/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.

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. */

#include "paddle/fluid/operators/fusion_lstm_op.h"
#include <string>
#include "paddle/fluid/operators/math/blas.h"
#include "paddle/fluid/operators/math/cpu_vec.h"
#include "paddle/fluid/operators/math/fc_compute.h"
#include "paddle/fluid/operators/math/sequence2batch.h"
#include "paddle/fluid/platform/cpu_info.h"

namespace paddle {
namespace operators {

void FusionLSTMOp::InferShape(framework::InferShapeContext* ctx) const {
  PADDLE_ENFORCE(ctx->HasInput("X"), "Input(X) of LSTM should not be null.");
  PADDLE_ENFORCE(ctx->HasInput("WeightX"),
                 "Input(WeightX) of LSTM should not be null.");
  PADDLE_ENFORCE(ctx->HasInput("WeightH"),
                 "Input(WeightH) of LSTM should not be null.");
  PADDLE_ENFORCE(ctx->HasInput("Bias"),
                 "Input(Bias) of LSTM should not be null.");

  PADDLE_ENFORCE(ctx->HasOutput("XX"),
                 "Output(XX) of LSTM should not be null.");
  PADDLE_ENFORCE(ctx->HasOutput("Hidden"),
                 "Output(Hidden) of LSTM should not be null.");
  PADDLE_ENFORCE(ctx->HasOutput("Cell"),
                 "Output(Cell) of LSTM should not be null.");

  auto x_dims = ctx->GetInputDim("X");
  PADDLE_ENFORCE_EQ(x_dims.size(), 2, "Input(X)'s rank must be 2.");

  if (ctx->HasInput("H0")) {
    PADDLE_ENFORCE(ctx->HasInput("C0"),
                   "Input(Cell) and Input(Hidden) of LSTM should not "
                   "be null at the same time.");
    auto h_dims = ctx->GetInputDim("H0");
    auto c_dims = ctx->GetInputDim("C0");
    PADDLE_ENFORCE(h_dims == c_dims,
                   "The dimension of Input(H0) and Input(C0) "
                   "should be the same.");
  }

  auto wx_dims = ctx->GetInputDim("WeightX");
  PADDLE_ENFORCE_EQ(wx_dims.size(), 2,
                    "The rank of Input(WeightX) should be 2.");
  PADDLE_ENFORCE_EQ(wx_dims[0], x_dims[1],
                    "The first dimension of Input(WeightX) "
                    "should be %d.",
                    x_dims[1]);

  int frame_size = wx_dims[1] / 4;
  auto wh_dims = ctx->GetInputDim("WeightH");
  PADDLE_ENFORCE_EQ(wh_dims.size(), 2,
                    "The rank of Input(WeightH) should be 2.");
  PADDLE_ENFORCE_EQ(wh_dims[0], frame_size,
                    "The first dimension of Input(WeightH) "
                    "should be %d.",
                    frame_size);
  PADDLE_ENFORCE_EQ(wh_dims[1], 4 * frame_size,
                    "The second dimension of Input(WeightH) "
                    "should be 4 * %d.",
                    frame_size);

  auto b_dims = ctx->GetInputDim("Bias");
  PADDLE_ENFORCE_EQ(b_dims.size(), 2, "The rank of Input(Bias) should be 2.");
  PADDLE_ENFORCE_EQ(b_dims[0], 1,
                    "The first dimension of Input(Bias) should be 1.");

  auto use_peepholes = ctx->Attrs().Get<bool>("use_peepholes");
  PADDLE_ENFORCE_EQ(b_dims[1], (use_peepholes ? 7 : 4) * frame_size,
                    "The second dimension of Input(Bias) should be "
                    "7 * %d if enable peepholes connection or"
                    "4 * %d if disable peepholes",
                    frame_size, frame_size);

