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Diffstat (limited to 'platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_rms_q31.c')
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1 files changed, 150 insertions, 0 deletions
diff --git a/platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_rms_q31.c b/platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_rms_q31.c new file mode 100644 index 0000000..ab54eb7 --- /dev/null +++ b/platform/CMSIS/DSP_Lib/Source/StatisticsFunctions/arm_rms_q31.c @@ -0,0 +1,150 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2014 ARM Limited. All rights reserved. +* +* $Date: 12. March 2014 +* $Revision: V1.4.4 +* +* Project: CMSIS DSP Library +* Title: arm_rms_q31.c +* +* Description: Root Mean Square of the elements of a Q31 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" + +/** + * @addtogroup RMS + * @{ + */ + + +/** + * @brief Root Mean Square of the elements of a Q31 vector. + * @param[in] *pSrc points to the input vector + * @param[in] blockSize length of the input vector + * @param[out] *pResult rms value returned here + * @return none. + * + * @details + * <b>Scaling and Overflow Behavior:</b> + * + *\par + * The function is implemented using an internal 64-bit accumulator. + * The input is represented in 1.31 format, and intermediate multiplication + * yields a 2.62 format. + * The accumulator maintains full precision of the intermediate multiplication results, + * but provides only a single guard bit. + * 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) bits, as a total of blockSize additions are performed internally. + * Finally, the 2.62 accumulator is right shifted by 31 bits to yield a 1.31 format value. + * + */ + +void arm_rms_q31( + q31_t * pSrc, + uint32_t blockSize, + q31_t * pResult) +{ + q63_t sum = 0; /* accumulator */ + q31_t in; /* Temporary variable to store the input */ + uint32_t blkCnt; /* loop counter */ + +#ifndef ARM_MATH_CM0_FAMILY + + /* Run the below code for Cortex-M4 and Cortex-M3 */ + + q31_t in1, in2, in3, in4; /* Temporary input variables */ + + /*loop Unrolling */ + blkCnt = blockSize >> 2u; + + /* First part of the processing with loop unrolling. Compute 8 outputs at a time. + ** a second loop below computes the remaining 1 to 7 samples. */ + while(blkCnt > 0u) + { + /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ + /* Compute sum of the squares and then store the result in a temporary variable, sum */ + /* read two samples from source buffer */ + in1 = pSrc[0]; + in2 = pSrc[1]; + + /* calculate power and accumulate to accumulator */ + sum += (q63_t) in1 *in1; + sum += (q63_t) in2 *in2; + + /* read two samples from source buffer */ + in3 = pSrc[2]; + in4 = pSrc[3]; + + /* calculate power and accumulate to accumulator */ + sum += (q63_t) in3 *in3; + sum += (q63_t) in4 *in4; + + + /* update source buffer to process next samples */ + pSrc += 4u; + + /* Decrement the loop counter */ + blkCnt--; + } + + /* If the blockSize is not a multiple of 8, compute any remaining output samples here. + ** No loop unrolling is used. */ + blkCnt = blockSize % 0x4u; + +#else + + /* Run the below code for Cortex-M0 */ + blkCnt = blockSize; + +#endif /* #ifndef ARM_MATH_CM0_FAMILY */ + + while(blkCnt > 0u) + { + /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ + /* Compute sum of the squares and then store the results in a temporary variable, sum */ + in = *pSrc++; + sum += (q63_t) in *in; + + /* Decrement the loop counter */ + blkCnt--; + } + + /* Convert data in 2.62 to 1.31 by 31 right shifts and saturate */ + /* Compute Rms and store the result in the destination vector */ + arm_sqrt_q31(clip_q63_to_q31((sum / (q63_t) blockSize) >> 31), pResult); +} + +/** + * @} end of RMS group + */ |