/**
 * \file dnn/src/cuda/conv_bias/chanwise_small.cpp
 * 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.
 */

#include "src/common/conv_bias.h"
#include "src/cuda/conv_bias/algo.h"
#include "src/cuda/conv_bias/chanwise/kern.cuh"
#include "src/cuda/utils.h"

using namespace megdnn;
using namespace cuda;
using namespace conv_bias;

namespace {
inline bool is_available_small(const chanwise::Param& param) {
    return param.chl_mul == 1 && param.stride_h == 1 && param.stride_w == 1 &&
           param.src_h <= 32 && param.src_w <= 32 &&
           param.src_h == param.out_h && param.src_w == param.out_w &&
           param.pad_h < param.flt_h && param.pad_w < param.flt_w &&
           param.flt_h * param.flt_w <= (param.src_h + 1) / 2 * param.src_w;
}
}  // anonymous namespace

bool ConvBiasForwardImpl::AlgoChanwiseSmall::is_available(
        const SizeArgs& args) const {
    if (!args.src_layout->is_contiguous() ||
        !args.dst_layout->is_contiguous()) {
        return false;
    }
    if (args.src_layout->dtype == args.filter_layout->dtype &&
        args.src_layout->dtype == dtype::BFloat16()) {
        return false;
    }
    if (args.z_layout->ndim > 0)
        return false;
#if CUDA_VERSION < 9000
    if (args.src_layout->dtype.enumv() == DTypeEnum::Float16)
        return false;
#endif
    auto param = chanwise::Param::from_fwd_args(args);
    auto&& fm = args.filter_meta;
    return args.filter_meta.format == Param::Format::NCHW &&
           args.src_layout->dtype.category() == DTypeCategory::FLOAT &&
           args.opr->param().compute_mode == Param::ComputeMode::DEFAULT &&
           fm.spatial_ndim == 2 && fm.icpg == 1 && fm.dilation[0] == 1 &&
           fm.dilation[1] == 1 && !fm.should_flip && is_available_small(param);
}

size_t ConvBiasForwardImpl::AlgoChanwiseSmall::get_workspace_in_bytes(
        const SizeArgs& args) const {
    auto dst_layout = *args.dst_layout;
    if (dst_layout.dtype.enumv() != args.bias_layout->dtype.enumv()) {
        dst_layout.dtype = DType();
        args.opr->check_or_deduce_dtype_fwd(args.src_layout->dtype,
                                            args.filter_layout->dtype,
                                            dst_layout.dtype);
        return dst_layout.span().dist_byte();
    }
    return 0;
}

void ConvBiasForwardImpl::AlgoChanwiseSmall::exec(const ExecArgs& args) const {
    WorkspaceBundle bundle{args.workspace.raw_ptr,
                           {get_workspace_in_bytes(args)}};
    auto conv_dst_tensor = *args.dst_tensor;
    if (args.dst_layout->dtype.enumv() != args.bias_layout->dtype.enumv()) {
        conv_dst_tensor.raw_ptr = bundle.get(0);
        conv_dst_tensor.layout.dtype = DType();
        args.opr->check_or_deduce_dtype_fwd(args.src_layout->dtype,
                                            args.filter_layout->dtype,
                                            conv_dst_tensor.layout.dtype);
    }
    {
        auto kparam = chanwise::Param::from_fwd_args(args);
        auto stream = cuda_stream(args.handle);
        switch (args.src_layout->dtype.enumv()) {
            case DTypeEnum::Float32:
                chanwise::run_fwd_small(conv_dst_tensor.ptr<float>(),
                                        args.src_tensor->ptr<float>(),
                                        args.filter_tensor->ptr<float>(),
                                        kparam, stream);
                break;
#if CUDA_VERSION >= 9000
            case DTypeEnum::Float16:
                chanwise::run_fwd_small(
                        static_cast<half*>(conv_dst_tensor.raw_ptr),
                        static_cast<half*>(args.src_tensor->raw_ptr),
                        static_cast<half*>(args.filter_tensor->raw_ptr), kparam,
                        stream);
                break;
#endif
            default:
                megdnn_assert_internal(0);
        }
    }
    handle_bias_and_nonlinear(args.handle, args.nonlinear_mode,
                              &conv_dst_tensor, args.dst_tensor,
                              args.bias_tensor);
}

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