  framework::DDim out_dims({x_dims[0], frame_size});
  ctx->SetOutputDim("Hidden", out_dims);
  ctx->SetOutputDim("Cell", out_dims);
  ctx->ShareLoD("X", "Hidden");
  ctx->ShareLoD("X", "Cell");
  int xx_width;
  if (ctx->Attrs().Get<bool>("use_seq")) {
    xx_width = wx_dims[1];
  } else {
    xx_width = x_dims[1] > wx_dims[1] ? wx_dims[1] : x_dims[1];
    PADDLE_ENFORCE(ctx->HasOutput("BatchedInput"),
                   "Output(BatchedInput) of LSTM should not be null.");
    PADDLE_ENFORCE(ctx->HasOutput("BatchedHidden"),
                   "Output(BatchedHidden) of LSTM should not be null.");
    PADDLE_ENFORCE(ctx->HasOutput("BatchedCell"),
                   "Output(BatchedCell) of LSTM should not be null.");
    PADDLE_ENFORCE(ctx->HasOutput("ReorderedH0"),
                   "Output(ReorderedH0) of LSTM should not be null.");
    PADDLE_ENFORCE(ctx->HasOutput("ReorderedC0"),
                   "Output(ReorderedC0) of LSTM should not be null.");
    ctx->SetOutputDim("BatchedInput", {x_dims[0], wx_dims[1]});
    ctx->SetOutputDim("BatchedHidden", out_dims);
    ctx->SetOutputDim("BatchedCell", out_dims);
  }
  ctx->SetOutputDim("XX", {x_dims[0], xx_width});
  ctx->ShareLoD("X", "XX");
}

framework::OpKernelType FusionLSTMOp::GetExpectedKernelType(
    const framework::ExecutionContext& ctx) const {
  return framework::OpKernelType(
      framework::ToDataType(ctx.Input<framework::LoDTensor>("X")->type()),
      ctx.device_context());
}

void FusionLSTMOpMaker::Make() {
  AddInput("X",
           "(LoDTensor) the input is a LodTensor, which support "
           "variable-time length input sequence. The underlying tensor in "
           "this LoDTensor is a matrix with shape (T X M), where T is the "
           "total time steps in this mini-batch, M is the dim size of x.");
  AddInput("WeightX",
           "(Tensor) the learnable weights of X."
           " - The shape is (M x 4D), where M is the dim size of x, D is the "
           "hidden size. "
           " - Weight = {W_cx, W_ix, W_fx, W_ox}");
  AddInput("WeightH",
           "(Tensor) same as LSTMOp, the learnable hidden-hidden weights."
           " - The shape is (D x 4D), where D is the hidden size. "
           " - Weight = {W_ch, W_ih, W_fh, W_oh}");
  AddInput("Bias",
           "(Tensor) the learnable weights. Almost same as LSTMOp"
           "Note: we should add the fc bias into this (1x4D) in bias."
           "input-hidden bias weight and peephole connections weight if "
           "setting `use_peepholes` True. "
           "1. `use_peepholes = False` "
           " - The shape is (1 x 4D). "
           " - Bias = {b_c, b_i, b_f, b_o}."
           "2. `use_peepholes = True` "
           " - The shape is (1 x 7D). "
           " - Bias = {b_c, b_i, b_f, b_o, W_ic, W_fc, W_oc}.");
  AddInput("H0",
           "(Tensor, optional) (same as LSTMOp) the initial hidden state is an "
           "optional "
           "input. This is a tensor with shape (N x D), where N is the "
           "batch size and D is the hidden size.")
      .AsDispensable();
  AddInput("C0",
           "(Tensor, optional) (same as LSTMOp) (the initial cell state is an "
           "optional "
           "input. This is a tensor with shape (N x D), where N is the "
           "batch size. `H0` and `C0` can be NULL but only at the same time.")
      .AsDispensable();
  AddOutput("Hidden",
            "(LoDTensor) (same as LSTMOp) the hidden state of LSTM operator. "
            "The shape is (T x D), and lod is the same with the `Input`.");
  AddOutput("Cell",
            "(LoDTensor) (same as LSTMOp) the cell state of LSTM operator. "
            "The shape is (T x D), and lod is the same with the `Input`.");
  AddOutput("XX",
            "(LoDTensor) the result after X * WeightX (size is T x 4D)"
            " or batched_X (size is T x M), this will be automatically chosen,"
            " where T is the total time steps in this mini-batch,"
            " D is the hidden size, M is the dim size of x input.")
      .AsIntermediate();
  AddOutput("BatchedInput", "(LoDTensor) (T x 4D).").AsIntermediate();
  AddOutput("BatchedHidden", "(LoDTensor) (T x D).").AsIntermediate();
  AddOutput("BatchedCell", "(LoDTensor) (T x D).").AsIntermediate();
  AddOutput("ReorderedH0", "(LoDTensor) (N x D).").AsIntermediate();
  AddOutput("ReorderedC0", "(LoDTensor) (N x D).").AsIntermediate();
  AddAttr<bool>("use_peepholes",
                "(bool, defalut: True) "
                "whether to enable diagonal/peephole connections.")
      .SetDefault(true);
  AddAttr<bool>("is_reverse",
                "(bool, defalut: False) "
                "whether to compute reversed LSTM.")
      .SetDefault(false);
  AddAttr<bool>("use_seq",
                "(bool, defalut: True) "
                "whether to use seq mode to compute.")
      .SetDefault(true);
  AddAttr<std::string>("gate_activation",
                       "(string, default: sigmoid)"
                       "The activation for input gate, forget gate and output "
                       "gate, `sigmoid` by default.")
      .SetDefault("sigmoid")
      .InEnum({"sigmoid", "tanh", "relu", "identity"});
  AddAttr<std::string>("cell_activation",
                       "(string, default: tanh)"
                       "The activation for cell output, `tanh` by defalut.")
      .SetDefault("tanh")
      .InEnum({"sigmoid", "tanh", "relu", "identity"});
  AddAttr<std::string>("candidate_activation",
                       "(string, default: tanh)"
                       "The activation for candidate hidden state, "
                       "`tanh` by default.")
      .SetDefault("tanh")
      .InEnum({"sigmoid", "tanh", "relu", "identity"});
  AddComment(R"DOC(
Fusion Long-Short Term Memory (LSTM) Operator.
This operator fuse the X into LSTM, more details can refer to LSTM op.
)DOC");
}

