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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_q15.c | |
| download | sdr-software-master.tar.gz | |
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q15.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q15.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q15.c b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q15.c new file mode 100644 index 0000000..aef47da --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q15.c @@ -0,0 +1,84 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_cos_q15.c
+ * Description: Fast cosine calculation for Q15 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
+ */
+
+/**
+ @addtogroup cos
+ @{
+ */
+
+/**
+ @brief Fast approximation to the trigonometric cosine function for Q15 data.
+ @param[in] x Scaled input value in radians
+ @return cos(x)
+
+ The Q15 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*PI).
+ */
+
+q15_t arm_cos_q15(
+ q15_t x)
+{
+ q15_t cosVal; /* Temporary input, output variables */
+ int32_t index; /* Index variable */
+ q15_t a, b; /* Two nearest output values */
+ q15_t fract; /* Temporary values for fractional values */
+
+ /* add 0.25 (pi/2) to read sine table */
+ x = (uint16_t)x + 0x2000;
+ if (x < 0)
+ { /* convert negative numbers to corresponding positive ones */
+ x = (uint16_t)x + 0x8000;
+ }
+
+ /* Calculate the nearest index */
+ index = (uint32_t)x >> FAST_MATH_Q15_SHIFT;
+
+ /* Calculation of fractional value */
+ fract = (x - (index << FAST_MATH_Q15_SHIFT)) << 9;
+
+ /* Read two nearest values of input value from the sin table */
+ a = sinTable_q15[index];
+ b = sinTable_q15[index+1];
+
+ /* Linear interpolation process */
+ cosVal = (q31_t) (0x8000 - fract) * a >> 16;
+ cosVal = (q15_t) ((((q31_t) cosVal << 16) + ((q31_t) fract * b)) >> 16);
+
+ /* Return output value */
+ return (cosVal << 1);
+}
+
+/**
+ @} end of cos group
+ */
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