ImmediateUnit.cc

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/*
    Copyright (c) 2002-2009 Tampere University.
 
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/**
 * @file ImmediateUnit.cc
 *
 * Implementation of ImmediateUnit class.
 *
 * @author Lasse Laasonen 2003 (lasse.laasonen-no.spam-tut.fi)
 * @author Esa Määttä 2007 (esa.maatta-no.spam-tut.fi)
 */
 
#include "ImmediateUnit.hh"
#include "Port.hh"
#include "ObjectState.hh"
 
using std::string;
 
// constant latency value for immediate unit
const int LATENCY = 1;
 
// constant max writes value for immediate unit
const int MAX_WRITES = 1;
 
// initialization of static data members
const string TTAMachine::ImmediateUnit::OSNAME_IMMEDIATE_UNIT = 
    "immediate-unit";
const string TTAMachine::ImmediateUnit::OSKEY_EXTENSION = "extension";
const string TTAMachine::ImmediateUnit::OSVALUE_SIGN = "sign";
const string TTAMachine::ImmediateUnit::OSVALUE_ZERO = "zero";
const string TTAMachine::ImmediateUnit::OSKEY_LATENCY = "latency";
 
namespace TTAMachine {
 
/**
 * Constructor.
 *
 * @param name Name of the immediate unit.
 * @param size Number of immediate registers in the immediate unit.
 * @param width Bit width of the long immediate registers in the immediate
 *              unit.
 * @param extension Extension mode applied to the long immediate when it is
 *                  narrower than the immediate register,
 *                  see Machine::Extension.
 * @param latency Number of cycles needed between the encoding of a long
 *                immediate and its earliest transport on a data bus.
 *                The value "0" indicates that the long immediate can be
 *                read onto a bus in the same cycle in which the instruction
 *                that encodes it is executed.
 * @exception OutOfRange If the given size or width is invalid.
 * @exception InvalidName If the given name is not a valid name for a
                          component.
 */
ImmediateUnit::ImmediateUnit(
    const string& name, unsigned int size, unsigned int width,
    unsigned int maxReads, unsigned int guardLatency,
    Machine::Extension extension)
    : RegisterFile(
          name, size, width, maxReads, MAX_WRITES, guardLatency,
          RegisterFile::NORMAL),
      extension_(extension),
      latency_(LATENCY) {
    RegisterFile::setNumberOfRegisters(size);
    setWidth(width);
}
 
/**
 * Constructor.
 *
 * Loads the state of the immediate unit from the given ObjectState instance.
 * Does not load references to other components.
 *
 * @param state The ObjectState instance.
 * @exception ObjectStateLoadingException If the given ObjectState instance
 *                                        is invalid or if connections to
 *                                        other machine parts cannot be made.
 */
ImmediateUnit::ImmediateUnit(const ObjectState* state) : RegisterFile(state) {
    loadStateWithoutReferences(state);
}
 
/**
 * Destructor.
 */
ImmediateUnit::~ImmediateUnit() {
    unsetMachine();
}
 
 
/**
 * Sets the name of the immediate unit.
 *
 * @param name Name of the immediate unit.
 * @exception ComponentAlreadyExists If an immediate unit with the given
 *                                   name is already in the same machine.
 * @exception InvalidName If the given name is not a valid name for a
 *                        component.
 */
void
ImmediateUnit::setName(const string& name) {
    if (name == this->name()) {
        return;
    }
 
    if (machine() != NULL) {
        if (machine()->immediateUnitNavigator().hasItem(name)) {
            string procName = "ImmediateUnit::setName";
            throw ComponentAlreadyExists(__FILE__, __LINE__, procName);
        } else {
            Component::setName(name);
        }
    } else {
        Component::setName(name);
    }
}
 
/**
 * Returns the extension mode of the immediate unit.
 *
 * @return The extension mode of the immediate unit.
 */
Machine::Extension
ImmediateUnit::extensionMode() const {
    return extension_;
}
 
 
/**
 * Returns the minimum number of cycles needed between the encoding of a long
 * immediate and its earliest transport on a data bus.
 *
 * @return Latency of the immediate unit.
 */
int
ImmediateUnit::latency() const {
    return latency_;
}
 
