GuardState.cc

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/**
 * @file GuardState.cc
 *
 * Definition of GuardState class.
 *
 * @author Pekka Jääskeläinen 2006 (pjaaskel-no.spam-cs.tut.fi)
 * @note rating: red
 */
 
#include "Application.hh"
#include "GuardState.hh"
#include "SimValue.hh"
 
using std::vector;
using std::string;
 
//////////////////////////////////////////////////////////////////////////////
// GuardState
//////////////////////////////////////////////////////////////////////////////
 
/**
 * Constructor.
 *
 * @param targetRegister The target register this guard watches.
 * @param latency The total guard latency modeled.
 */
GuardState::GuardState(
    const ReadableState& targetRegister, 
    int latency) :
    target_(&targetRegister) {
    assert(latency && "Use DirectGuardState for 0-cycle latency");
    for (int i = 0; i < latency; ++i) {
        history_.push_back(targetRegister.value());
    }
    position_ = 0;
}
 
/**
 * Constructor.
 *
 * Creates an empty GuardState, only to be used by subclasses, i.e.,
 * NullGuardState.
 */
GuardState::GuardState() : target_(NULL), position_(-1) {
}
 
/**
 * Destructor.
 */
GuardState::~GuardState() {
}
 
/**
 * Does nothing.
 *
 * The guard history is updated in advanceClock().
 */
void 
GuardState::endClock() {
}
 
/**
 * Updates the guard value history.
 */
void
GuardState::advanceClock() {
    history_[position_] = target_->value();
    position_ = (position_ + 1);
    if ((size_t)position_ >= history_.size())
      position_ = 0;
}
 
/**
 * Returns the current value of the guard, taking the latency in account.
 *
 * @return The current value of the guard.
 */
const SimValue&
GuardState::value() const {
    return history_[position_];
}
 
//////////////////////////////////////////////////////////////////////////////
// NullGuardState
//////////////////////////////////////////////////////////////////////////////
 
NullGuardState NullGuardState::instance_;
 
/**
 * Returns the instance of NullGuardState.
 *
 * @return Instance of NullGuardState.
 */
NullGuardState&
NullGuardState::instance() {
    return instance_;
}
 
/**
 * Constructor.
 */
NullGuardState::NullGuardState() {
}
 
/**
 * Destructor.
 */
NullGuardState::~NullGuardState() {
}
 
//////////////////////////////////////////////////////////////////////////////
// DirectGuardState
//////////////////////////////////////////////////////////////////////////////
/**
 * Constructor.
 * 
 * @param targetRegister The targer register this guard watches.
 */
DirectGuardState::DirectGuardState(const ReadableState& targetRegister) :
    target_(&targetRegister) {
}
 
/**
 * Destructor.
 */
DirectGuardState::~DirectGuardState() {
}
 
 
/**
 * Does nothing.
 */
void 
DirectGuardState::endClock() {
}
 
/**
 * Does nothing.
 */
void
DirectGuardState::advanceClock() {
}
 
/**
 * Returns the current value of the guard.
 *
 * @return The current value of the guard.
 */
const SimValue&
DirectGuardState::value() const {
    return target_->value();
}