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/*
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*
* This is a modification of omxSP_FFTInit_R_S32.c to support float
* instead of S32.
*/
#include "dl/api/armOMX.h"
#include "dl/api/omxtypes.h"
#include "dl/sp/api/armSP.h"
#include "dl/sp/api/omxSP.h"
/**
* Function: omxSP_FFTInit_R_F32
*
* Description:
* Initialize the real forward-FFT specification information struct.
*
* Remarks:
* This function is used to initialize the specification structures
* for functions <ippsFFTFwd_RToCCS_F32_Sfs> and
* <ippsFFTInv_CCSToR_F32_Sfs>. Memory for *pFFTSpec must be
* allocated prior to calling this function. The number of bytes
* required for *pFFTSpec can be determined using
* <FFTGetBufSize_R_F32>.
*
* Parameters:
* [in] order base-2 logarithm of the desired block length;
* valid in the range [1,12]. ([1,15] if
* BIG_FFT_TABLE is defined.)
* [out] pFFTFwdSpec pointer to the initialized specification structure.
*
* Return Value:
* Standard omxError result. See enumeration for possible result codes.
*
*/
OMXResult omxSP_FFTInit_R_F32(OMXFFTSpec_R_F32* pFFTSpec, OMX_INT order) {
OMX_INT i;
OMX_INT j;
OMX_FC32* pTwiddle;
OMX_FC32* pTwiddle1;
OMX_FC32* pTwiddle2;
OMX_FC32* pTwiddle3;
OMX_FC32* pTwiddle4;
OMX_F32* pBuf;
OMX_U16* pBitRev;
OMX_U32 pTmp;
OMX_INT Nby2;
OMX_INT N;
OMX_INT M;
OMX_INT diff;
OMX_INT step;
OMX_F32 x;
OMX_F32 y;
OMX_F32 xNeg;
ARMsFFTSpec_R_FC32* pFFTStruct = 0;
pFFTStruct = (ARMsFFTSpec_R_FC32 *) pFFTSpec;
/* Validate args */
if (!pFFTSpec || (order < 1) || (order > TWIDDLE_TABLE_ORDER))
return OMX_Sts_BadArgErr;
/* Do the initializations */
Nby2 = 1 << (order - 1);
N = Nby2 << 1;
/* optimized implementations don't use bitreversal */
pBitRev = NULL;
pTwiddle = (OMX_FC32 *) (sizeof(ARMsFFTSpec_R_SC32) + (OMX_S8*) pFFTSpec);
/* Align to 32 byte boundary */
pTmp = ((OMX_U32)pTwiddle) & 31;
if (pTmp)
pTwiddle = (OMX_FC32*) ((OMX_S8*)pTwiddle + (32 - pTmp));
pBuf = (OMX_F32*) (sizeof(OMX_FC32)*(5*N/8) + (OMX_S8*) pTwiddle);
/* Align to 32 byte boundary */
pTmp = ((OMX_U32)pBuf)&31; /* (OMX_U32)pBuf % 32 */
if (pTmp)
pBuf = (OMX_F32*) ((OMX_S8*)pBuf + (32 - pTmp));
/*
* Filling Twiddle factors :
*
* exp^(-j*2*PI*k/ (N/2) ) ; k=0,1,2,...,3/4(N/2)
*
* N/2 point complex FFT is used to compute N point real FFT The
* original twiddle table "armSP_FFT_F32TwiddleTable" is of size
* (MaxSize/8 + 1) Rest of the values i.e., upto MaxSize are
* calculated using the symmetries of sin and cos The max size of
* the twiddle table needed is 3/4(N/2) for a radix-4 stage
*
* W = (-2 * PI) / N
* N = 1 << order
* W = -PI >> (order - 1)
*/
M = Nby2 >> 3;
diff = TWIDDLE_TABLE_ORDER - (order - 1);
/* step into the twiddle table for the current order */
step = 1 << diff;
x = armSP_FFT_F32TwiddleTable[0];
y = armSP_FFT_F32TwiddleTable[1];
xNeg = 1;
if ((order - 1) >= 3) {
/* i = 0 case */
pTwiddle[0].Re = x;
pTwiddle[0].Im = y;
pTwiddle[2*M].Re = -y;
pTwiddle[2*M].Im = xNeg;
pTwiddle[4*M].Re = xNeg;
pTwiddle[4*M].Im = y;
for (i = 1; i <= M; i++) {
j = i*step;
x = armSP_FFT_F32TwiddleTable[2*j];
y = armSP_FFT_F32TwiddleTable[2*j+1];
pTwiddle[i].Re = x;
pTwiddle[i].Im = y;
pTwiddle[2*M-i].Re = -y;
pTwiddle[2*M-i].Im = -x;
pTwiddle[2*M+i].Re = y;
pTwiddle[2*M+i].Im = -x;
pTwiddle[4*M-i].Re = -x;
pTwiddle[4*M-i].Im = y;
pTwiddle[4*M+i].Re = -x;
pTwiddle[4*M+i].Im = -y;
pTwiddle[6*M-i].Re = y;
pTwiddle[6*M-i].Im = x;
}
} else if ((order - 1) == 2) {
pTwiddle[0].Re = x;
pTwiddle[0].Im = y;
pTwiddle[1].Re = -y;
pTwiddle[1].Im = xNeg;
pTwiddle[2].Re = xNeg;
pTwiddle[2].Im = y;
} else if ((order-1) == 1) {
pTwiddle[0].Re = x;
pTwiddle[0].Im = y;
}
/*
* Now fill the last N/4 values : exp^(-j*2*PI*k/N) ;
* k=1,3,5,...,N/2-1 These are used for the final twiddle fix-up for
* converting complex to real FFT
*/
M = N >> 3;
diff = TWIDDLE_TABLE_ORDER - order;
step = 1 << diff;
pTwiddle1 = pTwiddle + 3*N/8;
pTwiddle4 = pTwiddle1 + (N/4 - 1);
pTwiddle3 = pTwiddle1 + N/8;
pTwiddle2 = pTwiddle1 + (N/8 - 1);
x = armSP_FFT_F32TwiddleTable[0];
y = armSP_FFT_F32TwiddleTable[1];
xNeg = 1;
if (order >=3) {
for (i = 1; i <= M; i += 2) {
j = i*step;
x = armSP_FFT_F32TwiddleTable[2*j];
y = armSP_FFT_F32TwiddleTable[2*j+1];
pTwiddle1[0].Re = x;
pTwiddle1[0].Im = y;
pTwiddle1 += 1;
pTwiddle2[0].Re = -y;
pTwiddle2[0].Im = -x;
pTwiddle2 -= 1;
pTwiddle3[0].Re = y;
pTwiddle3[0].Im = -x;
pTwiddle3 += 1;
pTwiddle4[0].Re = -x;
pTwiddle4[0].Im = y;
pTwiddle4 -= 1;
}
} else {
if (order == 2) {
pTwiddle1[0].Re = -y;
pTwiddle1[0].Im = xNeg;
}
}
/* Update the structure */
pFFTStruct->N = N;
pFFTStruct->pTwiddle = pTwiddle;
pFFTStruct->pBitRev = pBitRev;
pFFTStruct->pBuf = pBuf;
return OMX_Sts_NoErr;
}
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