gecko-dev/ef/Utilities/General/Fifo.h

72 lines
1.8 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All Rights
* Reserved.
*/
#ifndef _FIFO_H_
#define _FIFO_H_
#include "Fundamentals.h"
template <class N>
class Fifo
{
private:
N* begin;
N* limit;
N* first;
N* last;
public:
Fifo(Uint32 size) {begin = first = last = new N[size]; limit = &begin[size];}
~Fifo() {delete begin;}
N& get(); // get at first element inserted.
void put(N n); // append an element.
bool empty() const {return (last == first);} // is the fifo empty ?
Uint32 count() const; // number of elements in the fifo.
};
template <class N> inline N&
Fifo<N>::get()
{
assert(last != first);
N* pos = first++;
if (first == limit)
first = begin;
return *pos;
}
template <class N> inline void
Fifo<N>::put(N n)
{
*last++ = n;
if (last == limit)
last = begin;
assert(last != first);
}
template <class N> inline Uint32
Fifo<N>::count() const
{
if (last >= first)
return Uint32(last - first);
else
return Uint32(limit - first) + Uint32(last - begin);
}
#endif /* _FIFO_H_ */