| 96 | |
| 97 | template <typename T> |
| 98 | void PopulateLookupTable(struct OpData* data, const TfLiteTensor* input, |
| 99 | TfLiteTensor* output, |
| 100 | const std::function<float(float)>& transform) { |
| 101 | static_assert(sizeof(T) == 1, "Lookup table valid only for 8bit"); |
| 102 | const float inverse_scale = 1 / output->params.scale; |
| 103 | int32_t maxval = std::numeric_limits<T>::max(); |
| 104 | int32_t minval = std::numeric_limits<T>::min(); |
| 105 | data->table_zero = &data->table[-minval]; |
| 106 | for (int32_t val = minval; val <= maxval; ++val) { |
| 107 | const float dequantized = |
| 108 | input->params.scale * (val - input->params.zero_point); |
| 109 | const float transformed = transform(dequantized); |
| 110 | const float rescaled = std::round(transformed * inverse_scale); |
| 111 | const int32_t quantized = |
| 112 | static_cast<int32_t>(rescaled + output->params.zero_point); |
| 113 | data->table_zero[val] = |
| 114 | static_cast<uint8_t>(std::max(std::min(maxval, quantized), minval)); |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | template <typename T> |
| 119 | void EvalUsingLookupTable(struct OpData* data, const TfLiteTensor* input, |