arm_rms_q15.c
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| text/x-c
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r41 | /* ---------------------------------------------------------------------- | ||
| * Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
| * | ||||
| * $Date: 15. July 2011 | ||||
| * $Revision: V1.0.10 | ||||
| * | ||||
| * Project: CMSIS DSP Library | ||||
| * Title: arm_rms_q15.c | ||||
| * | ||||
| * Description: Root Mean Square of the elements of a Q15 vector. | ||||
| * | ||||
| * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | ||||
| * | ||||
| * Version 1.0.10 2011/7/15 | ||||
| * Big Endian support added and Merged M0 and M3/M4 Source code. | ||||
| * | ||||
| * Version 1.0.3 2010/11/29 | ||||
| * Re-organized the CMSIS folders and updated documentation. | ||||
| * | ||||
| * Version 1.0.2 2010/11/11 | ||||
| * Documentation updated. | ||||
| * | ||||
| * Version 1.0.1 2010/10/05 | ||||
| * Production release and review comments incorporated. | ||||
| * | ||||
| * Version 1.0.0 2010/09/20 | ||||
| * Production release and review comments incorporated. | ||||
| * ---------------------------------------------------------------------------- */ | ||||
| #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 */ | ||||
| #ifndef ARM_MATH_CM0 | ||||
| /* 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 */ | ||||
| sum = __SSAT((q31_t) (sum >> 15), 16); | ||||
| in1 = (q15_t) (sum / blockSize); | ||||
| /* Store the result in the destination */ | ||||
| arm_sqrt_q15(in1, 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 */ | ||||
| sum = __SSAT((q31_t) (sum >> 15), 16); | ||||
| in = (q15_t) (sum / blockSize); | ||||
| /* Store the result in the destination */ | ||||
| arm_sqrt_q15(in, pResult); | ||||
| #endif /* #ifndef ARM_MATH_CM0 */ | ||||
| } | ||||
| /** | ||||
| * @} end of RMS group | ||||
| */ | ||||