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Make the image tags examples nicer.
[Rockbox.git] / apps / codecs / Tremor / mdct.c
blobdce2a9d1969758e7c90b7624cc8ba5fc67e587b3
1 /********************************************************************
2 * *
3 * THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE. *
4 * *
5 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
6 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
7 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
8 * *
9 * THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002 *
10 * BY THE Xiph.Org FOUNDATION http://www.xiph.org/ *
11 * *
12 ********************************************************************
13
14 function: normalized modified discrete cosine transform
15 power of two length transform only [64 <= n ]
16 last mod: $Id$
17
18 Original algorithm adapted long ago from _The use of multirate filter
19 banks for coding of high quality digital audio_, by T. Sporer,
20 K. Brandenburg and B. Edler, collection of the European Signal
21 Processing Conference (EUSIPCO), Amsterdam, June 1992, Vol.1, pp
22 211-214
23
24 The below code implements an algorithm that no longer looks much like
25 that presented in the paper, but the basic structure remains if you
26 dig deep enough to see it.
27
28 This module DOES NOT INCLUDE code to generate/apply the window
29 function. Everybody has their own weird favorite including me... I
30 happen to like the properties of y=sin(.5PI*sin^2(x)), but others may
31 vehemently disagree.
32
33 ********************************************************************/
34
35 #include "ivorbiscodec.h"
36 #include "os.h"
37 #include "misc.h"
38 #include "mdct.h"
39 #include "mdct_lookup.h"
40
41 #if defined(CPU_ARM) && CONFIG_CPU != S3C2440
42 /* C code is faster on S3C2440 */
43
44 extern void mdct_butterfly_32(DATA_TYPE *x);
45 extern void mdct_butterfly_generic_loop(DATA_TYPE *x1, DATA_TYPE *x2,
46 LOOKUP_T *T0, int step,
47 LOOKUP_T *Ttop);
48
49 STIN void mdct_butterfly_generic(DATA_TYPE *x,int points, int step){
50 mdct_butterfly_generic_loop(x + points, x + (points>>1),
51 sincos_lookup0, step, sincos_lookup0+1024);
52 }
53
54 #else
55
56 /* 8 point butterfly (in place) */
57 STIN void mdct_butterfly_8(DATA_TYPE *x){
58 REG_TYPE r0 = x[4] + x[0];
59 REG_TYPE r1 = x[4] - x[0];
60 REG_TYPE r2 = x[5] + x[1];
61 REG_TYPE r3 = x[5] - x[1];
62 REG_TYPE r4 = x[6] + x[2];
