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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:        15. July 2011
    00005 * $Revision:    V1.0.10
    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/Cortex-M0
    00013 *
    00014 * Version 1.0.10 2011/7/15
    00015 *    Big Endian support added and Merged M0 and M3/M4 Source code.
    00016 *
    00017 * Version 1.0.3 2010/11/29
    00018 *    Re-organized the CMSIS folders and updated documentation.
    00019 *
    00020 * Version 1.0.2 2010/11/11
    00021 *    Documentation updated.
    00022 *
    00023 * Version 1.0.1 2010/10/05
    00024 *    Production release and review comments incorporated.
    00025 *
    00026 * Version 1.0.0 2010/09/20
    00027 *    Production release and review comments incorporated.
    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
    00033 *    Initial version
    00034 * -------------------------------------------------------------------- */
    00035
    00036 #include "arm_math.h"
    00037
    00062 void arm_mult_q15(
    00063   q15_t * pSrcA,
    00064   q15_t * pSrcB,
    00065   q15_t * pDst,
    00066   uint32_t blockSize)
    00067 {
    00068   uint32_t blkCnt;                               /* loop counters */
    00069
    00070 #ifndef ARM_MATH_CM0
    00071
    00072 /* Run the below code for Cortex-M4 and Cortex-M3 */
    00073
    00074   /* loop Unrolling */
    00075   blkCnt = blockSize >> 2u;
    00076
    00077   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00078    ** a second loop below computes the remaining 1 to 3 samples. */
    00079   while(blkCnt > 0u)
    00080   {
    00081     /* C = A * B */
    00082     /* Multiply the inputs and store the result in the destination buffer */
    00083     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00084     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00085     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00086     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00087
    00088     /* Decrement the blockSize loop counter */
    00089     blkCnt--;
    00090   }
    00091
    00092   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00093    ** No loop unrolling is used. */
    00094   blkCnt = blockSize % 0x4u;
    00095
    00096 #else
    00097
    00098   /* Run the below code for Cortex-M0 */
    00099
    00100   /* Initialize blkCnt with number of samples */
    00101   blkCnt = blockSize;
    00102
    00103 #endif /* #ifndef ARM_MATH_CM0 */
    00104
    00105
    00106   while(blkCnt > 0u)
    00107   {
    00108     /* C = A * B */
    00109     /* Multiply the inputs and store the result in the destination buffer */
    00110     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
    00111
    00112     /* Decrement the blockSize loop counter */
    00113     blkCnt--;
    00114   }
    00115 }
    00116

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