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Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_sin_q15.c

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+/* ----------------------------------------------------------------------
+ * Project:      CMSIS DSP Library
+ * Title:        arm_sin_q15.c
+ * Description:  Fast sine 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.
+ */
+
+#include "dsp/fast_math_functions.h"
+#include "arm_common_tables.h"
+
+/**
+  @ingroup groupFastMath
+ */
+
+/**
+  @addtogroup sin
+  @{
+ */
+
+/**
+  @brief         Fast approximation to the trigonometric sine function for Q15 data.
+  @param[in]     x  Scaled input value in radians
+  @return        sin(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_sin_q15(
+  q15_t x)
+{
+  q15_t sinVal;                                  /* 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 */
+
+  
+  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 */
+  sinVal = (q31_t) (0x8000 - fract) * a >> 16;
+  sinVal = (q15_t) ((((q31_t) sinVal << 16) + ((q31_t) fract * b)) >> 16);
+
+  /* Return output value */
+  return (sinVal << 1);
+}
+
+/**
+  @} end of sin group
+ */