remove unused exptab1 of struct fft_context.
[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 #define DECLARE_ALIGNED(n,t,v) t v __attribute__ ((aligned (n)))
33 #define DECLARE_ALIGNED_16(t, v) DECLARE_ALIGNED(16, t, v)
34 #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */
35
36 struct fft_complex {
37 fftsample_t re, im;
38 };
39
40 struct fft_context {
41 int nbits;
42 int inverse;
43 uint16_t *revtab;
44 struct fft_complex *exptab;
45 struct fft_complex *tmp_buf;
46 };
47
48 struct mdct_context {
49 /** Size of MDCT (i.e. number of input data * 2). */
50 int n;
51 /** n = 2^n bits. */
52 int nbits;
53 /** pre/post rotation tables */
54 fftsample_t *tcos;
55 fftsample_t *tsin;
56 struct fft_context fft;
57 };
58
59 /* cos(2*pi*x/n) for 0<=x<=n/4, followed by its reverse */
60 DECLARE_ALIGNED_16(fftsample_t, ff_cos_16[8]);
61 DECLARE_ALIGNED_16(fftsample_t, ff_cos_32[16]);
62 DECLARE_ALIGNED_16(fftsample_t, ff_cos_64[32]);
63 DECLARE_ALIGNED_16(fftsample_t, ff_cos_128[64]);
64 DECLARE_ALIGNED_16(fftsample_t, ff_cos_256[128]);
65 DECLARE_ALIGNED_16(fftsample_t, ff_cos_512[256]);
66 DECLARE_ALIGNED_16(fftsample_t, ff_cos_1024[512]);
67 DECLARE_ALIGNED_16(fftsample_t, ff_cos_2048[1024]);
68 DECLARE_ALIGNED_16(fftsample_t, ff_cos_4096[2048]);
69 DECLARE_ALIGNED_16(fftsample_t, ff_cos_8192[4096]);
70 DECLARE_ALIGNED_16(fftsample_t, ff_cos_16384[8192]);
71 DECLARE_ALIGNED_16(fftsample_t, ff_cos_32768[16384]);
72 DECLARE_ALIGNED_16(fftsample_t, ff_cos_65536[32768]);
73
74 static fftsample_t *ff_cos_tabs[] = {
75 ff_cos_16, ff_cos_32, ff_cos_64, ff_cos_128, ff_cos_256,
76 ff_cos_512, ff_cos_1024, ff_cos_2048, ff_cos_4096, ff_cos_8192,
77 ff_cos_16384, ff_cos_32768, ff_cos_65536,
78 };
79
80 static int split_radix_permutation(int i, int n, int inverse)
81 {
82 int m;
83 if (n <= 2)
84 return i & 1;
85 m = n >> 1;
86 if (!(i & m))
87 return split_radix_permutation(i, m, inverse) * 2;
88 m >>= 1;
89 if (inverse == !(i & m))
90 return split_radix_permutation(i, m, inverse) * 4 + 1;
91 else
92 return split_radix_permutation(i, m, inverse) * 4 - 1;
93 }
94
95 #define sqrthalf (float)M_SQRT1_2
96
97 #define BF(x,y,a,b) {\
98 x = a - b;\
99 y = a + b;\
100 }
101
102 #define BUTTERFLIES(a0,a1,a2,a3) {\
103 BF(t3, t5, t5, t1);\
104 BF(a2.re, a0.re, a0.re, t5);\
105 BF(a3.im, a1.im, a1.im, t3);\
106 BF(t4, t6, t2, t6);\
107 BF(a3.re, a1.re, a1.re, t4);\
108 BF(a2.im, a0.im, a0.im, t6);\
109 }
110
111 // force loading all the inputs before storing any.
112 // this is slightly slower for small data, but avoids store->load aliasing
113 // for addresses separated by large powers of 2.
