3 * Copyright (c) 2002 Fabrice Bellard.
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * FFT/IFFT transforms.
30 * The size of the FFT is 2^nbits. If inverse is TRUE, inverse FFT is
33 int ff_fft_init(FFTContext *s, int nbits, int inverse)
36 float alpha, c1, s1, s2;
38 int av_unused has_vectors;
43 s->exptab = av_malloc((n / 2) * sizeof(FFTComplex));
46 s->revtab = av_malloc(n * sizeof(uint16_t));
51 s2 = inverse ? 1.0 : -1.0;
53 for(i=0;i<(n/2);i++) {
54 alpha = 2 * M_PI * (float)i / (float)n;
60 s->fft_calc = ff_fft_calc_c;
61 s->imdct_calc = ff_imdct_calc;
65 has_vectors = mm_support();
67 if (has_vectors & MM_3DNOWEXT) {
68 /* 3DNowEx for K7/K8 */
69 s->imdct_calc = ff_imdct_calc_3dn2;
70 s->fft_calc = ff_fft_calc_3dn2;
71 } else if (has_vectors & MM_3DNOW) {
72 /* 3DNow! for K6-2/3 */
73 s->fft_calc = ff_fft_calc_3dn;
74 } else if (has_vectors & MM_SSE) {
76 s->imdct_calc = ff_imdct_calc_sse;
77 s->fft_calc = ff_fft_calc_sse;
81 #elif defined HAVE_ALTIVEC && !defined ALTIVEC_USE_REFERENCE_C_CODE
82 has_vectors = mm_support();
83 if (has_vectors & MM_ALTIVEC) {
84 s->fft_calc = ff_fft_calc_altivec;
89 /* compute constant table for HAVE_SSE version */
91 int np, nblocks, np2, l;
97 s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
102 for(l = 0; l < np2; l += 2 * nblocks) {
104 *q++ = s->exptab[l + nblocks];
106 q->re = -s->exptab[l].im;
107 q->im = s->exptab[l].re;
109 q->re = -s->exptab[l + nblocks].im;
110 q->im = s->exptab[l + nblocks].re;
113 nblocks = nblocks >> 1;
114 } while (nblocks != 0);
115 av_freep(&s->exptab);
118 /* compute bit reverse table */
122 for(j=0;j<nbits;j++) {
123 m |= ((i >> j) & 1) << (nbits-j-1);
129 av_freep(&s->revtab);
130 av_freep(&s->exptab);
131 av_freep(&s->exptab1);
136 #define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
138 FFTSample ax, ay, bx, by;\
149 #define MUL16(a,b) ((a) * (b))
151 #define CMUL(pre, pim, are, aim, bre, bim) \
153 pre = (MUL16(are, bre) - MUL16(aim, bim));\
154 pim = (MUL16(are, bim) + MUL16(bre, aim));\
158 * Do a complex FFT with the parameters defined in ff_fft_init(). The
159 * input data must be permuted before with s->revtab table. No
160 * 1.0/sqrt(n) normalization is done.
162 void ff_fft_calc_c(FFTContext *s, FFTComplex *z)
167 register FFTComplex *p, *q;
168 FFTComplex *exptab = s->exptab;
170 FFTSample tmp_re, tmp_im;
179 BF(p[0].re, p[0].im, p[1].re, p[1].im,
180 p[0].re, p[0].im, p[1].re, p[1].im);
191 BF(p[0].re, p[0].im, p[2].re, p[2].im,
192 p[0].re, p[0].im, p[2].re, p[2].im);
193 BF(p[1].re, p[1].im, p[3].re, p[3].im,
194 p[1].re, p[1].im, -p[3].im, p[3].re);
199 BF(p[0].re, p[0].im, p[2].re, p[2].im,
200 p[0].re, p[0].im, p[2].re, p[2].im);
201 BF(p[1].re, p[1].im, p[3].re, p[3].im,
202 p[1].re, p[1].im, p[3].im, -p[3].re);
214 for (j = 0; j < nblocks; ++j) {
215 BF(p->re, p->im, q->re, q->im,
216 p->re, p->im, q->re, q->im);
220 for(l = nblocks; l < np2; l += nblocks) {
221 CMUL(tmp_re, tmp_im, exptab[l].re, exptab[l].im, q->re, q->im);
222 BF(p->re, p->im, q->re, q->im,
223 p->re, p->im, tmp_re, tmp_im);
231 nblocks = nblocks >> 1;
232 nloops = nloops << 1;
233 } while (nblocks != 0);
237 * Do the permutation needed BEFORE calling ff_fft_calc()
239 void ff_fft_permute(FFTContext *s, FFTComplex *z)
243 const uint16_t *revtab = s->revtab;
257 void ff_fft_end(FFTContext *s)
259 av_freep(&s->revtab);
260 av_freep(&s->exptab);
261 av_freep(&s->exptab1);