a981eeb99fe6d2e23f5a04af40881fdb18190b21
[paraslash.git] / imdct.c
1 /*
2 * FFT/IFFT transforms.
3 *
4 * Extracted 2009 from mplayer 2009-02-10 libavcodec/fft.c and libavcodec/mdct.c
5 *
6 * Copyright (c) 2008 Loren Merritt
7 * Copyright (c) 2002 Fabrice Bellard
8 * Partly based on libdjbfft by D. J. Bernstein
9 *
10 * Licensed under the GNU Lesser General Public License.
11 * For licencing details see COPYING.LIB.
12 */
13
14 /**
15 * \file imdct.c Inverse modified discrete cosine transform.
16 */
17
18 #include <inttypes.h>
19 #include <math.h>
20 #include <string.h>
21 #include <stdlib.h>
22 #include <regex.h>
23
24 #include "para.h"
25 #include "error.h"
26 #include "string.h"
27 #include "imdct.h"
28 #include "wma.h"
29
30 typedef float fftsample_t;
31
32 struct fft_complex {
33 fftsample_t re, im;
34 };
35
36 struct fft_context {
37 int nbits;
38 int inverse;
39 uint16_t *revtab;
40 struct fft_complex *exptab;
41 };
42
43 struct mdct_context {
44 /** Size of MDCT (i.e. number of input data * 2). */
45 int n;
46 /** n = 2^n bits. */
47 int nbits;
48 /** pre/post rotation tables */
49 fftsample_t *tcos;
50 fftsample_t *tsin;
51 struct fft_context fft;
52 };
53
54 /* cos(2*pi*x/n) for 0<=x<=n/4, followed by its reverse */
55 DECLARE_ALIGNED_16(fftsample_t, ff_cos_16[8]);
56 DECLARE_ALIGNED_16(fftsample_t, ff_cos_32[16]);
57 DECLARE_ALIGNED_16(fftsample_t, ff_cos_64[32]);
58 DECLARE_ALIGNED_16(fftsample_t, ff_cos_128[64]);
59 DECLARE_ALIGNED_16(fftsample_t, ff_cos_256[128]);
60 DECLARE_ALIGNED_16(fftsample_t, ff_cos_512[256]);
61 DECLARE_ALIGNED_16(fftsample_t, ff_cos_1024[512]);
62 DECLARE_ALIGNED_16(fftsample_t, ff_cos_2048[1024]);
63 DECLARE_ALIGNED_16(fftsample_t, ff_cos_4096[2048]);
64 DECLARE_ALIGNED_16(fftsample_t, ff_cos_8192[4096]);
65 DECLARE_ALIGNED_16(fftsample_t, ff_cos_16384[8192]);
66 DECLARE_ALIGNED_16(fftsample_t, ff_cos_32768[16384]);
67 DECLARE_ALIGNED_16(fftsample_t, ff_cos_65536[32768]);
68
69 static fftsample_t *ff_cos_tabs[] = {
70 ff_cos_16, ff_cos_32, ff_cos_64, ff_cos_128, ff_cos_256,
71 ff_cos_512, ff_cos_1024, ff_cos_2048, ff_cos_4096, ff_cos_8192,
72 ff_cos_16384, ff_cos_32768, ff_cos_65536,
73 };
74
75 static int split_radix_permutation(int i, int n, int inverse)
76 {
77 int m;
78 if (n <= 2)
79 return i & 1;
80 m = n >> 1;
81 if (!(i & m))
82 return split_radix_permutation(i, m, inverse) * 2;
83 m >>= 1;
84 if (inverse == !(i & m))
85 return split_radix_permutation(i, m, inverse) * 4 + 1;
86 else
87 return split_radix_permutation(i, m, inverse) * 4 - 1;
88 }
89
90 #define SQRTHALF (float)0.70710678118654752440 /* 1/sqrt(2) */
91
92 #define BF(x,y,a,b) {\
93 x = a - b;\
94 y = a + b;\
95 }
96
97 #define BUTTERFLIES(a0,a1,a2,a3) {\
98 BF(t3, t5, t5, t1);\
99 BF(a2.re, a0.re, a0.re, t5);\
100 BF(a3.im, a1.im, a1.im, t3);\
101 BF(t4, t6, t2, t6);\
102 BF(a3.re, a1.re, a1.re, t4);\
103 BF(a2.im, a0.im, a0.im, t6);\
104 }
105
106 // force loading all the inputs before storing any.