template <typename T>
class FuisonLSTMKernel : public framework::OpKernel<T> {
 public:
#define INIT_VEC_FUNC                                                          \
  std::function<void(const int, const T *, T *)> act_gate, act_cell, act_cand; \
  auto& act_gate_str = ctx.Attr<std::string>("gate_activation");               \
  auto& act_cell_str = ctx.Attr<std::string>("cell_activation");               \
  auto& act_cand_str = ctx.Attr<std::string>("candidate_activation");          \
  if (platform::jit::MayIUse(platform::jit::avx)) {                            \
    math::VecActivations<T, platform::jit::avx> act_functor;                   \
    act_gate = act_functor(act_gate_str);                                      \
    act_cell = act_functor(act_cell_str);                                      \
    act_cand = act_functor(act_cand_str);                                      \
  } else {                                                                     \
    math::VecActivations<T, platform::jit::isa_any> act_functor;               \
    act_gate = act_functor(act_gate_str);                                      \
    act_cell = act_functor(act_cell_str);                                      \
    act_cand = act_functor(act_cand_str);                                      \
  }

#define INIT_BASE_INPUT_OUTPUT                          \
  auto* x = ctx.Input<LoDTensor>("X");                  \
  auto* h0 = ctx.Input<Tensor>("H0");                   \
  auto* c0 = ctx.Input<Tensor>("C0");                   \
  auto* wx = ctx.Input<Tensor>("WeightX");              \
  auto* wh = ctx.Input<Tensor>("WeightH");              \
  auto* bias = ctx.Input<Tensor>("Bias");               \
  auto* xx = ctx.Output<LoDTensor>("XX");               \
  auto* hidden_out = ctx.Output<LoDTensor>("Hidden");   \
  auto* cell_out = ctx.Output<LoDTensor>("Cell");       \
  bool use_peepholes = ctx.Attr<bool>("use_peepholes"); \
  bool is_reverse = ctx.Attr<bool>("is_reverse");

