mirror of
https://github.com/IcedRooibos/py32f0-template.git
synced 2025-10-31 01:42:04 -07:00
123 lines
3.4 KiB
C
123 lines
3.4 KiB
C
/* ----------------------------------------------------------------------
|
|
* Project: CMSIS DSP Library
|
|
* Title: arm_sin_f32.c
|
|
* Description: Fast sine calculation for floating-point values
|
|
*
|
|
* $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 "dsp/fast_math_functions.h"
|
|
#include "arm_common_tables.h"
|
|
|
|
/**
|
|
@ingroup groupFastMath
|
|
*/
|
|
|
|
/**
|
|
@defgroup sin Sine
|
|
|
|
Computes the trigonometric sine function using a combination of table lookup
|
|
and linear interpolation. There are separate functions for
|
|
Q15, Q31, and floating-point data types.
|
|
The input to the floating-point version is in radians while the
|
|
fixed-point Q15 and Q31 have a scaled input with the range
|
|
[0 +0.9999] mapping to [0 2*pi). The fixed-point range is chosen so that a
|
|
value of 2*pi wraps around to 0.
|
|
|
|
The implementation is based on table lookup using 512 values together with linear interpolation.
|
|
The steps used are:
|
|
-# Calculation of the nearest integer table index
|
|
-# Compute the fractional portion (fract) of the table index.
|
|
-# The final result equals <code>(1.0f-fract)*a + fract*b;</code>
|
|
|
|
where
|
|
<pre>
|
|
b = Table[index];
|
|
c = Table[index+1];
|
|
</pre>
|
|
*/
|
|
|
|
/**
|
|
@addtogroup sin
|
|
@{
|
|
*/
|
|
|
|
/**
|
|
@brief Fast approximation to the trigonometric sine function for floating-point data.
|
|
@param[in] x input value in radians.
|
|
@return sin(x)
|
|
*/
|
|
|
|
float32_t arm_sin_f32(
|
|
float32_t x)
|
|
{
|
|
float32_t sinVal, fract, in; /* Temporary input, output variables */
|
|
uint16_t index; /* Index variable */
|
|
float32_t a, b; /* Two nearest output values */
|
|
int32_t n;
|
|
float32_t findex;
|
|
|
|
/* input x is in radians */
|
|
/* Scale input to [0 1] range from [0 2*PI] , divide input by 2*pi */
|
|
in = x * 0.159154943092f;
|
|
|
|
/* Calculation of floor value of input */
|
|
n = (int32_t) in;
|
|
|
|
/* Make negative values towards -infinity */
|
|
if (in < 0.0f)
|
|
{
|
|
n--;
|
|
}
|
|
|
|
/* Map input value to [0 1] */
|
|
in = in - (float32_t) n;
|
|
|
|
/* Calculation of index of the table */
|
|
findex = (float32_t)FAST_MATH_TABLE_SIZE * in;
|
|
index = (uint16_t)findex;
|
|
|
|
/* when "in" is exactly 1, we need to rotate the index down to 0 */
|
|
if (index >= FAST_MATH_TABLE_SIZE) {
|
|
index = 0;
|
|
findex -= (float32_t)FAST_MATH_TABLE_SIZE;
|
|
}
|
|
|
|
/* fractional value calculation */
|
|
fract = findex - (float32_t) index;
|
|
|
|
/* Read two nearest values of input value from the sin table */
|
|
a = sinTable_f32[index];
|
|
b = sinTable_f32[index+1];
|
|
|
|
/* Linear interpolation process */
|
|
sinVal = (1.0f - fract) * a + fract * b;
|
|
|
|
/* Return output value */
|
|
return (sinVal);
|
|
}
|
|
|
|
/**
|
|
@} end of sin group
|
|
*/
|