1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ANDROID_ML_NN_ACTIVATION_FUNCTOR_H 18 #define ANDROID_ML_NN_ACTIVATION_FUNCTOR_H 19 20 #include "android/log.h" 21 22 #include <algorithm> 23 #include <cmath> 24 25 enum ActivationFn { 26 kActivationNone = 0, 27 kActivationRelu, 28 kActivationRelu1, 29 kActivationRelu6, 30 kActivationTanh, 31 kActivationSignBit, 32 kActivationSigmoid, 33 }; 34 35 class ActivationFunctor { 36 public: ActivationFunctor(ActivationFn act)37 explicit ActivationFunctor(ActivationFn act) : act_(act) {} 38 operator()39 float operator()(float a) const { 40 switch (act_) { 41 case kActivationNone: 42 return a; 43 case kActivationRelu: 44 return a < 0.f ? 0.f : a; 45 case kActivationRelu6: 46 return std::max(0.f, std::min(a, 6.f)); 47 case kActivationTanh: 48 return std::tanh(a); 49 case kActivationSigmoid: 50 return 1.0f / (1.0f + std::exp(-a)); 51 default: 52 __android_log_print(ANDROID_LOG_ERROR, "NN API", 53 "Invalid enum value for activation function: 0x%0X", 54 act_); 55 abort(); 56 } 57 } 58 59 private: 60 ActivationFn act_; 61 }; 62 63 #endif // ANDROID_ML_NN_ACTIVATION_FUNCTOR_H 64