63 REG_TYPE r5 = x[6] - x[2];
64 REG_TYPE r6 = x[7] + x[3];
65 REG_TYPE r7 = x[7] - x[3];
66
67 x[0] = r5 + r3;
68 x[1] = r7 - r1;
69 x[2] = r5 - r3;
70 x[3] = r7 + r1;
71 x[4] = r4 - r0;
72 x[5] = r6 - r2;
73 x[6] = r4 + r0;
74 x[7] = r6 + r2;
75 MB();
76 }
77
78 /* 16 point butterfly (in place, 4 register) */
79 STIN void mdct_butterfly_16(DATA_TYPE *x){
80
81 REG_TYPE r0, r1;
82
83 r0 = x[ 0] - x[ 8]; x[ 8] += x[ 0];
84 r1 = x[ 1] - x[ 9]; x[ 9] += x[ 1];
85 x[ 0] = MULT31((r0 + r1) , cPI2_8);
86 x[ 1] = MULT31((r1 - r0) , cPI2_8);
87 MB();
88
89 r0 = x[10] - x[ 2]; x[10] += x[ 2];
90 r1 = x[ 3] - x[11]; x[11] += x[ 3];
91 x[ 2] = r1; x[ 3] = r0;
92 MB();
93
94 r0 = x[12] - x[ 4]; x[12] += x[ 4];
95 r1 = x[13] - x[ 5]; x[13] += x[ 5];
96 x[ 4] = MULT31((r0 - r1) , cPI2_8);
97 x[ 5] = MULT31((r0 + r1) , cPI2_8);
98 MB();
99
100 r0 = x[14] - x[ 6]; x[14] += x[ 6];
101 r1 = x[15] - x[ 7]; x[15] += x[ 7];
102 x[ 6] = r0; x[ 7] = r1;
103 MB();
104
105 mdct_butterfly_8(x);
106 mdct_butterfly_8(x+8);
107 }
108
109 /* 32 point butterfly (in place, 4 register) */
110 STIN void mdct_butterfly_32(DATA_TYPE *x){
111
112 REG_TYPE r0, r1;
113
114 r0 = x[30] - x[14]; x[30] += x[14];
115 r1 = x[31] - x[15]; x[31] += x[15];
116 x[14] = r0; x[15] = r1;
117 MB();
118
119 r0 = x[28] - x[12]; x[28] += x[12];
120 r1 = x[29] - x[13]; x[29] += x[13];
121 XNPROD31( r0, r1, cPI1_8, cPI3_8, &x[12], &x[13] );
122 MB();
123
124 r0 = x[26] - x[10]; x[26] += x[10];
125 r1 = x[27] - x[11]; x[27] += x[11];
126 x[10] = MULT31((r0 - r1) , cPI2_8);
127 x[11] = MULT31((r0 + r1) , cPI2_8);
128 MB();
129
130 r0 = x[24] - x[ 8]; x[24] += x[ 8];
131 r1 = x[25] - x[ 9]; x[25] += x[ 9];
132 XNPROD31( r0, r1, cPI3_8, cPI1_8, &x[ 8], &x[ 9] );
133 MB();
134
135 r0 = x[22] - x[ 6]; x[22] += x[ 6];
136 r1 = x[ 7] - x[23]; x[23] += x[ 7];
137 x[ 6] = r1; x[ 7] = r0;
138 MB();
139
140 r0 = x[ 4] - x[20]; x[20] += x[ 4];
141 r1 = x[ 5] - x[21]; x[21] += x[ 5];
142 XPROD31 ( r0, r1, cPI3_8, cPI1_8, &x[ 4], &x[ 5] );
143 MB();
144
145 r0 = x[ 2] - x[18]; x[18] += x[ 2];
146 r1 = x[ 3] - x[19]; x[19] += x[ 3];
147 x[ 2] = MULT31((r1 + r0) , cPI2_8);
148 x[ 3] = MULT31((r1 - r0) , cPI2_8);
149 MB();
150
151 r0 = x[ 0] - x[16]; x[16] += x[ 0];
152 r1 = x[ 1] - x[17]; x[17] += x[ 1];
153 XPROD31 ( r0, r1, cPI1_8, cPI3_8, &x[ 0], &x[ 1] );
154 MB();
155
156 mdct_butterfly_16(x);
157 mdct_butterfly_16(x+16);
158 }
159
160 /* N/stage point generic N stage butterfly (in place, 4 register) */