107 // this is slightly slower for small data, but avoids store->load aliasing
108 // for addresses separated by large powers of 2.
109 #define BUTTERFLIES_BIG(a0,a1,a2,a3) {\
110 fftsample_t r0=a0.re, i0=a0.im, r1=a1.re, i1=a1.im;\
111 BF(t3, t5, t5, t1);\
112 BF(a2.re, a0.re, r0, t5);\
113 BF(a3.im, a1.im, i1, t3);\
114 BF(t4, t6, t2, t6);\
115 BF(a3.re, a1.re, r1, t4);\
116 BF(a2.im, a0.im, i0, t6);\
117 }
118
119 #define TRANSFORM(a0,a1,a2,a3,wre,wim) {\
120 t1 = a2.re * wre + a2.im * wim;\
121 t2 = a2.im * wre - a2.re * wim;\
122 t5 = a3.re * wre - a3.im * wim;\
123 t6 = a3.im * wre + a3.re * wim;\
124 BUTTERFLIES(a0,a1,a2,a3)\
125 }
126
127 #define TRANSFORM_ZERO(a0,a1,a2,a3) {\
128 t1 = a2.re;\
129 t2 = a2.im;\
130 t5 = a3.re;\
131 t6 = a3.im;\
132 BUTTERFLIES(a0,a1,a2,a3)\
133 }
134
135 /* z[0...8n-1], w[1...2n-1] */
136 #define PASS(name)\
137 static void name(struct fft_complex *z, const fftsample_t *wre, unsigned int n)\
138 {\
139 fftsample_t t1, t2, t3, t4, t5, t6;\
140 int o1 = 2*n;\
141 int o2 = 4*n;\
142 int o3 = 6*n;\
143 const fftsample_t *wim = wre+o1;\
144 n--;\
145 \
146 TRANSFORM_ZERO(z[0],z[o1],z[o2],z[o3]);\
147 TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
148 do {\
149 z += 2;\
150 wre += 2;\
151 wim -= 2;\
152 TRANSFORM(z[0],z[o1],z[o2],z[o3],wre[0],wim[0]);\
153 TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
154 } while(--n);\
155 }
156
157 PASS(pass)
158 #undef BUTTERFLIES
159 #define BUTTERFLIES BUTTERFLIES_BIG
160
161 #define DECL_FFT(n,n2,n4)\
162 static void fft##n(struct fft_complex *z)\
163 {\
164 fft##n2(z);\
165 fft##n4(z+n4*2);\
166 fft##n4(z+n4*3);\
167 pass(z,ff_cos_##n,n4/2);\
168 }
169 static void fft4(struct fft_complex *z)
170 {
171 fftsample_t t1, t2, t3, t4, t5, t6, t7, t8;
172
173 BF(t3, t1, z[0].re, z[1].re);
174 BF(t8, t6, z[3].re, z[2].re);
175 BF(z[2].re, z[0].re, t1, t6);
176 BF(t4, t2, z[0].im, z[1].im);
177 BF(t7, t5, z[2].im, z[3].im);
178 BF(z[3].im, z[1].im, t4, t8);
179 BF(z[3].re, z[1].re, t3, t7);
180 BF(z[2].im, z[0].im, t2, t5);
181 }
182
183 static void fft8(struct fft_complex *z)
184 {
