aft: Avoid implicit fallthrough in switch statement.
[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, see file COPYING.LIB.
11 */
12
13 /**
14 * \file imdct.c Inverse modified discrete cosine transform.
15 */
16
17 #include <math.h>
18 #include <regex.h>
19
20 #include "para.h"
21 #include "error.h"
22 #include "string.h"
23 #include "imdct.h"
24 #include "wma.h"
25
26 typedef float fftsample_t;
27
28 /** Canonical representation of a complex number. */
29 struct fft_complex {
30 /** Real part. */
31 fftsample_t re;
32 /** Imaginary part. */
33 fftsample_t im;
34 };
35
36 /** FFT Lookup table. */
37 struct fft_context {
38 /** Number of bits of this instance of the FFT. */
39 int nbits;
40 /** The lookup table for cosine values. */
41 uint16_t *revtab;
42 };
43
44 struct mdct_context {
45 /** Size of MDCT (number of input data * 2). */
46 int n;
47 /** n = 2^n bits. */
48 int nbits;
49 /** Cosine table for pre/post rotation. */
50 fftsample_t *tcos;
51 /** Sine table for pre/post rotation. */
52 fftsample_t *tsin;
53 /** The context for the underlying fast Fourier transform. */
54 struct fft_context fft;
55 };
56
57 /** \cond cosine_tabs */
58
59 /* cos(2 * pi * x / n) for 0 <= x <= n / 4, followed by its reverse */
60 #define COSINE_TAB(n) static fftsample_t cos_ ## n[n / 2] __a_aligned(16)
61
62 COSINE_TAB(16);
63 COSINE_TAB(32);
64 COSINE_TAB(64);
65 COSINE_TAB(128);
66 COSINE_TAB(256);
67 COSINE_TAB(512);
68 COSINE_TAB(1024);
69 COSINE_TAB(2048);
70 COSINE_TAB(4096);
71 COSINE_TAB(8192);
72 COSINE_TAB(16384);
73 COSINE_TAB(32768);
74 COSINE_TAB(65536);
75
76 static fftsample_t *cos_tabs[] = {
77 cos_16, cos_32, cos_64, cos_128, cos_256, cos_512, cos_1024, cos_2048,
78 cos_4096, cos_8192, cos_16384, cos_32768, cos_65536,
79 };
80 /** \endcond cosine_tabs */
81
82 __a_const static int split_radix_permutation(int i, int n)
83 {
84 int m;
85 if (n <= 2)
86 return i & 1;
87 m = n >> 1;
88 if ((i & m) == 0)
89 return split_radix_permutation(i, m) * 2;
90 m >>= 1;
91 if ((i & m) == 0)
92 return split_radix_permutation(i, m) * 4 + 1;
93 else
94 return split_radix_permutation(i, m) * 4 - 1;
95 }
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 /*
112 * Force loading all the inputs before storing any. This is slightly slower for
113 * small data, but avoids store->load aliasing for addresses separated by large
114 * powers of 2.
115 */
116 #define BUTTERFLIES_BIG(a0, a1, a2, a3) {\
117 fftsample_t r0 = a0.re, i0 = a0.im, r1 = a1.re, i1 = a1.im;\
118 BF(t3, t5, t5, t1);\
119 BF(a2.re, a0.re, r0, t5);\
120 BF(a3.im, a1.im, i1, t3);\
121 BF(t4, t6, t2, t6);\
122 BF(a3.re, a1.re, r1, t4);\
123 BF(a2.im, a0.im, i0, t6);\
124 }
125
126 #define TRANSFORM(a0, a1, a2, a3, wre,wim) {\
127 t1 = a2.re * wre + a2.im * wim;\
128 t2 = a2.im * wre - a2.re * wim;\
129 t5 = a3.re * wre - a3.im * wim;\
130 t6 = a3.im * wre + a3.re * wim;\
131 BUTTERFLIES(a0, a1, a2, a3)\
132 }
133
134 #define TRANSFORM_ZERO(a0, a1, a2, a3) {\
135 t1 = a2.re;\
136 t2 = a2.im;\
137 t5 = a3.re;\
138 t6 = a3.im;\
139 BUTTERFLIES(a0, a1, a2, a3)\
140 }
141
142 /* z[0...8n - 1], w[1...2n - 1] */
