject: [PATCH] LaunchAPPL/Serial: UnreliableStram to simulate bit errors

---
 LaunchAPPL/Common/CMakeLists.txt     |  1 +
 LaunchAPPL/Common/ReliableStream.cc  |  5 ++-
 LaunchAPPL/Common/UnreliableStream.h | 56 ++++++++++++++++++++++++++++
 LaunchAPPL/Server/main.cc            | 11 +++++-
 4 files changed, 70 insertions(+), 3 deletions(-)
 create mode 100644 LaunchAPPL/Common/UnreliableStream.h

diff --git a/LaunchAPPL/Common/CMakeLists.txt b/LaunchAPPL/Common/CMakeLists.txt
index 95f2a5a7d5..f55ea48076 100644
--- a/LaunchAPPL/Common/CMakeLists.txt
+++ b/LaunchAPPL/Common/CMakeLists.txt
@@ -4,6 +4,7 @@ add_library(LaunchAPPLCommon
     ReliableStream.h
     ReliableStream.cc
     CRC32.h
+    UnreliableStream.h
 )
 target_include_directories(LaunchAPPLCommon PUBLIC .)
 
diff --git a/LaunchAPPL/Common/ReliableStream.cc b/LaunchAPPL/Common/ReliableStream.cc
index 49be3b29af..05ab9ca294 100644
--- a/LaunchAPPL/Common/ReliableStream.cc
+++ b/LaunchAPPL/Common/ReliableStream.cc
@@ -35,6 +35,7 @@ ReliableStream::ReliableStream(Stream& stream)
     : stream(stream)
 {
     incomingPacket.reserve(packetSize + 4);
+    stream.setListener(this);
 }
 ReliableStream::~ReliableStream()
 {
@@ -65,12 +66,12 @@ void ReliableStream::nack()
     printf("nack sent\n");
 }
 
-void ReliableStream::gotNack(uint8_t id)
+void ReliableStream::gotAck(uint8_t id)
 {
     printf("got ack\n");
 }
 
-void ReliableStream::gotAck(uint8_t id)
+void ReliableStream::gotNack(uint8_t id)
 {
     printf("got nack\n");
 }
diff --git a/LaunchAPPL/Common/UnreliableStream.h b/LaunchAPPL/Common/UnreliableStream.h
new file mode 100644
index 0000000000..cbe4fbc7f8
--- /dev/null
+++ b/LaunchAPPL/Common/UnreliableStream.h
@@ -0,0 +1,56 @@
+#ifndef UNRELIABLESTREAM_H_
+#define UNRELIABLESTREAM_H_
+
+#include "Stream.h"
+
+    // A stream filter to simulate bit errors
+class UnreliableStream : public Stream, private StreamListener
+{
+    Stream& stream_;
+    int nextError = 0;
+public:
+    UnreliableStream(Stream& stream)
+        : stream_(stream)
+    {
+        stream_.setListener(this);
+        setupNextError();
+    }
+    virtual void write(const void* p, size_t n) override
+    {
+        std::vector<uint8_t> tmp(n);
+        memcpy(tmp.data(), p, n);
+        maybeFlipBit(tmp.data(), n);
+        stream_.write(tmp.data(),n);
+    }
+    virtual void flushWrite() override
+    {
+        stream_.flushWrite();
+    }
+
+private:
+    virtual size_t onReceive(const uint8_t* p, size_t n) override
+    {
+        std::vector<uint8_t> tmp(n);
+        memcpy(tmp.data(), p, n);
+        maybeFlipBit(tmp.data(), n);
+        notifyReceive(tmp.data(), n);
+        return n;
+    }
+
+    void setupNextError()
+    {
+        nextError += 8 * 1000 + 3;
+    }
+
+    void maybeFlipBit(uint8_t* p, size_t n)
+    {
+        while(nextError < n * 8)
+        {
+            p[n / 8] ^= 0x80 >> (n%8);
+            setupNextError();
+        }
+        nextError -= n * 8;
+    }
+};
+
+#endif
diff --git a/LaunchAPPL/Server/main.cc b/LaunchAPPL/Server/main.cc
index 33d46a59af..d6ee50d79b 100644
--- a/LaunchAPPL/Server/main.cc
+++ b/LaunchAPPL/Server/main.cc
@@ -9,6 +9,8 @@
 #include <ReliableStream.h>
 #include <Processes.h>
 
+#include <UnreliableStream.h>
+
 class MacSerialStream : public Stream
 {
     static const long kInputBufferSize = 4096;
@@ -195,8 +197,15 @@ int main()
 	
     {
         MacSerialStream stream;
+
+//#define SIMULATE_ERRORS
+#ifdef SIMULATE_ERRORS
+        UnreliableStream uStream(stream);
+        ReliableStream rStream(uStream);
+#else
         ReliableStream rStream(stream);
-        stream.setListener(&rStream);
+#endif
+
         Listener listener;
         rStream.setListener(&listener);