4e32b039e8a754b0b874c2f94009f44e617b59e9
[libav.git] / libavcodec / fft.c
1 /*
2 * FFT/IFFT transforms
3 * Copyright (c) 2008 Loren Merritt
4 * Copyright (c) 2002 Fabrice Bellard.
5 * Partly based on libdjbfft by D. J. Bernstein
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 /**
25 * @file fft.c
26 * FFT/IFFT transforms.
27 */
28
29 #include "dsputil.h"
30
31 /* cos(2*pi*x/n) for 0<=x<=n/4, followed by its reverse */
32 DECLARE_ALIGNED_16(FFTSample, ff_cos_16[8]);
33 DECLARE_ALIGNED_16(FFTSample, ff_cos_32[16]);
34 DECLARE_ALIGNED_16(FFTSample, ff_cos_64[32]);
35 DECLARE_ALIGNED_16(FFTSample, ff_cos_128[64]);
36 DECLARE_ALIGNED_16(FFTSample, ff_cos_256[128]);
37 DECLARE_ALIGNED_16(FFTSample, ff_cos_512[256]);
38 DECLARE_ALIGNED_16(FFTSample, ff_cos_1024[512]);
39 DECLARE_ALIGNED_16(FFTSample, ff_cos_2048[1024]);
40 DECLARE_ALIGNED_16(FFTSample, ff_cos_4096[2048]);
41 DECLARE_ALIGNED_16(FFTSample, ff_cos_8192[4096]);
42 DECLARE_ALIGNED_16(FFTSample, ff_cos_16384[8192]);
43 DECLARE_ALIGNED_16(FFTSample, ff_cos_32768[16384]);
44 DECLARE_ALIGNED_16(FFTSample, ff_cos_65536[32768]);
45 static FFTSample *ff_cos_tabs[] = {
46 ff_cos_16, ff_cos_32, ff_cos_64, ff_cos_128, ff_cos_256, ff_cos_512, ff_cos_1024,
47 ff_cos_2048, ff_cos_4096, ff_cos_8192, ff_cos_16384, ff_cos_32768, ff_cos_65536,
48 };
49
50 static int split_radix_permutation(int i, int n, int inverse)
51 {
52 int m;
53 if(n <= 2) return i&1;
54 m = n >> 1;
55 if(!(i&m)) return split_radix_permutation(i, m, inverse)*2;
56 m >>= 1;
57 if(inverse == !(i&m)) return split_radix_permutation(i, m, inverse)*4 + 1;
58 else return split_radix_permutation(i, m, inverse)*4 - 1;
59 }
60
61 /**
62 * The size of the FFT is 2^nbits. If inverse is TRUE, inverse FFT is
63 * done
64 */
65 int ff_fft_init(FFTContext *s, int nbits, int inverse)
66 {
67 int i, j, m, n;
68 float alpha, c1, s1, s2;
69 int split_radix = 1;
70 int av_unused has_vectors;
71
72 if (nbits < 2 || nbits > 16)
73 goto fail;
74 s->nbits = nbits;
75 n = 1 << nbits;
76
77 s->tmp_buf = NULL;
78 s->exptab = av_malloc((n / 2) * sizeof(FFTComplex));
79 if (!s->exptab)
80 goto fail;
81 s->revtab = av_malloc(n * sizeof(uint16_t));
82 if (!s->revtab)
83 goto fail;
84 s->inverse = inverse;
85
86 s2 = inverse ? 1.0 : -1.0;
87
88 s->fft_permute = ff_fft_permute_c;
89 s->fft_calc = ff_fft_calc_c;
90 s->imdct_calc = ff_imdct_calc_c;
91 s->imdct_half = ff_imdct_half_c;
92 s->exptab1 = NULL;
93
94 #if defined HAVE_MMX && defined HAVE_YASM
95 has_vectors = mm_support();
96 if (has_vectors & MM_SSE) {
97 /* SSE for P3/P4/K8 */
98 s->imdct_calc = ff_imdct_calc_sse;
99 s->imdct_half = ff_imdct_half_sse;
100 s->fft_permute = ff_fft_permute_sse;
101 s->fft_calc = ff_fft_calc_sse;
102 } else if (has_vectors & MM_3DNOWEXT) {
103 /* 3DNowEx for K7 */
104 s->imdct_calc = ff_imdct_calc_3dn2;
105 s->imdct_half = ff_imdct_half_3dn2;
106 s->fft_calc = ff_fft_calc_3dn2;
107 } else if (has_vectors & MM_3DNOW) {
108 /* 3DNow! for K6-2/3 */
109 s->imdct_calc = ff_imdct_calc_3dn;
110 s->imdct_half = ff_imdct_half_3dn;
111 s->fft_calc = ff_fft_calc_3dn;