143 static void pass(struct fft_complex *z, const fftsample_t *wre, unsigned int n)
144 {
145 fftsample_t t1, t2, t3, t4, t5, t6;
146 int o1 = 2 * n;
147 int o2 = 4 * n;
148 int o3 = 6 * n;
149 const fftsample_t *wim = wre + o1;
150
151 n--;
152 TRANSFORM_ZERO(z[0], z[o1], z[o2], z[o3]);
153 TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]);
154 do {
155 z += 2;
156 wre += 2;
157 wim -= 2;
158 TRANSFORM(z[0], z[o1], z[o2], z[o3], wre[0], wim[0]);
159 TRANSFORM(z[1], z[o1 + 1], z[o2 + 1], z[o3 + 1], wre[1], wim[-1]);
160 } while (--n);
161 }
162
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, cos_ ## n, n4 / 2);\
173 }
174
175 static void fft4(struct fft_complex *z)
176 {
177 fftsample_t t1, t2, t3, t4, t5, t6, t7, t8;
178
179 BF(t3, t1, z[0].re, z[1].re);
180 BF(t8, t6, z[3].re, z[2].re);
181 BF(z[2].re, z[0].re, t1, t6);
182 BF(t4, t2, z[0].im, z[1].im);
183 BF(t7, t5, z[2].im, z[3].im);
184 BF(z[3].im, z[1].im, t4, t8);
185 BF(z[3].re, z[1].re, t3, t7);
186 BF(z[2].im, z[0].im, t2, t5);
187 }
188
189 static void fft8(struct fft_complex *z)
190 {
191 fftsample_t t1, t2, t3, t4, t5, t6, t7, t8;
192
193 fft4(z);
194
195 BF(t1, z[5].re, z[4].re, -z[5].re);
196 BF(t2, z[5].im, z[4].im, -z[5].im);
197 BF(t3, z[7].re, z[6].re, -z[7].re);
198 BF(t4, z[7].im, z[6].im, -z[7].im);
199 BF(t8, t1, t3, t1);
200 BF(t7, t2, t2, t4);
201 BF(z[4].re, z[0].re, z[0].re, t1);
202 BF(z[4].im, z[0].im, z[0].im, t2);
203 BF(z[6].re, z[2].re, z[2].re, t7);
204 BF(z[6].im, z[2].im, z[2].im, t8);
205
206 TRANSFORM(z[1], z[3], z[5], z[7], M_SQRT1_2, M_SQRT1_2);
207 }
208
209 static void fft16(struct fft_complex *z)
210 {
211 fftsample_t t1, t2, t3, t4, t5, t6;
212
213 fft8(z);
214 fft4(z + 8);
215 fft4(z + 12);
216
217 TRANSFORM_ZERO(z[0], z[4], z[8], z[12]);
218 TRANSFORM(z[2], z[6], z[10], z[14], M_SQRT1_2, M_SQRT1_2);
219 TRANSFORM(z[1], z[5], z[9], z[13], cos_16[1], cos_16[3]);
220 TRANSFORM(z[3], z[7], z[11], z[15], cos_16[3], cos_16[1]);
221 }
222
223 DECL_FFT(32, 16, 8)
224 DECL_FFT(64, 32, 16)
225 DECL_FFT(128, 64, 32)
226 DECL_FFT(256, 128, 64)
227 DECL_FFT(512, 256, 128)
228
229 DECL_FFT(1024, 512, 256)
230 DECL_FFT(2048, 1024, 512)
231 DECL_FFT(4096, 2048, 1024)
232 DECL_FFT(8192, 4096, 2048)
233 DECL_FFT(16384, 8192, 4096)
234 DECL_FFT(32768, 16384, 8192)
235 DECL_FFT(65536, 32768, 16384)
236
237 static void (*fft_dispatch[]) (struct fft_complex *) = {
238 fft4, fft8, fft16, fft32, fft64, fft128, fft256, fft512, fft1024,
239 fft2048, fft4096, fft8192, fft16384, fft32768, fft65536,
240 };
241
242 static void fft(struct fft_context *s, struct fft_complex *z)
243 {
244 fft_dispatch[s->nbits - 2] (z);
245 }
246
247 /* complex multiplication: p = a * b */
248 #define CMUL(pre, pim, are, aim, bre, bim) \
249 {\
250 fftsample_t _are = (are);\
251 fftsample_t _aim = (aim);\
252 fftsample_t _bre = (bre);\
253 fftsample_t _bim = (bim);\
254 (pre) = _are * _bre - _aim * _bim;\
255 (pim) = _are * _bim + _aim * _bre;\
256 }
257
258 /**
259 * Compute the middle half of the inverse MDCT of size N = 2^nbits
260 *
261 * Thus excluding the parts that can be derived by symmetry.
