3
* Copyright (c) 2002 Fabrice Bellard.
5
* This library is free software; you can redistribute it and/or
6
* modify it under the terms of the GNU Lesser General Public
7
* License as published by the Free Software Foundation; either
8
* version 2 of the License, or (at your option) any later version.
10
* This library is distributed in the hope that it will be useful,
11
* but WITHOUT ANY WARRANTY; without even the implied warranty of
12
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13
* Lesser General Public License for more details.
15
* You should have received a copy of the GNU Lesser General Public
16
* License along with this library; if not, write to the Free Software
17
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22
* FFT/IFFT transforms.
28
* The size of the FFT is 2^nbits. If inverse is TRUE, inverse FFT is
31
int ff_fft_init(FFTContext *s, int nbits, int inverse)
34
float alpha, c1, s1, s2;
39
s->exptab = av_malloc((n / 2) * sizeof(FFTComplex));
42
s->revtab = av_malloc(n * sizeof(uint16_t));
47
s2 = inverse ? 1.0 : -1.0;
49
for(i=0;i<(n/2);i++) {
50
alpha = 2 * M_PI * (float)i / (float)n;
56
s->fft_calc = ff_fft_calc_c;
59
/* compute constant table for HAVE_SSE version */
60
#if (defined(HAVE_MMX) && defined(HAVE_BUILTIN_VECTOR)) || defined(HAVE_ALTIVEC)
65
has_vectors = mm_support() & MM_SSE;
67
#if defined(HAVE_ALTIVEC) && !defined(ALTIVEC_USE_REFERENCE_C_CODE)
68
has_vectors = mm_support() & MM_ALTIVEC;
71
int np, nblocks, np2, l;
77
s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
82
for(l = 0; l < np2; l += 2 * nblocks) {
84
*q++ = s->exptab[l + nblocks];
86
q->re = -s->exptab[l].im;
87
q->im = s->exptab[l].re;
89
q->re = -s->exptab[l + nblocks].im;
90
q->im = s->exptab[l + nblocks].re;
93
nblocks = nblocks >> 1;
94
} while (nblocks != 0);
97
s->fft_calc = ff_fft_calc_sse;
99
s->fft_calc = ff_fft_calc_altivec;
105
/* compute bit reverse table */
109
for(j=0;j<nbits;j++) {
110
m |= ((i >> j) & 1) << (nbits-j-1);
116
av_freep(&s->revtab);
117
av_freep(&s->exptab);
118
av_freep(&s->exptab1);
123
#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
125
FFTSample ax, ay, bx, by;\
136
#define MUL16(a,b) ((a) * (b))
138
#define CMUL(pre, pim, are, aim, bre, bim) \
140
pre = (MUL16(are, bre) - MUL16(aim, bim));\
141
pim = (MUL16(are, bim) + MUL16(bre, aim));\
145
* Do a complex FFT with the parameters defined in ff_fft_init(). The
146
* input data must be permuted before with s->revtab table. No
147
* 1.0/sqrt(n) normalization is done.
149
void ff_fft_calc_c(FFTContext *s, FFTComplex *z)
154
register FFTComplex *p, *q;
155
FFTComplex *exptab = s->exptab;
157
FFTSample tmp_re, tmp_im;
166
BF(p[0].re, p[0].im, p[1].re, p[1].im,
167
p[0].re, p[0].im, p[1].re, p[1].im);
178
BF(p[0].re, p[0].im, p[2].re, p[2].im,
179
p[0].re, p[0].im, p[2].re, p[2].im);
180
BF(p[1].re, p[1].im, p[3].re, p[3].im,
181
p[1].re, p[1].im, -p[3].im, p[3].re);
186
BF(p[0].re, p[0].im, p[2].re, p[2].im,
187
p[0].re, p[0].im, p[2].re, p[2].im);
188
BF(p[1].re, p[1].im, p[3].re, p[3].im,
189
p[1].re, p[1].im, p[3].im, -p[3].re);
201
for (j = 0; j < nblocks; ++j) {
202
BF(p->re, p->im, q->re, q->im,
203
p->re, p->im, q->re, q->im);
207
for(l = nblocks; l < np2; l += nblocks) {
208
CMUL(tmp_re, tmp_im, exptab[l].re, exptab[l].im, q->re, q->im);
209
BF(p->re, p->im, q->re, q->im,
210
p->re, p->im, tmp_re, tmp_im);
218
nblocks = nblocks >> 1;
219
nloops = nloops << 1;
220
} while (nblocks != 0);
224
* Do the permutation needed BEFORE calling ff_fft_calc()
226
void ff_fft_permute(FFTContext *s, FFTComplex *z)
230
const uint16_t *revtab = s->revtab;
244
void ff_fft_end(FFTContext *s)
246
av_freep(&s->revtab);
247
av_freep(&s->exptab);
248
av_freep(&s->exptab1);