/*-----------------------------------------------------------------------------
* 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_fir_interpolate_q15.c
*
* Description:  Q15 FIR interpolation.
*
* 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,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* ---------------------------------------------------------------------------*/

#include "arm_math.h"

/**
 * @ingroup groupFilters
 */

/**
 * @addtogroup FIR_Interpolate
 * @{
 */

/**
 * @brief Processing function for the Q15 FIR interpolator.
 * @param[in] *S        points to an instance of the Q15 FIR interpolator structure.
 * @param[in] *pSrc     points to the block of input data.
 * @param[out] *pDst    points to the block of output data.
 * @param[in] blockSize number of input samples to process per call.
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function is implemented using a 64-bit internal accumulator.
 * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
 * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
 * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
 * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
 * Lastly, the accumulator is saturated to yield a result in 1.15 format.
 */

#ifndef ARM_MATH_CM0_FAMILY

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

void arm_fir_interpolate_q15(
    const arm_fir_interpolate_instance_q15 * S,
    q15_t * pSrc,
    q15_t * pDst,
    uint32_t blockSize)
{
    q15_t *pState = S->pState;                     /* State pointer                                            */
    q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer                                      */
    q15_t *pStateCurnt;                            /* Points to the current sample of the state                */
    q15_t *ptr1, *ptr2;                            /* Temporary pointers for state and coefficient buffers     */
    q63_t sum0;                                    /* Accumulators                                             */
    q15_t x0, c0;                                  /* Temporary variables to hold state and coefficient values */
    uint32_t i, blkCnt, j, tapCnt;                 /* Loop counters                                            */
    uint16_t phaseLen = S->phaseLength;            /* Length of each polyphase filter component */
    uint32_t blkCntN2;
    q63_t acc0, acc1;
    q15_t x1;

    /* S->pState buffer contains previous frame (phaseLen - 1) samples */
    /* pStateCurnt points to the location where the new input data should be written */
    pStateCurnt = S->pState + ((q31_t) phaseLen - 1);

    /* Initialise  blkCnt */
    blkCnt = blockSize / 2;
    blkCntN2 = blockSize - (2 * blkCnt);

    /* Samples loop unrolled by 2 */
    while(blkCnt > 0u)
    {
        /* Copy new input sample into the state buffer */
        *pStateCurnt++ = *pSrc++;
        *pStateCurnt++ = *pSrc++;

        /* Address modifier index of coefficient buffer */
        j = 1u;

        /* Loop over the Interpolation factor. */
        i = (S->L);

        while(i > 0u)
        {
            /* Set accumulator to zero */
            acc0 = 0;
            acc1 = 0;

            /* Initialize state pointer */
            ptr1 = pState;

            /* Initialize coefficient pointer */
            ptr2 = pCoeffs + (S->L - j);

            /* Loop over the polyPhase length. Unroll by a factor of 4.
             ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
            tapCnt = phaseLen >> 2u;

            x0 = *(ptr1++);

            while(tapCnt > 0u)
            {

                /* Read the input sample */
                x1 = *(ptr1++);

                /* Read the coefficient */
                c0 = *(ptr2);

                /* Perform the multiply-accumulate */
                acc0 += (q63_t) x0 * c0;
                acc1 += (q63_t) x1 * c0;


                /* Read the coefficient */
                c0 = *(ptr2 + S->L);

                /* Read the input sample */
                x0 = *(ptr1++);

                /* Perform the multiply-accumulate */
                acc0 += (q63_t) x1 * c0;
                acc1 += (q63_t) x0 * c0;


                /* Read the coefficient */
                c0 = *(ptr2 + S->L * 2);

                /* Read the input sample */
                x1 = *(ptr1++);

                /* Perform the multiply-accumulate */
                acc0 += (q63_t) x0 * c0;
                acc1 += (q63_t) x1 * c0;

                /* Read the coefficient */
                c0 = *(ptr2 + S->L * 3);

                /* Read the input sample */
                x0 = *(ptr1++);

