arm_shift_q31.c
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CLexer
r71 | /* ---------------------------------------------------------------------- | |||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 15. July 2011 | ||||
* $Revision: V1.0.10 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_shift_q31.c | ||||
* | ||||
* Description: Shifts the elements of a Q31 vector by a specified number of bits. | ||||
* | ||||
* 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. | ||||
* | ||||
* Version 0.0.7 2010/06/10 | ||||
* Misra-C changes done | ||||
* -------------------------------------------------------------------- */ | ||||
#include "arm_math.h" | ||||
/** | ||||
* @ingroup groupMath | ||||
*/ | ||||
/** | ||||
* @defgroup shift Vector Shift | ||||
* | ||||
* Shifts the elements of a fixed-point vector by a specified number of bits. | ||||
* There are separate functions for Q7, Q15, and Q31 data types. | ||||
* The underlying algorithm used is: | ||||
* | ||||
* <pre> | ||||
* pDst[n] = pSrc[n] << shift, 0 <= n < blockSize. | ||||
* </pre> | ||||
* | ||||
* If <code>shift</code> is positive then the elements of the vector are shifted to the left. | ||||
* If <code>shift</code> is negative then the elements of the vector are shifted to the right. | ||||
*/ | ||||
/** | ||||
* @addtogroup shift | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Shifts the elements of a Q31 vector a specified number of bits. | ||||
* @param[in] *pSrc points to the input vector | ||||
* @param[in] shiftBits number of bits to shift. A positive value shifts left; a negative value shifts right. | ||||
* @param[out] *pDst points to the output vector | ||||
* @param[in] blockSize number of samples in the vector | ||||
* @return none. | ||||
* | ||||
* | ||||
* <b>Scaling and Overflow Behavior:</b> | ||||
* \par | ||||
* The function uses saturating arithmetic. | ||||
* Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] will be saturated. | ||||
*/ | ||||
void arm_shift_q31( | ||||
q31_t * pSrc, | ||||
int8_t shiftBits, | ||||
q31_t * pDst, | ||||
uint32_t blockSize) | ||||
{ | ||||
uint32_t blkCnt; /* loop counter */ | ||||
uint8_t sign; /* Sign of shiftBits */ | ||||
/* Getting the sign of shiftBits */ | ||||
sign = (shiftBits & 0x80); | ||||
#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 (>> or <<) shiftBits */ | ||||
/* Shift the input and then store the results in the destination buffer. */ | ||||
*pDst++ = (sign == 0u) ? clip_q63_to_q31((q63_t) * pSrc++ << shiftBits) : | ||||
(*pSrc++ >> -shiftBits); | ||||
*pDst++ = (sign == 0u) ? clip_q63_to_q31((q63_t) * pSrc++ << shiftBits) : | ||||
(*pSrc++ >> -shiftBits); | ||||
*pDst++ = (sign == 0u) ? clip_q63_to_q31((q63_t) * pSrc++ << shiftBits) : | ||||
(*pSrc++ >> -shiftBits); | ||||
*pDst++ = (sign == 0u) ? clip_q63_to_q31((q63_t) * pSrc++ << shiftBits) : | ||||
(*pSrc++ >> -shiftBits); | ||||
/* 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 */ | ||||
/* Initialize blkCnt with number of samples */ | ||||
blkCnt = blockSize; | ||||
#endif /* #ifndef ARM_MATH_CM0 */ | ||||
while(blkCnt > 0u) | ||||
{ | ||||
/* C = A (>> or <<) shiftBits */ | ||||
/* Shift the input and then store the result in the destination buffer. */ | ||||
*pDst++ = (sign == 0u) ? clip_q63_to_q31((q63_t) * pSrc++ << shiftBits) : | ||||
(*pSrc++ >> -shiftBits); | ||||
/* Decrement the loop counter */ | ||||
blkCnt--; | ||||
} | ||||
} | ||||
/** | ||||
* @} end of shift group | ||||
*/ | ||||