diff options
author | Ali Labbene <ali.labbene@st.com> | 2019-12-11 08:59:21 +0100 |
---|---|---|
committer | Ali Labbene <ali.labbene@st.com> | 2019-12-16 16:35:24 +0100 |
commit | 9f95ff5b6ba01db09552b84a0ab79607060a2666 (patch) | |
tree | 8a6e0dda832555c692307869aed49d07ee7facfe /DSP/Source/StatisticsFunctions/arm_rms_q31.c | |
parent | 76177aa280494bb36d7a0bcbda1078d4db717020 (diff) | |
download | st-cmsis-core-lowfat-9f95ff5b6ba01db09552b84a0ab79607060a2666.tar.gz st-cmsis-core-lowfat-9f95ff5b6ba01db09552b84a0ab79607060a2666.tar.bz2 st-cmsis-core-lowfat-9f95ff5b6ba01db09552b84a0ab79607060a2666.zip |
Official ARM version: v5.4.0
Add CMSIS V5.4.0, please refer to index.html available under \docs folder.
Note: content of \CMSIS\Core\Include has been copied under \Include to keep the same structure
used in existing projects, and thus avoid projects mass update
Note: the following components have been removed from ARM original delivery (as not used in ST packages)
- CMSIS_EW2018.pdf
- .gitattributes
- .gitignore
- \Device
- \CMSIS
- \CoreValidation
- \DAP
- \Documentation
- \DoxyGen
- \Driver
- \Pack
- \RTOS\CMSIS_RTOS_Tutorial.pdf
- \RTOS\RTX
- \RTOS\Template
- \RTOS2\RTX
- \Utilities
- All ARM/GCC projects files are deleted from \DSP, \RTOS and \RTOS2
Change-Id: Ia026c3f0f0d016627a4fb5a9032852c33d24b4d3
Diffstat (limited to 'DSP/Source/StatisticsFunctions/arm_rms_q31.c')
-rw-r--r-- | DSP/Source/StatisticsFunctions/arm_rms_q31.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/DSP/Source/StatisticsFunctions/arm_rms_q31.c b/DSP/Source/StatisticsFunctions/arm_rms_q31.c new file mode 100644 index 0000000..cb3c58e --- /dev/null +++ b/DSP/Source/StatisticsFunctions/arm_rms_q31.c @@ -0,0 +1,137 @@ +/* ---------------------------------------------------------------------- + * Project: CMSIS DSP Library + * Title: arm_rms_q31.c + * Description: Root Mean Square of the elements of a Q31 vector + * + * $Date: 27. January 2017 + * $Revision: V.1.5.1 + * + * Target Processor: Cortex-M cores + * -------------------------------------------------------------------- */ +/* + * Copyright (C) 2010-2017 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" + +/** + * @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 */ + +#if defined (ARM_MATH_DSP) + /* 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 /* #if defined (ARM_MATH_DSP) */ + + 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 + */ |