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# arm_power_q7.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_q7.c
    00009 *
    00010 * Description:  sum of the square of the elements in an array of Q7 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_q7(
    00060   q7_t * pSrc,
    00061   uint32_t blockSize,
    00062   q31_t * pResult)
    00063 {
    00064   q31_t sum = 0;                                 /* Temporary result storage */
    00065   q31_t input1;                                  /* Temporary variable to store packed input */
    00066   q15_t in1, in2;                                /* Temporary variables to store input */
    00067   q7_t in;                                       /* Temporary variable to store input */
    00068   uint32_t blkCnt;                               /* loop counter */
    00069
    00070
    00071   /*loop Unrolling */
    00072   blkCnt = blockSize >> 2u;
    00073
    00074   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00075    ** a second loop below computes the remaining 1 to 3 samples. */
    00076   while(blkCnt > 0u)
    00077   {
    00078     /* Reading two inputs of pSrc vector and packing */
    00079     in1 = (q15_t) * pSrc++;
    00080     in2 = (q15_t) * pSrc++;
    00081     input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00082
    00083     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    00084     /* Compute Power and then store the result in a temporary variable, sum. */
    00085     sum = __SMLAD(input1, input1, sum);
    00086
    00087     /* Reading two inputs of pSrc vector and packing */
    00088     in1 = (q15_t) * pSrc++;
    00089     in2 = (q15_t) * pSrc++;
    00090     input1 = ((q31_t) in1 & 0x0000FFFF) | ((q31_t) in2 << 16);
    00091
    00092     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    00093     /* Compute Power and then store the result in a temporary variable, sum. */
    00094     sum = __SMLAD(input1, input1, sum);
    00095
    00096     /* Decrement the loop counter */
    00097     blkCnt--;
    00098   }
    00099
    00100   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00101    ** No loop unrolling is used. */
    00102   blkCnt = blockSize % 0x4u;
    00103
    00104   while(blkCnt > 0u)
    00105   {
    00106     /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
    00107     /* Compute Power and then store the result in a temporary variable, sum. */
    00108     in = *pSrc++;
    00109     sum += ((q15_t) in * in);
    00110
    00111     /* Decrement the loop counter */
    00112     blkCnt--;
    00113   }
    00114
    00115   /* Store the result in 18.14 format  */
    00116   *pResult = sum;
    00117 }
    00118

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