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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:        15. July 2011
    00005 * $Revision:    V1.0.10
    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/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 0.0.7  2010/06/10
    00030 *    Misra-C changes done
    00031 * -------------------------------------------------------------------- */
    00032
    00033 #include "arm_math.h"
    00034
    00057 void arm_negate_q31(
    00058   q31_t * pSrc,
    00059   q31_t * pDst,
    00060   uint32_t blockSize)
    00061 {
    00062   q31_t in;                                      /* Temporary variable */
    00063   uint32_t blkCnt;                               /* loop counter */
    00064
    00065 #ifndef ARM_MATH_CM0
    00066
    00067 /* Run the below code for Cortex-M4 and Cortex-M3 */
    00068
    00069   /*loop Unrolling */
    00070   blkCnt = blockSize >> 2u;
    00071
    00072   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00073    ** a second loop below computes the remaining 1 to 3 samples. */
    00074   while(blkCnt > 0u)
    00075   {
    00076     /* C = -A */
    00077     /* Negate and then store the results in the destination buffer. */
    00078     in = *pSrc++;
    00079     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00080     in = *pSrc++;
    00081     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00082     in = *pSrc++;
    00083     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00084     in = *pSrc++;
    00085     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00086
    00087     /* Decrement the 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 #else
    00096
    00097   /* Run the below code for Cortex-M0 */
    00098
    00099   /* Initialize blkCnt with number of samples */
    00100   blkCnt = blockSize;
    00101
    00102 #endif /* #ifndef ARM_MATH_CM0 */
    00103
    00104
    00105   while(blkCnt > 0u)
    00106   {
    00107     /* C = -A */
    00108     /* Negate and then store the result in the destination buffer. */
    00109     in = *pSrc++;
    00110     *pDst++ = (in == 0x80000000) ? 0x7fffffff : -in;
    00111
    00112     /* Decrement the loop counter */
    00113     blkCnt--;
    00114   }
    00115 }
    00116

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