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+///////////////////////////////////////////////////////////////////////
+// File:        svutil.h
+// Description: ScrollView Utilities
+// Author:      Joern Wanke
+//
+// (C) Copyright 2007, Google Inc.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+///////////////////////////////////////////////////////////////////////
+//
+// SVUtil contains the SVSync, SVSemaphore and SVNetwork
+// classes, which are used for thread/process creation & synchronization
+// and network connection.
+
+#ifndef TESSERACT_VIEWER_SVUTIL_H_
+#define TESSERACT_VIEWER_SVUTIL_H_
+
+#ifdef _WIN32
+#  include "host.h"  // also includes windows.h
+#else
+#include <semaphore.h>
+#endif
+
+#include <mutex>
+#include <string>
+
+namespace tesseract {
+
+/// The SVSync class provides functionality for Thread & Process Creation
+class SVSync {
+ public:
+  /// Starts a new process.
+  static void StartProcess(const char* executable, const char* args);
+};
+
+/// A semaphore class which encapsulates the main signaling
+/// and wait abilities of semaphores for windows and unix.
+class SVSemaphore {
+ public:
+  /// Sets up a semaphore.
+  SVSemaphore();
+  /// Signal a semaphore.
+  void Signal();
+  /// Wait on a semaphore.
+  void Wait();
+ private:
+#ifdef _WIN32
+  HANDLE semaphore_;
+#elif defined(__APPLE__)
+  sem_t *semaphore_;
+#else
+  sem_t semaphore_;
+#endif
+};
+
+/// The SVNetwork class takes care of the remote connection for ScrollView
+/// This means setting up and maintaining a remote connection, sending and
+/// receiving messages and closing the connection.
+/// It is designed to work on both Linux and Windows.
+class SVNetwork {
+ public:
+  /// Set up a connection to hostname on port.
+  SVNetwork(const char* hostname, int port);
+
+  /// Destructor.
+  ~SVNetwork();
+
+  /// Put a message in the messagebuffer to the server and try to send it.
+  void Send(const char* msg);
+
+  /// Receive a message from the server.
+  /// This will always return one line of char* (denoted by \\n).
+  char* Receive();
+
+  /// Close the connection to the server.
+  void Close();
+
+  /// Flush the buffer.
+  void Flush();
+
+ private:
+  /// The mutex for access to Send() and Flush().
+  std::mutex mutex_send_;
+  /// The actual stream_ to the server.
+  int stream_;
+  /// Stores the last received message-chunk from the server.
+  char* msg_buffer_in_;
+
+  /// Stores the messages which are supposed to go out.
+  std::string msg_buffer_out_;
+
+  /// Where we are at in our msg_buffer_in_
+  char* buffer_ptr_;  // strtok_r, strtok_s
+};
+
+} // namespace tesseract
+
+#endif  // TESSERACT_VIEWER_SVUTIL_H_