/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 16/10/14 6:01p $Revision:  V.1.4.5
*
* Project:      CMSIS DSP Library
* Title:        arm_cmplx_dot_prod_q15.c
*
* Description:  Processing function for the Q15 Complex Dot product
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
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*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupCmplxMath
 */

/**
 * @addtogroup cmplx_dot_prod
 * @{
 */

/**
 * @brief  Q15 complex dot product
 * @param  *pSrcA points to the first input vector
 * @param  *pSrcB points to the second input vector
 * @param  numSamples number of complex samples in each vector
 * @param  *realResult real part of the result returned here
 * @param  *imagResult imaginary part of the result returned here
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function is implemented using an internal 64-bit accumulator.
 * The intermediate 1.15 by 1.15 multiplications are performed with full precision and yield a 2.30 result.
 * These are accumulated in a 64-bit accumulator with 34.30 precision.
 * As a final step, the accumulators are converted to 8.24 format.
 * The return results <code>realResult</code> and <code>imagResult</code> are in 8.24 format.
 */

void arm_cmplx_dot_prod_q15(
    q15_t * pSrcA,
    q15_t * pSrcB,
    uint32_t numSamples,
    q31_t * realResult,
    q31_t * imagResult)
{
    q63_t real_sum = 0, imag_sum = 0;              /* Temporary result storage */
    q15_t a0, b0, c0, d0;

#ifndef ARM_MATH_CM0_FAMILY

    /* Run the below code for Cortex-M4 and Cortex-M3 */
    uint32_t blkCnt;                               /* loop counter */


    /*loop Unrolling */
    blkCnt = numSamples >> 2u;

    /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
     ** a second loop below computes the remaining 1 to 3 samples. */
    while(blkCnt > 0u)
    {
        a0 = *pSrcA++;
        b0 = *pSrcA++;
        c0 = *pSrcB++;
        d0 = *pSrcB++;

        real_sum += (q31_t)a0 * c0;
        imag_sum += (q31_t)a0 * d0;
        real_sum -= (q31_t)b0 * d0;
        imag_sum += (q31_t)b0 * c0;

        a0 = *pSrcA++;
        b0 = *pSrcA++;
        c0 = *pSrcB++;
        d0 = *pSrcB++;

        real_sum += (q31_t)a0 * c0;
        imag_sum += (q31_t)a0 * d0;
        real_sum -= (q31_t)b0 * d0;
        imag_sum += (q31_t)b0 * c0;

        a0 = *pSrcA++;
        b0 = *pSrcA++;
        c0 = *pSrcB++;
        d0 = *pSrcB++;

        real_sum += (q31_t)a0 * c0;
        imag_sum += (q31_t)a0 * d0;
        real_sum -= (q31_t)b0 * d0;
        imag_sum += (q31_t)b0 * c0;

        a0 = *pSrcA++;
        b0 = *pSrcA++;
        c0 = *pSrcB++;
        d0 = *pSrcB++;

        real_sum += (q31_t)a0 * c0;
        imag_sum += (q31_t)a0 * d0;
        real_sum -= (q31_t)b0 * d0;
        imag_sum += (q31_t)b0 * c0;

        /* Decrement the loop counter */
        blkCnt--;
    }

    /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
     ** No loop unrolling is used. */
    blkCnt = numSamples % 0x4u;

    while(blkCnt > 0u)
    {
        a0 = *pSrcA++;
        b0 = *pSrcA++;
        c0 = *pSrcB++;
        d0 = *pSrcB++;

        real_sum += (q31_t)a0 * c0;
        imag_sum += (q31_t)a0 * d0;
        real_sum -= (q31_t)b0 * d0;
        imag_sum += (q31_t)b0 * c0;

        /* Decrement the loop counter */
        blkCnt--;
    }

#else

    /* Run the below code for Cortex-M0 */

    while(numSamples > 0u)
    {
        a0 = *pSrcA++;
        b0 = *pSrcA++;
        c0 = *pSrcB++;
        d0 = *pSrcB++;

        real_sum += a0 * c0;
        imag_sum += a0 * d0;
        real_sum -= b0 * d0;
        imag_sum += b0 * c0;


        /* Decrement the loop counter */
        numSamples--;
    }

#endif /* #ifndef ARM_MATH_CM0_FAMILY */

    /* Store the real and imaginary results in 8.24 format  */
    /* Convert real data in 34.30 to 8.24 by 6 right shifts */
    *realResult = (q31_t)(real_sum >> 6);
    /* Convert imaginary data in 34.30 to 8.24 by 6 right shifts */
    *imagResult = (q31_t)(imag_sum >> 6);
}

/**
 * @} end of cmplx_dot_prod group
 */
