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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 file was originally licensed as follows. It has been
* relicensed with permission from the copyright holders.
*/
/**
*
* File Name: omxSP_FFTInit_R_S32.c
* OpenMAX DL: v1.0.2
* Last Modified Revision: 7777
* Last Modified Date: Thu, 27 Sep 2007
*
* (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
*
*
* Description:
* Initialize the real forward-FFT specification information struct.
*/
#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_S32
*
* Description:
* Initialize the real forward-FFT specification information struct.
*
* Remarks:
* This function is used to initialize the specification structures
* for functions <ippsFFTFwd_RToCCS_S32_Sfs> and
* <ippsFFTInv_CCSToR_S32_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_S32>.
*
* Parameters:
* [in] order base-2 logarithm of the desired block length;
* valid in the range [0,12].
* [out] pFFTFwdSpec pointer to the initialized specification structure.
*
* Return Value:
* Standard omxError result. See enumeration for possible result codes.
*
*/
OMXResult omxSP_FFTInit_R_S32(
OMXFFTSpec_R_S32* pFFTSpec,
OMX_INT order
)
{
OMX_INT i,j;
OMX_SC32 *pTwiddle,*pTwiddle1,*pTwiddle2,*pTwiddle3,*pTwiddle4;
OMX_S32 *pBuf;
OMX_U16 *pBitRev;
OMX_U32 pTmp;
OMX_INT Nby2,N,M,diff, step;
OMX_S32 x,y,xNeg;
ARMsFFTSpec_R_SC32 *pFFTStruct = 0;
pFFTStruct = (ARMsFFTSpec_R_SC32 *) pFFTSpec;
/* if order zero no init is needed */
if (order == 0)
{
pFFTStruct->N = 1;
pFFTStruct->pTwiddle = NULL;
pFFTStruct->pBuf = (OMX_S32 *)
(sizeof(ARMsFFTSpec_R_SC32) + (OMX_S8*) pFFTSpec);
return OMX_Sts_NoErr;
}
/* Do the initializations */
Nby2 = 1 << (order - 1);
N = Nby2 << 1;
pBitRev = NULL ; /* optimized implementations don't use bitreversal */
pTwiddle = (OMX_SC32 *)
(sizeof(ARMsFFTSpec_R_SC32) + (OMX_S8*) pFFTSpec);
/* Align to 32 byte boundary */
pTmp = ((OMX_U32)pTwiddle)&31; /* (OMX_U32)pTwiddle % 32 */
if(pTmp != 0)
pTwiddle = (OMX_SC32*) ((OMX_S8*)pTwiddle + (32-pTmp));
pBuf = (OMX_S32*)
(sizeof(OMX_SC32) * (5*N/8) + (OMX_S8*) pTwiddle);
/* Align to 32 byte boundary */
pTmp = ((OMX_U32)pBuf)&31; /* (OMX_U32)pBuf % 32 */
if(pTmp != 0)
pBuf = (OMX_S32*) ((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_S32TwiddleTable" 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 = 12 - (order-1);
step = 1<<diff; /* step into the twiddle table for the current order */
x = armSP_FFT_S32TwiddleTable[0];
y = armSP_FFT_S32TwiddleTable[1];
xNeg = 0x7FFFFFFF;
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_S32TwiddleTable[2*j];
y = armSP_FFT_S32TwiddleTable[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;
}
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 = 12 - 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_S32TwiddleTable[0];
y = armSP_FFT_S32TwiddleTable[1];
xNeg = 0x7FFFFFFF;
if((order) >=3)
{
for (i=1; i<=M; i+=2 )
{
j = i*step;
x = armSP_FFT_S32TwiddleTable[2*j];
y = armSP_FFT_S32TwiddleTable[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;
}
/*****************************************************************************
* END OF FILE
*****************************************************************************/
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