1 files changed, 76 insertions, 7 deletions

diff --git a/noncore/apps/opie-reader/Navigation.h b/noncore/apps/opie-reader/Navigation.h
index 19d7f81..d88443b 100644
--- a/noncore/apps/opie-reader/Navigation.h
+++ b/noncore/apps/opie-reader/Navigation.h
@@ -1,18 +1,87 @@
+#ifndef __NAVIGATION_H
+#define __NAVIGATION_H
+
 #include <string.h>
 #include <stdlib.h>
 
 const size_t NAVIGATION_HISTORY_SIZE = 32;
 
-class CNavigation
+template<class T>
+class CNavigation_base
 {
-    size_t history[NAVIGATION_HISTORY_SIZE];
+protected:
+    T history[NAVIGATION_HISTORY_SIZE];
     size_t historystart, historyend, historycurrent;
  public:
-    CNavigation() : historystart(0),historyend(0),historycurrent(0) {}
-    void saveposn(size_t posn);
-    void writeposn(size_t posn);
-    bool forward(size_t& loc);
-    bool back(size_t& loc);
+    CNavigation_base() : historystart(0),historyend(0),historycurrent(0) {}
+    void saveposn(T posn);
+    void writeposn(T posn);
+    bool forward(T& loc);
+    bool back(T& loc);
+};
+
+class CNavigation : public CNavigation_base<size_t>
+{
+ public:
     void setSaveData(unsigned char*& data, unsigned short& len, unsigned char* src, unsigned short srclen);
     void putSaveData(unsigned char*& src, unsigned short& srclen);
 };
+
+template<class T>
+inline void CNavigation_base<T>::saveposn(T posn)
+{
+    history[historycurrent] = posn;
+    historycurrent=(historycurrent+1)%NAVIGATION_HISTORY_SIZE;
+    if (historycurrent==historystart)
+      {
+        historystart=(historystart+1)%NAVIGATION_HISTORY_SIZE;
+      }
+    historyend = historycurrent;
+}
+
+template<class T>
+inline void CNavigation_base<T>::writeposn(T posn)
+{
+    history[historycurrent] = posn;
+}
+
+template<class T>
+inline bool CNavigation_base<T>::back(T& posn)
+{
+  if (historycurrent!=historystart)
+    {
+      // buffer is not empty
+      if (historycurrent==0)
+	{
+	  historycurrent=NAVIGATION_HISTORY_SIZE-1;
+	}
+      else
+	{
+	  historycurrent--;
+	}
+      posn=history[historycurrent];
+      return true;   
+    }
+  else
+    {
+      // circular buffer empty
+      return false;
+    }
+}
+
+template<class T>
+inline bool CNavigation_base<T>::forward(T& posn)
+{
+  if (historycurrent!=historyend)
+    {
+      historycurrent=(historycurrent+1)%NAVIGATION_HISTORY_SIZE;
+      posn = history[historycurrent];
+      return true;
+    }
+  else
+    {
+      return false;
+    }
+}
+
+#endif