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# arm_negate_q31.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_negate_q31.c
    00009 *
    00010 * Description:  Negates Q31 vectors.
    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
    00030 #include "arm_math.h"
    00031
    00054 void arm_negate_q31(
    00055   q31_t * pSrc,
    00056   q31_t * pDst,
    00057   uint32_t blockSize)
    00058 {
    00059   q31_t in;                                      /* Temporary variable */
    00060   uint32_t blkCnt;                               /* loop counter */
    00061
    00062
    00063   /*loop Unrolling */
    00064   blkCnt = blockSize >> 2u;
    00065
    00066   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00067    ** a second loop below computes the remaining 1 to 3 samples. */
    00068   while(blkCnt > 0u)
    00069   {
    00070     /* C = ~A */
    00071     /* Negate and then store the results in the destination buffer. */
    00072     in = *pSrc++;
    00073     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00074     in = *pSrc++;
    00075     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00076     in = *pSrc++;
    00077     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00078     in = *pSrc++;
    00079     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00080
    00081     /* Decrement the 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 */
    00092     /* Negate and then store the result in the destination buffer. */
    00093     in = *pSrc++;
    00094     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00095
    00096     /* Decrement the loop counter */
    00097     blkCnt--;
    00098   }
    00099 }
    00100

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