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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_cfft_radix2_q31.c
* Description: Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function
*
* $Date: 18. March 2019
* $Revision: V1.6.0
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2019 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"
void arm_radix2_butterfly_q31(
q31_t * pSrc,
uint32_t fftLen,
const q31_t * pCoef,
uint16_t twidCoefModifier);
void arm_radix2_butterfly_inverse_q31(
q31_t * pSrc,
uint32_t fftLen,
const q31_t * pCoef,
uint16_t twidCoefModifier);
void arm_bitreversal_q31(
q31_t * pSrc,
uint32_t fftLen,
uint16_t bitRevFactor,
const uint16_t * pBitRevTab);
/**
@ingroup groupTransforms
*/
/**
@addtogroup ComplexFFT
@{
*/
/**
@brief Processing function for the fixed-point CFFT/CIFFT.
@deprecated Do not use this function. It has been superseded by \ref arm_cfft_q31 and will be removed in the future.
@param[in] S points to an instance of the fixed-point CFFT/CIFFT structure
@param[in,out] pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place
@return none
*/
void arm_cfft_radix2_q31(
const arm_cfft_radix2_instance_q31 * S,
q31_t * pSrc)
{
if (S->ifftFlag == 1U)
{
arm_radix2_butterfly_inverse_q31(pSrc, S->fftLen,
S->pTwiddle, S->twidCoefModifier);
}
else
{
arm_radix2_butterfly_q31(pSrc, S->fftLen,
S->pTwiddle, S->twidCoefModifier);
}
arm_bitreversal_q31(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
}
/**
@} end of ComplexFFT group
*/
void arm_radix2_butterfly_q31(
q31_t * pSrc,
uint32_t fftLen,
const q31_t * pCoef,
uint16_t twidCoefModifier)
{
unsigned i, j, k, l, m;
unsigned n1, n2, ia;
q31_t xt, yt, cosVal, sinVal;
q31_t p0, p1;
//N = fftLen;
n2 = fftLen;
n1 = n2;
n2 = n2 >> 1;
ia = 0;
// loop for groups
for (i = 0; i < n2; i++)
{
cosVal = pCoef[ia * 2];
sinVal = pCoef[(ia * 2) + 1];
ia = ia + twidCoefModifier;
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;
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;
pSrc[2U * l + 1U] = p1;
} // groups loop end
twidCoefModifier <<= 1U;
// loop for stage
for (k = fftLen / 2; k > 2; k = k >> 1)
{
n1 = n2;
n2 = n2 >> 1;
ia = 0;
// loop for groups
for (j = 0; j < n2; j++)
{
cosVal = pCoef[ia * 2];
sinVal = pCoef[(ia * 2) + 1];
ia = ia + twidCoefModifier;
// loop for butterfly
i = j;
m = fftLen / n1;
do
{
l = i + n2;
xt = pSrc[2 * i] - pSrc[2 * l];
pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;
yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;
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;
pSrc[2U * l + 1U] = p1;
i += n1;
m--;
} while ( m > 0); // butterfly loop end
} // groups loop end
twidCoefModifier <<= 1U;
} // stages loop end
n1 = n2;
n2 = n2 >> 1;
ia = 0;
cosVal = pCoef[ia * 2];
sinVal = pCoef[(ia * 2) + 1];
ia = ia + twidCoefModifier;
// loop for butterfly
for (i = 0; i < fftLen; i += n1)
{
l = i + n2;
xt = pSrc[2 * i] - pSrc[2 * l];
pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
pSrc[2U * l] = xt;
pSrc[2U * l + 1U] = yt;
i += n1;
l = i + n2;
xt = pSrc[2 * i] - pSrc[2 * l];
pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
pSrc[2U * l] = xt;
pSrc[2U * l + 1U] = yt;
} // butterfly loop end
}
void arm_radix2_butterfly_inverse_q31(
q31_t * pSrc,
uint32_t fftLen,
const q31_t * pCoef,
uint16_t twidCoefModifier)
{
unsigned i, j, k, l;
unsigned n1, n2, ia;
q31_t xt, yt, cosVal, sinVal;
q31_t p0, p1;
//N = fftLen;
n2 = fftLen;
n1 = n2;
n2 = n2 >> 1;
ia = 0;
// loop for groups
for (i = 0; i < n2; i++)
{
cosVal = pCoef[ia * 2];
sinVal = pCoef[(ia * 2) + 1];
ia = ia + twidCoefModifier;
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;
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;
pSrc[2U * l + 1U] = p1;
} // groups loop end
twidCoefModifier = twidCoefModifier << 1U;
// loop for stage
for (k = fftLen / 2; k > 2; k = k >> 1)
{
n1 = n2;
n2 = n2 >> 1;
ia = 0;
// loop for groups
for (j = 0; j < n2; j++)
{
cosVal = pCoef[ia * 2];
sinVal = pCoef[(ia * 2) + 1];
ia = ia + twidCoefModifier;
// loop for butterfly
for (i = j; i < fftLen; i += n1)
{
l = i + n2;
xt = pSrc[2 * i] - pSrc[2 * l];
pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;
yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;
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;
pSrc[2U * l + 1U] = p1;
} // butterfly loop end
} // groups loop end
twidCoefModifier = twidCoefModifier << 1U;
} // stages loop end
n1 = n2;
n2 = n2 >> 1;
ia = 0;
cosVal = pCoef[ia * 2];
sinVal = pCoef[(ia * 2) + 1];
ia = ia + twidCoefModifier;
// loop for butterfly
for (i = 0; i < fftLen; i += n1)
{
l = i + n2;
xt = pSrc[2 * i] - pSrc[2 * l];
pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
pSrc[2U * l] = xt;
pSrc[2U * l + 1U] = yt;
i += n1;
l = i + n2;
xt = pSrc[2 * i] - pSrc[2 * l];
pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
pSrc[2U * l] = xt;
pSrc[2U * l + 1U] = yt;
} // butterfly loop end
}
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