/* ----------------------------------------------------------------------
* 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_dot_prod_q7.c
*
* Description:  Q7 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
* are met:
*   - Redistributions of source code must retain the above copyright
*     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
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup dot_prod
 * @{
 */

/**
 * @brief Dot product of Q7 vectors.
 * @param[in]       *pSrcA points to the first input vector
 * @param[in]       *pSrcB points to the second input vector
 * @param[in]       blockSize number of samples in each vector
 * @param[out]      *result output result returned here
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The intermediate multiplications are in 1.7 x 1.7 = 2.14 format and these
 * results are added to an accumulator in 18.14 format.
 * Nonsaturating additions are used and there is no danger of wrap around as long as
 * the vectors are less than 2^18 elements long.
 * The return result is in 18.14 format.
 */

void arm_dot_prod_q7(
    q7_t * pSrcA,
    q7_t * pSrcB,
    uint32_t blockSize,
    q31_t * result)
{
    uint32_t blkCnt;                               /* loop counter */

    q31_t sum = 0;                                 /* Temporary variables to store output */

#ifndef ARM_MATH_CM0_FAMILY

    /* Run the below code for Cortex-M4 and Cortex-M3 */

    q31_t input1, input2;                          /* Temporary variables to store input */
    q31_t inA1, inA2, inB1, inB2;                  /* Temporary variables to store input */



    /*loop Unrolling */
    blkCnt = blockSize >> 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)
    {
        /* read 4 samples at a time from sourceA */
        input1 = *__SIMD32(pSrcA)++;
        /* read 4 samples at a time from sourceB */
        input2 = *__SIMD32(pSrcB)++;

        /* extract two q7_t samples to q15_t samples */
        inA1 = __SXTB16(__ROR(input1, 8));
        /* extract reminaing two samples */
        inA2 = __SXTB16(input1);
        /* extract two q7_t samples to q15_t samples */
        inB1 = __SXTB16(__ROR(input2, 8));
        /* extract reminaing two samples */
        inB2 = __SXTB16(input2);

        /* multiply and accumulate two samples at a time */
        sum = __SMLAD(inA1, inB1, sum);
        sum = __SMLAD(inA2, inB2, sum);

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

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

    while(blkCnt > 0u)
    {
        /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
        /* Dot product and then store the results in a temporary buffer. */
        sum = __SMLAD(*pSrcA++, *pSrcB++, sum);

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

#else

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



    /* Initialize blkCnt with number of samples */
    blkCnt = blockSize;

    while(blkCnt > 0u)
    {
        /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */
        /* Dot product and then store the results in a temporary buffer. */
        sum += (q31_t)((q15_t) * pSrcA++ * *pSrcB++);

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

#endif /* #ifndef ARM_MATH_CM0_FAMILY */


    /* Store the result in the destination buffer in 18.14 format */
    *result = sum;
}

/**
 * @} end of dot_prod group
 */