                /* Perform the multiply-accumulate */
                acc0 += (q63_t) x1 * c0;
                acc1 += (q63_t) x0 * c0;


                /* Upsampling is done by stuffing L-1 zeros between each sample.
                 * So instead of multiplying zeros with coefficients,
                 * Increment the coefficient pointer by interpolation factor times. */
                ptr2 += 4 * S->L;

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

            /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
            tapCnt = phaseLen % 0x4u;

            while(tapCnt > 0u)
            {

                /* Read the input sample */
                x1 = *(ptr1++);

                /* Read the coefficient */
                c0 = *(ptr2);

                /* Perform the multiply-accumulate */
                acc0 += (q63_t) x0 * c0;
                acc1 += (q63_t) x1 * c0;

                /* Increment the coefficient pointer by interpolation factor times. */
                ptr2 += S->L;

                /* update states for next sample processing */
                x0 = x1;

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

            /* The result is in the accumulator, store in the destination buffer. */
            *pDst = (q15_t)(__SSAT((acc0 >> 15), 16));
            *(pDst + S->L) = (q15_t)(__SSAT((acc1 >> 15), 16));

            pDst++;

            /* Increment the address modifier index of coefficient buffer */
            j++;

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

        /* Advance the state pointer by 1
         * to process the next group of interpolation factor number samples */
        pState = pState + 2;

        pDst += S->L;

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

    /* If the blockSize is not a multiple of 2, compute any remaining output samples here.
     ** No loop unrolling is used. */
    blkCnt = blkCntN2;

    /* Loop over the blockSize. */
    while(blkCnt > 0u)
    {
        /* Copy new input sample into the state buffer */
        *pStateCurnt++ = *pSrc++;

        /* Address modifier index of coefficient buffer */
        j = 1u;

        /* Loop over the Interpolation factor. */
        i = S->L;
        while(i > 0u)
        {
            /* Set accumulator to zero */
            sum0 = 0;

            /* Initialize state pointer */
            ptr1 = pState;

            /* Initialize coefficient pointer */
            ptr2 = pCoeffs + (S->L - j);

            /* Loop over the polyPhase length. Unroll by a factor of 4.
             ** Repeat until we've computed numTaps-(4*S->L) coefficients. */
            tapCnt = phaseLen >> 2;
            while(tapCnt > 0u)
            {

                /* Read the coefficient */
                c0 = *(ptr2);

                /* Upsampling is done by stuffing L-1 zeros between each sample.
                 * So instead of multiplying zeros with coefficients,
                 * Increment the coefficient pointer by interpolation factor times. */
                ptr2 += S->L;

                /* Read the input sample */
                x0 = *(ptr1++);

                /* Perform the multiply-accumulate */
                sum0 += (q63_t) x0 * c0;

                /* Read the coefficient */
                c0 = *(ptr2);

                /* Increment the coefficient pointer by interpolation factor times. */
                ptr2 += S->L;

                /* Read the input sample */
                x0 = *(ptr1++);

                /* Perform the multiply-accumulate */
                sum0 += (q63_t) x0 * c0;

                /* Read the coefficient */
                c0 = *(ptr2);

                /* Increment the coefficient pointer by interpolation factor times. */
                ptr2 += S->L;

                /* Read the input sample */
                x0 = *(ptr1++);

                /* Perform the multiply-accumulate */
                sum0 += (q63_t) x0 * c0;

                /* Read the coefficient */
                c0 = *(ptr2);

                /* Increment the coefficient pointer by interpolation factor times. */
                ptr2 += S->L;

                /* Read the input sample */
                x0 = *(ptr1++);

                /* Perform the multiply-accumulate */
                sum0 += (q63_t) x0 * c0;

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

            /* If the polyPhase length is not a multiple of 4, compute the remaining filter taps */
            tapCnt = phaseLen & 0x3u;

            while(tapCnt > 0u)
            {
                /* Read the coefficient */
                c0 = *(ptr2);

                /* Increment the coefficient pointer by interpolation factor times. */
                ptr2 += S->L;