112 }
113 #elif defined HAVE_ALTIVEC && !defined ALTIVEC_USE_REFERENCE_C_CODE
114 has_vectors = mm_support();
115 if (has_vectors & MM_ALTIVEC) {
116 s->fft_calc = ff_fft_calc_altivec;
117 split_radix = 0;
118 }
119 #endif
120
121 if (split_radix) {
122 for(j=4; j<=nbits; j++) {
123 int m = 1<<j;
124 double freq = 2*M_PI/m;
125 FFTSample *tab = ff_cos_tabs[j-4];
126 for(i=0; i<=m/4; i++)
127 tab[i] = cos(i*freq);
128 for(i=1; i<m/4; i++)
129 tab[m/2-i] = tab[i];
130 }
131 for(i=0; i<n; i++)
132 s->revtab[-split_radix_permutation(i, n, s->inverse) & (n-1)] = i;
133 s->tmp_buf = av_malloc(n * sizeof(FFTComplex));
134 } else {
135 int np, nblocks, np2, l;
136 FFTComplex *q;
137
138 for(i=0; i<(n/2); i++) {
139 alpha = 2 * M_PI * (float)i / (float)n;
140 c1 = cos(alpha);
141 s1 = sin(alpha) * s2;
142 s->exptab[i].re = c1;
143 s->exptab[i].im = s1;
144 }
145
146 np = 1 << nbits;
147 nblocks = np >> 3;
148 np2 = np >> 1;
149 s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
150 if (!s->exptab1)
151 goto fail;
152 q = s->exptab1;
153 do {
154 for(l = 0; l < np2; l += 2 * nblocks) {
155 *q++ = s->exptab[l];
156 *q++ = s->exptab[l + nblocks];
157
158 q->re = -s->exptab[l].im;
159 q->im = s->exptab[l].re;
160 q++;
161 q->re = -s->exptab[l + nblocks].im;
162 q->im = s->exptab[l + nblocks].re;
163 q++;
164 }
165 nblocks = nblocks >> 1;
166 } while (nblocks != 0);
167 av_freep(&s->exptab);
168
169 /* compute bit reverse table */
170 for(i=0;i<n;i++) {
171 m=0;
172 for(j=0;j<nbits;j++) {
173 m |= ((i >> j) & 1) << (nbits-j-1);
174 }
175 s->revtab[i]=m;
176 }
177 }
178
179 return 0;
180 fail:
181 av_freep(&s->revtab);
182 av_freep(&s->exptab);
183 av_freep(&s->exptab1);
184 av_freep(&s->tmp_buf);
185 return -1;
186 }
187
188 /**
189 * Do the permutation needed BEFORE calling ff_fft_calc()
190 */
191 void ff_fft_permute_c(FFTContext *s, FFTComplex *z)
192 {
193 int j, k, np;
194 FFTComplex tmp;
195 const uint16_t *revtab = s->revtab;
196 np = 1 << s->nbits;
197
198 if (s->tmp_buf) {
199 /* TODO: handle split-radix permute in a more optimal way, probably in-place */
200 for(j=0;j<np;j++) s->tmp_buf[revtab[j]] = z[j];
201 memcpy(z, s->tmp_buf, np * sizeof(FFTComplex));
202 return;
203 }
204
205 /* reverse */
206 for(j=0;j<np;j++) {
207 k = revtab[j];
208 if (k < j) {
209 tmp = z[k];
210 z[k] = z[j];
211 z[j] = tmp;
212 }
213 }
214 }
215
216 void ff_fft_end(FFTContext *s)
217 {
218 av_freep(&s->revtab);
219 av_freep(&s->exptab);
220 av_freep(&s->exptab1);
221 av_freep(&s->tmp_buf);
222 }
223
224 #define sqrthalf (float)M_SQRT1_2
225
226 #define BF(x,y,a,b) {\
227 x = a - b;\
228 y = a + b;\
229 }
230
231 #define BUTTERFLIES(a0,a1,a2,a3) {\
232 BF(t3, t5, t5, t1);\
233 BF(a2.re, a0.re, a0.re, t5);\
234 BF(a3.im, a1.im, a1.im, t3);\
235 BF(t4, t6, t2, t6);\
236 BF(a3.re, a1.re, a1.re, t4);\
237 BF(a2.im, a0.im, a0.im, t6);\
238 }
239
240 // force loading all the inputs before storing any.
241 // this is slightly slower for small data, but avoids store->load aliasing
242 // for addresses separated by large powers of 2.
