arm_mean_q15.c
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| 3.2 KiB
| text/x-c
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CLexer
jeandet@pc-de-jeandet3.LAB-LPP.LOCAL
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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_mean_q15.c | ||||
| * | ||||
| * Description: Mean value 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" | ||||
| /** | ||||
| * @ingroup groupStats | ||||
| */ | ||||
| /** | ||||
| * @addtogroup mean | ||||
| * @{ | ||||
| */ | ||||
| /** | ||||
| * @brief Mean value of a Q15 vector. | ||||
| * @param[in] *pSrc points to the input vector | ||||
| * @param[in] blockSize length of the input vector | ||||
| * @param[out] *pResult mean value returned here | ||||
| * @return none. | ||||
| * | ||||
| * @details | ||||
| * <b>Scaling and Overflow Behavior:</b> | ||||
| * \par | ||||
| * The function is implemented using a 32-bit internal accumulator. | ||||
| * The input is represented in 1.15 format and is accumulated in a 32-bit | ||||
| * accumulator in 17.15 format. | ||||
| * There is no risk of internal overflow with this approach, and the | ||||
| * full precision of intermediate result is preserved. | ||||
| * Finally, the accumulator is saturated and truncated to yield a result of 1.15 format. | ||||
| * | ||||
| */ | ||||
| void arm_mean_q15( | ||||
| q15_t * pSrc, | ||||
| uint32_t blockSize, | ||||
| q15_t * pResult) | ||||
| { | ||||
| q31_t sum = 0; /* Temporary result storage */ | ||||
| uint32_t blkCnt; /* loop counter */ | ||||
| #ifndef ARM_MATH_CM0 | ||||
| /* Run the below code for Cortex-M4 and Cortex-M3 */ | ||||
| /*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[1] + A[2] + ... + A[blockSize-1]) */ | ||||
| sum += *pSrc++; | ||||
| sum += *pSrc++; | ||||
| sum += *pSrc++; | ||||
| sum += *pSrc++; | ||||
| /* 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; | ||||
| #else | ||||
| /* Run the below code for Cortex-M0 */ | ||||
| /* Loop over blockSize number of values */ | ||||
| blkCnt = blockSize; | ||||
| #endif /* #ifndef ARM_MATH_CM0 */ | ||||
| while(blkCnt > 0u) | ||||
| { | ||||
| /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ | ||||
| sum += *pSrc++; | ||||
| /* Decrement the loop counter */ | ||||
| blkCnt--; | ||||
| } | ||||
| /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */ | ||||
| /* Store the result to the destination */ | ||||
| *pResult = (q15_t) (sum / blockSize); | ||||
| } | ||||
| /** | ||||
| * @} end of mean group | ||||
| */ | ||||