/*
 *  TU Eindhoven
 *  Eindhoven, The Netherlands
 *
 *  Name            :   selftimed.cc
 *
 *  Author          :   Sander Stuijk (sander@ics.ele.tue.nl)
 *
 *  Date            :   September 14, 2006
 *
 *  Function        :   Compute latency of SDFG while using self-timed
 *                      execution.
 *
 *  History         :
 *      14-09-06    :   Initial version.
 *      12-02-08    :   Complete re-write in which code is restructed into
 *                      a C++ class.
 *
 * $Id: selftimed.cc,v 1.1.2.1 2010-04-22 07:18:39 mgeilen Exp $
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * In other words, you are welcome to use, share and improve this program.
 * You are forbidden to forbid anyone else to use, share and improve
 * what you give them.   Happy coding!
 */

#include "selftimed.h"
#include "../../base/algo/repetition_vector.h"
#include "../../base/algo/components.h"

namespace SDF
{
    /******************************************************************************
     * State
     *****************************************************************************/

    /**
     * printState ()
     * Print the state to the supplied stream.
     */
    void SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::State::print(
        ostream &out)
    {
        out << "### State ###" << endl;

        for (uint i = 0; i < actClk.size(); i++)
        {
            out << "actClk[" << i << "] =";

            for (list<SDFtime>::const_iterator iter = actClk[i].begin();
                 iter != actClk[i].end(); iter++)
            {
                out << " " << (*iter) << ", ";
            }

            out << endl;
        }

        for (uint i = 0; i < ch.size(); i++)
        {
            out << "ch[" << i << "] = " << ch[i] << endl;
        }

        out << "glbClk = " << glbClk << endl;
    }

    /**
     * clearState ()
     * The function sets the state to zero.
     */
    void SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::State::clear()
    {
        for (uint i = 0; i < actClk.size(); i++)
        {
            actClk[i].clear();
        }

        for (uint i = 0; i < ch.size(); i++)
        {
            ch[i] = 0;
        }

        glbClk = 0;
    }

    /**
     * operator== ()
     * The function compares to states and returns true if they are equal.
     */
    bool SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::State::operator==(
        const State &s)
    {
        if (glbClk != s.glbClk)
            return false;

        for (uint i = 0; i < ch.size(); i++)
        {
            if (ch[i] != s.ch[i])
                return false;
        }

        for (uint i = 0; i < actClk.size(); i++)
        {
            if (actClk[i] != s.actClk[i])
                return false;
        }

        return true;
    }

    /******************************************************************************
     * Transition system
     *****************************************************************************/

    /**
     * initOutputActor ()
     * The function selects an actor to be used as output actor in the
     * state transition system.
     */
    void SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::initOutputActor()
    {
        RepetitionVector repVec;
        int min = INT_MAX;
        SDFactor *a = NULL;

        // Compute repetition vector
        repVec = computeRepetitionVector(g);

        // Select actor with lowest entry in repetition vector as output actor
        for (SDFactorsIter iter = g->actorsBegin(); iter != g->actorsEnd(); iter++)
        {
            if (repVec[(*iter)->getId()] < min)
            {
                a = *iter;
                min = repVec[a->getId()];
            }
        }

        // Set output actor and its repetition vector count
        outputActor = a->getId();
        outputActorRepCnt = repVec[outputActor];
    }

    /**
     * storeState ()
     * The function stores the state s on whenever s is not already in the
     * list of storedStates. When s is stored, the function returns true. When the
     * state s is already in the list, the state s is not stored. The function
     * returns false. The function always sets the pos variable to the position
     * where the state s is in the list.
     */
    bool SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::storeState(
        State &s, StatesIter &pos)
    {
        // Find state in the list of stored states
        for (StatesIter iter = storedStates.begin();
             iter != storedStates.end(); iter++)
        {
            State &x = *iter;

            // State s at position iter in the list?
            if (x == s)
            {
                pos = iter;
                return false;
            }
        }

        // State not found, store it at the end of the list
        storedStates.push_back(s);

        // Added state to the end of the list
        pos = storedStates.end();

        return true;
    }

    /**
     * computeThroughput ()
     * The function calculates the throughput of the states on the cycle. Its
     * value is equal to the average number of firings of an actor per time unit.
     */
    TDtime SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem
    ::computeThroughput(const StatesIter cycleIter)
    {
        int nr_fire = 0;
        TDtime time = 0;

        // Check all state from stack till cycle complete
        for (StatesIter iter = cycleIter; iter != storedStates.end(); iter++)
        {
            State &s = *iter;

            // Number of states in cycle is equal to number of iterations
            // in the period
            nr_fire++;

            // Time between previous state
            time += s.glbClk;
        }

        return (TDtime)(nr_fire) / (time);
    }

    /******************************************************************************
     * SDF
     *****************************************************************************/