114 #define BUTTERFLIES_BIG(a0,a1,a2,a3) {\
115 fftsample_t r0=a0.re, i0=a0.im, r1=a1.re, i1=a1.im;\
116 BF(t3, t5, t5, t1);\
117 BF(a2.re, a0.re, r0, t5);\
118 BF(a3.im, a1.im, i1, t3);\
119 BF(t4, t6, t2, t6);\
120 BF(a3.re, a1.re, r1, t4);\
121 BF(a2.im, a0.im, i0, t6);\
122 }
123
124 #define TRANSFORM(a0,a1,a2,a3,wre,wim) {\
125 t1 = a2.re * wre + a2.im * wim;\
126 t2 = a2.im * wre - a2.re * wim;\
127 t5 = a3.re * wre - a3.im * wim;\
128 t6 = a3.im * wre + a3.re * wim;\
129 BUTTERFLIES(a0,a1,a2,a3)\
130 }
131
132 #define TRANSFORM_ZERO(a0,a1,a2,a3) {\
133 t1 = a2.re;\
134 t2 = a2.im;\
135 t5 = a3.re;\
136 t6 = a3.im;\
137 BUTTERFLIES(a0,a1,a2,a3)\
138 }
139
140 /* z[0...8n-1], w[1...2n-1] */
141 #define PASS(name)\
142 static void name(struct fft_complex *z, const fftsample_t *wre, unsigned int n)\
143 {\
144 fftsample_t t1, t2, t3, t4, t5, t6;\
145 int o1 = 2*n;\
146 int o2 = 4*n;\
147 int o3 = 6*n;\
148 const fftsample_t *wim = wre+o1;\
149 n--;\
150 \
151 TRANSFORM_ZERO(z[0],z[o1],z[o2],z[o3]);\
152 TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
153 do {\
154 z += 2;\
155 wre += 2;\
156 wim -= 2;\
157 TRANSFORM(z[0],z[o1],z[o2],z[o3],wre[0],wim[0]);\
158 TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
159 } while(--n);\
160 }
161
162 PASS(pass)
163 #undef BUTTERFLIES
164 #define BUTTERFLIES BUTTERFLIES_BIG
165
166 #define DECL_FFT(n,n2,n4)\
167 static void fft##n(struct fft_complex *z)\
168 {\
169 fft##n2(z);\
170 fft##n4(z+n4*2);\
171 fft##n4(z+n4*3);\
172 pass(z,ff_cos_##n,n4/2);\
173 }
174 static void fft4(struct fft_complex *z)
175 {
176 fftsample_t t1, t2, t3, t4, t5, t6, t7, t8;
177
178 BF(t3, t1, z[0].re, z[1].re);
179 BF(t8, t6, z[3].re, z[2].re);
180 BF(z[2].re, z[0].re, t1, t6);
181 BF(t4, t2, z[0].im, z[1].im);
182 BF(t7, t5, z[2].im, z[3].im);
183 BF(z[3].im, z[1].im, t4, t8);
184 BF(z[3].re, z[1].re, t3, t7);
185 BF(z[2].im, z[0].im, t2, t5);
186 }
187
188 static void fft8(struct fft_complex *z)
189 {
190 fftsample_t t1, t2, t3, t4, t5, t6, t7, t8;
191
192 fft4(z);
193
194 BF(t1, z[5].re, z[4].re, -z[5].re);
195 BF(t2, z[5].im, z[4].im, -z[5].im);
196 BF(t3, z[7].re, z[6].re, -z[7].re);
197 BF(t4, z[7].im, z[6].im, -z[7].im);
198 BF(t8, t1, t3, t1);
199 BF(t7, t2, t2, t4);
200 BF(z[4].re, z[0].re, z[0].re, t1);
201 BF(z[4].im, z[0].im, z[0].im, t2);
202 BF(z[6].re, z[2].re, z[2].re, t7);
203 BF(z[6].im, z[2].im, z[2].im, t8);
204
205 TRANSFORM(z[1], z[3], z[5], z[7], sqrthalf, sqrthalf);
206 }
207
208 static void fft16(struct fft_complex *z)
209 {
210 fftsample_t t1, t2, t3, t4, t5, t6;
211
212 fft8(z);
213 fft4(z + 8);
214 fft4(z + 12);
215
216 TRANSFORM_ZERO(z[0], z[4], z[8], z[12]);
