From d63d2c3c6cbbd574dda4f8b00ebe6c661735edd5 Mon Sep 17 00:00:00 2001
From: Felix Domke <tmbinc@elitedvb.net>
Date: Fri, 17 Oct 2003 15:36:42 +0000
Subject: import of enigma2

---
 lib/base/ringbuffer.h | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 lib/base/ringbuffer.h

(limited to 'lib/base/ringbuffer.h')

diff --git a/lib/base/ringbuffer.h b/lib/base/ringbuffer.h
new file mode 100644
index 00000000..f2cd9058
--- /dev/null
+++ b/lib/base/ringbuffer.h
@@ -0,0 +1,109 @@
+#ifndef QueueRingBufferH
+#define QueueRingBufferH
+
+template <class T>
+class queueRingBuffer
+{
+	template <class A>
+	struct link
+	{
+		link ( const A &val )
+			:value(val)
+		{}
+		A value;
+		link *nextLink;
+		link *prevLink;
+	};
+
+	link<T> *lastFilled;
+	link<T> *lastFree;
+	unsigned int max;
+	int count;
+public:
+	queueRingBuffer( unsigned int max );
+	~queueRingBuffer();
+	int size() { return count; }
+	T& queueRingBuffer::dequeue();
+	T& queueRingBuffer::current();
+	void queueRingBuffer::enqueue( const T &val );
+};
+
+template <class T>
+queueRingBuffer<T>::queueRingBuffer( unsigned int max )
+{
+	// constructor for queues based on ring buffers
+	// create the first link
+	T initialvalue;
+	lastFree = new link<T>( initialvalue );
+	lastFilled = lastFree;
+	// make value point to itself
+	lastFilled->nextLink = lastFilled;
+	lastFilled->prevLink = lastFilled;
+	// now add the remainder of the elements
+	while ( max-- > 0 )
+	{
+		link<T> * newLink = new link<T>( initialvalue );
+		newLink->prevLink = lastFilled;
+		newLink->nextLink = lastFilled->nextLink;
+		lastFilled->nextLink->prevLink = newLink;
+		lastFilled->nextLink = newLink;
+	}
+}
+
+template <class T>
+queueRingBuffer<T>::~queueRingBuffer()
+{
+	// delete all memory associated with ring buffer
+	link<T> * p = lastFree;
+	link<T> * next;
+
+	// walk around the circle deleting nodes
+	while( p->nextLink != lastFree )
+	{
+		next = p->nextLink;
+		delete p;
+		p = next;
+	}
+}
+
+template <class T>
+T& queueRingBuffer<T>::dequeue()
+{
+	// remove element form front of queue
+	// advance last free position
+	lastFree = lastFree->nextLink;
+	count--;
+	// return value stored in last free position
+	return lastFree->value;
+}
+
+template <class T>
+T& queueRingBuffer<T>::current()
+{
+	// return value stored in current
+	return lastFree->nextLink->value;
+}
+
+template <class T>
+void queueRingBuffer<T>::enqueue( const T &val )
+{
+	// add new element to end of queue buffer
+	// first check for potential overflow
+	if( lastFilled->nextLink == lastFree )
+	{
+		eDebug("increase size %d", count);
+		link<T> * newLink = new link<T>( val );
+		newLink->prevLink = lastFilled;
+		newLink->nextLink = lastFilled->nextLink;
+		lastFilled->nextLink->prevLink = newLink;
+		lastFilled->nextLink = newLink;
+	}
+	else
+	{
+		// simply advance the last filled pointer
+		lastFilled = lastFilled->nextLink;
+		lastFilled->value = val;
+	}
+	count++;
+}
+#endif
-- 
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