From 86608c6770cf08c138a2bdab5855072f64be09ef Mon Sep 17 00:00:00 2001 From: joshua Date: Sat, 30 Dec 2023 23:54:31 -0500 Subject: initial commit --- .../DSP/Source/StatisticsFunctions/arm_var_q31.c | 147 +++++++++++++++++++++ 1 file changed, 147 insertions(+) create mode 100644 Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_q31.c (limited to 'Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_q31.c') diff --git a/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_q31.c b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_q31.c new file mode 100644 index 0000000..6b552db --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_var_q31.c @@ -0,0 +1,147 @@ +/* ---------------------------------------------------------------------- + * Project: CMSIS DSP Library + * Title: arm_var_q31.c + * Description: Variance of an array of Q31 type + * + * $Date: 18. March 2019 + * $Revision: V1.6.0 + * + * Target Processor: Cortex-M cores + * -------------------------------------------------------------------- */ +/* + * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. + * + * SPDX-License-Identifier: Apache-2.0 + * + * Licensed under the Apache License, Version 2.0 (the License); you may + * not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an AS IS BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "arm_math.h" + +/** + @ingroup groupStats + */ + +/** + @addtogroup variance + @{ + */ + +/** + @brief Variance of the elements of a Q31 vector. + @param[in] pSrc points to the input vector + @param[in] blockSize number of samples in input vector + @param[out] pResult variance value returned here + @return none + + @par Scaling and Overflow Behavior + The function is implemented using an internal 64-bit accumulator. + The input is represented in 1.31 format, which is then downshifted by 8 bits + which yields 1.23, and intermediate multiplication yields a 2.46 format. + The accumulator maintains full precision of the intermediate multiplication results, + but provides only a 16 guard bits. + 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)-8 bits, as a total of blockSize additions are performed internally. + After division, internal variables should be Q18.46 + Finally, the 18.46 accumulator is right shifted by 15 bits to yield a 1.31 format value. + */ + +void arm_var_q31( + const q31_t * pSrc, + uint32_t blockSize, + q31_t * pResult) +{ + uint32_t blkCnt; /* Loop counter */ + q63_t sum = 0; /* Temporary result storage */ + q63_t meanOfSquares, squareOfMean; /* Square of mean and mean of square */ + q63_t sumOfSquares = 0; /* Sum of squares */ + q31_t in; /* Temporary variable to store input value */ + + if (blockSize <= 1U) + { + *pResult = 0; + return; + } + +#if defined (ARM_MATH_LOOPUNROLL) + + /* Loop unrolling: Compute 4 outputs at a time */ + blkCnt = blockSize >> 2U; + + while (blkCnt > 0U) + { + /* C = A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1] */ + /* C = A[0] + A[1] + ... + A[blockSize-1] */ + + in = *pSrc++ >> 8U; + /* Compute sum of squares and store result in a temporary variable, sumOfSquares. */ + sumOfSquares += ((q63_t) (in) * (in)); + /* Compute sum and store result in a temporary variable, sum. */ + sum += in; + + in = *pSrc++ >> 8U; + sumOfSquares += ((q63_t) (in) * (in)); + sum += in; + + in = *pSrc++ >> 8U; + sumOfSquares += ((q63_t) (in) * (in)); + sum += in; + + in = *pSrc++ >> 8U; + sumOfSquares += ((q63_t) (in) * (in)); + sum += in; + + /* Decrement loop counter */ + blkCnt--; + } + + /* Loop unrolling: Compute remaining outputs */ + blkCnt = blockSize % 0x4U; + +#else + + /* Initialize blkCnt with number of samples */ + blkCnt = blockSize; + +#endif /* #if defined (ARM_MATH_LOOPUNROLL) */ + + while (blkCnt > 0U) + { + /* C = A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1] */ + /* C = A[0] + A[1] + ... + A[blockSize-1] */ + + in = *pSrc++ >> 8U; + /* Compute sum of squares and store result in a temporary variable, sumOfSquares. */ + sumOfSquares += ((q63_t) (in) * (in)); + /* Compute sum and store result in a temporary variable, sum. */ + sum += in; + + /* Decrement loop counter */ + blkCnt--; + } + + /* Compute Mean of squares and store result in a temporary variable, meanOfSquares. */ + meanOfSquares = (sumOfSquares / (q63_t)(blockSize - 1U)); + + /* Compute square of mean */ + squareOfMean = ( sum * sum / (q63_t)(blockSize * (blockSize - 1U))); + + /* Compute variance and store result in destination */ + *pResult = (meanOfSquares - squareOfMean) >> 15U; +} + +/** + @} end of variance group + */ -- cgit v1.2.3