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| 2 | mjames | 1 | /* |
| 2 | * Copyright (C) 2010-2018 Arm Limited or its affiliates. All rights reserved. |
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| 3 | * |
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| 4 | * SPDX-License-Identifier: Apache-2.0 |
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| 5 | * |
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| 6 | * Licensed under the Apache License, Version 2.0 (the License); you may |
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| 7 | * not use this file except in compliance with the License. |
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| 8 | * You may obtain a copy of the License at |
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| 9 | * |
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| 10 | * www.apache.org/licenses/LICENSE-2.0 |
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| 11 | * |
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| 12 | * Unless required by applicable law or agreed to in writing, software |
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| 13 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
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| 14 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 15 | * See the License for the specific language governing permissions and |
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| 16 | * limitations under the License. |
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| 17 | */ |
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| 18 | |||
| 19 | /* ---------------------------------------------------------------------- |
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| 20 | * Project: CMSIS NN Library |
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| 21 | * Title: arm_nn_activations_q15.c |
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| 22 | * Description: Q15 neural network activation function using direct table look-up |
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| 23 | * |
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| 24 | * $Date: 17. January 2018 |
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| 25 | * $Revision: V.1.0.0 |
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| 26 | * |
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| 27 | * Target Processor: Cortex-M cores |
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| 28 | * |
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| 29 | * -------------------------------------------------------------------- */ |
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| 30 | |||
| 31 | #include "arm_math.h" |
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| 32 | #include "arm_common_tables.h" |
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| 33 | #include "arm_nnfunctions.h" |
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| 34 | |||
| 35 | /** |
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| 36 | * @ingroup groupNN |
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| 37 | */ |
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| 38 | |||
| 39 | /** |
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| 40 | * @addtogroup Acti |
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| 41 | * @{ |
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| 42 | */ |
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| 43 | |||
| 44 | /** |
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| 45 | * @brief Q15 neural network activation function using direct table look-up |
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| 46 | * @param[in,out] data pointer to input |
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| 47 | * @param[in] size number of elements |
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| 48 | * @param[in] int_width bit-width of the integer part, assume to be smaller than 3 |
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| 49 | * @param[in] type type of activation functions |
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| 50 | * @return none. |
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| 51 | * |
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| 52 | * @details |
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| 53 | * |
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| 54 | * This is the direct table look-up approach. |
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| 55 | * |
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| 56 | * Assume here the integer part of the fixed-point is <= 3. |
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| 57 | * More than 3 just not making much sense, makes no difference with |
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| 58 | * saturation followed by any of these activation functions. |
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| 59 | */ |
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| 60 | |||
| 61 | void arm_nn_activations_direct_q15(q15_t * data, uint16_t size, uint16_t int_width, arm_nn_activation_type type) |
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| 62 | { |
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| 63 | uint16_t i = size; |
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| 64 | q15_t *pIn = data; |
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| 65 | q15_t *pOut = data; |
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| 66 | uint16_t shift_size = 8 + 3 - int_width; |
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| 67 | uint32_t bit_mask = 0x7FF >> int_width; |
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| 68 | uint32_t full_frac = bit_mask + 1; |
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| 69 | const q15_t *lookup_table; |
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| 70 | |||
| 71 | switch (type) |
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| 72 | { |
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| 73 | case ARM_SIGMOID: |
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| 74 | lookup_table = sigmoidTable_q15; |
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| 75 | break; |
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| 76 | case ARM_TANH: |
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| 77 | default: |
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| 78 | lookup_table = tanhTable_q15; |
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| 79 | break; |
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| 80 | } |
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| 81 | |||
| 82 | while (i) |
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| 83 | { |
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| 84 | q15_t out; |
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| 85 | q15_t in = *pIn++; |
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| 86 | q15_t frac = (uint32_t) in & bit_mask; |
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| 87 | q15_t value = lookup_table[__USAT(in >> shift_size, 8)]; |
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| 88 | q15_t value2 = lookup_table[__USAT(1 + (in >> shift_size), 8)]; |
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| 89 | |||
| 90 | /* doing the interpolation here for better accuracy */ |
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| 91 | out = ((q31_t) (full_frac - frac) * value + (q31_t) value2 * frac) >> shift_size; |
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| 92 | |||
| 93 | *pOut++ = out; |
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| 94 | i--; |
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| 95 | } |
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| 96 | |||
| 97 | } |
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| 98 | |||
| 99 | /** |
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| 100 | * @} end of Acti group |
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| 101 | */ |