| /* ---------------------------------------------------------------------- | |
| * Project: CMSIS DSP Library | |
| * Title: arm_cos_q15.c | |
| * Description: Fast cosine calculation for Q15 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. | |
| */ | |
| /** | |
| @ingroup groupFastMath | |
| */ | |
| /** | |
| @defgroup divide Fixed point division | |
| */ | |
| /** | |
| @addtogroup divide | |
| @{ | |
| */ | |
| /** | |
| @brief Fixed point division | |
| @param[in] numerator Numerator | |
| @param[in] denominator Denominator | |
| @param[out] quotient Quotient value normalized between -1.0 and 1.0 | |
| @param[out] shift Shift left value to get the unnormalized quotient | |
| @return error status | |
| When dividing by 0, an error ARM_MATH_NANINF is returned. And the quotient is forced | |
| to the saturated negative or positive value. | |
| */ | |
| arm_status arm_divide_q15(q15_t numerator, | |
| q15_t denominator, | |
| q15_t *quotient, | |
| int16_t *shift) | |
| { | |
| int16_t sign=0; | |
| q31_t temp; | |
| int16_t shiftForNormalizing; | |
| *shift = 0; | |
| sign = (numerator>>15) ^ (denominator>>15); | |
| if (denominator == 0) | |
| { | |
| if (sign) | |
| { | |
| *quotient = 0x8000; | |
| } | |
| else | |
| { | |
| *quotient = 0x7FFF; | |
| } | |
| return(ARM_MATH_NANINF); | |
| } | |
| arm_abs_q15(&numerator,&numerator,1); | |
| arm_abs_q15(&denominator,&denominator,1); | |
| temp = ((q31_t)numerator << 15) / ((q31_t)denominator); | |
| shiftForNormalizing= 17 - __CLZ(temp); | |
| if (shiftForNormalizing > 0) | |
| { | |
| *shift = shiftForNormalizing; | |
| temp = temp >> shiftForNormalizing; | |
| } | |
| if (sign) | |
| { | |
| temp = -temp; | |
| } | |
| *quotient=temp; | |
| return(ARM_MATH_SUCCESS); | |
| } | |
| /** | |
| @} end of divide group | |
| */ | |