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FFmpeg/libavcodec/i386/fft_sse.c
Zuxy Meng 2ffb22d2ad use xorps instead of mulps to toggle the sign of a float, as suggested by Software Optimization Guide for AMD64 Processors.
Patch by Zuxy Meng < zuxy POIS meng AH  gmail POIS com > OKed by Michael
Original thread:
Date: Mar 5, 2006 8:15 PM
Subject: [Ffmpeg-devel] [PATCH] Little optimization to fft_sse.c

Originally committed as revision 5112 to svn://svn.ffmpeg.org/ffmpeg/trunk
2006-03-05 20:25:18 +00:00

141 lines
3.8 KiB
C

/*
* FFT/MDCT transform with SSE optimizations
* Copyright (c) 2002 Fabrice Bellard.
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "../dsputil.h"
#include <math.h>
#ifdef HAVE_BUILTIN_VECTOR
#include <xmmintrin.h>
static const int p1p1p1m1[4] __attribute__((aligned(16))) =
{ 0, 0, 0, 1 << 31 };
static const int p1p1m1p1[4] __attribute__((aligned(16))) =
{ 0, 0, 1 << 31, 0 };
static const int p1p1m1m1[4] __attribute__((aligned(16))) =
{ 0, 0, 1 << 31, 1 << 31 };
#if 0
static void print_v4sf(const char *str, __m128 a)
{
float *p = (float *)&a;
printf("%s: %f %f %f %f\n",
str, p[0], p[1], p[2], p[3]);
}
#endif
/* XXX: handle reverse case */
void ff_fft_calc_sse(FFTContext *s, FFTComplex *z)
{
int ln = s->nbits;
int j, np, np2;
int nblocks, nloops;
register FFTComplex *p, *q;
FFTComplex *cptr, *cptr1;
int k;
np = 1 << ln;
{
__m128 *r, a, b, a1, c1, c2;
r = (__m128 *)&z[0];
c1 = *(__m128 *)p1p1m1m1;
if (s->inverse)
c2 = *(__m128 *)p1p1m1p1;
else
c2 = *(__m128 *)p1p1p1m1;
j = (np >> 2);
do {
a = r[0];
b = _mm_shuffle_ps(a, a, _MM_SHUFFLE(1, 0, 3, 2));
a = _mm_xor_ps(a, c1);
/* do the pass 0 butterfly */
a = _mm_add_ps(a, b);
a1 = r[1];
b = _mm_shuffle_ps(a1, a1, _MM_SHUFFLE(1, 0, 3, 2));
a1 = _mm_xor_ps(a1, c1);
/* do the pass 0 butterfly */
b = _mm_add_ps(a1, b);
/* multiply third by -i */
/* by toggling the sign bit */
b = _mm_shuffle_ps(b, b, _MM_SHUFFLE(2, 3, 1, 0));
b = _mm_xor_ps(b, c2);
/* do the pass 1 butterfly */
r[0] = _mm_add_ps(a, b);
r[1] = _mm_sub_ps(a, b);
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 {
__m128 a, b, c, t1, t2;
a = *(__m128 *)p;
b = *(__m128 *)q;
/* complex mul */
c = *(__m128 *)cptr;
/* cre*re cim*re */
t1 = _mm_mul_ps(c,
_mm_shuffle_ps(b, b, _MM_SHUFFLE(2, 2, 0, 0)));
c = *(__m128 *)(cptr + 2);
/* -cim*im cre*im */
t2 = _mm_mul_ps(c,
_mm_shuffle_ps(b, b, _MM_SHUFFLE(3, 3, 1, 1)));
b = _mm_add_ps(t1, t2);
/* butterfly */
*(__m128 *)p = _mm_add_ps(a, b);
*(__m128 *)q = _mm_sub_ps(a, b);
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);
}
#endif