#include        <iostream.h>
#include        "Cirbuf.h"

Cirbuf::Cirbuf(int s /* = D_SIZE */)
{    head = tail = length = 0;
     size = s;
     cb = new char[s];  // allocate buffer space
}

Cirbuf::~Cirbuf()
{    delete [] cb;      // free up space
}

Cirbuf& Cirbuf::operator = (const Cirbuf& b)
{   if (&b == this) return(*this);
    head = 0;
    tail = length = b.length;
    if ( size != b.size )
    {   delete [] cb;
        size = b.size;
        cb = new char[size];
    }
    for (int i=0 ; i < length ; i++)
        cb[i] = b.cb[(b.head + i) % size];
    return(*this);
}

int Cirbuf::produce(char c)
{    if ( is_full() ) 
     {    cerr << "produce: buffer full\n";
          return(-1);
     }
     cb[tail++] = c;
     length++;
     tail = mod(tail);
     return(0);
}

int Cirbuf::consume()
{    char c;
     if ( is_empty() )
     {    cerr << "consume: buffer empty\n";
          return(-1);
     }
     c = cb[head++];
     length--;
     head = mod(head);
     return(c);
}

int Cirbuf::next(char& c)
{  static int ind = -1;
   if ( ind == -1 ) ind = head;
   if ( ind == tail ) return(ind = -1);
   c = cb[ind++];
   ind = mod(ind);
   return(ind);
}

CirbufIterator::CirbufIterator(Cirbuf& buf)
: b(buf), ind(buf.head)
{ }

int CirbufIterator::operator() (char& c)
{
   if ( ind == b.tail ) return(0);
   c = b.cb[ind++];
   ind = b.mod(ind);
   return(1);
}