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#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 )
{
count = 0;
// 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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