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

 * Project:      CMSIS DSP Library

 * Title:        arm_cfft_q15.c

 * Description:  Combined Radix Decimation in Q15 Frequency CFFT 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_q15(

    q15_t * pSrc,

    uint32_t fftLen,

    q15_t * pCoef,

    uint32_t twidCoefModifier);

extern void arm_radix4_butterfly_inverse_q15(

    q15_t * pSrc,

    uint32_t fftLen,

    q15_t * pCoef,

    uint32_t twidCoefModifier);

extern void arm_bitreversal_16(

    uint16_t * pSrc,

    const uint16_t bitRevLen,

    const uint16_t * pBitRevTable);

void arm_cfft_radix4by2_q15(

    q15_t * pSrc,

    uint32_t fftLen,

    const q15_t * pCoef);

void arm_cfft_radix4by2_inverse_q15(

    q15_t * pSrc,

    uint32_t fftLen,

    const q15_t * pCoef);

/**

* @ingroup groupTransforms

*/

/**

* @addtogroup ComplexFFT

* @{

*/

/**

* @details

* @brief       Processing function for the Q15 complex FFT.

* @param[in]      *S    points to an instance of the Q15 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_q15(

    const arm_cfft_instance_q15 * S,

    q15_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_q15  ( p1, L, (q15_t*)S->pTwiddle, 1 );

            break;

        case 32:

        case 128:

        case 512:

        case 2048:

            arm_cfft_radix4by2_inverse_q15  ( p1, L, S->pTwiddle );

            break;

        }

    }

    else

    {

        switch (L)

        {

        case 16:

        case 64:

        case 256:

        case 1024:

        case 4096:

            arm_radix4_butterfly_q15  ( p1, L, (q15_t*)S->pTwiddle, 1 );

            break;

        case 32:

        case 128:

        case 512:

        case 2048:

            arm_cfft_radix4by2_q15  ( p1, L, S->pTwiddle );

            break;

        }

    }

    if ( bitReverseFlag )

        arm_bitreversal_16((uint16_t*)p1,S->bitRevLength,S->pBitRevTable);

}

/**

* @} end of ComplexFFT group

*/

void arm_cfft_radix4by2_q15(

    q15_t * pSrc,

    uint32_t fftLen,

    const q15_t * pCoef)

{

    uint32_t i;

    uint32_t n2;

    q15_t p0, p1, p2, p3;

#if defined (ARM_MATH_DSP)

    q31_t T, S, R;

    q31_t coeff, out1, out2;

    const q15_t *pC = pCoef;

    q15_t *pSi = pSrc;

    q15_t *pSl = pSrc + fftLen;

#else

    uint32_t ia, l;

    q15_t xt, yt, cosVal, sinVal;

#endif

    n2 = fftLen >> 1;

#if defined (ARM_MATH_DSP)

    for (i = n2; i > 0; i--)

    {

        coeff = _SIMD32_OFFSET(pC);

        pC += 2;

        T = _SIMD32_OFFSET(pSi);

        T = __SHADD16(T, 0); // this is just a SIMD arithmetic shift right by 1

        S = _SIMD32_OFFSET(pSl);

        S = __SHADD16(S, 0); // this is just a SIMD arithmetic shift right by 1

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSi) = __SHADD16(T, S);

        pSi += 2;

    #ifndef ARM_MATH_BIG_ENDIAN

        out1 = __SMUAD(coeff, R) >> 16;

        out2 = __SMUSDX(coeff, R);

    #else

        out1 = __SMUSDX(R, coeff) >> 16U;

        out2 = __SMUAD(coeff, R);

    #endif //     #ifndef ARM_MATH_BIG_ENDIAN

        _SIMD32_OFFSET(pSl) =

        (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

        pSl += 2;

    }

#else //    #if defined (ARM_MATH_DSP)

    ia = 0;

    for (i = 0; i < n2; i++)

    {

        cosVal = pCoef[ia * 2];

        sinVal = pCoef[(ia * 2) + 1];

        ia++;

        l = i + n2;

        xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);

