##// END OF EJS Templates
HG_REPOSITORIES » LPP » INSTRUMENTATION » libuc2
RSS

Clone from http://pc-instru.lpp.polytechnique.fr:5000/libuc2

Removed error on fat32 library, seems now to be able navigate among sectors in...
Removed error on fat32 library, seems now to be able navigate among sectors in both directions. Improved SDLCD drawing performances by almost 1000x.
jeandet@pc-de-jeandet3.LAB-LPP.LOCAL - - Load All Authors

File last commit:

r41:27c5438a4566 dev_alexis
r68:104125d87b89 dev_alexis
Show More
arm_std_q15.c
229 lines | 7.4 KiB | text/x-c | CLexer
/ lib / src / stm32f4 / CPU / CMSIS / DSP_Lib / Source / StatisticsFunctions / arm_std_q15.c
History | Annotation | Raw |Copy content |Copy permalink
/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 15. July 2011
* $Revision: V1.0.10
*
* Project: CMSIS DSP Library
* Title: arm_std_q15.c
*
* Description: Standard deviation of an array of Q15 type.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.0.10 2011/7/15
* Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
* Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
* Documentation updated.
*
* Version 1.0.1 2010/10/05
* Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
* Production release and review comments incorporated.
* -------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupStats
*/
/**
* @addtogroup STD
* @{
*/
/**
* @brief Standard deviation of the elements of a Q15 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 a 64-bit internal accumulator.
* The input is represented in 1.15 format.
* Intermediate multiplication yields a 2.30 format, and this
* result is added without saturation to a 64-bit accumulator in 34.30 format.
* With 33 guard bits in the accumulator, there is no risk of overflow, and the
* full precision of the intermediate multiplication is preserved.
* Finally, the 34.30 result is truncated to 34.15 format by discarding the lower
* 15 bits, and then saturated to yield a result in 1.15 format.
*/
void arm_std_q15(
q15_t * pSrc,
uint32_t blockSize,
q15_t * pResult)
{
q63_t sum = 0; /* Accumulator */
q31_t meanOfSquares, squareOfMean; /* square of mean and mean of square */
q15_t mean; /* mean */
uint32_t blkCnt; /* loop counter */
q15_t t; /* Temporary variable */
#ifndef ARM_MATH_CM0
/* Run the below code for Cortex-M4 and Cortex-M3 */
q15_t *pIn; /* Temporary pointer */
q31_t in; /* input value */
q15_t in1; /* input value */
pIn = pSrc;
/*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 = *__SIMD32(pSrc)++;
sum = __SMLALD(in, in, sum);
in = *__SIMD32(pSrc)++;
sum = __SMLALD(in, in, sum);
/* 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. */
in1 = *pSrc++;
sum = __SMLALD(in1, in1, sum);
/* Decrement the loop counter */
blkCnt--;
}
/* Compute Mean of squares of the input samples
* and then store the result in a temporary variable, meanOfSquares. */
t = (q15_t) ((1.0 / (blockSize - 1)) * 16384LL);
sum = __SSAT((sum >> 15u), 16u);
meanOfSquares = (q31_t) ((sum * t) >> 14u);
/* Reset the accumulator */
sum = 0;
/*loop Unrolling */
blkCnt = blockSize >> 2u;
/* Reset the input working pointer */
pSrc = pIn;
/* 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[1] + A[2] + ... + A[blockSize-1]) */
/* Compute sum of all input values and then store the result in a temporary variable, sum. */
sum += *pSrc++;
sum += *pSrc++;
sum += *pSrc++;
sum += *pSrc++;
/* 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[1] + A[2] + ... + A[blockSize-1]) */
/* Compute sum of all input values and then store the result in a temporary variable, sum. */
sum += *pSrc++;
/* Decrement the loop counter */
blkCnt--;
}
/* Compute mean of all input values */
t = (q15_t) ((1.0 / (blockSize * (blockSize - 1))) * 32768LL);
mean = (q15_t) __SSAT(sum, 16u);
/* Compute square of mean */
squareOfMean = ((q31_t) mean * mean) >> 15;
squareOfMean = (q31_t) (((q63_t) squareOfMean * t) >> 15);
/* mean of the squares minus the square of the mean. */
in1 = (q15_t) (meanOfSquares - squareOfMean);
/* Compute standard deviation and store the result to the destination */
arm_sqrt_q15(in1, pResult);
#else
/* Run the below code for Cortex-M0 */
q63_t sumOfSquares = 0; /* Accumulator */
q15_t in; /* input value */
/* 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[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 = (q15_t) ((1.0 / (blockSize - 1)) * 16384LL);
sumOfSquares = __SSAT((sumOfSquares >> 15u), 16u);
meanOfSquares = (q31_t) ((sumOfSquares * t) >> 14u);
/* Compute mean of all input values */
mean = (q15_t) __SSAT(sum, 16u);
/* Compute square of mean of the input samples
* and then store the result in a temporary variable, squareOfMean.*/
t = (q15_t) ((1.0 / (blockSize * (blockSize - 1))) * 32768LL);
squareOfMean = ((q31_t) mean * mean) >> 15;
squareOfMean = (q31_t) (((q63_t) squareOfMean * t) >> 15);
/* mean of the squares minus the square of the mean. */
in = (q15_t) (meanOfSquares - squareOfMean);
/* Compute standard deviation and store the result to the destination */
arm_sqrt_q15(in, pResult);
#endif /* #ifndef ARM_MATH_CM0 */
}
/**
* @} end of STD group
*/