arm_q15_to_q7.c
101 lines
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| 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_q15_to_q7.c | ||||
* | ||||
* Description: Processing function for the Conversion from Q15 to Q7 | ||||
* | ||||
* 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. | ||||
* ---------------------------------------------------------------------------- */ | ||||
#include "arm_math.h" | ||||
/** | ||||
* @ingroup groupSupport | ||||
*/ | ||||
/** | ||||
* @addtogroup q15_to_x | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @brief Converts the elements of the Q15 vector to Q7 vector. | ||||
* @param[in] *pSrc points to the Q15 input vector | ||||
* @param[out] *pDst points to the Q7 output vector | ||||
* @param[in] blockSize length of the input vector | ||||
* @return none. | ||||
* | ||||
* \par Description: | ||||
* | ||||
* The equation used for the conversion process is: | ||||
* | ||||
* <pre> | ||||
* pDst[n] = (q7_t) pSrc[n] >> 8; 0 <= n < blockSize. | ||||
* </pre> | ||||
* | ||||
*/ | ||||
void arm_q15_to_q7( | ||||
q15_t * pSrc, | ||||
q7_t * pDst, | ||||
uint32_t blockSize) | ||||
{ | ||||
q15_t *pIn = pSrc; /* Src pointer */ | ||||
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 = (q7_t) A >> 8 */ | ||||
/* convert from q15 to q7 and then store the results in the destination buffer */ | ||||
*pDst++ = (q7_t) (*pIn++ >> 8); | ||||
*pDst++ = (q7_t) (*pIn++ >> 8); | ||||
*pDst++ = (q7_t) (*pIn++ >> 8); | ||||
*pDst++ = (q7_t) (*pIn++ >> 8); | ||||
/* 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 = (q7_t) A >> 8 */ | ||||
/* convert from q15 to q7 and then store the results in the destination buffer */ | ||||
*pDst++ = (q7_t) (*pIn++ >> 8); | ||||
/* Decrement the loop counter */ | ||||
blkCnt--; | ||||
} | ||||
} | ||||
/** | ||||
* @} end of q15_to_x group | ||||
*/ | ||||