///////    File Cirbuf.C    ///////

#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 (const Cirbuf& buf) {
    _head   = buf._head;
    _tail   = buf._tail;
    _length = buf._length;
    _size   = buf._size;
    
    _cb = new char [_size];  // allocate buffer
                         
    for (int i = 0; i < _size; ++i) {
        _cb[i] = buf._cb[i];  // copy elements
    }
}

Cirbuf::~Cirbuf() {
     delete [] _cb;      // deallocate buffer
}

Cirbuf& Cirbuf::operator= (const Cirbuf& buf) {
    
    if (this == &buf) {   // self-assignment
        return *this;
    }
    
    if (_size != buf._size) {
        _size = buf._size;
        delete [] _cb;
        _cb = new char [_size];  // allocate buffer
    }
    
    for (int i = 0; i < _size; ++i) {
        _cb[i] = buf._cb[i];    // copy elements
    }
    
    _head   = buf._head;
    _tail   = buf._tail;
    _length = buf._length;

    return *this;
}

int Cirbuf::Produce (char c) {
     if ( IsFull() ) {
          cerr << "produce: buffer full\n";
          return (-1);
     }
     _cb [_tail++] = c;
     _length++;
     _tail = mod (_tail);
     return (0);
}

int Cirbuf::Consume() {
     char c;
     if ( IsEmpty() ) {
          cerr << "consume: buffer empty\n";
          return (-1);
     }
     c = _cb [_head++];
     _length--;
     _head = mod (_head);
     return (c);
}