/*
 * Copyright (c) 2014-2015 Advanced Micro Devices, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef __FETCH_STAGE_HH__
#define __FETCH_STAGE_HH__

#include <string>
#include <vector>

#include "base/statistics.hh"
#include "base/stats/group.hh"
#include "gpu-compute/fetch_unit.hh"

namespace gem5
{

// Instruction fetch stage.
// All dispatched wavefronts for all SIMDS are analyzed for the
// need to fetch instructions. From the fetch eligible waves,
// one wave is selected from each SIMD and fetch is initiated
// for the selected waves.

class ComputeUnit;
class Wavefront;

class FetchStage
{
  public:
    FetchStage(const ComputeUnitParams &p, ComputeUnit &cu);
    ~FetchStage();
    void init();
    void exec();
    void processFetchReturn(PacketPtr pkt);
    void fetch(PacketPtr pkt, Wavefront *wave);

    // Stats related variables and methods
    const std::string& name() const { return _name; }
    FetchUnit &fetchUnit(int simdId) { return _fetchUnit.at(simdId); }

  private:
    int numVectorALUs;
    ComputeUnit &computeUnit;

    // List of fetch units. A fetch unit is
    // instantiated per VALU/SIMD
    std::vector<FetchUnit> _fetchUnit;
    const std::string _name;

  protected:
    struct FetchStageStats : public statistics::Group
    {
        FetchStageStats(statistics::Group *parent);

        statistics::Distribution instFetchInstReturned;
    } stats;
};

} // namespace gem5

#endif // __FETCH_STAGE_HH__