/**
 * \file dnn/src/cuda/rng/opr_impl.h
 * MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
 *
 * Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 */
#pragma once

#include <curand.h>
#include "megdnn/oprs.h"
#include "src/cuda/handle.h"

namespace megdnn {
namespace cuda {

class CuRandHandle {
    curandGenerator_t m_gen;
    uint64_t m_seed;

    CuRandHandle(const CuRandHandle&) = delete;
    CuRandHandle& operator=(const CuRandHandle&) = delete;

public:
    CuRandHandle(cudaStream_t stream, uint64_t seed = 0);
    ~CuRandHandle();

    void seed(uint64_t seed);

    curandGenerator_t gen() const { return m_gen; }

    void ensure_seed(uint64_t seed) {
        if (m_seed != seed) {
            this->seed(seed);
        }
    }
};

class UniformRNGImpl : public UniformRNG {
    CuRandHandle m_curand_handle;

public:
    UniformRNGImpl(Handle* handle);
    void exec(_megdnn_tensor_inout dst, _megdnn_workspace) override;

    size_t get_workspace_in_bytes(const TensorLayout&) override { return 0; }
};

class GaussianRNGImpl : public GaussianRNG {
    CuRandHandle m_curand_handle;

public:
    GaussianRNGImpl(Handle* handle);

    void exec(_megdnn_tensor_inout dst, _megdnn_workspace) override;

    size_t get_workspace_in_bytes(const TensorLayout& layout) override;
};

class GammaRNGImpl : public GammaRNG {
    uint64_t m_seed, m_offset;
    cudaStream_t m_stream;

public:
    GammaRNGImpl(Handle* handle);

    void exec(_megdnn_tensor_in shape,_megdnn_tensor_in scale, 
              _megdnn_tensor_out dst, _megdnn_workspace) override;

    size_t get_workspace_in_bytes(const TensorLayout&, const TensorLayout&,
                                  const TensorLayout&) override {
        return 0;
    }

    void seed(uint64_t seed) { m_seed = seed; }

    void ensure_seed(uint64_t seed) {
        if (m_seed != seed) {
            this->seed(seed);
        }
    }
};

class BetaRNGImpl : public BetaRNG {
    uint64_t m_seed, m_offset;
    cudaStream_t m_stream;

public:
    BetaRNGImpl(Handle* handle);

    void exec(_megdnn_tensor_in alpha,_megdnn_tensor_in beta, 
              _megdnn_tensor_out dst, _megdnn_workspace) override;

    size_t get_workspace_in_bytes(const TensorLayout&, const TensorLayout&,
                                  const TensorLayout&) override {
        return 0;
    }

    void seed(uint64_t seed) { m_seed = seed; }

    void ensure_seed(uint64_t seed) {
        if (m_seed != seed) {
            this->seed(seed);
        }
    }
};

class PoissonRNGImpl : public PoissonRNG {
    uint64_t m_seed, m_offset;
    cudaStream_t m_stream;

public:
    PoissonRNGImpl(Handle* handle);

    void exec(_megdnn_tensor_in lam, _megdnn_tensor_out dst,
              _megdnn_workspace) override;

    size_t get_workspace_in_bytes(const TensorLayout&,
                                  const TensorLayout&) override {
        return 0;
    }

    void seed(uint64_t seed) { m_seed = seed; }

    void ensure_seed(uint64_t seed) {
        if (m_seed != seed) {
            this->seed(seed);
        }
    }
};

class PermutationRNGImpl : public PermutationRNG {
    uint64_t m_seed, m_offset;
    cudaStream_t m_stream;

public:
    PermutationRNGImpl(Handle* handle);

    void exec(_megdnn_tensor_inout dst, _megdnn_workspace) override;

    size_t get_workspace_in_bytes(const TensorLayout& layout) override;

    void seed(uint64_t seed) { m_seed = seed; }

    void ensure_seed(uint64_t seed) {
        if (m_seed != seed) {
            this->seed(seed);
        }
    }
};

}  // namespace cuda
}  // namespace megdnn
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