RTS/include/UNIX/simpleQ.hh

#ifndef SIMPLEQ_HH
#define SIMPLEQ_HH

#include <sys/types.h>

template <class T, int S> class simpleQ
{
public:
  simpleQ();

  void clear();
  int put(T* a) ;     // returns 0 on success  -1 if list is full (end of list)
  int prepend(T* a) ; // beginning of list
  int get(T* a) ;     // like first, but removes element 
  int query(T* a) ;

  int entries()      // number of entries in List
    {
      return in;
    };

  int free()        // returns number of free entries
    {
      return(S - in) ;
    };  
  
  T* element(int i)
    { 
      if(i < S) return(&store[i]) ;  
      return(NULL) ;
    };

  //private:
  T store[S] ;     // array of allocated buffers 
  int f ;  // index to first 
  int l;
  int in;
};

//***********************************************
template <class T, int S> simpleQ<T,S>::simpleQ() 
{
  f = l = 0 ;
  in = 0 ;
};

template <class T, int S> void simpleQ<T,S>::clear()
{
  in = 0 ;
  l = f = 0 ;
};

template <class T, int S> int simpleQ<T,S>::put(T* a) // inserts at end 
{
  if(in == S) return(-1) ;
  in++ ;
  store[l++] = *a ;
  if(l == S) l = 0 ;
  return(0) ;
};

template <class T, int S> int simpleQ<T,S>::get(T* a) // removes first element of list
{
  if(!in)return(-1) ; // empty 
  in-- ;
  *a = store[f++] ; 
  if(f == S) f = 0 ;
  return(0) ;
};

template <class T, int S> int simpleQ<T,S>::prepend(T* a) // adds element at the front
{
  if(in == S) return(-1) ;
  in++ ;

  f--;
  if(f<0) f = S - 1;
  store[f] = *a;

  return 0;
};

template <class T, int S> int simpleQ<T,S>::query(T* a)
{
  int i=f;
  
  while(i != l) 
  {
    if(memcmp(a,&store[i],sizeof(T)) == 0) return 1;
    i++;
    if(i==S) i=0;
  }

  return 0;
};

#endif 

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