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#include "mem/qos/policy_pf.hh"

#include <algorithm>

#include "base/logging.hh"
#include "params/QoSPropFairPolicy.hh"

namespace gem5
{

namespace memory
{

GEM5_DEPRECATED_NAMESPACE(QoS, qos);
namespace qos
{

PropFairPolicy::PropFairPolicy(const Params &p)
  : Policy(p), weight(p.weight)
{
    fatal_if(weight < 0 || weight > 1,
        "weight must be a value between 0 and 1");
}

PropFairPolicy::~PropFairPolicy()
{}

template <typename Requestor>
void
PropFairPolicy::initRequestor(const Requestor requestor, const double score)
{
    RequestorID id = memCtrl->system()->lookupRequestorId(requestor);

    assert(id != Request::invldRequestorId);

    // Setting the Initial score for the selected requestor.
    history.push_back(std::make_pair(id, score));

    fatal_if(history.size() > memCtrl->numPriorities(),
        "Policy's maximum number of requestors is currently dictated "
        "by the maximum number of priorities\n");
}

void
PropFairPolicy::initRequestorName(const std::string requestor, const double score)
{
    initRequestor(requestor, score);
}

void
PropFairPolicy::initRequestorObj(const SimObject* requestor, const double score)
{
    initRequestor(requestor, score);
}

double
PropFairPolicy::updateScore(
    const double old_score, const uint64_t served_bytes) const
{
    return ((1.0 - weight) * old_score) + (weight * served_bytes);
}

uint8_t
PropFairPolicy::schedule(const RequestorID pkt_id, const uint64_t pkt_size)
{
    auto sort_pred =
    [] (const RequestorHistory& lhs, const RequestorHistory& rhs)
    { return lhs.second > rhs.second; };

    // Sorting in reverse in base of personal history:
    // First elements have higher history/score -> lower priority.
    // The qos priority is the position in the sorted vector.
    std::sort(history.begin(), history.end(), sort_pred);

    const double served_bytes = static_cast<double>(pkt_size);

    uint8_t pkt_priority = 0;
    for (auto m_hist = history.begin(); m_hist != history.end(); m_hist++) {

        RequestorID curr_id = m_hist->first;
        double& curr_score = m_hist->second;

        if (curr_id == pkt_id) {
            // The qos priority is the position in the sorted vector.
            pkt_priority = std::distance(history.begin(), m_hist);

            curr_score = updateScore(curr_score, served_bytes);
        } else {
            curr_score = updateScore(curr_score, 0);
        }
    }

    return pkt_priority;
}

} // namespace qos
} // namespace memory
} // namespace gem5