#define CH(c)               currentState.ch[c]
#define CH_TOKENS(c,n)      (CH(c) >= n)
#define CONSUME(c,n)        CH(c) = CH(c) - n;
#define PRODUCE(c,n)        CH(c) = CH(c) + n;

#define CH_TOKENS_PREV(c,n) (previousState.ch[c] >= n)

    /**
     * actorReadyToFire ()
     * The function returns true when the actor is ready to fire in state
     * s. Else it returns false.
     */
    bool SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::actorReadyToFire(
        SDFactor *a)
    {
        // Check all input ports for tokens
        for (SDFportsIter iter = a->portsBegin(); iter != a->portsEnd(); iter++)
        {
            SDFport *p = *iter;
            SDFchannel *c = p->getChannel();

            // Actor is destination of the channel?
            if (p->getType() == SDFport::In)
            {
                if (!CH_TOKENS(c->getId(), p->getRate()))
                {
                    return false;
                }
            }
        }

        return true;
    }

    /**
     * startActorFiring ()
     * Start the actor firing. Remove tokens from all input channels and add the
     * actor firing to the list of active actor firings and advance sequence
     * position.
     */
    void SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::startActorFiring(
        TimedSDFactor *a)
    {
        // Consume tokens from inputs and space for output tokens
        for (SDFportsIter iter = a->portsBegin(); iter != a->portsEnd(); iter++)
        {
            SDFport *p = *iter;
            SDFchannel *c = p->getChannel();

            // Actor is destination of the channel?
            if (p->getType() == SDFport::In)
            {
                CONSUME(c->getId(), p->getRate());
            }
        }

        // Add actor firing to the list of active firings of this actor
        currentState.actClk[a->getId()].push_back(a->getExecutionTime());
    }

    /**
     * actorReadyToEnd ()
     * The function returns true when the actor is ready to end its firing. Else
     * the function returns false.
     */
    bool SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::actorReadyToEnd(
        SDFactor *a)
    {
        if (currentState.actClk[a->getId()].empty())
            return false;

        // First actor firing in sorted list has execution time left?
        if (currentState.actClk[a->getId()].front() != 0)
            return false;

        return true;
    }

    /**
     * endActorFiring ()
     * Produce tokens on all output channels and remove the actor firing from the
     * list of active firings.
     */
    void SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::endActorFiring(
        SDFactor *a)
    {
        for (SDFportsIter iter = a->portsBegin(); iter != a->portsEnd(); iter++)
        {
            SDFport *p = *iter;
            SDFchannel *c = p->getChannel();

            // Actor is source of the channel?
            if (p->getType() == SDFport::Out)
            {
                PRODUCE(c->getId(), p->getRate());
            }
        }

        // Remove the firing from the list of active actor firings
        currentState.actClk[a->getId()].pop_front();
    }

    /**
     * clockStep ()
     * The function progresses time till the first end of firing transition
     * becomes enabled. The time step is returned. In case of deadlock, the
     * time step is equal to UINT_MAX.
     */
    SDFtime SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::clockStep()
    {
        SDFtime step = UINT_MAX;

        // Find maximal time progress
        for (uint a = 0; a < g->nrActors(); a++)
        {
            if (!currentState.actClk[a].empty())
            {
                SDFtime actClk = currentState.actClk[a].front();

                if (step > actClk)
                    step = actClk;
            }
        }

        // Still actors ready to end their firing?
        if (step == 0)
            return 0;

        // Check for progress (i.e. no deadlock)
        if (step == UINT_MAX)
            return UINT_MAX;

        // Lower remaining execution time actors
        for (uint a = 0; a < g->nrActors(); a++)
        {
            for (list<SDFtime>::iterator iter = currentState.actClk[a].begin();
                 iter != currentState.actClk[a].end(); iter++)
            {
                SDFtime &actFiringTime = *iter;

                // Lower remaining execution time of the actor firing
                actFiringTime -= step;
            }
        }

        // Advance the global clock
        currentState.glbClk += step;

        return step;
    }

    /**
     * execSDFgraph()
     * Execute the SDF graph till a deadlock is found or a recurrent state.
     * The throughput is returned.
     */
    TDtime SDFstateSpaceSelfTimedLatencyAnalysis::TransitionSystem::execSDFgraph(
        SDFactor *srcActor, SDFactor *dstActor, vector<SDFtime> &timeSrcFire,
        vector<SDFtime> &timeDstFire, uint distance)
    {
        bool foundRecurrentState = false;
        SDFtime clkStep, globalTime = 0;
        StatesIter recurrentState;
        int repCnt = 0;

        // Clear the list of stored states
        clearStoredStates();

        // Create initial state
        currentState.init(g->nrActors(), g->nrChannels());
        currentState.clear();
        previousState.init(g->nrActors(), g->nrChannels());
        previousState.clear();

        // Initial tokens and space
        for (SDFchannelsIter iter = g->channelsBegin();
             iter != g->channelsEnd(); iter++)
        {
            SDFchannel *c = *iter;

