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

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 HL_SEQUENCE_H_
#define HL_SEQUENCE_H_

#include "hl_base.h"

/**
 * @brief   Maximum sequence forward.
 *
 * @param[in]   input           each sequence contains some instances.
 * @param[in]   sequence        sequence index..
 * @param[out]  output          max instance in this sequence.
 * @param[out]  index           index of max instance.
 * @param[in]   numSequences    size of sequence[in].
 * @param[in]   dim             input dimension.
 *
 */
extern void hl_max_sequence_forward(real* input,
                                    const int* sequence,
                                    real* output,
                                    int* index,
                                    int numSequences,
                                    int dim);

/**
 * @brief   Maximum sequence backward.
 *
 * @param[in]   outputGrad      output gradient.
 * @param[in]   index           index of max instance.
 * @param[out]  inputGrad       input gradient.
 * @param[in]   numSequences    size of sequence[in].
 * @param[in]   dim             input dimension.
 *
 */
extern void hl_max_sequence_backward(
    real* outputGrad, int* index, real* inputGrad, int numSequences, int dim);

/**
 * @brief   Memory copy from sequence to batch.
 *
 * if seq2batch == true
 *
 *    copy from sequence to batch: batch[i] = sequence[batchIndex[i]].
 *
 * if seq2batch == false
 *
 *    copy from batch to sequence: sequence[batchIndex[i]] = batch[i].
 *
 * @param[in,out]   batch       batch matrix.
 * @param[in,out]   sequence    equence matrix.
 * @param[in]       batchIndex  index vector.
 * @param[in]       seqWidth    width of sequence.
 * @param[in]       batchCount  number of batchIndex.
 * @param[in]       seq2batch   copy direction.
 *
 */
extern void hl_sequence2batch_copy(real* batch,
                                   real* sequence,
                                   const int* batchIndex,
                                   int seqWidth,
                                   int batchCount,
                                   bool seq2batch);

/**
 * @brief   Add sequence to batch.
 *
 * if seq2batch == true
 *
 *    add sequence to batch: batch[i] = sequence[batchIndex[i]].
 *
 * if seq2batch == false
 *
 *    add batch to sequence: sequence[batchIndex[i]] = batch[i].
 *
 * @param[in,out]   batch       batch matrix.
 * @param[in,out]   sequence    equence matrix.
 * @param[in]       batchIndex  index vector.
 * @param[in]       seqWidth    width of sequence.
 * @param[in]       batchCount  number of batchIndex.
 * @param[in]       seq2batch   copy direction.
 *
 */
extern void hl_sequence2batch_add(real* batch,
                                  real* sequence,
                                  int* batchIndex,
                                  int seqWidth,
                                  int batchCount,
                                  bool seq2batch);

/**
 * @brief   Memory copy from sequence to batch,
 *          while padding all sequences to the same length.
 *
 * if seq2batch == true
 *
 *    copy from sequence to batch:
 *        batch[i] = sequence[sequenceStartPositions[i]]
 *
 * if seq2batch == false
 *
 *    copy from batch to sequence:
 *        sequence[sequenceStartPositions[i]] = batch[i]
 *
 * @param[in,out]   batch                   batch matrix.
 * @param[in,out]   sequence                sequence matrix.
 * @param[in]       sequenceStartPositions  index vector.
 * @param[in]       sequenceWidth           width of sequence.
 * @param[in]       maxSequenceLength       maximum length of sequences.
 * @param[in]       numSequences            number of sequences.
 * @param[in]       normByTimes             whether dividing sequence's length.
 * @param[in]       seq2batch               copy direction.
 *
 */
extern void hl_sequence2batch_copy_padding(real* batch,
                                           real* sequence,
                                           const int* sequenceStartPositions,
                                           const size_t sequenceWidth,
                                           const size_t maxSequenceLength,
                                           const size_t numSequences,
                                           bool normByTimes,
                                           bool seq2batch);

/**
 * @brief  dst = Op(src), src is sequence.
 *
 * mode = 0, Op is average.
 *
 * mode = 1, Op is sum.
 *
 * mode = 2, Op is sum(src)/sqrt(N), N is sequence length.
 *
 * @param[in,out]   dst       destination data.
 * @param[in]       src       source data.
 * @param[in]       starts    sequence start positions.
 * @param[in]       height    height of dst data.
 * @param[in]       width     width of dst data.
 * @param[in]       mode      0: avreage,
 *                            1: sum,
 *                            2: divide by square root
 *                            of sequenceLength
 */
extern void hl_sequence_avg_forward(real* dst,
                                    real* src,
                                    const int* starts,
                                    int height,
                                    int width,
                                    const int mode);

#endif /* HL_SEQUENCE_H_ */
