/* ----------------------------------------------------------------------
* 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;
}
}