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

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

        pSrc[2 * i + 1] =

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

        pSrc[2U * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) +

                  ((int16_t) (((q31_t) yt * sinVal) >> 16)));

        pSrc[2U * l + 1U] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) -

                       ((int16_t) (((q31_t) xt * sinVal) >> 16)));

    }

#endif //    #if defined (ARM_MATH_DSP)

    // first col

    arm_radix4_butterfly_q15( pSrc, n2, (q15_t*)pCoef, 2U);

    // second col

    arm_radix4_butterfly_q15( pSrc + fftLen, n2, (q15_t*)pCoef, 2U);

    for (i = 0; i < fftLen >> 1; i++)

    {

        p0 = pSrc[4*i+0];

        p1 = pSrc[4*i+1];

        p2 = pSrc[4*i+2];

        p3 = pSrc[4*i+3];

        p0 <<= 1;

        p1 <<= 1;

        p2 <<= 1;

        p3 <<= 1;

        pSrc[4*i+0] = p0;

        pSrc[4*i+1] = p1;

        pSrc[4*i+2] = p2;

        pSrc[4*i+3] = p3;

    }

}

void arm_cfft_radix4by2_inverse_q15(

    q15_t * pSrc,

    uint32_t fftLen,

    const q15_t * pCoef)

{

    uint32_t i;

    uint32_t n2;

    q15_t p0, p1, p2, p3;

#if defined (ARM_MATH_DSP)

    q31_t T, S, R;

    q31_t coeff, out1, out2;

    const q15_t *pC = pCoef;

    q15_t *pSi = pSrc;

    q15_t *pSl = pSrc + fftLen;

#else

    uint32_t ia, l;

    q15_t xt, yt, cosVal, sinVal;

#endif

    n2 = fftLen >> 1;

#if defined (ARM_MATH_DSP)

    for (i = n2; i > 0; i--)

    {

        coeff = _SIMD32_OFFSET(pC);

        pC += 2;

        T = _SIMD32_OFFSET(pSi);

        T = __SHADD16(T, 0); // this is just a SIMD arithmetic shift right by 1

        S = _SIMD32_OFFSET(pSl);

        S = __SHADD16(S, 0); // this is just a SIMD arithmetic shift right by 1

        R = __QSUB16(T, S);

        _SIMD32_OFFSET(pSi) = __SHADD16(T, S);

        pSi += 2;

    #ifndef ARM_MATH_BIG_ENDIAN

        out1 = __SMUSD(coeff, R) >> 16;

        out2 = __SMUADX(coeff, R);

    #else

        out1 = __SMUADX(R, coeff) >> 16U;

        out2 = __SMUSD(__QSUB(0, coeff), R);

    #endif //     #ifndef ARM_MATH_BIG_ENDIAN

        _SIMD32_OFFSET(pSl) =

        (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF);

        pSl += 2;

    }

#else //    #if defined (ARM_MATH_DSP)

    ia = 0;

    for (i = 0; i < n2; i++)

    {

        cosVal = pCoef[ia * 2];

        sinVal = pCoef[(ia * 2) + 1];

        ia++;

        l = i + n2;

        xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);

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

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

        pSrc[2 * i + 1] =

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

        pSrc[2U * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) -

                        ((int16_t) (((q31_t) yt * sinVal) >> 16)));

        pSrc[2U * l + 1U] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) +

                           ((int16_t) (((q31_t) xt * sinVal) >> 16)));

    }

#endif //    #if defined (ARM_MATH_DSP)

    // first col

    arm_radix4_butterfly_inverse_q15( pSrc, n2, (q15_t*)pCoef, 2U);

    // second col

    arm_radix4_butterfly_inverse_q15( pSrc + fftLen, n2, (q15_t*)pCoef, 2U);

    for (i = 0; i < fftLen >> 1; i++)

    {

        p0 = pSrc[4*i+0];

        p1 = pSrc[4*i+1];

        p2 = pSrc[4*i+2];

        p3 = pSrc[4*i+3];

        p0 <<= 1;

        p1 <<= 1;

        p2 <<= 1;

        p3 <<= 1;

        pSrc[4*i+0] = p0;

        pSrc[4*i+1] = p1;

        pSrc[4*i+2] = p2;

        pSrc[4*i+3] = p3;

    }

}