243 #define BUTTERFLIES_BIG(a0,a1,a2,a3) {\
244 FFTSample r0=a0.re, i0=a0.im, r1=a1.re, i1=a1.im;\
245 BF(t3, t5, t5, t1);\
246 BF(a2.re, a0.re, r0, t5);\
247 BF(a3.im, a1.im, i1, t3);\
248 BF(t4, t6, t2, t6);\
249 BF(a3.re, a1.re, r1, t4);\
250 BF(a2.im, a0.im, i0, t6);\
251 }
252
253 #define TRANSFORM(a0,a1,a2,a3,wre,wim) {\
254 t1 = a2.re * wre + a2.im * wim;\
255 t2 = a2.im * wre - a2.re * wim;\
256 t5 = a3.re * wre - a3.im * wim;\
257 t6 = a3.im * wre + a3.re * wim;\
258 BUTTERFLIES(a0,a1,a2,a3)\
259 }
260
261 #define TRANSFORM_ZERO(a0,a1,a2,a3) {\
262 t1 = a2.re;\
263 t2 = a2.im;\
264 t5 = a3.re;\
265 t6 = a3.im;\
266 BUTTERFLIES(a0,a1,a2,a3)\
267 }
268
269 /* z[0...8n-1], w[1...2n-1] */
270 #define PASS(name)\
271 static void name(FFTComplex *z, const FFTSample *wre, unsigned int n)\
272 {\
273 FFTSample t1, t2, t3, t4, t5, t6;\
274 int o1 = 2*n;\
275 int o2 = 4*n;\
276 int o3 = 6*n;\
277 const FFTSample *wim = wre+o1;\
278 n--;\
279 \
280 TRANSFORM_ZERO(z[0],z[o1],z[o2],z[o3]);\
281 TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
282 do {\
283 z += 2;\
284 wre += 2;\
285 wim -= 2;\
286 TRANSFORM(z[0],z[o1],z[o2],z[o3],wre[0],wim[0]);\
287 TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
288 } while(--n);\
289 }
290
291 PASS(pass)
292 #undef BUTTERFLIES
293 #define BUTTERFLIES BUTTERFLIES_BIG
294 PASS(pass_big)
295
296 #define DECL_FFT(n,n2,n4)\
297 static void fft##n(FFTComplex *z)\
298 {\
299 fft##n2(z);\
300 fft##n4(z+n4*2);\
301 fft##n4(z+n4*3);\
302 pass(z,ff_cos_##n,n4/2);\
303 }
304
305 static void fft4(FFTComplex *z)
306 {
307 FFTSample t1, t2, t3, t4, t5, t6, t7, t8;
308
309 BF(t3, t1, z[0].re, z[1].re);
310 BF(t8, t6, z[3].re, z[2].re);
311 BF(z[2].re, z[0].re, t1, t6);
312 BF(t4, t2, z[0].im, z[1].im);
313 BF(t7, t5, z[2].im, z[3].im);
314 BF(z[3].im, z[1].im, t4, t8);
315 BF(z[3].re, z[1].re, t3, t7);
316 BF(z[2].im, z[0].im, t2, t5);
317 }
318
319 static void fft8(FFTComplex *z)
320 {
321 FFTSample t1, t2, t3, t4, t5, t6, t7, t8;
322
323 fft4(z);
324
325 BF(t1, z[5].re, z[4].re, -z[5].re);
326 BF(t2, z[5].im, z[4].im, -z[5].im);
327 BF(t3, z[7].re, z[6].re, -z[7].re);
328 BF(t4, z[7].im, z[6].im, -z[7].im);
329 BF(t8, t1, t3, t1);
330 BF(t7, t2, t2, t4);
331 BF(z[4].re, z[0].re, z[0].re, t1);
332 BF(z[4].im, z[0].im, z[0].im, t2);
333 BF(z[6].re, z[2].re, z[2].re, t7);
334 BF(z[6].im, z[2].im, z[2].im, t8);
335
336 TRANSFORM(z[1],z[3],z[5],z[7],sqrthalf,sqrthalf);
337 }
338
339 #ifndef CONFIG_SMALL
340 static void fft16(FFTComplex *z)
341 {
342 FFTSample t1, t2, t3, t4, t5, t6;
343
344 fft8(z);
345 fft4(z+8);
346 fft4(z+12);
347
348 TRANSFORM_ZERO(z[0],z[4],z[8],z[12]);
349 TRANSFORM(z[2],z[6],z[10],z[14],sqrthalf,sqrthalf);
350 TRANSFORM(z[1],z[5],z[9],z[13],ff_cos_16[1],ff_cos_16[3]);
351 TRANSFORM(z[3],z[7],z[11],z[15],ff_cos_16[3],ff_cos_16[1]);
352 }
353 #else
354 DECL_FFT(16,8,4)
355 #endif
356 DECL_FFT(32,16,8)
357 DECL_FFT(64,32,16)
358 DECL_FFT(128,64,32)
359 DECL_FFT(256,128,64)
360 DECL_FFT(512,256,128)
361 #ifndef CONFIG_SMALL
362 #define pass pass_big
363 #endif
364 DECL_FFT(1024,512,256)
365 DECL_FFT(2048,1024,512)
366 DECL_FFT(4096,2048,1024)
367 DECL_FFT(8192,4096,2048)
368 DECL_FFT(16384,8192,4096)
369 DECL_FFT(32768,16384,8192)
370 DECL_FFT(65536,32768,16384)
371
372 static void (*fft_dispatch[])(FFTComplex*) = {
373 fft4, fft8, fft16, fft32, fft64, fft128, fft256, fft512, fft1024,
374 fft2048, fft4096, fft8192, fft16384, fft32768, fft65536,
375 };
376
377 /**
378 * Do a complex FFT with the parameters defined in ff_fft_init(). The
379 * input data must be permuted before with s->revtab table. No
380 * 1.0/sqrt(n) normalization is done.
381 */
382 void ff_fft_calc_c(FFTContext *s, FFTComplex *z)
383 {
384 fft_dispatch[s->nbits-2](z);
385 }
386