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cmsis_dsp/TransformFunctions/arm_cfft_radix2_q31.c
- Committer:
- emilmont
- Date:
- 2013-05-30
- Revision:
- 2:da51fb522205
- Parent:
- 1:fdd22bb7aa52
- Child:
- 3:7a284390b0ce
File content as of revision 2:da51fb522205:
/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 15. February 2012
* $Revision: V1.1.0
*
* Project: CMSIS DSP Library
* Title: arm_cfft_radix2_q31.c
*
* Description: Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function
*
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
* Updated with more optimizations, bug fixes and minor API changes.
*
* Version 0.0.3 2010/03/10
* Initial version
* -------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupTransforms
*/
/**
* @defgroup Radix2_CFFT_CIFFT Radix-2 Complex FFT Functions
*
* \par
* Complex Fast Fourier Transform(CFFT) and Complex Inverse Fast Fourier Transform(CIFFT) is an efficient algorithm to compute Discrete Fourier Transform(DFT) and Inverse Discrete Fourier Transform(IDFT).
* Computational complexity of CFFT reduces drastically when compared to DFT.
*/
/**
* @addtogroup Radix2_CFFT_CIFFT
* @{
*/
/**
* @details
* @brief Processing function for the fixed-point CFFT/CIFFT.
* @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 Radix2_CFFT_CIFFT group
*/
void arm_radix2_butterfly_q31(
q31_t * pSrc,
uint32_t fftLen,
q31_t * pCoef,
uint16_t twidCoefModifier)
{
int i, j, k, l;
int n1, n2, ia;
q31_t xt, yt, cosVal, sinVal;
//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] >> 2u) - (pSrc[2 * l] >> 2u);
pSrc[2 * i] = ((pSrc[2 * i] >> 2u) + (pSrc[2 * l] >> 2u)) >> 1u;
yt = (pSrc[2 * i + 1] >> 2u) - (pSrc[2 * l + 1] >> 2u);
pSrc[2 * i + 1] =
((pSrc[2 * l + 1] >> 2u) + (pSrc[2 * i + 1] >> 2u)) >> 1u;
pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) +
((int32_t) (((q63_t) yt * sinVal) >> 32)));
pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) -
((int32_t) (((q63_t) xt * sinVal) >> 32)));
} // 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;
pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) +
((int32_t) (((q63_t) yt * sinVal) >> 32)));
pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) -
((int32_t) (((q63_t) xt * sinVal) >> 32)));
} // 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
}
void arm_radix2_butterfly_inverse_q31(
q31_t * pSrc,
uint32_t fftLen,
q31_t * pCoef,
uint16_t twidCoefModifier)
{
int i, j, k, l;
int n1, n2, ia;
q31_t xt, yt, cosVal, sinVal;
//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] >> 2u) - (pSrc[2 * l] >> 2u);
pSrc[2 * i] = ((pSrc[2 * i] >> 2u) + (pSrc[2 * l] >> 2u)) >> 1u;
yt = (pSrc[2 * i + 1] >> 2u) - (pSrc[2 * l + 1] >> 2u);
pSrc[2 * i + 1] =
((pSrc[2 * l + 1] >> 2u) + (pSrc[2 * i + 1] >> 2u)) >> 1u;
pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) -
((int32_t) (((q63_t) yt * sinVal) >> 32)));
pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) +
((int32_t) (((q63_t) xt * sinVal) >> 32)));
} // 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;
pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) -
((int32_t) (((q63_t) yt * sinVal) >> 32)));
pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) +
((int32_t) (((q63_t) xt * sinVal) >> 32)));
} // 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
}