arm_sub_q15.c
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| 2.7 KiB
| text/x-c
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CLexer
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r16 | /* ---------------------------------------------------------------------- | ||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 29. November 2010 | ||||
* $Revision: V1.0.3 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_sub_q15.c | ||||
* | ||||
* Description: Q15 vector subtraction. | ||||
* | ||||
* Target Processor: Cortex-M4/Cortex-M3 | ||||
* | ||||
* 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. | ||||
* | ||||
* Version 0.0.7 2010/06/10 | ||||
* Misra-C changes done | ||||
* -------------------------------------------------------------------- */ | ||||
#include "arm_math.h" | ||||
/** | ||||
* @ingroup groupMath | ||||
*/ | ||||
/** | ||||
* @addtogroup BasicSub | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Q15 vector subtraction. | ||||
* @param[in] *pSrcA points to the first input vector | ||||
* @param[in] *pSrcB points to the second input vector | ||||
* @param[out] *pDst points to the output vector | ||||
* @param[in] blockSize number of samples in each vector | ||||
* @return none. | ||||
* | ||||
* <b>Scaling and Overflow Behavior:</b> | ||||
* \par | ||||
* The function uses saturating arithmetic. | ||||
* Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated. | ||||
*/ | ||||
void arm_sub_q15( | ||||
q15_t * pSrcA, | ||||
q15_t * pSrcB, | ||||
q15_t * pDst, | ||||
uint32_t blockSize) | ||||
{ | ||||
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 - B */ | ||||
/* Subtract and then store the results in the destination buffer two samples at a time. */ | ||||
*__SIMD32(pDst)++ = __QSUB16(*__SIMD32(pSrcA)++, *__SIMD32(pSrcB)++); | ||||
*__SIMD32(pDst)++ = __QSUB16(*__SIMD32(pSrcA)++, *__SIMD32(pSrcB)++); | ||||
/* 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 - B */ | ||||
/* Subtract and then store the result in the destination buffer. */ | ||||
*pDst++ = (q15_t) __QSUB16(*pSrcA++, *pSrcB++); | ||||
/* Decrement the loop counter */ | ||||
blkCnt--; | ||||
} | ||||
} | ||||
/** | ||||
* @} end of BasicSub group | ||||
*/ | ||||