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# arm_mult_q7.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_q7.c
    00009 *
    00010 * Description:  Q7 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 0.0.7  2010/06/10
    00027 *    Misra-C changes done
    00028 *
    00029 * Version 0.0.5  2010/04/26
    00030 *    incorporated review comments and updated with latest CMSIS layer
    00031 *
    00032 * Version 0.0.3  2010/03/10 DP
    00033 *    Initial version
    00034 * -------------------------------------------------------------------- */
    00035
    00036 #include "arm_math.h"
    00037
    00061 void arm_mult_q7(
    00062   q7_t * pSrcA,
    00063   q7_t * pSrcB,
    00064   q7_t * pDst,
    00065   uint32_t blockSize)
    00066 {
    00067   uint32_t blkCnt;                               /* loop counters */
    00068   q7_t out1, out2, out3, out4;                   /* Temporary variables to store the product */
    00069
    00070   /* loop Unrolling */
    00071   blkCnt = blockSize >> 2u;
    00072
    00073   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00074    ** a second loop below computes the remaining 1 to 3 samples. */
    00075   while(blkCnt > 0u)
    00076   {
    00077     /* C = A * B */
    00078     /* Multiply the inputs and store the results in temporary variables */
    00079     out1 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7);
    00080     out2 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7);
    00081     out3 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7);
    00082     out4 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7);
    00083
    00084     /* Store the results of 4 inputs in the destination buffer in single cycle by packing */
    00085     *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
    00086
    00087     /* Decrement the blockSize loop counter */
    00088     blkCnt--;
    00089   }
    00090
    00091   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00092    ** No loop unrolling is used. */
    00093   blkCnt = blockSize % 0x4u;
    00094
    00095   while(blkCnt > 0u)
    00096   {
    00097     /* C = A * B */
    00098     /* Multiply the inputs and store the result in the destination buffer */
    00099     *pDst++ = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7);
    00100
    00101     /* Decrement the blockSize loop counter */
    00102     blkCnt--;
    00103   }
    00104 }
    00105

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