102 lines
2.9 KiB
C
102 lines
2.9 KiB
C
/*
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* Copyright (C) 2010-2018 Arm Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* ----------------------------------------------------------------------
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* Project: CMSIS NN Library
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* Title: arm_nn_activations_q15.c
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* Description: Q15 neural network activation function using direct table look-up
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*
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* $Date: 17. January 2018
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* $Revision: V.1.0.0
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*
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* Target Processor: Cortex-M cores
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*
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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#include "arm_common_tables.h"
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#include "arm_nnfunctions.h"
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/**
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* @ingroup groupNN
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*/
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/**
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* @addtogroup Acti
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* @{
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*/
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/**
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* @brief Q15 neural network activation function using direct table look-up
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* @param[in,out] data pointer to input
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* @param[in] size number of elements
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* @param[in] int_width bit-width of the integer part, assume to be smaller than 3
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* @param[in] type type of activation functions
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* @return none.
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*
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* @details
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*
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* This is the direct table look-up approach.
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*
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* Assume here the integer part of the fixed-point is <= 3.
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* More than 3 just not making much sense, makes no difference with
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* saturation followed by any of these activation functions.
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*/
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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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{
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uint16_t i = size;
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q15_t *pIn = data;
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q15_t *pOut = data;
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uint16_t shift_size = 8 + 3 - int_width;
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uint32_t bit_mask = 0x7FF >> int_width;
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uint32_t full_frac = bit_mask + 1;
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const q15_t *lookup_table;
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switch (type)
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{
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case ARM_SIGMOID:
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lookup_table = sigmoidTable_q15;
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break;
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case ARM_TANH:
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default:
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lookup_table = tanhTable_q15;
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break;
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}
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while (i)
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{
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q15_t out;
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q15_t in = *pIn++;
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q15_t frac = (uint32_t) in & bit_mask;
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q15_t value = lookup_table[__USAT(in >> shift_size, 8)];
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q15_t value2 = lookup_table[__USAT(1 + (in >> shift_size), 8)];
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/* doing the interpolation here for better accuracy */
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out = ((q31_t) (full_frac - frac) * value + (q31_t) value2 * frac) >> shift_size;
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*pOut++ = out;
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i--;
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}
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}
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/**
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* @} end of Acti group
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*/
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