209 lines
6.5 KiB
C
209 lines
6.5 KiB
C
|
/* ----------------------------------------------------------------------
|
||
|
|
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
|
||
|
|
*
|
||
|
|
* $Date: 19. March 2015
|
||
|
|
* $Revision: V.1.4.5
|
||
|
|
*
|
||
|
|
* Project: CMSIS DSP Library
|
||
|
|
* Title: arm_std_f32.c
|
||
|
|
*
|
||
|
|
* Description: Standard deviation of the elements of a floating-point vector.
|
||
|
|
*
|
||
|
|
* 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
|
||
|
|
*/
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @defgroup STD Standard deviation
|
||
|
|
*
|
||
|
|
* Calculates the standard deviation of the elements in the input vector.
|
||
|
|
* The underlying algorithm is used:
|
||
|
|
*
|
||
|
|
* <pre>
|
||
|
|
* Result = sqrt((sumOfSquares - sum<sup>2</sup> / blockSize) / (blockSize - 1))
|
||
|
|
*
|
||
|
|
* where, sumOfSquares = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]
|
||
|
|
*
|
||
|
|
* sum = pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]
|
||
|
|
* </pre>
|
||
|
|
*
|
||
|
|
* There are separate functions for floating point, Q31, and Q15 data types.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @addtogroup STD
|
||
|
|
* @{
|
||
|
|
*/
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Standard deviation of the elements of a floating-point 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.
|
||
|
|
*
|
||
|
|
*/
|
||
|
|
|
||
|
|
|
||
|
|
void arm_std_f32(
|
||
|
|
float32_t * pSrc,
|
||
|
|
uint32_t blockSize,
|
||
|
|
float32_t * pResult)
|
||
|
|
{
|
||
|
|
float32_t sum = 0.0f; /* Temporary result storage */
|
||
|
|
float32_t sumOfSquares = 0.0f; /* Sum of squares */
|
||
|
|
float32_t in; /* input value */
|
||
|
|
uint32_t blkCnt; /* loop counter */
|
||
|
|
|
||
|
|
#ifndef ARM_MATH_CM0_FAMILY
|
||
|
|
|
||
|
|
/* Run the below code for Cortex-M4 and Cortex-M3 */
|
||
|
|
|
||
|
|
float32_t meanOfSquares, mean, squareOfMean;
|
||
|
|
|
||
|
|
if(blockSize == 1)
|
||
|
|
{
|
||
|
|
*pResult = 0;
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*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 += in * in;
|
||
|
|
in = *pSrc++;
|
||
|
|
sum += in;
|
||
|
|
sumOfSquares += in * in;
|
||
|
|
in = *pSrc++;
|
||
|
|
sum += in;
|
||
|
|
sumOfSquares += in * in;
|
||
|
|
in = *pSrc++;
|
||
|
|
sum += in;
|
||
|
|
sumOfSquares += 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 += in * in;
|
||
|
|
|
||
|
|
/* Decrement the loop counter */
|
||
|
|
blkCnt--;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Compute Mean of squares of the input samples
|
||
|
|
* and then store the result in a temporary variable, meanOfSquares. */
|
||
|
|
meanOfSquares = sumOfSquares / ((float32_t) blockSize - 1.0f);
|
||
|
|
|
||
|
|
/* Compute mean of all input values */
|
||
|
|
mean = sum / (float32_t) blockSize;
|
||
|
|
|
||
|
|
/* Compute square of mean */
|
||
|
|
squareOfMean = (mean * mean) * (((float32_t) blockSize) /
|
||
|
|
((float32_t) blockSize - 1.0f));
|
||
|
|
|
||
|
|
/* Compute standard deviation and then store the result to the destination */
|
||
|
|
arm_sqrt_f32((meanOfSquares - squareOfMean), pResult);
|
||
|
|
|
||
|
|
#else
|
||
|
|
|
||
|
|
/* Run the below code for Cortex-M0 */
|
||
|
|
|
||
|
|
float32_t squareOfSum; /* Square of Sum */
|
||
|
|
float32_t var; /* Temporary varaince storage */
|
||
|
|
|
||
|
|
if(blockSize == 1)
|
||
|
|
{
|
||
|
|
*pResult = 0;
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* 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 += in * in;
|
||
|
|
|
||
|
|
/* C = (A[0] + A[1] + ... + A[blockSize-1]) */
|
||
|
|
/* Compute Sum of the input samples
|
||
|
|
* and then store the result in a temporary variable, sum. */
|
||
|
|
sum += in;
|
||
|
|
|
||
|
|
/* Decrement the loop counter */
|
||
|
|
blkCnt--;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Compute the square of sum */
|
||
|
|
squareOfSum = ((sum * sum) / (float32_t) blockSize);
|
||
|
|
|
||
|
|
/* Compute the variance */
|
||
|
|
var = ((sumOfSquares - squareOfSum) / (float32_t) (blockSize - 1.0f));
|
||
|
|
|
||
|
|
/* Compute standard deviation and then store the result to the destination */
|
||
|
|
arm_sqrt_f32(var, pResult);
|
||
|
|
|
||
|
|
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @} end of STD group
|
||
|
|
*/
|