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#include "sim/power_state.hh"

#include "base/logging.hh"

PowerState::PowerState(const PowerStateParams *p) :
    SimObject(p), _currState(p->default_state),
    stats(*this)
{
}

void
PowerState::serialize(CheckpointOut &cp) const
{
    unsigned int currState = (unsigned int)_currState;

    SERIALIZE_SCALAR(currState);
    SERIALIZE_SCALAR(prvEvalTick);
}

void
PowerState::unserialize(CheckpointIn &cp)
{
    unsigned int currState;

    UNSERIALIZE_SCALAR(currState);
    UNSERIALIZE_SCALAR(prvEvalTick);

    _currState = Enums::PwrState(currState);
}

void
PowerState::set(Enums::PwrState p)
{
    // Function should ideally be called only when there is a state change
    if (_currState == p) {
        warn_once("PowerState: Already in the requested power state, "
                  "request ignored");
        return;
    }

    // No need to compute stats if in the same tick, update state though. This
    // can happen in cases like a) during start of the simulation multiple
    // state changes happens in init/startup phase, b) one takes a decision to
    // migrate state but decides to reverts back to the original state in the
    // same tick if other conditions are not met elsewhere.
    // Any state change related stats would have been recorded on previous call
    // to this function.
    if (prvEvalTick == curTick() && curTick() != 0) {
        warn("PowerState: More than one power state change request "
             "encountered within the same simulation tick");
        _currState = p;
        return;
    }

    // Record stats for previous state.
    computeStats();

    _currState = p;

    stats.numTransitions++;
}

void
PowerState::computeStats()
{
    // Calculate time elapsed from last (valid) state change
    Tick elapsed_time = curTick() - prvEvalTick;

    stats.pwrStateResidencyTicks[_currState] += elapsed_time;

    // Time spent in CLK_GATED state, this might change depending on
    // transition to other low power states in respective simulation
    // objects.
    if (_currState == Enums::PwrState::CLK_GATED) {
        stats.ticksClkGated.sample(elapsed_time);
    }

    prvEvalTick = curTick();
}

std::vector<double>
PowerState::getWeights() const
{
    // Get residency stats
    std::vector<double> ret;
    Stats::VCounter residencies;
    stats.pwrStateResidencyTicks.value(residencies);

    // Account for current state too!
    Tick elapsed_time = curTick() - prvEvalTick;
    residencies[_currState] += elapsed_time;

    ret.resize(Enums::PwrState::Num_PwrState);
    for (unsigned i = 0; i < Enums::PwrState::Num_PwrState; i++)
        ret[i] = residencies[i] / \
                     (stats.pwrStateResidencyTicks.total() + elapsed_time);

    return ret;
}

PowerState::PowerStateStats::PowerStateStats(PowerState &co)
    : Stats::Group(&co),
    powerState(co),
    ADD_STAT(numTransitions,
             "Number of power state transitions"),
    ADD_STAT(ticksClkGated,
             "Distribution of time spent in the clock gated state"),
    ADD_STAT(pwrStateResidencyTicks,
             "Cumulative time (in ticks) in various power states")
{
}

void
PowerState::PowerStateStats::regStats()
{
    Stats::Group::regStats();

    using namespace Stats;

    const PowerStateParams *p = powerState.params();

    numTransitions.flags(nozero);

    // Each sample is time in ticks
    unsigned num_bins = std::max(p->clk_gate_bins, 10U);
    ticksClkGated
        .init(p->clk_gate_min, p->clk_gate_max,
              (p->clk_gate_max / num_bins))
        .flags(pdf | nozero | nonan)
        ;

    pwrStateResidencyTicks
        .init(Enums::PwrState::Num_PwrState)
        .flags(nozero)
        ;
    for (int i = 0; i < Enums::PwrState::Num_PwrState; i++) {
        pwrStateResidencyTicks.subname(i, Enums::PwrStateStrings[i]);
    }

    numTransitions = 0;
}

void
PowerState::PowerStateStats::preDumpStats()
{
    Stats::Group::preDumpStats();

    /**
     * For every stats dump, the power state residency and other distribution
     * stats should be computed just before the dump to ensure correct stats
     * value being reported for current dump window. It avoids things like
     * having any unreported time spent in a power state to be forwarded to the
     * next dump window which might have rather unpleasant effects (like
     * perturbing the distribution stats).
     */
    powerState.computeStats();
}

PowerState*
PowerStateParams::create()
{
    return new PowerState(this);
}