// Copyright 2017 The NXT Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef BACKEND_D3D12_COMMANDALLOCATORMANAGER_H_
#define BACKEND_D3D12_COMMANDALLOCATORMANAGER_H_

#include "backend/d3d12/d3d12_platform.h"

#include "common/SerialQueue.h"

#include <bitset>

namespace backend {
namespace d3d12 {

    class Device;

    class CommandAllocatorManager {
        public:
            CommandAllocatorManager(Device* device);

            // A CommandAllocator that is reserved must be used on the next ExecuteCommandLists
            // otherwise its commands may be reset before execution has completed on the GPU
            ComPtr<ID3D12CommandAllocator> ReserveCommandAllocator();
            void Tick(uint64_t lastCompletedSerial);

        private:
            Device* device;

            // This must be at least 2 because the Device and Queue use separate command allocators
            static constexpr unsigned int kMaxCommandAllocators = 32;
            unsigned int allocatorCount;

            struct IndexedCommandAllocator {
                ComPtr<ID3D12CommandAllocator> commandAllocator;
                unsigned int index;
            };

            ComPtr<ID3D12CommandAllocator> commandAllocators[kMaxCommandAllocators];
            std::bitset<kMaxCommandAllocators> freeAllocators;
            SerialQueue<IndexedCommandAllocator> inFlightCommandAllocators;
    };

}
}

#endif // BACKEND_D3D12_COMMANDALLOCATORMANAGER_H_