217 TRANSFORM(z[2], z[6], z[10], z[14], sqrthalf, sqrthalf);
218 TRANSFORM(z[1], z[5], z[9], z[13], ff_cos_16[1], ff_cos_16[3]);
219 TRANSFORM(z[3], z[7], z[11], z[15], ff_cos_16[3], ff_cos_16[1]);
220 }
221
222 DECL_FFT(32, 16, 8)
223 DECL_FFT(64, 32, 16)
224 DECL_FFT(128, 64, 32)
225 DECL_FFT(256, 128, 64)
226 DECL_FFT(512, 256, 128)
227
228 DECL_FFT(1024, 512, 256)
229 DECL_FFT(2048, 1024, 512)
230 DECL_FFT(4096, 2048, 1024)
231 DECL_FFT(8192, 4096, 2048)
232 DECL_FFT(16384, 8192, 4096)
233 DECL_FFT(32768, 16384, 8192)
234 DECL_FFT(65536, 32768, 16384)
235
236 static void (*fft_dispatch[]) (struct fft_complex *) = {
237 fft4, fft8, fft16, fft32, fft64, fft128, fft256, fft512, fft1024,
238 fft2048, fft4096, fft8192, fft16384, fft32768, fft65536,
239 };
240
241 static void fft(struct fft_context *s, struct fft_complex *z)
242 {
243 fft_dispatch[s->nbits - 2] (z);
244 }
245
246 /* complex multiplication: p = a * b */
247 #define CMUL(pre, pim, are, aim, bre, bim) \
248 {\
249 fftsample_t _are = (are);\
250 fftsample_t _aim = (aim);\
251 fftsample_t _bre = (bre);\
252 fftsample_t _bim = (bim);\
253 (pre) = _are * _bre - _aim * _bim;\
254 (pim) = _are * _bim + _aim * _bre;\
255 }
256
257 /**
258 * Compute the middle half of the inverse MDCT of size N = 2^nbits
259 *
260 * Thus excluding the parts that can be derived by symmetry.
261 *
262 * \param output N/2 samples.
263 * \param input N/2 samples.
264 */
265 static void imdct_half(struct mdct_context *s, fftsample_t *output,
266 const fftsample_t *input)
267 {
268 int k, n8, n4, n2, n, j;
269 const uint16_t *revtab = s->fft.revtab;
270 const fftsample_t *tcos = s->tcos;
271 const fftsample_t *tsin = s->tsin;
272 const fftsample_t *in1, *in2;
273 struct fft_complex *z = (struct fft_complex *)output;
274
275 n = 1 << s->nbits;
276 n2 = n >> 1;
277 n4 = n >> 2;
278 n8 = n >> 3;
279
280 /* pre rotation */
281 in1 = input;
282 in2 = input + n2 - 1;
283 for (k = 0; k < n4; k++) {
284 j = revtab[k];
285 CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]);
286 in1 += 2;
287 in2 -= 2;
288 }
289 fft(&s->fft, z);
290
291 /* post rotation + reordering */
292 output += n4;
293 for (k = 0; k < n8; k++) {
294 fftsample_t r0, i0, r1, i1;
295 CMUL(r0, i1, z[n8 - k - 1].im, z[n8 - k - 1].re,
296 tsin[n8 - k - 1], tcos[n8 - k - 1]);
297 CMUL(r1, i0, z[n8 + k].im, z[n8 + k].re, tsin[n8 + k],
298 tcos[n8 + k]);
299 z[n8 - k - 1].re = r0;
300 z[n8 - k - 1].im = i0;
301 z[n8 + k].re = r1;
302 z[n8 + k].im = i1;
303 }
304 }
305
306 /**
307 * Compute the inverse MDCT of size N = 2^nbits.
308 *
309 * \param output N samples.
310 * \param input N/2 samples.
