//
// Adder.C
//
// Description:
//  A simple adder object used for addition only
//
// Version:
//      $Id$
//
// Revision:
//      $Log$
//
// Author:
//  Brian J. Alliet
//  Jonathon W. Donaldson
//

#include "includes.h"

Adder::Adder(const char *id, int numbits) :

    CPUObject(id,numbits), // superclass

    Connector(id,numbits), // superclass

    m_output(id,numbits,*this), // initialize outflow

    m_op1(0),
    m_op2(0)

    { }

Adder::~Adder() { }


/*
 * Fetches the operand values
 */
void Adder::connectFrom(OutFlow &op1, OutFlow &op2) {

    if(Clock::getTime()) {
        throw ArchLibError("Adder connection attempted after start of simulation");
    }

    m_op1 = &op1;
    m_op2 = &op2;

}


/*
 * Compute value in the adder
 */
long Adder::computeValue() {

    bool trace = CPUObject::debug & CPUObject::trace;

    // if either operand is not connected then BLOW-UP!
    if(!m_op1 || !m_op2) {
        throw ArchLibError("Adder not connected to two operands");
    }

    if(trace) { cout << "("; }

    long op1 = m_op1->fetchValue();

    if(trace) { cout << ") + ("; }

    long op2 = m_op2->fetchValue();

    if(trace) { cout << ") "; }

    // and'ing with mask removes any bits larger than the bus size
    return (op1 + op2) & get_mask();

}