1 /* Copyright 2018 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 #ifndef TENSORFLOW_LITE_EXPERIMENTAL_MICROFRONTEND_LIB_PCAN_GAIN_CONTROL_H_ 16 #define TENSORFLOW_LITE_EXPERIMENTAL_MICROFRONTEND_LIB_PCAN_GAIN_CONTROL_H_ 17 18 #include <stdint.h> 19 #include <stdlib.h> 20 21 #define kPcanSnrBits 12 22 #define kPcanOutputBits 6 23 24 #ifdef __cplusplus 25 extern "C" { 26 #endif 27 28 // Details at https://research.google/pubs/pub45911.pdf 29 struct PcanGainControlState { 30 int enable_pcan; 31 uint32_t* noise_estimate; 32 int num_channels; 33 int16_t* gain_lut; 34 int32_t snr_shift; 35 }; 36 37 int16_t WideDynamicFunction(const uint32_t x, const int16_t* lut); 38 39 uint32_t PcanShrink(const uint32_t x); 40 41 void PcanGainControlApply(struct PcanGainControlState* state, uint32_t* signal); 42 43 #ifdef __cplusplus 44 } // extern "C" 45 #endif 46 47 #endif // TENSORFLOW_LITE_EXPERIMENTAL_MICROFRONTEND_LIB_PCAN_GAIN_CONTROL_H_ 48