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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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);