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# arm_abs_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_abs_q15.c
    00009 *
    00010 * Description:  Q15 vector absolute value.
    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_abs_q15(
    00055   q15_t * pSrc,
    00056   q15_t * pDst,
    00057   uint32_t blockSize)
    00058 {
    00059   uint32_t blkCnt;                               /* loop counter */
    00060   q15_t in1;                                     /* Input value1 */
    00061   q15_t in2;                                     /* Input value2 */
    00062
    00063
    00064   /*loop Unrolling */
    00065   blkCnt = blockSize >> 2u;
    00066
    00067   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00068    ** a second loop below computes the remaining 1 to 3 samples. */
    00069   while(blkCnt > 0u)
    00070   {
    00071     /* C = |A| */
    00072     /* Read two inputs */
    00073     in1 = *pSrc++;
    00074     in2 = *pSrc++;
    00075     /* Store the Absolute result in the destination buffer by packing the two values, in a single cycle */
    00076     *__SIMD32(pDst)++ =
    00077       __PKHBT(((in1 > 0) ? in1 : __SSAT(-in1, 16)),
    00078               ((in2 > 0) ? in2 : __SSAT(-in2, 16)), 16);
    00079
    00080     in1 = *pSrc++;
    00081     in2 = *pSrc++;
    00082     *__SIMD32(pDst)++ =
    00083       __PKHBT(((in1 > 0) ? in1 : __SSAT(-in1, 16)),
    00084               ((in2 > 0) ? in2 : __SSAT(-in2, 16)), 16);
    00085
    00086     /* Decrement the loop counter */
    00087     blkCnt--;
    00088   }
    00089
    00090   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00091    ** No loop unrolling is used. */
    00092   blkCnt = blockSize % 0x4u;
    00093
    00094   while(blkCnt > 0u)
    00095   {
    00096     /* C = |A| */
    00097     /* Read the input */
    00098     in1 = *pSrc++;
    00099
    00100     /* Calculate absolute value of input and then store the result in the destination buffer. */
    00101     *pDst++ = (in1 > 0) ? in1 : __SSAT(-in1, 16);
    00102
    00103     /* Decrement the loop counter */
    00104     blkCnt--;
    00105   }
    00106 }
    00107

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