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# arm_mult_q15.c

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    00001 /* ----------------------------------------------------------------------
    00002 * Copyright (C) 2010 ARM Limited. All rights reserved.
    00003 *
    00004 * $Date:        29. November 2010
    00005 * $Revision:    V1.0.3
    00006 *
    00007 * Project:      CMSIS DSP Library
    00008 * Title:        arm_mult_q15.c
    00009 *
    00010 * Description:  Q15 vector multiplication.
    00011 *
    00012 * Target Processor: Cortex-M4/Cortex-M3
    00013 *
    00014 * Version 1.0.3 2010/11/29
    00015 *    Re-organized the CMSIS folders and updated documentation.
    00016 *
    00017 * Version 1.0.2 2010/11/11
    00018 *    Documentation updated.
    00019 *
    00020 * Version 1.0.1 2010/10/05
    00021 *    Production release and review comments incorporated.
    00022 *
    00023 * Version 1.0.0 2010/09/20
    00024 *    Production release and review comments incorporated.
    00025 *
    00026 * Version 0.0.5  2010/04/26
    00027 *    incorporated review comments and updated with latest CMSIS layer
    00028 *
    00029 * Version 0.0.3  2010/03/10
    00030 *    Initial version
    00031 * -------------------------------------------------------------------- */
    00032
    00033 #include "arm_math.h"
    00034
    00059 void arm_mult_q15(
    00060   q15_t * pSrcA,
    00061   q15_t * pSrcB,
    00062   q15_t * pDst,
    00063   uint32_t blockSize)
    00064 {
    00065   uint32_t blkCnt;                               /* loop counters */
    00066
    00067   /* loop Unrolling */
    00068   blkCnt = blockSize >> 2u;
    00069
    00070   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00071    ** a second loop below computes the remaining 1 to 3 samples. */
    00072   while(blkCnt > 0u)
    00073   {
    00074     /* C = A * B */
    00075     /* Multiply the inputs and store the result in the destination buffer */
    00076     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00077     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00078     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00079     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00080
    00081     /* Decrement the blockSize loop counter */
    00082     blkCnt--;
    00083   }
    00084
    00085   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00086    ** No loop unrolling is used. */
    00087   blkCnt = blockSize % 0x4u;
    00088
    00089   while(blkCnt > 0u)
    00090   {
    00091     /* C = A * B */
    00092     /* Multiply the inputs and store the result in the destination buffer */
    00093     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00094
    00095     /* Decrement the blockSize loop counter */
    00096     blkCnt--;
    00097   }
    00098 }
    00099

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