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/*
* FFT/IFFT transforms
* AltiVec-enabled
* Copyright (c) 2003 Romain Dolbeau <romain@dolbeau.org>
* Based on code Copyright (c) 2002 Fabrice Bellard.
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/dsputil.h"
#include "gcc_fixes.h"
#include "dsputil_ppc.h"
#include "util_altivec.h"
/**
* Do a complex FFT with the parameters defined in ff_fft_init(). The
* input data must be permuted before with s->revtab table. No
* 1.0/sqrt(n) normalization is done.
* AltiVec-enabled
* This code assumes that the 'z' pointer is 16 bytes-aligned
* It also assumes all FFTComplex are 8 bytes-aligned pair of float
* The code is exactly the same as the SSE version, except
* that successive MUL + ADD/SUB have been merged into
* fused multiply-add ('vec_madd' in altivec)
*/
void ff_fft_calc_altivec(FFTContext *s, FFTComplex *z)
{
POWERPC_PERF_DECLARE(altivec_fft_num, s->nbits >= 6);
register const vector float vczero = (const vector float)vec_splat_u32(0.);
int ln = s->nbits;
int j, np, np2;
int nblocks, nloops;
register FFTComplex *p, *q;
FFTComplex *cptr, *cptr1;
int k;
POWERPC_PERF_START_COUNT(altivec_fft_num, s->nbits >= 6);
np = 1 << ln;
{
vector float *r, a, b, a1, c1, c2;
r = (vector float *)&z[0];
c1 = vcii(p,p,n,n);
if (s->inverse) {
c2 = vcii(p,p,n,p);
} else {
c2 = vcii(p,p,p,n);
}
j = (np >> 2);
do {
a = vec_ld(0, r);
a1 = vec_ld(sizeof(vector float), r);
b = vec_perm(a,a,vcprmle(1,0,3,2));
a = vec_madd(a,c1,b);
/* do the pass 0 butterfly */
b = vec_perm(a1,a1,vcprmle(1,0,3,2));
b = vec_madd(a1,c1,b);
/* do the pass 0 butterfly */
/* multiply third by -i */
b = vec_perm(b,b,vcprmle(2,3,1,0));
/* do the pass 1 butterfly */
vec_st(vec_madd(b,c2,a), 0, r);
vec_st(vec_nmsub(b,c2,a), sizeof(vector float), r);
r += 2;
} while (--j != 0);
}
/* pass 2 .. ln-1 */
nblocks = np >> 3;
nloops = 1 << 2;
np2 = np >> 1;
cptr1 = s->exptab1;
do {
p = z;
q = z + nloops;
j = nblocks;
do {
cptr = cptr1;
k = nloops >> 1;
do {
vector float a,b,c,t1;
a = vec_ld(0, (float*)p);
b = vec_ld(0, (float*)q);
/* complex mul */
c = vec_ld(0, (float*)cptr);
/* cre*re cim*re */
t1 = vec_madd(c, vec_perm(b,b,vcprmle(2,2,0,0)),vczero);
c = vec_ld(sizeof(vector float), (float*)cptr);
/* -cim*im cre*im */
b = vec_madd(c, vec_perm(b,b,vcprmle(3,3,1,1)),t1);
/* butterfly */
vec_st(vec_add(a,b), 0, (float*)p);
vec_st(vec_sub(a,b), 0, (float*)q);
p += 2;
q += 2;
cptr += 4;
} while (--k);
p += nloops;
q += nloops;
} while (--j);
cptr1 += nloops * 2;
nblocks = nblocks >> 1;
nloops = nloops << 1;
} while (nblocks != 0);
POWERPC_PERF_STOP_COUNT(altivec_fft_num, s->nbits >= 6);
}
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