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Diffstat (limited to 'platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_var_q15.c')
| -rw-r--r-- | platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_var_q15.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_var_q15.c b/platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_var_q15.c new file mode 100644 index 0000000..377c06c --- /dev/null +++ b/platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_var_q15.c @@ -0,0 +1,195 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2014 ARM Limited. All rights reserved. +* +* $Date: 12. March 2014 +* $Revision: V1.4.4 +* +* Project: CMSIS DSP Library +* Title: arm_var_q15.c +* +* Description: Variance of an array of Q15 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 variance + * @{ + */ + +/** + * @brief Variance 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 variance 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_var_q15( + q15_t * pSrc, + uint32_t blockSize, + q15_t * pResult) +{ + + q31_t sum = 0; /* Accumulator */ + q31_t meanOfSquares, squareOfMean; /* square of mean and mean of square */ + 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 */ + + q31_t in; /* input value */ + q15_t in1; /* input value */ + + 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 = *__SIMD32(pSrc)++; + sum += ((in << 16) >> 16); + sum += (in >> 16); + sumOfSquares = __SMLALD(in, in, sumOfSquares); + in = *__SIMD32(pSrc)++; + sum += ((in << 16) >> 16); + sum += (in >> 16); + sumOfSquares = __SMLALD(in, in, sumOfSquares); + + /* 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++; + sumOfSquares = __SMLALD(in1, in1, sumOfSquares); + sum += in1; + + /* Decrement the loop counter */ + blkCnt--; + } + + /* Compute Mean of squares of the input samples + * and then store the result in a temporary variable, meanOfSquares. */ + meanOfSquares = (q31_t) (sumOfSquares / (q63_t)(blockSize - 1)); + + /* Compute square of mean */ + squareOfMean = (q31_t)((q63_t)sum * sum / (q63_t)(blockSize * (blockSize - 1))); + + /* mean of the squares minus the square of the mean. */ + *pResult = (meanOfSquares - squareOfMean) >> 15; + +#else + + /* Run the below code for Cortex-M0 */ + q15_t in; /* input value */ + + 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[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. */ + meanOfSquares = (q31_t) (sumOfSquares / (q63_t)(blockSize - 1)); + + /* Compute square of mean */ + squareOfMean = (q31_t)((q63_t)sum * sum / (q63_t)(blockSize * (blockSize - 1))); + + /* mean of the squares minus the square of the mean. */ + *pResult = (meanOfSquares - squareOfMean) >> 15; + +#endif /* #ifndef ARM_MATH_CM0_FAMILY */ + +} + +/** + * @} end of variance group + */ |