 
/**
 * Sets the maximum number of ports that can write a register all in the same
 * cycle.
 *
 * For immediate unit the value is fixed to 1.
 *
 * @param writes Maximum number of ports.
 * @exception OutOfRange If the given number of maximum writes is out of
 *                       range.
 */
void
ImmediateUnit::setMaxWrites(int maxWrites) {
    if (maxWrites != MAX_WRITES) {
        std::string procName = "ImmediateUnit::setMaxWrites";
        throw OutOfRange(__FILE__, __LINE__, procName);
    }
    RegisterFile::setMaxWrites(maxWrites);
}
 
/**
 * Sets the extension mode for the immediate unit.
 *
 * @param mode The new extension mode.
 */
void
ImmediateUnit::setExtensionMode(Machine::Extension mode) {
    extension_ = mode;
}
 
 
/**
 * Sets the latency of the immediate unit.
 *
 * @param latency The new latency.
 * @exception OutOfRange If the given latency is less than zero.
 */
void
ImmediateUnit::setLatency(int latency) {
    if (latency != LATENCY) {
        string procName = "ImmediateUnit::setLatency";
        throw OutOfRange(__FILE__, __LINE__, procName);
    }
    latency_ = latency;
}
 
/**
 * Removes the immediate unit from machine.
 */
void
ImmediateUnit::unsetMachine() {
    Machine* mach = machine();
    if (mach == NULL) {
        return;
    }
 
    Machine::InstructionTemplateNavigator itNav =
        mach->instructionTemplateNavigator();
    Machine::BusNavigator busNav = mach->busNavigator();
    for (int itIndex = 0; itIndex < itNav.count(); itIndex++) {
        InstructionTemplate* it = itNav.item(itIndex);
        it->removeSlots(*this);
    }
    BaseRegisterFile::unsetMachine();
    mach->removeImmediateUnit(*this);
}
 
 
/**
 * Saves the contents to an ObjectState tree.
 *
 * @return The newly created ObjectState tree.
 */
ObjectState*
ImmediateUnit::saveState() const {
 
    ObjectState* iUnit = RegisterFile::saveState();
    iUnit->setName(OSNAME_IMMEDIATE_UNIT);
    
    // set extension mode
    if (extension_ == Machine::SIGN) {
        iUnit->setAttribute(OSKEY_EXTENSION, OSVALUE_SIGN);
    } else {
        iUnit->setAttribute(OSKEY_EXTENSION, OSVALUE_ZERO);
    }
 
    iUnit->setAttribute(OSKEY_LATENCY, latency_);
 
    return iUnit;
}
 
 
/**
 * Loads its state from the given ObjectState instance.
 *
 * @param state The ObjectState instance.
 * @exception ObjectStateLoadingException If the given ObjectState instance
 *                                        is invalid or if the connections
 *                                        to other machine parts cannot be
 *                                        made.
 */
void
ImmediateUnit::loadState(const ObjectState* state) {
    loadStateWithoutReferences(state);
    RegisterFile::loadState(state);
}
 
/**
 * Loads the state of the immediate unit without references to other
 * components.
 *
 * @param state The ObjectState instance from which the state is loaded.
 * @exception ObjectStateLoadingException If an error occurs while loading
 *                                        the state.
 */
void
ImmediateUnit::loadStateWithoutReferences(const ObjectState* state) {
    const string procName = "ImmediateUnit::loadStateWithoutReferences";
 
    if (state->name() != OSNAME_IMMEDIATE_UNIT) {
        throw ObjectStateLoadingException(__FILE__, __LINE__, procName);
    }
 
    try {
        string extension = state->stringAttribute(OSKEY_EXTENSION);
        if (extension == OSVALUE_SIGN) {
            setExtensionMode(Machine::SIGN);
        } else if (extension == OSVALUE_ZERO) {
            setExtensionMode(Machine::ZERO);
        } else {
            throw ObjectStateLoadingException(__FILE__, __LINE__, procName);
        }
 
        setLatency(state->intAttribute(OSKEY_LATENCY));
        assert(latency_ >= 0);
 
    } catch (const Exception& e) {
        throw ObjectStateLoadingException(
            __FILE__, __LINE__, procName, e.errorMessage());
    }
}
}