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/* ----------------------------------------------------------------------

 * Project:      CMSIS DSP Library

 * Title:        arm_cfft_q31.c

 * Description:  Combined Radix Decimation in Frequency CFFT fixed point processing function

 *

 * $Date:        27. January 2017

 * $Revision:    V.1.5.1

 *

 * Target Processor: Cortex-M cores

 * -------------------------------------------------------------------- */

/*

 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.

 *

 * SPDX-License-Identifier: Apache-2.0

 *

 * Licensed under the Apache License, Version 2.0 (the License); you may

 * not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 * www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an AS IS BASIS, WITHOUT

 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include "arm_math.h"

extern void arm_radix4_butterfly_q31(

    q31_t * pSrc,

    uint32_t fftLen,

    q31_t * pCoef,

    uint32_t twidCoefModifier);

extern void arm_radix4_butterfly_inverse_q31(

    q31_t * pSrc,

    uint32_t fftLen,

    q31_t * pCoef,

    uint32_t twidCoefModifier);

extern void arm_bitreversal_32(

    uint32_t * pSrc,

    const uint16_t bitRevLen,

    const uint16_t * pBitRevTable);

void arm_cfft_radix4by2_q31(

    q31_t * pSrc,

    uint32_t fftLen,

    const q31_t * pCoef);

void arm_cfft_radix4by2_inverse_q31(

    q31_t * pSrc,

    uint32_t fftLen,

    const q31_t * pCoef);

/**

* @ingroup groupTransforms

*/

/**

* @addtogroup ComplexFFT

* @{

*/

/**

* @details

* @brief       Processing function for the fixed-point complex FFT in Q31 format.

* @param[in]      *S    points to an instance of the fixed-point CFFT structure.

* @param[in, out] *p1   points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.

* @param[in]     ifftFlag       flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.

* @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.

* @return none.

*/

void arm_cfft_q31(

    const arm_cfft_instance_q31 * S,

    q31_t * p1,

    uint8_t ifftFlag,

    uint8_t bitReverseFlag)

{

    uint32_t L = S->fftLen;

    if (ifftFlag == 1U)

    {

        switch (L)

        {

        case 16:

        case 64:

        case 256:

        case 1024:

        case 4096:

            arm_radix4_butterfly_inverse_q31  ( p1, L, (q31_t*)S->pTwiddle, 1 );

            break;

        case 32:

        case 128:

        case 512:

        case 2048:

            arm_cfft_radix4by2_inverse_q31  ( p1, L, S->pTwiddle );

            break;

        }

    }

    else

    {

        switch (L)

        {

        case 16:

        case 64:

        case 256:

        case 1024:

        case 4096:

            arm_radix4_butterfly_q31  ( p1, L, (q31_t*)S->pTwiddle, 1 );

            break;

        case 32:

        case 128:

        case 512:

        case 2048:

            arm_cfft_radix4by2_q31  ( p1, L, S->pTwiddle );

            break;

        }

    }

    if ( bitReverseFlag )

        arm_bitreversal_32((uint32_t*)p1,S->bitRevLength,S->pBitRevTable);

}

/**

* @} end of ComplexFFT group

*/

void arm_cfft_radix4by2_q31(

    q31_t * pSrc,

    uint32_t fftLen,

    const q31_t * pCoef)

{

    uint32_t i, l;

    uint32_t n2, ia;

    q31_t xt, yt, cosVal, sinVal;

    q31_t p0, p1;

    n2 = fftLen >> 1;

    ia = 0;

    for (i = 0; i < n2; i++)

    {

        cosVal = pCoef[2*ia];

        sinVal = pCoef[2*ia + 1];

        ia++;

        l = i + n2;

        xt = (pSrc[2 * i] >> 2) - (pSrc[2 * l] >> 2);

        pSrc[2 * i] = (pSrc[2 * i] >> 2) + (pSrc[2 * l] >> 2);

        yt = (pSrc[2 * i + 1] >> 2) - (pSrc[2 * l + 1] >> 2);

        pSrc[2 * i + 1] = (pSrc[2 * l + 1] >> 2) + (pSrc[2 * i + 1] >> 2);

        mult_32x32_keep32_R(p0, xt, cosVal);

        mult_32x32_keep32_R(p1, yt, cosVal);

        multAcc_32x32_keep32_R(p0, yt, sinVal);

        multSub_32x32_keep32_R(p1, xt, sinVal);

        pSrc[2U * l] = p0 << 1;

        pSrc[2U * l + 1U] = p1 << 1;

    }

    // first col

    arm_radix4_butterfly_q31( pSrc, n2, (q31_t*)pCoef, 2U);

    // second col

    arm_radix4_butterfly_q31( pSrc + fftLen, n2, (q31_t*)pCoef, 2U);

    for (i = 0; i < fftLen >> 1; i++)

    {

        p0 = pSrc[4*i+0];

        p1 = pSrc[4*i+1];

        xt = pSrc[4*i+2];

        yt = pSrc[4*i+3];

        p0 <<= 1;

        p1 <<= 1;

        xt <<= 1;

        yt <<= 1;

        pSrc[4*i+0] = p0;

        pSrc[4*i+1] = p1;

        pSrc[4*i+2] = xt;

        pSrc[4*i+3] = yt;

    }

}

void arm_cfft_radix4by2_inverse_q31(

    q31_t * pSrc,

    uint32_t fftLen,

    const q31_t * pCoef)

{

    uint32_t i, l;

    uint32_t n2, ia;

    q31_t xt, yt, cosVal, sinVal;

    q31_t p0, p1;

    n2 = fftLen >> 1;

    ia = 0;

    for (i = 0; i < n2; i++)

    {

        cosVal = pCoef[2*ia];

        sinVal = pCoef[2*ia + 1];

        ia++;

        l = i + n2;

        xt = (pSrc[2 * i] >> 2) - (pSrc[2 * l] >> 2);

        pSrc[2 * i] = (pSrc[2 * i] >> 2) + (pSrc[2 * l] >> 2);

        yt = (pSrc[2 * i + 1] >> 2) - (pSrc[2 * l + 1] >> 2);

        pSrc[2 * i + 1] = (pSrc[2 * l + 1] >> 2) + (pSrc[2 * i + 1] >> 2);

        mult_32x32_keep32_R(p0, xt, cosVal);

        mult_32x32_keep32_R(p1, yt, cosVal);

        multSub_32x32_keep32_R(p0, yt, sinVal);

        multAcc_32x32_keep32_R(p1, xt, sinVal);

        pSrc[2U * l] = p0 << 1;

        pSrc[2U * l + 1U] = p1 << 1;

    }

    // first col

    arm_radix4_butterfly_inverse_q31( pSrc, n2, (q31_t*)pCoef, 2U);

    // second col

    arm_radix4_butterfly_inverse_q31( pSrc + fftLen, n2, (q31_t*)pCoef, 2U);

    for (i = 0; i < fftLen >> 1; i++)

    {

        p0 = pSrc[4*i+0];

        p1 = pSrc[4*i+1];

        xt = pSrc[4*i+2];

        yt = pSrc[4*i+3];

        p0 <<= 1;

        p1 <<= 1;

        xt <<= 1;

        yt <<= 1;

        pSrc[4*i+0] = p0;

        pSrc[4*i+1] = p1;

        pSrc[4*i+2] = xt;

        pSrc[4*i+3] = yt;

    }

}