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| author | joshua <joshua@joshuayun.com> | 2023-12-30 23:54:31 -0500 |
|---|---|---|
| committer | joshua <joshua@joshuayun.com> | 2023-12-30 23:54:31 -0500 |
| commit | 86608c6770cf08c138a2bdab5855072f64be09ef (patch) | |
| tree | 494a61b3ef37e76f9235a0d10f5c93d97290a35f /Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_f32.c | |
| download | sdr-software-master.tar.gz | |
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_f32.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_f32.c | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_f32.c b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_f32.c new file mode 100644 index 0000000..78207d8 --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_f32.c @@ -0,0 +1,122 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_cos_f32.c
+ * Description: Fast cosine calculation for floating-point values
+ *
+ * $Date: 18. March 2019
+ * $Revision: V1.6.0
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2019 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 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];
+ 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 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, 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;
+
+ /* 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 cos table */
+ a = sinTable_f32[index];
+ b = sinTable_f32[index+1];
+
+ /* Linear interpolation process */
+ cosVal = (1.0f - fract) * a + fract * b;
+
+ /* Return output value */
+ return (cosVal);
+}
+
+/**
+ @} end of cos group
+ */
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