185 fftsample_t t1, t2, t3, t4, t5, t6, t7, t8;
186
187 fft4(z);
188
189 BF(t1, z[5].re, z[4].re, -z[5].re);
190 BF(t2, z[5].im, z[4].im, -z[5].im);
191 BF(t3, z[7].re, z[6].re, -z[7].re);
192 BF(t4, z[7].im, z[6].im, -z[7].im);
193 BF(t8, t1, t3, t1);
194 BF(t7, t2, t2, t4);
195 BF(z[4].re, z[0].re, z[0].re, t1);
196 BF(z[4].im, z[0].im, z[0].im, t2);
197 BF(z[6].re, z[2].re, z[2].re, t7);
198 BF(z[6].im, z[2].im, z[2].im, t8);
199
200 TRANSFORM(z[1], z[3], z[5], z[7], SQRTHALF, SQRTHALF);
201 }
202
203 static void fft16(struct fft_complex *z)
204 {
205 fftsample_t t1, t2, t3, t4, t5, t6;
206
207 fft8(z);
208 fft4(z + 8);
209 fft4(z + 12);
210
211 TRANSFORM_ZERO(z[0], z[4], z[8], z[12]);
212 TRANSFORM(z[2], z[6], z[10], z[14], SQRTHALF, SQRTHALF);
213 TRANSFORM(z[1], z[5], z[9], z[13], ff_cos_16[1], ff_cos_16[3]);
214 TRANSFORM(z[3], z[7], z[11], z[15], ff_cos_16[3], ff_cos_16[1]);
215 }
216
217 DECL_FFT(32, 16, 8)
218 DECL_FFT(64, 32, 16)
219 DECL_FFT(128, 64, 32)
220 DECL_FFT(256, 128, 64)
221 DECL_FFT(512, 256, 128)
222
223 DECL_FFT(1024, 512, 256)
224 DECL_FFT(2048, 1024, 512)
225 DECL_FFT(4096, 2048, 1024)
226 DECL_FFT(8192, 4096, 2048)
227 DECL_FFT(16384, 8192, 4096)
228 DECL_FFT(32768, 16384, 8192)
229 DECL_FFT(65536, 32768, 16384)
230
231 static void (*fft_dispatch[]) (struct fft_complex *) = {
232 fft4, fft8, fft16, fft32, fft64, fft128, fft256, fft512, fft1024,
233 fft2048, fft4096, fft8192, fft16384, fft32768, fft65536,
234 };
235
236 static void fft(struct fft_context *s, struct fft_complex *z)
237 {
238 fft_dispatch[s->nbits - 2] (z);
239 }
240
241 /* complex multiplication: p = a * b */
242 #define CMUL(pre, pim, are, aim, bre, bim) \
243 {\
244 fftsample_t _are = (are);\
245 fftsample_t _aim = (aim);\
246 fftsample_t _bre = (bre);\
247 fftsample_t _bim = (bim);\
248 (pre) = _are * _bre - _aim * _bim;\
249 (pim) = _are * _bim + _aim * _bre;\
250 }
251
252 /**
253 * Compute the middle half of the inverse MDCT of size N = 2^nbits
254 *
255 * Thus excluding the parts that can be derived by symmetry.
256 *
257 * \param output N/2 samples.
258 * \param input N/2 samples.
