mirror of
https://github.com/IcedRooibos/py32f0-template.git
synced 2025-10-30 17:32:05 -07:00
128 lines
4.3 KiB
C
Executable File
128 lines
4.3 KiB
C
Executable File
/* ----------------------------------------------------------------------
|
|
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
|
|
*
|
|
* $Date: 21. September 2015
|
|
* $Revision: V.1.4.5 a
|
|
*
|
|
* Project: CMSIS DSP Library
|
|
* Title: arm_cos_f32.c
|
|
*
|
|
* Description: Fast cosine calculation for floating-point values.
|
|
*
|
|
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* - Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* - Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* - Neither the name of ARM LIMITED nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this
|
|
* software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
|
|
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
* -------------------------------------------------------------------- */
|
|
|
|
#include "arm_math.h"
|
|
#include "arm_common_tables.h"
|
|
/**
|
|
* @ingroup groupFastMath
|
|
*/
|
|
|
|
/**
|
|
* @defgroup cos Cosine
|
|
*
|
|
* Computes the trigonometric cosine 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 256 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+0];
|
|
* c=Table[index+1];
|
|
* </pre>
|
|
*/
|
|
|
|
/**
|
|
* @addtogroup cos
|
|
* @{
|
|
*/
|
|
|
|
/**
|
|
* @brief Fast approximation to the trigonometric cosine function for floating-point data.
|
|
* @param[in] x input value in radians.
|
|
* @return cos(x).
|
|
*/
|
|
|
|
float32_t arm_cos_f32(
|
|
float32_t x)
|
|
{
|
|
float32_t cosVal, fract, in; /* Temporary variables for input, output */
|
|
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 the input to [0 1] range from [0 2*PI] , divide input by 2*pi, add 0.25 (pi/2) to read sine table */
|
|
in = x * 0.159154943092f + 0.25f;
|
|
|
|
/* 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) & 0x1ff;
|
|
|
|
/* fractional value calculation */
|
|
fract = findex - (float32_t) index;
|
|
|
|
/* Read two nearest values of input value from the cos table */
|
|
a = sinTable_f32[index];
|
|
b = sinTable_f32[index+1];
|
|
|
|
/* Linear interpolation process */
|
|
cosVal = (1.0f-fract)*a + fract*b;
|
|
|
|
/* Return the output value */
|
|
return (cosVal);
|
|
}
|
|
|
|
/**
|
|
* @} end of cos group
|
|
*/
|