311 */
312 void imdct(struct mdct_context *s, float *output, const float *input)
313 {
314 int k;
315 int n = 1 << s->nbits;
316 int n2 = n >> 1;
317 int n4 = n >> 2;
318
319 imdct_half(s, output + n4, input);
320
321 for (k = 0; k < n4; k++) {
322 output[k] = -output[n2 - k - 1];
323 output[n - k - 1] = output[n2 + k];
324 }
325 }
326
327 static int fft_init(struct fft_context *s, int nbits, int inverse)
328 {
329 int i, j, n;
330
331 if (nbits < 2 || nbits > 16)
332 return -E_FFT_BAD_PARAMS;
333 s->nbits = nbits;
334 n = 1 << nbits;
335
336 s->tmp_buf = NULL;
337 s->exptab = para_malloc((n / 2) * sizeof(struct fft_complex));
338 s->revtab = para_malloc(n * sizeof(uint16_t));
339 s->inverse = inverse;
340
341 for (j = 4; j <= nbits; j++) {
342 int k = 1 << j;
343 double freq = 2 * M_PI / k;
344 fftsample_t *tab = ff_cos_tabs[j - 4];
345 for (i = 0; i <= k / 4; i++)
346 tab[i] = cos(i * freq);
347 for (i = 1; i < k / 4; i++)
348 tab[k / 2 - i] = tab[i];
349 }
350 for (i = 0; i < n; i++)
351 s->revtab[-split_radix_permutation(
352 i, n, s->inverse) & (n - 1)] = i;
353 s->tmp_buf = para_malloc(n * sizeof(struct fft_complex));
354 return 0;
355 }
356
357 static void fft_end(struct fft_context *ctx)
358 {
359 freep(&ctx->revtab);
360 freep(&ctx->exptab);
361 freep(&ctx->tmp_buf);
362 }
363
364 DECLARE_ALIGNED(16, float, ff_sine_128[128]);
365 DECLARE_ALIGNED(16, float, ff_sine_256[256]);
366 DECLARE_ALIGNED(16, float, ff_sine_512[512]);
367 DECLARE_ALIGNED(16, float, ff_sine_1024[1024]);
368 DECLARE_ALIGNED(16, float, ff_sine_2048[2048]);
369 DECLARE_ALIGNED(16, float, ff_sine_4096[4096]);
370
371 float *ff_sine_windows[6] = {
372 ff_sine_128, ff_sine_256, ff_sine_512, ff_sine_1024,
373 ff_sine_2048, ff_sine_4096
374 };
375
376 // Generate a sine window.
377 void sine_window_init(float *window, int n)
378 {
379 int i;
380
381 for (i = 0; i < n; i++)
382 window[i] = sinf((i + 0.5) * (M_PI / (2.0 * n)));
383 }
384
385 /**
386 * Init MDCT or IMDCT computation.
387 */
388 int imdct_init(int nbits, int inverse, struct mdct_context **result)
389 {
390 int ret, n, n4, i;
391 double alpha;
392 struct mdct_context *s;
393
394 s = para_calloc(sizeof(*s));
395 n = 1 << nbits;
396 s->nbits = nbits;
397 s->n = n;
398 n4 = n >> 2;
399 s->tcos = para_malloc(n4 * sizeof(fftsample_t));
400 s->tsin = para_malloc(n4 * sizeof(fftsample_t));
401
402 for (i = 0; i < n4; i++) {
403 alpha = 2 * M_PI * (i + 1.0 / 8.0) / n;
404 s->tcos[i] = -cos(alpha);
405 s->tsin[i] = -sin(alpha);
406 }
407 ret = fft_init(&s->fft, s->nbits - 2, inverse);
408 if (ret < 0)
409 goto fail;
410 *result = s;
411 return 0;
412 fail:
413 freep(&s->tcos);
414 freep(&s->tsin);
415 free(s);
416 return ret;
417 }
418
419 void imdct_end(struct mdct_context *ctx)
420 {
421 freep(&ctx->tcos);
422 freep(&ctx->tsin);
423 fft_end(&ctx->fft);
424 free(ctx);
425 }