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author | Ali Labbene <ali.labbene@st.com> | 2019-12-11 08:59:21 +0100 |
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committer | Ali Labbene <ali.labbene@st.com> | 2019-12-16 16:35:24 +0100 |
commit | 9f95ff5b6ba01db09552b84a0ab79607060a2666 (patch) | |
tree | 8a6e0dda832555c692307869aed49d07ee7facfe /DSP/Source/FastMathFunctions/arm_cos_f32.c | |
parent | 76177aa280494bb36d7a0bcbda1078d4db717020 (diff) | |
download | st-cmsis-core-lowfat-9f95ff5b6ba01db09552b84a0ab79607060a2666.tar.gz st-cmsis-core-lowfat-9f95ff5b6ba01db09552b84a0ab79607060a2666.tar.bz2 st-cmsis-core-lowfat-9f95ff5b6ba01db09552b84a0ab79607060a2666.zip |
Official ARM version: v5.4.0
Add CMSIS V5.4.0, please refer to index.html available under \docs folder.
Note: content of \CMSIS\Core\Include has been copied under \Include to keep the same structure
used in existing projects, and thus avoid projects mass update
Note: the following components have been removed from ARM original delivery (as not used in ST packages)
- CMSIS_EW2018.pdf
- .gitattributes
- .gitignore
- \Device
- \CMSIS
- \CoreValidation
- \DAP
- \Documentation
- \DoxyGen
- \Driver
- \Pack
- \RTOS\CMSIS_RTOS_Tutorial.pdf
- \RTOS\RTX
- \RTOS\Template
- \RTOS2\RTX
- \Utilities
- All ARM/GCC projects files are deleted from \DSP, \RTOS and \RTOS2
Change-Id: Ia026c3f0f0d016627a4fb5a9032852c33d24b4d3
Diffstat (limited to 'DSP/Source/FastMathFunctions/arm_cos_f32.c')
-rw-r--r-- | DSP/Source/FastMathFunctions/arm_cos_f32.c | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/DSP/Source/FastMathFunctions/arm_cos_f32.c b/DSP/Source/FastMathFunctions/arm_cos_f32.c new file mode 100644 index 0000000..e604b3c --- /dev/null +++ b/DSP/Source/FastMathFunctions/arm_cos_f32.c @@ -0,0 +1,115 @@ +/* ---------------------------------------------------------------------- + * Project: CMSIS DSP Library + * Title: arm_cos_f32.c + * Description: Fast cosine calculation for floating-point values + * + * $Date: 27. January 2017 + * $Revision: V.1.5.1 + * + * Target Processor: Cortex-M cores + * -------------------------------------------------------------------- */ +/* + * Copyright (C) 2010-2017 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 "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 and in the range [0 2*pi) 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 + */ |