File size: 3,511 Bytes
25ade36 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 | #include "edge-impulse-sdk/dsp/config.hpp"
#if EIDSP_LOAD_CMSIS_DSP_SOURCES
/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_sqrt_q31.c
* Description: Q31 square root function
*
* $Date: 23 April 2021
* $Revision: V1.9.0
*
* Target Processor: Cortex-M and Cortex-A cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "edge-impulse-sdk/CMSIS/DSP/Include/dsp/fast_math_functions.h"
#include "edge-impulse-sdk/CMSIS/DSP/Include/arm_common_tables.h"
#define Q28QUARTER 0x20000000
/**
@ingroup groupFastMath
*/
/**
@addtogroup SQRT
@{
*/
/**
@brief Q31 square root function.
@param[in] in input value. The range of the input value is [0 +1) or 0x00000000 to 0x7FFFFFFF
@param[out] pOut points to square root of input value
@return execution status
- \ref ARM_MATH_SUCCESS : input value is positive
- \ref ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0
*/
arm_status arm_sqrt_q31(
q31_t in,
q31_t * pOut)
{
q31_t number, var1, signBits1 ,temp;
number = in;
/* If the input is a positive number then compute the signBits. */
if (number > 0)
{
signBits1 = __CLZ(number) - 1;
/* Shift by the number of signBits1 */
if ((signBits1 % 2) == 0)
{
number = number << signBits1;
}
else
{
number = number << (signBits1 - 1);
}
/* Start value for 1/sqrt(x) for the Newton iteration */
var1 = sqrt_initial_lut_q31[(number>> 26) - (Q28QUARTER >> 26)];
/* 0.5 var1 * (3 - number * var1 * var1) */
/* 1st iteration */
temp = ((q63_t) var1 * var1) >> 28;
temp = ((q63_t) number * temp) >> 31;
temp = 0x30000000 - temp;
var1 = ((q63_t) var1 * temp) >> 29;
/* 2nd iteration */
temp = ((q63_t) var1 * var1) >> 28;
temp = ((q63_t) number * temp) >> 31;
temp = 0x30000000 - temp;
var1 = ((q63_t) var1 * temp) >> 29;
/* 3nd iteration */
temp = ((q63_t) var1 * var1) >> 28;
temp = ((q63_t) number * temp) >> 31;
temp = 0x30000000 - temp;
var1 = ((q63_t) var1 * temp) >> 29;
/* Multiply the inverse square root with the original value */
var1 = ((q31_t) (((q63_t) number * var1) >> 28));
/* Shift the output down accordingly */
if ((signBits1 % 2) == 0)
{
var1 = var1 >> (signBits1 / 2);
}
else
{
var1 = var1 >> ((signBits1 - 1) / 2);
}
*pOut = var1;
return (ARM_MATH_SUCCESS);
}
/* If the number is a negative number then store zero as its square root value */
else
{
*pOut = 0;
return (ARM_MATH_ARGUMENT_ERROR);
}
}
/**
@} end of SQRT group
*/
#endif // EIDSP_LOAD_CMSIS_DSP_SOURCES
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