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# arm_power_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_power_q15.c
    00009 *
    00010 * Description:  sum of the square of the elements in an array of Q15 type
    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
    00027 #include "arm_math.h"
    00028
    00059 void arm_power_q15(
    00060   q15_t * pSrc,
    00061   uint32_t blockSize,
    00062   q63_t * pResult)
    00063 {
    00064   q63_t sum = 0;                                 /* Temporary result storage */
    00065   q31_t in32;                                    /* Temporary variable to store input value */
    00066   q15_t in16;                                    /* Temporary variable to store input value */
    00067   uint32_t blkCnt;                               /* loop counter */
    00068
    00069
    00070   /* loop Unrolling */
    00071   blkCnt = blockSize >> 2u;
    00072
    00073   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00074    ** a second loop below computes the remaining 1 to 3 samples. */
    00075   while(blkCnt > 0u)
    00076   {
    00077     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    00078     /* Compute Power and then store the result in a temporary variable, sum. */
    00079     in32 = *__SIMD32(pSrc)++;
    00080     sum = __SMLALD(in32, in32, sum);
    00081     in32 = *__SIMD32(pSrc)++;
    00082     sum = __SMLALD(in32, in32, sum);
    00083
    00084     /* Decrement the loop counter */
    00085     blkCnt--;
    00086   }
    00087
    00088   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00089    ** No loop unrolling is used. */
    00090   blkCnt = blockSize % 0x4u;
    00091
    00092   while(blkCnt > 0u)
    00093   {
    00094     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    00095     /* Compute Power and then store the result in a temporary variable, sum. */
    00096     in16 = *pSrc++;
    00097     sum = __SMLALD(in16, in16, sum);
    00098
    00099     /* Decrement the loop counter */
    00100     blkCnt--;
    00101   }
    00102
    00103   /* Store the results in 34.30 format  */
    00104   *pResult = sum;
    00105 }
    00106

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