CMSIS DSP Library from CMSIS 2.0. See http://www.onarm.com/cmsis/ for full details
Dependents: K22F_DSP_Matrix_least_square BNO055-ELEC3810 1BNO055 ECE4180Project--Slave2 ... more
Diff: src/Cortex-M4-M3/SupportFunctions/arm_q31_to_q7.c
- Revision:
- 0:1014af42efd9
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/Cortex-M4-M3/SupportFunctions/arm_q31_to_q7.c Thu Mar 10 15:07:50 2011 +0000 @@ -0,0 +1,100 @@ +/* ---------------------------------------------------------------------------- +* Copyright (C) 2010 ARM Limited. All rights reserved. +* +* $Date: 29. November 2010 +* $Revision: V1.0.3 +* +* Project: CMSIS DSP Library +* Title: arm_q31_to_q7.c +* +* Description: Processing function for the Conversion from Q31 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 q31_to_x + * @{ + */ + +/** + * @brief Converts the elements of the Q31 vector to Q7 vector. + * @param[in] *pSrc points to the Q31 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] >> 24; 0 <= n < blockSize. + * </pre> + * + */ + + +void arm_q31_to_q7( + q31_t * pSrc, + q7_t * pDst, + uint32_t blockSize) +{ + q31_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 >> 24 */ + /* convert from q31 to q7 and then store the results in the destination buffer */ + *pDst++ = (q7_t) (*pIn++ >> 24); + *pDst++ = (q7_t) (*pIn++ >> 24); + *pDst++ = (q7_t) (*pIn++ >> 24); + *pDst++ = (q7_t) (*pIn++ >> 24); + + /* 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 >> 24 */ + /* convert from q31 to q7 and then store the results in the destination buffer */ + *pDst++ = (q7_t) (*pIn++ >> 24); + + /* Decrement the loop counter */ + blkCnt--; + } + +} + +/** + * @} end of q31_to_x group + */