262 *
263 * \param output N/2 samples.
264 * \param input N/2 samples.
265 */
266 static void imdct_half(struct mdct_context *s, fftsample_t *output,
267 const fftsample_t *input)
268 {
269 int k, n8, n4, n2, n, j;
270 const uint16_t *revtab = s->fft.revtab;
271 const fftsample_t *tcos = s->tcos;
272 const fftsample_t *tsin = s->tsin;
273 const fftsample_t *in1, *in2;
274 struct fft_complex *z = (struct fft_complex *)output;
275
276 n = 1 << s->nbits;
277 n2 = n >> 1;
278 n4 = n >> 2;
279 n8 = n >> 3;
280
281 /* pre rotation */
282 in1 = input;
283 in2 = input + n2 - 1;
284 for (k = 0; k < n4; k++) {
285 j = revtab[k];
286 CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]);
287 in1 += 2;
288 in2 -= 2;
289 }
290 fft(&s->fft, z);
291
292 /* post rotation + reordering */
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.
308 *
309 * \param ctx The initialized context structure.
310 * \param output N samples.
311 * \param input N/2 samples.
312 *
313 * \sa \ref imdct_init().
314 */
315 void imdct(struct mdct_context *ctx, float *output, const float *input)
316 {
317 int k;
318 int n = 1 << ctx->nbits;
319 int n2 = n >> 1;
320 int n4 = n >> 2;
321
322 imdct_half(ctx, output + n4, input);
323
324 for (k = 0; k < n4; k++) {
325 output[k] = -output[n2 - k - 1];
326 output[n - k - 1] = output[n2 + k];
327 }
328 }
329
330 static int fft_init(struct fft_context *s, int nbits)
331 {
332 int i, j, n;
333
334 if (nbits < 2 || nbits > 16)
335 return -E_FFT_BAD_PARAMS;
336 s->nbits = nbits;
337 n = 1 << nbits;
338
339 s->revtab = para_malloc(n * sizeof(uint16_t));
340 for (j = 4; j <= nbits; j++) {
341 int k = 1 << j;
342 double freq = 2 * M_PI / k;
343 fftsample_t *tab = cos_tabs[j - 4];
344 for (i = 0; i <= k / 4; i++)
345 tab[i] = cos(i * freq);
346 for (i = 1; i < k / 4; i++)
347 tab[k / 2 - i] = tab[i];
348 }
349 for (i = 0; i < n; i++)
350 s->revtab[-split_radix_permutation(i, n) & (n - 1)] = i;
351 return 0;
352 }
353
354 /**
355 * Initialize the inverse modified cosine transform.
356 *
357 * \param nbits The number of bits to use (4 <= \a nbits <= 18).
358 *
359 * \param result Opaque structure that must be passed to \ref imdct().
360 *
361 * \return Standard.
362 */
363 int imdct_init(int nbits, struct mdct_context **result)
364 {
365 int ret, n, n4, i;
366 double alpha;
367 struct mdct_context *s;
368
369 s = para_calloc(sizeof(*s));
370 n = 1 << nbits;
371 s->nbits = nbits;
372 s->n = n;
373 n4 = n >> 2;
374 s->tcos = para_malloc(n4 * sizeof(fftsample_t));
375 s->tsin = para_malloc(n4 * sizeof(fftsample_t));
376
377 for (i = 0; i < n4; i++) {
378 alpha = 2 * M_PI * (i + 1.0 / 8.0) / n;
379 s->tcos[i] = -cos(alpha);
380 s->tsin[i] = -sin(alpha);
381 }
382 ret = fft_init(&s->fft, s->nbits - 2);
383 if (ret < 0)
384 goto fail;
385 *result = s;
386 return 0;
387 fail:
388 freep(&s->tcos);
389 freep(&s->tsin);
390 free(s);
391 return ret;
392 }
393
394 /**
395 * Deallocate imdct resources.
396 *
397 * \param ctx The pointer obtained by imdct_init().
398 */
399 void imdct_end(struct mdct_context *ctx)
400 {
401 free(ctx->tcos);
402 free(ctx->tsin);
403 free(ctx->fft.revtab);
404 free(ctx);
405 }