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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_C_SC16.c
* OpenMAX DL: v1.0.2
* Last Modified Revision: 15322
* Last Modified Date: Wed, 15 Oct 2008
*
* (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
*
*
* Description:
* Initializes the specification structures required
*/
#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_C_SC16
*
* Description:
* These functions initialize the specification structures required for the
* complex FFT and IFFT functions.
*
* Remarks:
* Desired block length is specified as an input. The function is used to
* initialize the specification structures for functions <FFTFwd_CToC_SC16_Sfs>
* and <FFTInv_CToC_SC16_Sfs>. Memory for the specification structure *pFFTSpec
* must be allocated prior to calling this function. The space required for
* *pFFTSpec, in bytes, can be determined using <FFTGetBufSize_C_SC16>.
*
* Parameters:
* [in] order base-2 logarithm of the desired block length;
* valid in the range [0,12].
* [out] pFFTSpec pointer to initialized specification structure.
*
* Return Value:
* Standard omxError result. See enumeration for possible result codes.
*
*/
OMXResult omxSP_FFTInit_C_SC16(
OMXFFTSpec_C_SC16* pFFTSpec,
OMX_INT order
)
{
OMX_INT i,j;
OMX_SC16 *pTwiddle, *pBuf;
OMX_U16 *pBitRev;
OMX_INT Nby2,N,M,diff,step;
OMX_U32 pTmp;
ARMsFFTSpec_SC16 *pFFTStruct = 0;
OMX_S16 x,y,xNeg;
OMX_S32 xS32,yS32;
pFFTStruct = (ARMsFFTSpec_SC16 *) pFFTSpec;
/* if order zero no init is needed */
if (order == 0)
{
pFFTStruct->N = 1;
return OMX_Sts_NoErr;
}
/* Do the initializations */
Nby2 = 1 << (order - 1);
N = Nby2 << 1;
M = N>>3;
pBitRev = NULL ;
pTwiddle = (OMX_SC16 *)
(sizeof(ARMsFFTSpec_SC16) + (OMX_S8*) pFFTSpec);
/* Align to 32 byte boundary */
pTmp = ((OMX_U32)pTwiddle)&31; /* (OMX_U32)pTwiddle % 32 */
if(pTmp != 0)
pTwiddle = (OMX_SC16*) ((OMX_S8*)pTwiddle + (32-pTmp));
pBuf = (OMX_SC16 *)
(sizeof(OMX_SC16) * (3*N/4) + (OMX_S8*) pTwiddle);
/* Align to 32 byte boundary */
pTmp = ((OMX_U32)pBuf)&31; /* (OMX_U32)pBuf % 32 */
if(pTmp != 0)
pBuf = (OMX_SC16*) ((OMX_S8*)pBuf + (32-pTmp));
/*
* Filling Twiddle factors :
* The original twiddle table "armSP_FFT_S16TwiddleTable" 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 3N/4 for a radix-4 stage
*
* W = (-2 * PI) / N
* N = 1 << order
* W = -PI >> (order - 1)
*/
diff = 12 - order;
step = 1<<diff; /* step into the twiddle table for the current order */
xS32 = armSP_FFT_S32TwiddleTable[0];
yS32 = armSP_FFT_S32TwiddleTable[1];
x = (xS32+0x8000)>>16;
y = (yS32+0x8000)>>16;
xNeg = 0x7FFF;
if(order >=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;
xS32 = armSP_FFT_S32TwiddleTable[2*j];
yS32 = armSP_FFT_S32TwiddleTable[2*j+1];
x = (xS32+0x8000)>>16;
y = (yS32+0x8000)>>16;
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 == 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)
{
pTwiddle[0].Re = x;
pTwiddle[0].Im = y;
}
}
/* 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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