Subversion Repositories DashDisplay

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

* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    

*    

* $Date:        19. March 2015

* $Revision:    V.1.4.5  

*    

* Project:          CMSIS DSP Library    

* Title:            arm_cfft_q31.c  

*    

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

*    

* 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;

* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

* POSSIBILITY OF SUCH DAMAGE.  

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

#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;

    }

}