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172 lines
3.7 KiB
C
172 lines
3.7 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_atan2_f16.c
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* Description: float16 Arc tangent of y/x
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*
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* $Date: 22 April 2022
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* $Revision: V1.10.0
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*
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* Target Processor: Cortex-M and Cortex-A cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2022 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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#include "dsp/fast_math_functions_f16.h"
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#if defined(ARM_FLOAT16_SUPPORTED)
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/*
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atan for argument between in [0, 1.0]
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*/
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#define PIF16 3.14f16
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#define PI16HALF 1.571f16
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#define ATANHALFF16 0.463648f16
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#define ATAN2_NB_COEFS_F16 5
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static const float16_t atan2_coefs_f16[ATAN2_NB_COEFS_F16]={0.f16
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,1.f16
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,0.f16
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,-0.367f16
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,0.152f16
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};
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__STATIC_FORCEINLINE float16_t arm_atan_limited_f16(float16_t x)
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{
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float16_t res=atan2_coefs_f16[ATAN2_NB_COEFS_F16-1];
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int i=1;
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for(i=1;i<ATAN2_NB_COEFS_F16;i++)
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{
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res = (_Float16)x*(_Float16)res + (_Float16)atan2_coefs_f16[ATAN2_NB_COEFS_F16-1-i];
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}
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return(res);
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}
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__STATIC_FORCEINLINE float16_t arm_atan_f16(float16_t x)
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{
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int sign=0;
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float16_t res=0.0f16;
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if ((_Float16)x < 0.0f16)
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{
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sign=1;
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x=-(_Float16)x;
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}
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if ((_Float16)x > 1.0f16)
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{
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x = 1.0f16 / (_Float16)x;
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res = (_Float16)PI16HALF - (_Float16)arm_atan_limited_f16(x);
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}
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else
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{
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res += (_Float16)arm_atan_limited_f16(x);
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}
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if (sign)
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{
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res = -(_Float16)res;
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}
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return(res);
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}
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/**
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@ingroup groupFastMath
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*/
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/**
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@addtogroup atan2
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@{
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*/
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/**
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@brief Arc Tangent of y/x using sign of y and x to get right quadrant
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@param[in] y y coordinate
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@param[in] x x coordinate
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@param[out] result Result
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@return error status.
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@par Compute the Arc tangent of y/x:
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The sign of y and x are used to determine the right quadrant
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and compute the right angle.
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*/
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arm_status arm_atan2_f16(float16_t y,float16_t x,float16_t *result)
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{
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if ((_Float16)x > 0.0f16)
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{
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*result=arm_atan_f16((_Float16)y/(_Float16)x);
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return(ARM_MATH_SUCCESS);
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}
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if ((_Float16)x < 0.0f16)
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{
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if ((_Float16)y > 0.0f16)
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{
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*result=(_Float16)arm_atan_f16((_Float16)y/(_Float16)x) + (_Float16)PIF16;
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}
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else if ((_Float16)y < 0.0f16)
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{
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*result=(_Float16)arm_atan_f16((_Float16)y/(_Float16)x) - (_Float16)PIF16;
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}
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else
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{
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if (signbit(y))
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{
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*result= -(_Float16)PIF16;
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}
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else
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{
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*result= PIF16;
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}
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}
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return(ARM_MATH_SUCCESS);
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}
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if ((_Float16)x == 0.0f16)
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{
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if ((_Float16)y > 0.0f16)
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{
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*result=PI16HALF;
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return(ARM_MATH_SUCCESS);
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}
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if ((_Float16)y < 0.0f16)
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{
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*result=-(_Float16)PI16HALF;
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return(ARM_MATH_SUCCESS);
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}
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}
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return(ARM_MATH_NANINF);
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}
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#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */
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/**
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@} end of atan2 group
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*/
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