1 files changed, 123 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_sqrt_q15.c b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_sqrt_q15.c
new file mode 100644
index 0000000..defeebe
--- /dev/null
+++ b/Drivers/CMSIS/DSP/Source/FastMathFunctions/arm_sqrt_q15.c
@@ -0,0 +1,123 @@
+/* ----------------------------------------------------------------------
+ * Project:      CMSIS DSP Library
+ * Title:        arm_sqrt_q15.c
+ * Description:  Q15 square root function
+ *
+ * $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 SQRT
+  @{
+ */
+
+/**
+  @brief         Q15 square root function.
+  @param[in]     in    input value.  The range of the input value is [0 +1) or 0x0000 to 0x7FFF
+  @param[out]    pOut  points to square root of input value
+  @return        execution status
+                   - \ref ARM_MATH_SUCCESS        : input value is positive
+                   - \ref ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0
+ */
+
+#define Q12QUARTER 0x2000
+arm_status arm_sqrt_q15(
+  q15_t in,
+  q15_t * pOut)
+{
+  q15_t number, var1, signBits1,temp;
+
+  number = in;
+
+  /* If the input is a positive number then compute the signBits. */
+  if (number > 0)
+  {
+    signBits1 = __CLZ(number) - 17;
+
+    /* Shift by the number of signBits1 */
+    if ((signBits1 % 2) == 0)
+    {
+      number = number << signBits1;
+    }
+    else
+    {
+      number = number << (signBits1 - 1);
+    }
+    /* Start value for 1/sqrt(x) for the Newton iteration */
+    var1 = sqrt_initial_lut_q15[(number>> 11) - (Q12QUARTER >> 11)];
+
+    /* 0.5 var1 * (3 - number * var1 * var1) */
+    /* 1st iteration */
+
+   temp = ((q31_t) var1 * var1) >> 12;
+   temp = ((q31_t) number * temp) >> 15;
+   temp = 0x3000 - temp; 
+   var1 = ((q31_t) var1 * temp) >> 13;
+
+   temp = ((q31_t) var1 * var1) >> 12;
+   temp = ((q31_t) number * temp) >> 15;
+   temp = 0x3000 - temp; 
+   var1 = ((q31_t) var1 * temp) >> 13;
+
+   temp = ((q31_t) var1 * var1) >> 12;
+   temp = ((q31_t) number * temp) >> 15;
+   temp = 0x3000 - temp; 
+   var1 = ((q31_t) var1 * temp) >> 13;
+
+    /* Multiply the inverse square root with the original value */
+
+    var1 = ((q15_t) (((q31_t) number * var1) >> 12));
+
+    /* Shift the output down accordingly */
+    if ((signBits1 % 2) == 0)
+    {
+      var1 = var1 >> (signBits1 / 2);
+    }
+    else
+    {
+      var1 = var1 >> ((signBits1 - 1) / 2);
+    }
+    *pOut = var1;
+
+
+    return (ARM_MATH_SUCCESS);
+  }
+  /* If the number is a negative number then store zero as its square root value */
+  else
+  {
+    *pOut = 0;
+
+    return (ARM_MATH_ARGUMENT_ERROR);
+  }
+}
+
+/**
+  @} end of SQRT group
+ */