            CH(c->getId()) = c->getInitialTokens();
        }

        // Fire the actors
        while (true)
        {
            // Store partial state to check for progress
            for (uint i = 0; i < g->nrChannels(); i++)
            {
                previousState.ch[i] = currentState.ch[i];
            }

            // Finish actor firings
            for (SDFactorsIter iter = g->actorsBegin();
                 iter != g->actorsEnd(); iter++)
            {
                SDFactor *a = *iter;

                while (actorReadyToEnd(a))
                {
                    if (outputActor == a->getId())
                    {
                        repCnt++;
                        if (repCnt == outputActorRepCnt)
                        {
                            // Reccurent state not yet seen
                            if (!foundRecurrentState)
                            {
                                // Add state to hash of visited states
                                if (!storeState(currentState, recurrentState))
                                {
                                    foundRecurrentState = true;
                                }
                            }
                            currentState.glbClk = 0;
                            repCnt = 0;
                        }
                    }

                    // End the actor firing
                    endActorFiring(a);

                    // Firing the destination actor?
                    if (dstActor->getId() == a->getId())
                    {
                        timeDstFire.push_back(globalTime);

                        // Explored full state-space and found all destination
                        // firings related to the source firings in te space?
                        if (timeDstFire.size() >= timeSrcFire.size() + distance
                            && foundRecurrentState)
                        {
                            return computeThroughput(recurrentState);
                        }
                    }
                }
            }

            // Start actor firings
            for (SDFactorsIter iter = g->actorsBegin();
                 iter != g->actorsEnd(); iter++)
            {
                TimedSDFactor *a = (TimedSDFactor *)(*iter);

                // Ready to fire actor a?
                while (actorReadyToFire(a))
                {
                    // Fire actor a
                    startActorFiring(a);

                    // Only add source actor firing if the reccurent state is not
                    // yet found
                    if (!foundRecurrentState && srcActor->getId() == a->getId())
                    {
                        timeSrcFire.push_back(globalTime);
                    }
                }
            }

            // Clock step
            clkStep = clockStep();

            // Advance the global time (this is the total time since the beginning
            // of everything)
            globalTime += clkStep;

            // Deadlocked?
            if (clkStep == UINT_MAX)
            {
                return 0;
            }
        }

        return 0;
    }

    /**
     * analyze ()
     * Compute the throughput of an SDF graph for unconstrained buffer sizes and
     * using auto-concurrency using a state-space traversal.
     */
    void SDFstateSpaceSelfTimedLatencyAnalysis::analyze(TimedSDFgraph *g,
            SDFactor *srcActor, SDFactor *dstActor, TDtime &latency,
            TDtime &throughput)
    {
        vector<SDFtime> timeSrcFire, timeDstFire;
        TransitionSystem *transitionSystem;
        RepetitionVector repVec;
        TimedSDFchannel *ch;
        TDtime actorLatency;
        uint distance, dist;

        // Check that the graph g is a strongly connected graph
        if (!isStronglyConnectedGraph(g))
        {
            throw CException("[ERROR] Graph is not strongly connected.");
        }

        // Find distance between source and destination. Add self-loop to source
        // actor in graph g with no tokens
        ch = g->createChannel(srcActor, 1, srcActor, 1, 0);

        // Create a transition system
        transitionSystem = new TransitionSystem(g);

        // Execute graph
        transitionSystem->execSDFgraph(srcActor, dstActor, timeSrcFire,
                                       timeDstFire, 0);
        distance = timeDstFire.size();
        timeSrcFire.clear();
        timeDstFire.clear();

        // Delete transition system
        delete transitionSystem;

        // Compute repetition vector of the SDFG
        repVec = computeRepetitionVector(g);

        // Distance (look at last firing of dst actor in iteration)
        dist = distance - (distance % repVec[dstActor->getId()]);
        dist = dist + repVec[dstActor->getId()] - 1;

        // Remove self-loop on source actor
        ch->getSrcActor()->removePort(ch->getSrcPort()->getName());
        ch->getDstActor()->removePort(ch->getDstPort()->getName());
        g->removeChannel(ch->getName());

        // Create a transition system
        transitionSystem = new TransitionSystem(g);

        // Find all moments in time at which src and dst actor fire
        throughput = transitionSystem->execSDFgraph(srcActor, dstActor,
                     timeSrcFire, timeDstFire, dist);

        // Delete transition system
        delete transitionSystem;

        // Compute latency
        latency = 0;
        for (uint i = 0; repVec[srcActor->getId()] * (i + 1) < timeSrcFire.size()
             && repVec[dstActor->getId()] * i + dist < timeDstFire.size();
             i++)
        {
            actorLatency = timeDstFire[repVec[dstActor->getId()] * i + dist]
                           - timeSrcFire[repVec[srcActor->getId()] * i];

            if (actorLatency > latency)
                latency = actorLatency;
        }
    }
}//namespace