161 void mdct_butterfly_generic(DATA_TYPE *x,int points, int step)
162 ICODE_ATTR_TREMOR_MDCT;
163 void mdct_butterfly_generic(DATA_TYPE *x,int points, int step){
164 LOOKUP_T *T = sincos_lookup0;
165 DATA_TYPE *x1 = x + points - 8;
166 DATA_TYPE *x2 = x + (points>>1) - 8;
167 REG_TYPE r0;
168 REG_TYPE r1;
169 REG_TYPE r2;
170 REG_TYPE r3;
171
172 do{
173 r0 = x1[6] - x2[6]; x1[6] += x2[6];
174 r1 = x2[7] - x1[7]; x1[7] += x2[7];
175 r2 = x1[4] - x2[4]; x1[4] += x2[4];
176 r3 = x2[5] - x1[5]; x1[5] += x2[5];
177 XPROD31( r1, r0, T[0], T[1], &x2[6], &x2[7] ); T+=step;
178 XPROD31( r3, r2, T[0], T[1], &x2[4], &x2[5] ); T+=step;
179
180 r0 = x1[2] - x2[2]; x1[2] += x2[2];
181 r1 = x2[3] - x1[3]; x1[3] += x2[3];
182 r2 = x1[0] - x2[0]; x1[0] += x2[0];
183 r3 = x2[1] - x1[1]; x1[1] += x2[1];
184 XPROD31( r1, r0, T[0], T[1], &x2[2], &x2[3] ); T+=step;
185 XPROD31( r3, r2, T[0], T[1], &x2[0], &x2[1] ); T+=step;
186
187 x1-=8; x2-=8;
188 }while(T<sincos_lookup0+1024);
189 do{
190 r0 = x1[6] - x2[6]; x1[6] += x2[6];
191 r1 = x1[7] - x2[7]; x1[7] += x2[7];
192 r2 = x1[4] - x2[4]; x1[4] += x2[4];
193 r3 = x1[5] - x2[5]; x1[5] += x2[5];
194 XNPROD31( r0, r1, T[0], T[1], &x2[6], &x2[7] ); T-=step;
195 XNPROD31( r2, r3, T[0], T[1], &x2[4], &x2[5] ); T-=step;
196
197 r0 = x1[2] - x2[2]; x1[2] += x2[2];
198 r1 = x1[3] - x2[3]; x1[3] += x2[3];
199 r2 = x1[0] - x2[0]; x1[0] += x2[0];
200 r3 = x1[1] - x2[1]; x1[1] += x2[1];
201 XNPROD31( r0, r1, T[0], T[1], &x2[2], &x2[3] ); T-=step;
202 XNPROD31( r2, r3, T[0], T[1], &x2[0], &x2[1] ); T-=step;
203
204 x1-=8; x2-=8;
205 }while(T>sincos_lookup0);
206 do{
207 r0 = x2[6] - x1[6]; x1[6] += x2[6];
208 r1 = x2[7] - x1[7]; x1[7] += x2[7];
209 r2 = x2[4] - x1[4]; x1[4] += x2[4];
210 r3 = x2[5] - x1[5]; x1[5] += x2[5];
211 XPROD31( r0, r1, T[0], T[1], &x2[6], &x2[7] ); T+=step;
212 XPROD31( r2, r3, T[0], T[1], &x2[4], &x2[5] ); T+=step;
213
214 r0 = x2[2] - x1[2]; x1[2] += x2[2];
215 r1 = x2[3] - x1[3]; x1[3] += x2[3];
216 r2 = x2[0] - x1[0]; x1[0] += x2[0];
217 r3 = x2[1] - x1[1]; x1[1] += x2[1];
218 XPROD31( r0, r1, T[0], T[1], &x2[2], &x2[3] ); T+=step;
219 XPROD31( r2, r3, T[0], T[1], &x2[0], &x2[1] ); T+=step;
220
221 x1-=8; x2-=8;
222 }while(T<sincos_lookup0+1024);
223 do{
224 r0 = x1[6] - x2[6]; x1[6] += x2[6];
225 r1 = x2[7] - x1[7]; x1[7] += x2[7];
226 r2 = x1[4] - x2[4]; x1[4] += x2[4];
227 r3 = x2[5] - x1[5]; x1[5] += x2[5];