#define INIT_BASE_SIZES                  \
  auto x_dims = x->dims();   /* T x M*/  \
  auto wh_dims = wh->dims(); /* D x 4D*/ \
  const int M = x_dims[1];               \
  const int D = wh_dims[0];              \
  const int D2 = D * 2;                  \
  const int D3 = D * 3;                  \
  const int D4 = wh_dims[1];

  void SeqCompute(const framework::ExecutionContext& ctx) const {
    using DeviceContext = paddle::platform::CPUDeviceContext;
    INIT_BASE_INPUT_OUTPUT
    INIT_BASE_SIZES
    INIT_VEC_FUNC

    auto x_lod = x->lod();
    const int total_T = x_dims[0];
    const int N = x_lod[0].size() - 1;  // batch size

    const T* x_data = x->data<T>();
    const T* h0_data = h0 ? h0->data<T>() : nullptr;
    const T* c0_data = c0 ? c0->data<T>() : nullptr;
    const T* bias_data = bias->data<T>();
    const T* wc_data = bias_data + D4;  // w_ic, w_fc, w_oc
    const T* wx_data = wx->data<T>();
    const T* wh_data = wh->data<T>();

    T* xx_data = xx->mutable_data<T>(ctx.GetPlace());
    T* hidden_out_data = hidden_out->mutable_data<T>(ctx.GetPlace());
    T* cell_out_data = cell_out->mutable_data<T>(ctx.GetPlace());

    // use local variable
    framework::DDim check_dims({3, D});
    Tensor checked_cell;  // w_ic * Ct-1, w_fc * Ct-1, w_oc * Ct
    auto checked_cell_data =
        checked_cell.mutable_data<T>(check_dims, ctx.GetPlace());

    auto blas = math::GetBlas<DeviceContext, T>(ctx);
    math::FCCompute<DeviceContext, T>(blas, total_T, D4, M, x_data, wx_data,
                                      xx_data, bias->data<T>());
    int xx_offset = D4;
    int gate_offset = D;
    if (is_reverse) {
      const int offset = (total_T - 1) * D;
      xx_data = xx_data + offset * 4;
      hidden_out_data = hidden_out_data + offset;
      cell_out_data = cell_out_data + offset;
      xx_offset = -D4;
      gate_offset = -D;
    }

    auto move_step = [&]() {
      xx_data = xx_data + xx_offset;
      hidden_out_data = hidden_out_data + gate_offset;
      cell_out_data = cell_out_data + gate_offset;
    };

    for (int i = 0; i < N; ++i) {
      int bid = is_reverse ? N - 1 - i : i;
      int seq_len = x_lod[0][bid + 1] - x_lod[0][bid];
      const T* prev_c_data = nullptr;
      const T* prev_h_data = nullptr;

      int tstart = 0;
      if (h0_data) {
        prev_h_data = h0_data + bid * D;
        prev_c_data = c0_data + bid * D;
      } else {
        // If step == 0 and there is no initialized hidden state, that is to say
        // the H0 is zeros. Then W_h * H_t-1 can be skipped

        // ~C_t
        act_cand(D, xx_data, xx_data);
        if (use_peepholes) {
          // I_t, F_t
          act_gate(D2, xx_data + D, xx_data + D);
        } else {
          // I_t, F_t, O_t
          act_gate(D3, xx_data + D, xx_data + D);
        }
        // C_t = I_t * ~C_t
        blas.VMUL(D, xx_data, xx_data + D, cell_out_data);

        if (use_peepholes) {
          // + W_oc * C_t for peephole connection
          blas.VMUL(D, wc_data + D2, cell_out_data, checked_cell_data + D2);
          blas.VADD(D, xx_data + D3, checked_cell_data + D2, xx_data + D3);
          // O_t
          act_gate(D, xx_data + D3, xx_data + D3);
        }

        // hidden out= act_state(cellout) * outgate
        act_cell(D, cell_out_data, xx_data + D2);
        // H_t = O_t * act_state(C_t)
        blas.VMUL(D, xx_data + D2, xx_data + D3, hidden_out_data);

