//
// SuperBus.C
//
// Description:
//  Bus for sign-extension and shifting
//
// Version:
//  $Id$
//
// Revision:
//  $Log$
//
// Author:
//  Brian J. Alliet
//  Jonathon W. Donaldson
//

#include "includes.h"

SuperBus::SuperBus(const char *id, int numbits, long mask, int shift) :
    CPUObject(id,numbits),
    Bus(id,numbits),
    m_mask(mask), // specifies which bits user wants from input (and then sign extend only those)
    m_shift(shift) // used to multiply by four for branch operations
    { }

SuperBus::~SuperBus() { }


long SuperBus::computeValue() {

    long val = Bus::computeValue() & m_mask;

    // sign-extend given value
    if( val&(~m_mask>>1) ) {
        val |= ~m_mask;
    }

    // only display debug if we are actually performing a sign-extension
    if(~m_mask != 0 && CPUObject::debug&CPUObject::trace) {
        cout << "--signext-->" << val;
    }

    // shift the value
    val = m_shift < 0 ? val >> -m_shift : val << m_shift;

    // only display debug if we are actually performing a shift
    if(m_shift != 0 && CPUObject::debug&CPUObject::trace) {
        cout << "--<<"<<m_shift<<"-->" << val;
    }

    return val;

}