228 XNPROD31( r1, r0, T[0], T[1], &x2[6], &x2[7] ); T-=step;
229 XNPROD31( r3, r2, T[0], T[1], &x2[4], &x2[5] ); T-=step;
230
231 r0 = x1[2] - x2[2]; x1[2] += x2[2];
232 r1 = x2[3] - x1[3]; x1[3] += x2[3];
233 r2 = x1[0] - x2[0]; x1[0] += x2[0];
234 r3 = x2[1] - x1[1]; x1[1] += x2[1];
235 XNPROD31( r1, r0, T[0], T[1], &x2[2], &x2[3] ); T-=step;
236 XNPROD31( r3, r2, T[0], T[1], &x2[0], &x2[1] ); T-=step;
237
238 x1-=8; x2-=8;
239 }while(T>sincos_lookup0);
240 }
241
242 #endif /* CPU_ARM */
243
244 STIN void mdct_butterflies(DATA_TYPE *x,int points,int shift) {
245
246 int stages=8-shift;
247 int i,j;
248
249 for(i=0;--stages>0;i++){
250 for(j=0;j<(1<<i);j++)
251 mdct_butterfly_generic(x+(points>>i)*j,points>>i,4<<(i+shift));
252 }
253
254 for(j=0;j<points;j+=32)
255 mdct_butterfly_32(x+j);
256 }
257
258
259 static const unsigned char bitrev[16] ICONST_ATTR =
260 {0,8,4,12,2,10,6,14,1,9,5,13,3,11,7,15};
261
262 STIN int bitrev12(int x){
263 return bitrev[x>>8]|(bitrev[(x&0x0f0)>>4]<<4)|(((int)bitrev[x&0x00f])<<8);
264 }
265
266 STIN void mdct_bitreverse(DATA_TYPE *x,int n,int step,int shift) {
267
268 int bit = 0;
269 DATA_TYPE *w0 = x;
270 DATA_TYPE *w1 = x = w0+(n>>1);
271 LOOKUP_T *T = (step>=4)?(sincos_lookup0+(step>>1)):sincos_lookup1;
272 LOOKUP_T *Ttop = T+1024;
273 REG_TYPE r2;
274
275 do{
276 REG_TYPE r3 = bitrev12(bit++);
277 DATA_TYPE *x0 = x + ((r3 ^ 0xfff)>>shift) -1;
278 DATA_TYPE *x1 = x + (r3>>shift);
279
280 REG_TYPE r0 = x0[0] + x1[0];
281 REG_TYPE r1 = x1[1] - x0[1];
282
283 XPROD32( r0, r1, T[1], T[0], r2, r3 ); T+=step;
284
285 w1 -= 4;
286
287 r0 = (x0[1] + x1[1])>>1;
288 r1 = (x0[0] - x1[0])>>1;
289 w0[0] = r0 + r2;
290 w0[1] = r1 + r3;
291 w1[2] = r0 - r2;
292 w1[3] = r3 - r1;
293
294 r3 = bitrev12(bit++);
295 x0 = x + ((r3 ^ 0xfff)>>shift) -1;
296 x1 = x + (r3>>shift);
297
298 r0 = x0[0] + x1[0];
299 r1 = x1[1] - x0[1];
300
301 XPROD32( r0, r1, T[1], T[0], r2, r3 ); T+=step;
302
303 r0 = (x0[1] + x1[1])>>1;
304 r1 = (x0[0] - x1[0])>>1;
305 w0[2] = r0 + r2;
306 w0[3] = r1 + r3;
307 w1[0] = r0 - r2;
308 w1[1] = r3 - r1;
309
310 w0 += 4;
311 }while(T<Ttop);
312 do{
313 REG_TYPE r3 = bitrev12(bit++);
314 DATA_TYPE *x0 = x + ((r3 ^ 0xfff)>>shift) -1;
315 DATA_TYPE *x1 = x + (r3>>shift);
316
317 REG_TYPE r0 = x0[0] + x1[0];
318 REG_TYPE r1 = x1[1] - x0[1];
319
320 T-=step; XPROD32( r0, r1, T[0], T[1], r2, r3 );
321
322 w1 -= 4;
323
324 r0 = (x0[1] + x1[1])>>1;