        // prev
        prev_h_data = hidden_out_data;
        prev_c_data = cell_out_data;

        tstart = 1;
        move_step();
      }

      for (int step = tstart; step < seq_len; ++step) {
        // + W_h * H_t-1
        blas.GEMM(CblasNoTrans, CblasNoTrans, 1, D4, D, static_cast<T>(1),
                  prev_h_data, D, wh_data, D4, static_cast<T>(1), xx_data, D4);

        // ~C_t
        act_cand(D, xx_data, xx_data);

        if (use_peepholes) {
          // + W_ic|W_fc * C_t-1 for peephole connection
          blas.VMUL(D, wc_data, prev_c_data, checked_cell_data);
          blas.VMUL(D, wc_data + D, prev_c_data, checked_cell_data + D);
          blas.VADD(D2, xx_data + D, checked_cell_data, xx_data + D);
          // I_t, F_t
          act_gate(D2, xx_data + D, xx_data + D);
        } else {
          // I_t, F_t, O_t
          act_gate(D3, xx_data + D, xx_data + D);
        }

        // F_t * C_t-1
        blas.VMUL(D, xx_data + D2, prev_c_data, xx_data + D2);
        // I_t * ~C_t
        blas.VMUL(D, xx_data, xx_data + D, xx_data + D);
        // C_t = F_t * C_t-1 + I_t * ~C_t
        blas.VADD(D, xx_data + D, xx_data + D2, cell_out_data);

        if (use_peepholes) {
          // + W_oc * C_t for peephole connection
          blas.VMUL(D, wc_data + D2, cell_out_data, checked_cell_data + D2);
          blas.VADD(D, xx_data + D3, checked_cell_data + D2, xx_data + D3);
          // O_t
          act_gate(D, xx_data + D3, xx_data + D3);
        }

        // hidden out= act_state(cellout) * outgate
        act_cell(D, cell_out_data, xx_data + D2);
        // H_t = O_t * act_state(C_t)
        blas.VMUL(D, xx_data + D2, xx_data + D3, hidden_out_data);

        // prev
        prev_h_data = hidden_out_data;
        prev_c_data = cell_out_data;

        move_step();
      }  // for each step in batch
    }    // for each batch
  }

  void BatchCompute(const framework::ExecutionContext& ctx) const {
    using DeviceContext = platform::CPUDeviceContext;
    INIT_BASE_INPUT_OUTPUT
    if (x->lod()[0].size() == 2) {  // batch size == 1
      SeqCompute(ctx);
      return;
    }
    INIT_BASE_SIZES
    INIT_VEC_FUNC

    auto* reordered_h0 = ctx.Output<Tensor>("ReorderedH0");
    auto* reordered_c0 = ctx.Output<Tensor>("ReorderedC0");
    auto* batched_input = ctx.Output<LoDTensor>("BatchedInput");
    auto* batched_c_out = ctx.Output<LoDTensor>("BatchedCell");
    auto* batched_h_out = ctx.Output<LoDTensor>("BatchedHidden");

    const T* x_data = x->data<T>();
    const T* wx_data = wx->data<T>();
    const T* wh_data = wh->data<T>();
    const T* bias_data = bias->data<T>();
    const T* wc_data = bias_data + D4;  // w_ic, w_fc, w_oc
    auto place = ctx.GetPlace();
    T* xx_data = xx->mutable_data<T>(place);
    T* batched_input_data = batched_input->mutable_data<T>(place);
    T* batched_c_out_data = batched_c_out->mutable_data<T>(place);
    T* batched_h_out_data = batched_h_out->mutable_data<T>(place);
    hidden_out->mutable_data<T>(place);
    cell_out->mutable_data<T>(place);

