Diff: cmsis_dsp/StatisticsFunctions/arm_std_q31.c

Revision:

5:a912b042151f

Parent:

4:9cee975aadce

--- a/cmsis_dsp/StatisticsFunctions/arm_std_q31.c	Mon Jun 23 09:30:09 2014 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,192 +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_std_q31.c    
-*    
-* Description:	Standard deviation of an array of Q31 type.    
-*    
-* 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"
-
-/**    
- * @ingroup groupStats    
- */
-
-/**    
- * @addtogroup STD    
- * @{    
- */
-
-
-/**    
- * @brief Standard deviation of the elements of a Q31 vector.    
- * @param[in]       *pSrc points to the input vector    
- * @param[in]       blockSize length of the input vector    
- * @param[out]      *pResult standard deviation value returned here    
- * @return none.    
- * @details    
- * <b>Scaling and Overflow Behavior:</b>    
- *    
- *\par    
- * The function is implemented using an internal 64-bit accumulator.    
- * The input is represented in 1.31 format, and intermediate multiplication    
- * yields a 2.62 format.    
- * The accumulator maintains full precision of the intermediate multiplication results,     
- * but provides only a single guard bit.    
- * There is no saturation on intermediate additions.    
- * If the accumulator overflows it wraps around and distorts the result.    
- * In order to avoid overflows completely the input signal must be scaled down by     
- * log2(blockSize) bits, as a total of blockSize additions are performed internally.     
- * Finally, the 2.62 accumulator is right shifted by 31 bits to yield a 1.31 format value.    
- *    
- */
-
-
-void arm_std_q31(
-  q31_t * pSrc,
-  uint32_t blockSize,
-  q31_t * pResult)
-{
-  q63_t sum = 0;                                 /* Accumulator */
-  q31_t meanOfSquares, squareOfMean;             /* square of mean and mean of square */
-  q31_t mean;                                    /* mean */
-  q31_t in;                                      /* input value */
-  q31_t t;                                       /* Temporary variable */
-  uint32_t blkCnt;                               /* loop counter */
-  q63_t sumOfSquares = 0;                        /* Accumulator */
-
-#ifndef ARM_MATH_CM0_FAMILY
-
-  /* Run the below code for Cortex-M4 and Cortex-M3 */
-
-  /*loop Unrolling */
-  blkCnt = blockSize >> 2u;
-
-  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
-   ** a second loop below computes the remaining 1 to 3 samples. */
-  while(blkCnt > 0u)
-  {
-    /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1])  */
-    /* Compute Sum of squares of the input samples    
-     * and then store the result in a temporary variable, sum. */
-    in = *pSrc++;
-    sum += in;
-    sumOfSquares += ((q63_t) (in) * (in));
-    in = *pSrc++;
-    sum += in;
-    sumOfSquares += ((q63_t) (in) * (in));
-    in = *pSrc++;
-    sum += in;
-    sumOfSquares += ((q63_t) (in) * (in));
-    in = *pSrc++;
-    sum += in;
-    sumOfSquares += ((q63_t) (in) * (in));
-
-    /* Decrement the loop counter */
-    blkCnt--;
-  }
-
-  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
-   ** No loop unrolling is used. */
-  blkCnt = blockSize % 0x4u;
-
-  while(blkCnt > 0u)
-  {
-    /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
-    /* Compute Sum of squares of the input samples    
-     * and then store the result in a temporary variable, sum. */
-    in = *pSrc++;
-    sum += in;
-    sumOfSquares += ((q63_t) (in) * (in));
-
-    /* Decrement the loop counter */
-    blkCnt--;
-  }
-
-  t = (q31_t) ((1.0f / (float32_t) (blockSize - 1u)) * 1073741824.0f);
-
-  /* Compute Mean of squares of the input samples    
-   * and then store the result in a temporary variable, meanOfSquares. */
-  sumOfSquares = (sumOfSquares >> 31);
-  meanOfSquares = (q31_t) ((sumOfSquares * t) >> 30);
-
-#else
-
-  /* Run the below code for Cortex-M0 */
-
-  /* Loop over blockSize number of values */
-  blkCnt = blockSize;
-
-  while(blkCnt > 0u)
-  {
-    /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
-    /* Compute Sum of squares of the input samples     
-     * and then store the result in a temporary variable, sumOfSquares. */
-    in = *pSrc++;
-    sumOfSquares += ((q63_t) (in) * (in));
-
-    /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
-    /* Compute sum of all input values and then store the result in a temporary variable, sum. */
-    sum += in;
-
-    /* Decrement the loop counter */
-    blkCnt--;
-  }
-
-  /* Compute Mean of squares of the input samples     
-   * and then store the result in a temporary variable, meanOfSquares. */
-  t = (q31_t) ((1.0f / (float32_t) (blockSize - 1u)) * 1073741824.0f);
-  sumOfSquares = (sumOfSquares >> 31);
-  meanOfSquares = (q31_t) ((sumOfSquares * t) >> 30);
-
-#endif /* #ifndef ARM_MATH_CM0_FAMILY */
-
-  /* Compute mean of all input values */
-  t = (q31_t) ((1.0f / (blockSize * (blockSize - 1u))) * 2147483648.0f);
-  mean = (q31_t) (sum);
-
-  /* Compute square of mean */
-  squareOfMean = (q31_t) (((q63_t) mean * mean) >> 31);
-  squareOfMean = (q31_t) (((q63_t) squareOfMean * t) >> 31);
-
-
-  /* Compute standard deviation and then store the result to the destination */
-  arm_sqrt_q31(meanOfSquares - squareOfMean, pResult);
-
-}
-
-/**    
- * @} end of STD group    
- */