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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;
}
}
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