From 86608c6770cf08c138a2bdab5855072f64be09ef Mon Sep 17 00:00:00 2001
From: joshua <joshua@joshuayun.com>
Date: Sat, 30 Dec 2023 23:54:31 -0500
Subject: initial commit

---
 .../DSP/Source/FastMathFunctions/arm_cos_q31.c     | 84 ++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q31.c

(limited to 'Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q31.c')

diff --git a/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q31.c b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q31.c
new file mode 100644
index 0000000..fa42eee
--- /dev/null
+++ b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_cos_q31.c
@@ -0,0 +1,84 @@
+/* ----------------------------------------------------------------------
+ * Project:      CMSIS DSP Library
+ * Title:        arm_cos_q31.c
+ * Description:  Fast cosine calculation for Q31 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 Q31 data.
+  @param[in]     x  Scaled input value in radians
+  @return        cos(x)
+
+  The Q31 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*PI).
+ */
+
+q31_t arm_cos_q31(
+  q31_t x)
+{
+  q31_t cosVal;                                  /* Temporary input, output variables */
+  int32_t index;                                 /* Index variable */
+  q31_t a, b;                                    /* Two nearest output values */
+  q31_t fract;                                   /* Temporary values for fractional values */
+
+  /* add 0.25 (pi/2) to read sine table */
+  x = (uint32_t)x + 0x20000000;
+  if (x < 0)
+  { /* convert negative numbers to corresponding positive ones */
+    x = (uint32_t)x + 0x80000000;
+  }
+
+  /* Calculate the nearest index */
+  index = (uint32_t)x >> FAST_MATH_Q31_SHIFT;
+
+  /* Calculation of fractional value */
+  fract = (x - (index << FAST_MATH_Q31_SHIFT)) << 9;
+
+  /* Read two nearest values of input value from the sin table */
+  a = sinTable_q31[index];
+  b = sinTable_q31[index+1];
+
+  /* Linear interpolation process */
+  cosVal = (q63_t) (0x80000000 - fract) * a >> 32;
+  cosVal = (q31_t) ((((q63_t) cosVal << 32) + ((q63_t) fract * b)) >> 32);
+
+  /* Return output value */
+  return (cosVal << 1);
+}
+
+/**
+  @} end of cos group
+ */
-- 
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