259 */
260 static void imdct_half(struct mdct_context *s, fftsample_t *output,
261 const fftsample_t *input)
262 {
263 int k, n8, n4, n2, n, j;
264 const uint16_t *revtab = s->fft.revtab;
265 const fftsample_t *tcos = s->tcos;
266 const fftsample_t *tsin = s->tsin;
267 const fftsample_t *in1, *in2;
268 struct fft_complex *z = (struct fft_complex *)output;
269
270 n = 1 << s->nbits;
271 n2 = n >> 1;
272 n4 = n >> 2;
273 n8 = n >> 3;
274
275 /* pre rotation */
276 in1 = input;
277 in2 = input + n2 - 1;
278 for (k = 0; k < n4; k++) {
279 j = revtab[k];
280 CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]);
281 in1 += 2;
282 in2 -= 2;
283 }
284 fft(&s->fft, z);
285
286 /* post rotation + reordering */
287 output += n4;
288 for (k = 0; k < n8; k++) {
289 fftsample_t r0, i0, r1, i1;
290 CMUL(r0, i1, z[n8 - k - 1].im, z[n8 - k - 1].re,
291 tsin[n8 - k - 1], tcos[n8 - k - 1]);
292 CMUL(r1, i0, z[n8 + k].im, z[n8 + k].re, tsin[n8 + k],
293 tcos[n8 + k]);
294 z[n8 - k - 1].re = r0;
295 z[n8 - k - 1].im = i0;
296 z[n8 + k].re = r1;
297 z[n8 + k].im = i1;
298 }
299 }
300
301 /**
302 * Compute the inverse MDCT of size N = 2^nbits.
303 *
304 * \param output N samples.
305 * \param input N/2 samples.
306 */
307 void imdct(struct mdct_context *s, float *output, const float *input)
308 {
309 int k;
310 int n = 1 << s->nbits;
311 int n2 = n >> 1;
312 int n4 = n >> 2;
313
314 imdct_half(s, output + n4, input);
315
316 for (k = 0; k < n4; k++) {
317 output[k] = -output[n2 - k - 1];
318 output[n - k - 1] = output[n2 + k];
319 }
320 }
321
322 static int fft_init(struct fft_context *s, int nbits, int inverse)
323 {
324 int i, j, n;
325
326 if (nbits < 2 || nbits > 16)
327 return -E_FFT_BAD_PARAMS;
328 s->nbits = nbits;
329 n = 1 << nbits;
330
331 s->exptab = para_malloc((n / 2) * sizeof(struct fft_complex));
332 s->revtab = para_malloc(n * sizeof(uint16_t));
333 s->inverse = inverse;
334 for (j = 4; j <= nbits; j++) {
335 int k = 1 << j;
336 double freq = 2 * M_PI / k;
337 fftsample_t *tab = ff_cos_tabs[j - 4];
338 for (i = 0; i <= k / 4; i++)
339 tab[i] = cos(i * freq);
340 for (i = 1; i < k / 4; i++)
341 tab[k / 2 - i] = tab[i];
342 }
343 for (i = 0; i < n; i++)
344 s->revtab[-split_radix_permutation(
345 i, n, s->inverse) & (n - 1)] = i;
346 return 0;
347 }
348
349 static void fft_end(struct fft_context *ctx)
350 {
351 freep(&ctx->revtab);
352 freep(&ctx->exptab);
353 }
354
355 /**
356 * Init MDCT or IMDCT computation.
357 */
358 int imdct_init(int nbits, int inverse, struct mdct_context **result)
359 {
360 int ret, n, n4, i;
361 double alpha;
362 struct mdct_context *s;
363
364 s = para_calloc(sizeof(*s));
365 n = 1 << nbits;
366 s->nbits = nbits;
367 s->n = n;
368 n4 = n >> 2;
369 s->tcos = para_malloc(n4 * sizeof(fftsample_t));
370 s->tsin = para_malloc(n4 * sizeof(fftsample_t));
371
372 for (i = 0; i < n4; i++) {
373 alpha = 2 * M_PI * (i + 1.0 / 8.0) / n;
374 s->tcos[i] = -cos(alpha);
375 s->tsin[i] = -sin(alpha);
376 }
377 ret = fft_init(&s->fft, s->nbits - 2, inverse);
378 if (ret < 0)
379 goto fail;
380 *result = s;
381 return 0;
382 fail:
383 freep(&s->tcos);
384 freep(&s->tsin);
385 free(s);
386 return ret;
387 }
388
389 void imdct_end(struct mdct_context *ctx)
390 {
391 freep(&ctx->tcos);
392 freep(&ctx->tsin);
393 fft_end(&ctx->fft);
394 free(ctx);
395 }