Diff: cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c

Revision:

3:7a284390b0ce

Parent:

2:da51fb522205

--- a/cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c	Thu May 30 17:10:11 2013 +0100
+++ b/cmsis_dsp/FastMathFunctions/arm_sqrt_q31.c	Fri Nov 08 13:45:10 2013 +0000
@@ -1,8 +1,8 @@
 /* ----------------------------------------------------------------------     
-* Copyright (C) 2011 ARM Limited. All rights reserved.  
+* Copyright (C) 2010-2013 ARM Limited. All rights reserved.  
 *     
-* $Date:        15. February 2012  
-* $Revision: 	V1.1.0  
+* $Date:        17. January 2013
+* $Revision: 	V1.4.1
 *     
 * Project:      CMSIS DSP Library  
 * Title:		arm_sqrt_q31.c     
@@ -11,15 +11,31 @@
 *     
 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
 *  
-* Version 1.1.0 2012/02/15 
-*    Updated with more optimizations, bug fixes and minor API changes.  
-* 
-* Version 1.0.0 2011/03/08 
-*     Alpha release. 
-* 
-* Version 1.0.1 2011/09/30 
-*     Beta release.  
-*     
+* 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"
@@ -37,8 +53,9 @@
  * @brief Q31 square root function.    
  * @param[in]   in    input value.  The range of the input value is [0 +1) or 0x00000000 to 0x7FFFFFFF.    
  * @param[out]  *pOut square root of input value.    
- * @return The function returns ARM_MATH_SUCCESS if input value is positive value or ARM_MATH_ARGUMENT_ERROR if    
- * <code>in</code> is negative value and returns zero output for negative values.    
+ * @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_q31(
@@ -47,6 +64,11 @@
 {
   q31_t number, temp1, bits_val1, var1, signBits1, half;
   float32_t temp_float1;
+  union
+  {
+      q31_t fracval;
+      float32_t floatval;
+  } tempconv;
 
   number = in;
 
@@ -73,11 +95,13 @@
     /*Convert to float */
     temp_float1 = number * 4.6566128731e-010f;
     /*Store as integer */
-    bits_val1 = *(int *) &temp_float1;
+    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 */
-    temp_float1 = *(float *) &bits_val1;
+    tempconv.fracval = bits_val1;
+    temp_float1 = tempconv.floatval;
     /* Convert to integer format */
     var1 = (q31_t) (temp_float1 * 1073741824);