W. Eric Norum
158 lines
4.3 KiB
C++
158 lines
4.3 KiB
C++
/*************************************************************************\
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* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
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* National Laboratory.
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* Copyright (c) 2002 The Regents of the University of California, as
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* Operator of Los Alamos National Laboratory.
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* EPICS BASE Versions 3.13.7
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* and higher are distributed subject to a Software License Agreement found
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* in file LICENSE that is included with this distribution.
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\*************************************************************************/
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/*epicsRingPointer.h */
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/* Author: Marty Kraimer Date: 15JUL99 */
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#ifndef INCepicsRingPointerh
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#define INCepicsRingPointerh
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/* NOTES
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* If there is only one writer it is not necessary to lock push
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* If there is a single reader it is not necessary to lock pop
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*/
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#include "shareLib.h"
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#ifdef __cplusplus
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template <class T>
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class epicsRingPointer {
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public: /* Functions */
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epicsRingPointer(int size);
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~epicsRingPointer();
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bool push(T *p);
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T* pop();
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void flush();
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int getFree() const;
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int getUsed() const;
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int getSize() const;
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bool isEmpty() const;
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bool isFull() const;
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private: /* Prevent compiler-generated member functions */
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/* default constructor, copy constructor, assignment operator */
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epicsRingPointer();
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epicsRingPointer(const epicsRingPointer &);
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epicsRingPointer& operator=(const epicsRingPointer &);
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private: /* Data */
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volatile int nextPush;
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volatile int nextPop;
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int size;
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T * volatile * buffer;
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};
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extern "C" {
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#endif /*__cplusplus */
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typedef void *epicsRingPointerId;
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epicsShareFunc epicsRingPointerId epicsShareAPI epicsRingPointerCreate(int size);
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epicsShareFunc void epicsShareAPI epicsRingPointerDelete(epicsRingPointerId id);
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/*ringPointerPush returns (0,1) if p (was not, was) put on ring*/
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epicsShareFunc int epicsShareAPI epicsRingPointerPush(epicsRingPointerId id,void *p);
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/*ringPointerPop returns 0 if ring is empty*/
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epicsShareFunc void* epicsShareAPI epicsRingPointerPop(epicsRingPointerId id) ;
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epicsShareFunc void epicsShareAPI epicsRingPointerFlush(epicsRingPointerId id);
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epicsShareFunc int epicsShareAPI epicsRingPointerGetFree(epicsRingPointerId id);
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epicsShareFunc int epicsShareAPI epicsRingPointerGetUsed(epicsRingPointerId id);
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epicsShareFunc int epicsShareAPI epicsRingPointerGetSize(epicsRingPointerId id);
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epicsShareFunc int epicsShareAPI epicsRingPointerIsEmpty(epicsRingPointerId id);
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epicsShareFunc int epicsShareAPI epicsRingPointerIsFull(epicsRingPointerId id);
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#ifdef __cplusplus
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}
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#endif
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/* END OF DECLARATIONS */
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/* INLINE FUNCTIONS */
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/* Algorithm note
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* Space is allocated for one additional element.
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* A put request is rejected if the it would cause nextPush to equal nextPop
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* The algorithm does not require locking puts for a single writer
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* or locking of gets for a single reader
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*/
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#ifdef __cplusplus
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template <class T>
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inline epicsRingPointer<T>::epicsRingPointer(int sz) :
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nextPush(0), nextPop(0), size(sz+1), buffer(new T* [sz+1]) {}
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template <class T>
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inline epicsRingPointer<T>::~epicsRingPointer()
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{ delete [] buffer;}
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template <class T>
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inline bool epicsRingPointer<T>::push(T *p)
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{
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int next = nextPush;
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int newNext = next + 1;
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if(newNext>=size) newNext=0;
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if(newNext==nextPop) return(false);
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buffer[next] = p;
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nextPush = newNext;
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return(true);
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}
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template <class T>
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inline T* epicsRingPointer<T>::pop()
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{
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int next = nextPop;
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if(next == nextPush) return(0);
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T*p = buffer[next];
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++next;
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if(next >=size) next = 0;
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nextPop = next;
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return(p);
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}
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template <class T>
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inline void epicsRingPointer<T>::flush()
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{
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nextPop = 0;
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nextPush = 0;
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}
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template <class T>
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inline int epicsRingPointer<T>::getFree() const
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{
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int n = nextPop - nextPush - 1;
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if (n < 0) n += size;
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return n;
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}
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template <class T>
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inline int epicsRingPointer<T>::getUsed() const
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{
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int n = nextPush - nextPop;
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if (n < 0) n += size;
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return n;
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}
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template <class T>
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inline int epicsRingPointer<T>::getSize() const
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{ return(size-1);}
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template <class T>
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inline bool epicsRingPointer<T>::isEmpty() const
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{ return(nextPush==nextPop);}
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template <class T>
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inline bool epicsRingPointer<T>::isFull() const
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{
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int count = nextPush - nextPop +1;
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return((count == 0) || (count == size));
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}
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#endif /* __cplusplus */
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#endif /* INCepicsRingPointerh */
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