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Diffstat (limited to 'tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_std_q15.c')
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1 files changed, 205 insertions, 0 deletions
diff --git a/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_std_q15.c b/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_std_q15.c new file mode 100644 index 0000000000..b6c2d13d21 --- /dev/null +++ b/tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_std_q15.c @@ -0,0 +1,205 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2013 ARM Limited. All rights reserved. +* +* $Date: 17. January 2013 +* $Revision: V1.4.1 +* +* 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 +* +* 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 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) +{ + q31_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 */ + 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 */ + + /*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. */ + 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 */ + 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 */ + 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_FAMILY */ + + +} + +/** + * @} end of STD group + */ |