Diff: cmsis_dsp/FastMathFunctions/arm_sqrt_q15.c

Revision:

5:a912b042151f

Parent:

4:9cee975aadce

diff -r 9cee975aadce -r a912b042151f cmsis_dsp/FastMathFunctions/arm_sqrt_q15.c
--- a/cmsis_dsp/FastMathFunctions/arm_sqrt_q15.c	Mon Jun 23 09:30:09 2014 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,155 +0,0 @@
-/* ----------------------------------------------------------------------     
-* Copyright (C) 2010-2013 ARM Limited. All rights reserved.  
-*     
-* $Date:        17. January 2013
-* $Revision: 	V1.4.1
-*     
-* Project:      CMSIS DSP Library  
-* Title:		arm_sqrt_q15.c     
-*     
-* Description:	Q15 square root function.    
-*     
-* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
-*  
-* Redistribution and use in source and binary forms, with or without 
-* modification, are permitted provided that the following conditions
-* are met:
-*   - Redistributions of source code must retain the above copyright
-*     notice, this list of conditions and the following disclaimer.
-*   - Redistributions in binary form must reproduce the above copyright
-*     notice, this list of conditions and the following disclaimer in
-*     the documentation and/or other materials provided with the 
-*     distribution.
-*   - Neither the name of ARM LIMITED nor the names of its contributors
-*     may be used to endorse or promote products derived from this
-*     software without specific prior written permission.
-*
-* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
-* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
-* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
-* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
-* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
-* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-* POSSIBILITY OF SUCH DAMAGE. 
-* -------------------------------------------------------------------- */
-#include "arm_math.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  square root of input value.    
-   * @return The function returns ARM_MATH_SUCCESS if the input value is positive
-   * and ARM_MATH_ARGUMENT_ERROR if the input is negative.  For
-   * negative inputs, the function returns *pOut = 0.
-   */
-
-arm_status arm_sqrt_q15(
-  q15_t in,
-  q15_t * pOut)
-{
-  q15_t number, temp1, var1, signBits1, half;
-  q31_t bits_val1;
-  float32_t temp_float1;
-  union
-  {
-    q31_t fracval;
-    float32_t floatval;
-  } tempconv;
-
-  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);
-    }
-
-    /* Calculate half value of the number */
-    half = number >> 1;
-    /* Store the number for later use */
-    temp1 = number;
-
-    /*Convert to float */
-    temp_float1 = number * 3.051757812500000e-005f;
-    /*Store as integer */
-    tempconv.floatval = temp_float1;
-    bits_val1 = tempconv.fracval;
-    /* Subtract the shifted value from the magic number to give intial guess */
-    bits_val1 = 0x5f3759df - (bits_val1 >> 1);  // gives initial guess  
-    /* Store as float */
-    tempconv.fracval = bits_val1;
-    temp_float1 = tempconv.floatval;
-    /* Convert to integer format */
-    var1 = (q31_t) (temp_float1 * 16384);
-
-    /* 1st iteration */
-    var1 = ((q15_t) ((q31_t) var1 * (0x3000 -
-                                     ((q15_t)
-                                      ((((q15_t)
-                                         (((q31_t) var1 * var1) >> 15)) *
-                                        (q31_t) half) >> 15))) >> 15)) << 2;
-    /* 2nd iteration */
-    var1 = ((q15_t) ((q31_t) var1 * (0x3000 -
-                                     ((q15_t)
-                                      ((((q15_t)
-                                         (((q31_t) var1 * var1) >> 15)) *
-                                        (q31_t) half) >> 15))) >> 15)) << 2;
-    /* 3rd iteration */
-    var1 = ((q15_t) ((q31_t) var1 * (0x3000 -
-                                     ((q15_t)
-                                      ((((q15_t)
-                                         (((q31_t) var1 * var1) >> 15)) *
-                                        (q31_t) half) >> 15))) >> 15)) << 2;
-
-    /* Multiply the inverse square root with the original value */
-    var1 = ((q15_t) (((q31_t) temp1 * var1) >> 15)) << 1;
-
-    /* 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     
- */