/* ----------------------------------------------------------------------
* 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_shift_q7.c
*
* Description:  Processing function for the Q7 Shifting
*
* 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
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* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup shift
 * @{
 */


/**
 * @brief  Shifts the elements of a Q7 vector a specified number of bits.
 * @param[in]  *pSrc points to the input vector
 * @param[in]  shiftBits number of bits to shift.  A positive value shifts left; a negative value shifts right.
 * @param[out]  *pDst points to the output vector
 * @param[in]  blockSize number of samples in the vector
 * @return none.
 *
 * \par Conditions for optimum performance
 *  Input and output buffers should be aligned by 32-bit
 *
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function uses saturating arithmetic.
 * Results outside of the allowable Q7 range [0x8 0x7F] will be saturated.
 */

void arm_shift_q7(
    q7_t * pSrc,
    int8_t shiftBits,
    q7_t * pDst,
    uint32_t blockSize)
{
    uint32_t blkCnt;                               /* loop counter */
    uint8_t sign;                                  /* Sign of shiftBits */

#ifndef ARM_MATH_CM0_FAMILY

    /* Run the below code for Cortex-M4 and Cortex-M3 */
    q7_t in1;                                      /* Input value1 */
    q7_t in2;                                      /* Input value2 */
    q7_t in3;                                      /* Input value3 */
    q7_t in4;                                      /* Input value4 */


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

    /* Getting the sign of shiftBits */
    sign = (shiftBits & 0x80);

    /* If the shift value is positive then do right shift else left shift */
    if(sign == 0u)
    {
        /* 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)
        {
            /* C = A << shiftBits */
            /* Read 4 inputs */
            in1 = *pSrc;
            in2 = *(pSrc + 1);
            in3 = *(pSrc + 2);
            in4 = *(pSrc + 3);

            /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */
            *__SIMD32(pDst)++ = __PACKq7(__SSAT((in1 << shiftBits), 8),
                                         __SSAT((in2 << shiftBits), 8),
                                         __SSAT((in3 << shiftBits), 8),
                                         __SSAT((in4 << shiftBits), 8));
            /* Update source pointer to process next sampels */
            pSrc += 4u;

            /* 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 << shiftBits */
            /* Shift the input and then store the result in the destination buffer. */
            *pDst++ = (q7_t) __SSAT((*pSrc++ << shiftBits), 8);

            /* Decrement the loop counter */
            blkCnt--;
        }
    }
    else
    {
        shiftBits = -shiftBits;
        /* 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)
        {
            /* C = A >> shiftBits */
            /* Read 4 inputs */
            in1 = *pSrc;
            in2 = *(pSrc + 1);
            in3 = *(pSrc + 2);
            in4 = *(pSrc + 3);

            /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */
            *__SIMD32(pDst)++ = __PACKq7((in1 >> shiftBits), (in2 >> shiftBits),
                                         (in3 >> shiftBits), (in4 >> shiftBits));


            pSrc += 4u;

            /* 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 >> shiftBits */
            /* Shift the input and then store the result in the destination buffer. */
            in1 = *pSrc++;
            *pDst++ = (in1 >> shiftBits);

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

#else

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

    /* Getting the sign of shiftBits */
    sign = (shiftBits & 0x80);

    /* If the shift value is positive then do right shift else left shift */
    if(sign == 0u)
    {
        /* Initialize blkCnt with number of samples */
        blkCnt = blockSize;

        while(blkCnt > 0u)
        {
            /* C = A << shiftBits */
            /* Shift the input and then store the result in the destination buffer. */
            *pDst++ = (q7_t) __SSAT(((q15_t) * pSrc++ << shiftBits), 8);

            /* Decrement the loop counter */
            blkCnt--;
        }
    }
    else
    {
        /* Initialize blkCnt with number of samples */
        blkCnt = blockSize;

        while(blkCnt > 0u)
        {
            /* C = A >> shiftBits */
            /* Shift the input and then store the result in the destination buffer. */
            *pDst++ = (*pSrc++ >> -shiftBits);

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

#endif /* #ifndef ARM_MATH_CM0_FAMILY */
}

/**
 * @} end of shift group
 */
