signal/src/overlap_add.h

/* Copyright 2021 The TensorFlow 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.
==============================================================================*/
#ifndef SIGNAL_SRC_OVERLAP_ADD_H_
#define SIGNAL_SRC_OVERLAP_ADD_H_

#include <stddef.h>
#include <stdint.h>

namespace tflm_signal {
// Adds (with saturation) the contents of `input` to the contents of `buffer`,
// both of size `input_size`, then copies the first `output_size` elements of
// `buffer` to `output`, shifts the last `input_size`-`output_size` elements of
// `buffer` to the beginning of `buffer` and fills the trailing `output_size`
// samples in `buffer` with zeros.
// input: {input[0] ... input[input_size-1]}
// buffer: {buffer[0] ... buffer[input_size-1]}
// After invocation:
// output: {saturate(input[0] + buffer[0]),
//          ... ,
//          saturate(input[output_size-1] + buffer[output_size-1])}
// buffer: {saturate(input[output_size] + buffer[output_size]),
//          ...
//          saturate(  input[input_size-output_size-1]
//                   + buffer[input_size-output_size-1]),
//          zeros(output_size)}
void OverlapAdd(const int16_t* input, int16_t* buffer, int input_size,
                int16_t* output, int output_size);

// The same as the int16_t variant above, but without saturation
void OverlapAdd(const float* input, float* buffer, int input_size,
                float* output, int output_size);

}  //  namespace tflm_signal
#endif  // SIGNAL_SRC_OVERLAP_ADD_H_