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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:        15. July 2011
    00005 * $Revision:    V1.0.10
    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/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_abs_q15(
    00058   q15_t * pSrc,
    00059   q15_t * pDst,
    00060   uint32_t blockSize)
    00061 {
    00062   uint32_t blkCnt;                               /* loop counter */
    00063
    00064 #ifndef ARM_MATH_CM0
    00065
    00066 /* Run the below code for Cortex-M4 and Cortex-M3 */
    00067
    00068   q15_t in1;                                     /* Input value1 */
    00069   q15_t in2;                                     /* Input value2 */
    00070
    00071
    00072   /*loop Unrolling */
    00073   blkCnt = blockSize >> 2u;
    00074
    00075   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00076    ** a second loop below computes the remaining 1 to 3 samples. */
    00077   while(blkCnt > 0u)
    00078   {
    00079     /* C = |A| */
    00080     /* Read two inputs */
    00081     in1 = *pSrc++;
    00082     in2 = *pSrc++;
    00083
    00084
    00085     /* Store the Absolute result in the destination buffer by packing the two values, in a single cycle */
    00086
    00087 #ifndef  ARM_MATH_BIG_ENDIAN
    00088
    00089     *__SIMD32(pDst)++ =
    00090       __PKHBT(((in1 > 0) ? in1 : __SSAT(-in1, 16)),
    00091               ((in2 > 0) ? in2 : __SSAT(-in2, 16)), 16);
    00092
    00093 #else
    00094
    00095
    00096     *__SIMD32(pDst)++ =
    00097       __PKHBT(((in2 > 0) ? in2 : __SSAT(-in2, 16)),
    00098               ((in1 > 0) ? in1 : __SSAT(-in1, 16)), 16);
    00099
    00100 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
    00101
    00102     in1 = *pSrc++;
    00103     in2 = *pSrc++;
    00104
    00105
    00106 #ifndef  ARM_MATH_BIG_ENDIAN
    00107
    00108     *__SIMD32(pDst)++ =
    00109       __PKHBT(((in1 > 0) ? in1 : __SSAT(-in1, 16)),
    00110               ((in2 > 0) ? in2 : __SSAT(-in2, 16)), 16);
    00111
    00112
    00113 #else
    00114
    00115     *__SIMD32(pDst)++ =
    00116       __PKHBT(((in2 > 0) ? in2 : __SSAT(-in2, 16)),
    00117               ((in1 > 0) ? in1 : __SSAT(-in1, 16)), 16);
    00118
    00119 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
    00120
    00121     /* Decrement the loop counter */
    00122     blkCnt--;
    00123   }
    00124
    00125   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00126    ** No loop unrolling is used. */
    00127   blkCnt = blockSize % 0x4u;
    00128
    00129   while(blkCnt > 0u)
    00130   {
    00131     /* C = |A| */
    00132     /* Read the input */
    00133     in1 = *pSrc++;
    00134
    00135     /* Calculate absolute value of input and then store the result in the destination buffer. */
    00136     *pDst++ = (in1 > 0) ? in1 : __SSAT(-in1, 16);
    00137
    00138     /* Decrement the loop counter */
    00139     blkCnt--;
    00140   }
    00141
    00142 #else
    00143
    00144   /* Run the below code for Cortex-M0 */
    00145
    00146   q15_t in;                                      /* Temporary input variable */
    00147
    00148   /* Initialize blkCnt with number of samples */
    00149   blkCnt = blockSize;
    00150
    00151   while(blkCnt > 0u)
    00152   {
    00153     /* C = |A| */
    00154     /* Read the input */
    00155     in = *pSrc++;
    00156
    00157     /* Calculate absolute value of input and then store the result in the destination buffer. */
    00158     *pDst++ = (in > 0) ? in : __SSAT(-in, 16);
    00159
    00160     /* Decrement the loop counter */
    00161     blkCnt--;
    00162   }
    00163
    00164 #endif /* #ifndef ARM_MATH_CM0 */
    00165
    00166 }
    00167

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