    // use local variable
    framework::DDim check_dims({3, D});
    Tensor checked_cell;  // w_ic * Ct-1, w_fc * Ct-1, w_oc * Ct
    auto checked_cell_data =
        checked_cell.mutable_data<T>(check_dims, ctx.GetPlace());

    math::LoDTensor2BatchFunctor<DeviceContext, T> to_batch;
    auto& dev_ctx = ctx.template device_context<DeviceContext>();
    auto blas = math::GetBlas<DeviceContext, T>(dev_ctx);
    if (M > D4) {
      math::FCCompute<DeviceContext, T>(blas, x_dims[0], D4, M, x_data, wx_data,
                                        xx_data, bias->data<T>());
      to_batch(dev_ctx, *xx, batched_input, true, is_reverse);
    } else {
      to_batch(dev_ctx, *x, xx, true, is_reverse);
      batched_input->set_lod(xx->lod());
      math::FCCompute<DeviceContext, T>(blas, x_dims[0], D4, M, xx_data,
                                        wx_data, batched_input_data,
                                        bias->data<T>());
    }

    auto batched_lod = batched_input->lod();
    const auto& seq_order = batched_lod[2];
    const int max_bs = seq_order.size();
    reordered_h0->Resize({max_bs, D});
    reordered_c0->Resize({max_bs, D});

    T* prev_batch_h_data = nullptr;
    T* prev_batch_c_data = nullptr;
    T* cur_batch_in_data = batched_input_data;
    T* cur_batch_h_out_data = batched_h_out_data;
    T* cur_batch_c_out_data = batched_c_out_data;

    auto move_step = [&](int bs) {
      cur_batch_in_data += bs * D4;
      cur_batch_c_out_data += bs * D;
      cur_batch_h_out_data += bs * D;
    };

    int tstart = 0;
    if (h0) {
      // reorder h0, c0
      T* reordered_h0_data = reordered_h0->mutable_data<T>(place);
      T* reordered_c0_data = reordered_c0->mutable_data<T>(place);
      const T* h0_data = h0->data<T>();
      const T* c0_data = c0->data<T>();
      prev_batch_h_data = reordered_h0_data;
      prev_batch_c_data = reordered_c0_data;
      size_t sz = sizeof(T) * D;
      for (int i = 0; i < max_bs; ++i) {
        std::memcpy(reordered_h0_data, h0_data + seq_order[i] * D, sz);
        std::memcpy(reordered_c0_data, c0_data + seq_order[i] * D, sz);
        reordered_h0_data += D;
        reordered_c0_data += D;
      }
    } else {
      // Compute with no H0/C0
      T* cur_in_data = cur_batch_in_data;
      T* cur_c_out_data = cur_batch_c_out_data;
      T* cur_h_out_data = cur_batch_h_out_data;

      // If step == 0 and there is no initialized hidden state, that is to say
      // the H0 is zeros. Then W_h * H_t-1 can be skiped

      for (int i = 0; i < max_bs; ++i) {  // iterate each data in 1st batch
        // ~C_t
        act_cand(D, cur_in_data, cur_in_data);

        if (use_peepholes) {
          // I_t, F_t
          act_gate(D2, cur_in_data + D, cur_in_data + D);
        } else {
          // I_t, F_t, O_t
          act_gate(D3, cur_in_data + D, cur_in_data + D);
        }

        // C_t = I_t * ~C_t
        blas.VMUL(D, cur_in_data, cur_in_data + D, cur_c_out_data);

        if (use_peepholes) {
          // + W_oc * C_t for peephole connection
          blas.VMUL(D, wc_data + D2, cur_c_out_data, checked_cell_data + D2);
          blas.VADD(D, cur_in_data + D3, checked_cell_data + D2,
                    cur_in_data + D3);
          // O_t
          act_gate(D, cur_in_data + D3, cur_in_data + D3);
        }

        // hidden out= act_state(cellout) * outgate
        act_cell(D, cur_c_out_data, cur_in_data + D2);
        // H_t = O_t * act_state(C_t)
        blas.VMUL(D, cur_in_data + D2, cur_in_data + D3, cur_h_out_data);

        // move to next data in the same batch
        cur_in_data += D4;
        cur_c_out_data += D;
        cur_h_out_data += D;
      }

      // move to data for next timestep
      prev_batch_h_data = cur_batch_h_out_data;
      prev_batch_c_data = cur_batch_c_out_data;
      move_step(max_bs);
      tstart = 1;
    }

    const auto& batch_starts = batched_lod[0];
    const int max_seq_len = batch_starts.size() - 1;
    for (int step = tstart; step < max_seq_len; ++step) {
      const int cur_bs = batch_starts[step + 1] - batch_starts[step];
      // + W_h * H_t-1
      blas.GEMM(CblasNoTrans, CblasNoTrans, cur_bs, D4, D, static_cast<T>(1),
                prev_batch_h_data, D, wh_data, D4, static_cast<T>(1),
                cur_batch_in_data, D4);

