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;
62 s->imdct_half = ff_imdct_half;
66 has_vectors = mm_support();
68 if (has_vectors & MM_3DNOWEXT) {
69 /* 3DNowEx for K7/K8 */
70 s->imdct_calc = ff_imdct_calc_3dn2;
71 s->imdct_half = ff_imdct_half_3dn2;
72 s->fft_calc = ff_fft_calc_3dn2;
73 } else if (has_vectors & MM_3DNOW) {
74 /* 3DNow! for K6-2/3 */
75 s->fft_calc = ff_fft_calc_3dn;
76 } else if (has_vectors & MM_SSE) {
78 s->imdct_calc = ff_imdct_calc_sse;
79 s->imdct_half = ff_imdct_half_sse;
80 s->fft_calc = ff_fft_calc_sse;
84 #elif defined HAVE_ALTIVEC && !defined ALTIVEC_USE_REFERENCE_C_CODE
85 has_vectors = mm_support();
86 if (has_vectors & MM_ALTIVEC) {
87 s->fft_calc = ff_fft_calc_altivec;
92 /* compute constant table for HAVE_SSE version */
94 int np, nblocks, np2, l;
100 s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
105 for(l = 0; l < np2; l += 2 * nblocks) {
107 *q++ = s->exptab[l + nblocks];
109 q->re = -s->exptab[l].im;
110 q->im = s->exptab[l].re;
112 q->re = -s->exptab[l + nblocks].im;
113 q->im = s->exptab[l + nblocks].re;
116 nblocks = nblocks >> 1;
117 } while (nblocks != 0);
118 av_freep(&s->exptab);
121 /* compute bit reverse table */
125 for(j=0;j<nbits;j++) {
126 m |= ((i >> j) & 1) << (nbits-j-1);
132 av_freep(&s->revtab);
133 av_freep(&s->exptab);
134 av_freep(&s->exptab1);
139 #define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
141 FFTSample ax, ay, bx, by;\
152 #define MUL16(a,b) ((a) * (b))
154 #define CMUL(pre, pim, are, aim, bre, bim) \
156 pre = (MUL16(are, bre) - MUL16(aim, bim));\
157 pim = (MUL16(are, bim) + MUL16(bre, aim));\
161 * Do a complex FFT with the parameters defined in ff_fft_init(). The
162 * input data must be permuted before with s->revtab table. No
163 * 1.0/sqrt(n) normalization is done.
165 void ff_fft_calc_c(FFTContext *s, FFTComplex *z)
170 register FFTComplex *p, *q;
171 FFTComplex *exptab = s->exptab;
173 FFTSample tmp_re, tmp_im;
182 BF(p[0].re, p[0].im, p[1].re, p[1].im,
183 p[0].re, p[0].im, p[1].re, p[1].im);
194 BF(p[0].re, p[0].im, p[2].re, p[2].im,
195 p[0].re, p[0].im, p[2].re, p[2].im);
196 BF(p[1].re, p[1].im, p[3].re, p[3].im,
197 p[1].re, p[1].im, -p[3].im, p[3].re);
202 BF(p[0].re, p[0].im, p[2].re, p[2].im,
203 p[0].re, p[0].im, p[2].re, p[2].im);
204 BF(p[1].re, p[1].im, p[3].re, p[3].im,
205 p[1].re, p[1].im, p[3].im, -p[3].re);
217 for (j = 0; j < nblocks; ++j) {
218 BF(p->re, p->im, q->re, q->im,
219 p->re, p->im, q->re, q->im);
223 for(l = nblocks; l < np2; l += nblocks) {
224 CMUL(tmp_re, tmp_im, exptab[l].re, exptab[l].im, q->re, q->im);
225 BF(p->re, p->im, q->re, q->im,
226 p->re, p->im, tmp_re, tmp_im);
234 nblocks = nblocks >> 1;
235 nloops = nloops << 1;
236 } while (nblocks != 0);
240 * Do the permutation needed BEFORE calling ff_fft_calc()
242 void ff_fft_permute(FFTContext *s, FFTComplex *z)
246 const uint16_t *revtab = s->revtab;
260 void ff_fft_end(FFTContext *s)
262 av_freep(&s->revtab);
263 av_freep(&s->exptab);
264 av_freep(&s->exptab1);