                /* Read the input sample */
                x0 = *(ptr1++);

                /* Perform the multiply-accumulate */
                sum0 += (q63_t) x0 * c0;

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

            /* The result is in the accumulator, store in the destination buffer. */
            *pDst++ = (q15_t)(__SSAT((sum0 >> 15), 16));

            j++;

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

        /* Advance the state pointer by 1
         * to process the next group of interpolation factor number samples */
        pState = pState + 1;

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


    /* Processing is complete.
     ** Now copy the last phaseLen - 1 samples to the satrt of the state buffer.
     ** This prepares the state buffer for the next function call. */

    /* Points to the start of the state buffer */
    pStateCurnt = S->pState;

    i = ((uint32_t) phaseLen - 1u) >> 2u;

    /* copy data */
    while(i > 0u)
    {
#ifndef UNALIGNED_SUPPORT_DISABLE

        *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
        *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;

#else

        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;
        *pStateCurnt++ = *pState++;

#endif  /*  #ifndef UNALIGNED_SUPPORT_DISABLE   */

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

    i = ((uint32_t) phaseLen - 1u) % 0x04u;

    while(i > 0u)
    {
        *pStateCurnt++ = *pState++;

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

#else

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

void arm_fir_interpolate_q15(
    const arm_fir_interpolate_instance_q15 * S,
    q15_t * pSrc,
    q15_t * pDst,
    uint32_t blockSize)
{
    q15_t *pState = S->pState;                     /* State pointer                                            */
    q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer                                      */
    q15_t *pStateCurnt;                            /* Points to the current sample of the state                */
    q15_t *ptr1, *ptr2;                            /* Temporary pointers for state and coefficient buffers     */
    q63_t sum;                                     /* Accumulator */
    q15_t x0, c0;                                  /* Temporary variables to hold state and coefficient values */
    uint32_t i, blkCnt, tapCnt;                    /* Loop counters                                            */
    uint16_t phaseLen = S->phaseLength;            /* Length of each polyphase filter component */


    /* S->pState buffer contains previous frame (phaseLen - 1) samples */
    /* pStateCurnt points to the location where the new input data should be written */
    pStateCurnt = S->pState + (phaseLen - 1u);

    /* Total number of intput samples */
    blkCnt = blockSize;

    /* Loop over the blockSize. */
    while(blkCnt > 0u)
    {
        /* Copy new input sample into the state buffer */
        *pStateCurnt++ = *pSrc++;

        /* Loop over the Interpolation factor. */
        i = S->L;

        while(i > 0u)
        {
            /* Set accumulator to zero */
            sum = 0;

            /* Initialize state pointer */
            ptr1 = pState;

            /* Initialize coefficient pointer */
            ptr2 = pCoeffs + (i - 1u);

            /* Loop over the polyPhase length */
            tapCnt = (uint32_t) phaseLen;

            while(tapCnt > 0u)
            {
                /* Read the coefficient */
                c0 = *ptr2;

                /* Increment the coefficient pointer by interpolation factor times. */
                ptr2 += S->L;

                /* Read the input sample */
                x0 = *ptr1++;

                /* Perform the multiply-accumulate */
                sum += ((q31_t) x0 * c0);

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

            /* Store the result after converting to 1.15 format in the destination buffer */
            *pDst++ = (q15_t)(__SSAT((sum >> 15), 16));

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

        /* Advance the state pointer by 1
         * to process the next group of interpolation factor number samples */
        pState = pState + 1;

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

    /* Processing is complete.
     ** Now copy the last phaseLen - 1 samples to the start of the state buffer.
     ** This prepares the state buffer for the next function call. */

    /* Points to the start of the state buffer */
    pStateCurnt = S->pState;

    i = (uint32_t) phaseLen - 1u;

    while(i > 0u)
    {
        *pStateCurnt++ = *pState++;

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

}

#endif /*   #ifndef ARM_MATH_CM0_FAMILY */


/**
 * @} end of FIR_Interpolate group
 */