      T* cur_in_data = cur_batch_in_data;
      T* cur_c_out_data = cur_batch_c_out_data;
      T* cur_h_out_data = cur_batch_h_out_data;
      T* prev_c_data = prev_batch_c_data;  // NULL if no C0 in step0
      T* prev_h_data = prev_batch_h_data;  // NULL if no H0 in step0
      auto next_data_in_batch = [&]() {
        cur_in_data += D4;
        cur_c_out_data += D;
        cur_h_out_data += D;
        prev_c_data = prev_c_data ? prev_c_data + D : nullptr;
        prev_h_data = prev_h_data ? prev_h_data + D : nullptr;
      };

      for (int i = 0; i < cur_bs; ++i) {  // iterate each data in same batch
        // ~C_t
        act_cand(D, cur_in_data, cur_in_data);

        if (use_peepholes) {
          // + W_ic|W_fc * C_t-1 for peephole connection
          blas.VMUL(D, wc_data, prev_c_data, checked_cell_data);
          blas.VMUL(D, wc_data + D, prev_c_data, checked_cell_data + D);
          blas.VADD(D2, cur_in_data + D, checked_cell_data, cur_in_data + D);
          // I_t, F_t
          act_gate(D2, cur_in_data + D, cur_in_data + D);
        } else {
          // I_t, F_t, O_t
          act_gate(D3, cur_in_data + D, cur_in_data + D);
        }

        // F_t * C_t-1
        blas.VMUL(D, cur_in_data + D2, prev_c_data, cur_in_data + D2);
        // I_t * ~C_t
        blas.VMUL(D, cur_in_data, cur_in_data + D, cur_in_data + D);
        // C_t = F_t * C_t-1 + I_t * ~C_t
        blas.VADD(D, cur_in_data + D, cur_in_data + D2, cur_c_out_data);

        if (use_peepholes) {
          // + W_oc * C_t for peephole connection
          blas.VMUL(D, wc_data + D2, cur_c_out_data, checked_cell_data + D2);
          blas.VADD(D, cur_in_data + D3, checked_cell_data + D2,
                    cur_in_data + D3);
          // O_t
          act_gate(D, cur_in_data + D3, cur_in_data + D3);
        }

        // hidden out= act_state(cellout) * outgate
        act_cell(D, cur_c_out_data, cur_in_data + D2);
        // H_t = O_t * act_state(C_t)
        blas.VMUL(D, cur_in_data + D2, cur_in_data + D3, cur_h_out_data);

        // move to next data in same batch
        next_data_in_batch();
      }
      // move to data for next timestep
      prev_batch_h_data = cur_batch_h_out_data;
      prev_batch_c_data = cur_batch_c_out_data;
      move_step(cur_bs);
    }

    math::Batch2LoDTensorFunctor<DeviceContext, T> to_seq;
    batched_h_out->set_lod(batched_lod);
    to_seq(dev_ctx, *batched_h_out, hidden_out);
    batched_c_out->set_lod(batched_lod);
    to_seq(dev_ctx, *batched_c_out, cell_out);
  }

  void Compute(const framework::ExecutionContext& ctx) const override {
    if (ctx.Attr<bool>("use_seq")) {
      SeqCompute(ctx);
    } else {
      BatchCompute(ctx);
    }
  }
#undef INIT_BASE_SIZES
#undef INIT_BASE_INPUT_OUTPUT
#undef INIT_VEC_FUNC
};

}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;
REGISTER_OPERATOR(fusion_lstm, ops::FusionLSTMOp, ops::FusionLSTMOpMaker,
                  paddle::framework::DefaultGradOpDescMaker<true>);

REGISTER_OP_CPU_KERNEL(fusion_lstm, ops::FuisonLSTMKernel<float>,
                       ops::FuisonLSTMKernel<double>);