/*************************************************************************
 * Copyright (c) 2022-2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 *
 * See LICENSE for license information.
 ************************************************************************/

#include <transformer_engine/activation.h>
#include <cuda_runtime.h>
#include <cfloat>
#include <iostream>
#include "../utils.cuh"
#include "../common.h"
#include <cstdlib>
#include <../util/vectorized_pointwise.h>

namespace transformer_engine {

namespace detail {

struct GELUParam {};

__device__ inline fp32 gelu(fp32 value, const GELUParam &) {
  return value * (0.5F + 0.5F * tanhf(value * (0.79788456F + 0.03567741F * value * value)));
}

}

void gelu_cast(const Tensor &input,
               Tensor *output,
               cudaStream_t stream) {
  CheckInputTensor(input, "gelu_input");
  CheckOutputTensor(*output, "gelu_output");
  NVTE_CHECK(input.data.shape.size() == 2, "Input must have 2 dimensions.");
  NVTE_CHECK(output->data.shape.size() == 2, "Output must have 2 dimensions.");
  NVTE_CHECK(input.data.shape == output->data.shape, "Input and output shapes must match.");
  const size_t tot_elts = input.data.shape[1] * input.data.shape[0];

  TRANSFORMER_ENGINE_TYPE_SWITCH_INPUT(input.data.dtype, IType,
    TRANSFORMER_ENGINE_TYPE_SWITCH_OUTPUT(output->data.dtype, OType,
      constexpr int nvec = 32 / sizeof(IType);
      VectorizedUnaryKernelLauncher<nvec, detail::GELUParam, detail::gelu>(
        reinterpret_cast<const IType*>(input.data.dptr),
        reinterpret_cast<OType*>(output->data.dptr),
        reinterpret_cast<const fp32*>(output->scale.dptr),
        reinterpret_cast<fp32*>(output->scale_inv.dptr),
        reinterpret_cast<fp32*>(output->amax.dptr),
        tot_elts,
        {},
        stream);
    );  // NOLINT(*)
  );  // NOLINT(*)
}

}  // namespace transformer_engine

void nvte_gelu(const NVTETensor input,
               NVTETensor output,
               cudaStream_t stream) {
  using namespace transformer_engine;
  gelu_cast(*reinterpret_cast<const Tensor*>(input),
            reinterpret_cast<Tensor*>(output),
            stream);
}