140 lines
4.4 KiB
C
140 lines
4.4 KiB
C
/* ----------------------------------------------------------------------
|
|
* Project: CMSIS DSP Library
|
|
* Title: arm_rms_q15.c
|
|
* Description: Root Mean Square of the elements of a Q15 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 Q15 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 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_rms_q15(
|
|
q15_t * pSrc,
|
|
uint32_t blockSize,
|
|
q15_t * pResult)
|
|
{
|
|
q63_t sum = 0; /* accumulator */
|
|
|
|
#if defined (ARM_MATH_DSP)
|
|
/* Run the below code for Cortex-M4 and Cortex-M3 */
|
|
|
|
q31_t in; /* temporary variable to store the input value */
|
|
q15_t in1; /* temporary variable to store the input value */
|
|
uint32_t blkCnt; /* loop counter */
|
|
|
|
/* 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 the squares and then store the results in a temporary variable, sum */
|
|
in = *__SIMD32(pSrc)++;
|
|
sum = __SMLALD(in, in, sum);
|
|
in = *__SIMD32(pSrc)++;
|
|
sum = __SMLALD(in, in, sum);
|
|
|
|
/* 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 the squares and then store the results in a temporary variable, sum */
|
|
in1 = *pSrc++;
|
|
sum = __SMLALD(in1, in1, sum);
|
|
|
|
/* Decrement the loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* Truncating and saturating the accumulator to 1.15 format */
|
|
/* Store the result in the destination */
|
|
arm_sqrt_q15(__SSAT((sum / (q63_t)blockSize) >> 15, 16), pResult);
|
|
|
|
#else
|
|
/* Run the below code for Cortex-M0 */
|
|
|
|
q15_t in; /* temporary variable to store the input value */
|
|
uint32_t blkCnt; /* loop counter */
|
|
|
|
/* 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 the squares and then store the results in a temporary variable, sum */
|
|
in = *pSrc++;
|
|
sum += ((q31_t) in * in);
|
|
|
|
/* Decrement the loop counter */
|
|
blkCnt--;
|
|
}
|
|
|
|
/* Truncating and saturating the accumulator to 1.15 format */
|
|
/* Store the result in the destination */
|
|
arm_sqrt_q15(__SSAT((sum / (q63_t)blockSize) >> 15, 16), pResult);
|
|
|
|
#endif /* #if defined (ARM_MATH_DSP) */
|
|
|
|
}
|
|
|
|
/**
|
|
* @} end of RMS group
|
|
*/
|