325 r1 = (x0[0] - x1[0])>>1;
326 w0[0] = r0 + r2;
327 w0[1] = r1 + r3;
328 w1[2] = r0 - r2;
329 w1[3] = r3 - r1;
330
331 r3 = bitrev12(bit++);
332 x0 = x + ((r3 ^ 0xfff)>>shift) -1;
333 x1 = x + (r3>>shift);
334
335 r0 = x0[0] + x1[0];
336 r1 = x1[1] - x0[1];
337
338 T-=step; XPROD32( r0, r1, T[0], T[1], r2, r3 );
339
340 r0 = (x0[1] + x1[1])>>1;
341 r1 = (x0[0] - x1[0])>>1;
342 w0[2] = r0 + r2;
343 w0[3] = r1 + r3;
344 w1[0] = r0 - r2;
345 w1[1] = r3 - r1;
346
347 w0 += 4;
348 }while(w0<w1);
349 }
350
351
352 void mdct_backward(int n, DATA_TYPE *in, DATA_TYPE *out)
353 ICODE_ATTR_TREMOR_MDCT;
354 void mdct_backward(int n, DATA_TYPE *in, DATA_TYPE *out) {
355 int n2=n>>1;
356 int n4=n>>2;
357 DATA_TYPE *iX;
358 DATA_TYPE *oX;
359 LOOKUP_T *T;
360 LOOKUP_T *V;
361 int shift;
362 int step;
363
364 for (shift=6;!(n&(1<<shift));shift++);
365 shift=13-shift;
366 step=2<<shift;
367
368 /* rotate */
369
370 iX = in+n2-7;
371 oX = out+n2+n4;
372 T = sincos_lookup0;
373
374 do{
375 oX-=4;
376 XPROD31( iX[4], iX[6], T[0], T[1], &oX[2], &oX[3] ); T+=step;
377 XPROD31( iX[0], iX[2], T[0], T[1], &oX[0], &oX[1] ); T+=step;
378 iX-=8;
379 }while(iX>=in+n4);
380 do{
381 oX-=4;
382 XPROD31( iX[4], iX[6], T[1], T[0], &oX[2], &oX[3] ); T-=step;
383 XPROD31( iX[0], iX[2], T[1], T[0], &oX[0], &oX[1] ); T-=step;
384 iX-=8;
385 }while(iX>=in);
386
387 iX = in+n2-8;
388 oX = out+n2+n4;
389 T = sincos_lookup0;
390
391 do{
392 T+=step; XNPROD31( iX[6], iX[4], T[0], T[1], &oX[0], &oX[1] );
393 T+=step; XNPROD31( iX[2], iX[0], T[0], T[1], &oX[2], &oX[3] );
394 iX-=8;
395 oX+=4;
396 }while(iX>=in+n4);
397 do{
398 T-=step; XNPROD31( iX[6], iX[4], T[1], T[0], &oX[0], &oX[1] );
399 T-=step; XNPROD31( iX[2], iX[0], T[1], T[0], &oX[2], &oX[3] );
400 iX-=8;
401 oX+=4;
402 }while(iX>=in);
403
404 mdct_butterflies(out+n2,n2,shift);
405 mdct_bitreverse(out,n,step,shift);
406 /* rotate + window */
407
408 step>>=2;
409 {
410 DATA_TYPE *oX1=out+n2+n4;
411 DATA_TYPE *oX2=out+n2+n4;
412 DATA_TYPE *iX =out;
413
414 switch(step) {
415 default: {
416 T=(step>=4)?(sincos_lookup0+(step>>1)):sincos_lookup1;
417 do{
418 oX1-=4;
419 XPROD31( iX[0], -iX[1], T[0], T[1], &oX1[3], &oX2[0] ); T+=step;
420 XPROD31( iX[2], -iX[3], T[0], T[1], &oX1[2], &oX2[1] ); T+=step;
421 XPROD31( iX[4], -iX[5], T[0], T[1], &oX1[1], &oX2[2] ); T+=step;
422 XPROD31( iX[6], -iX[7], T[0], T[1], &oX1[0], &oX2[3] ); T+=step;
423 oX2+=4;
424 iX+=8;
425 }while(iX<oX1);
426 break;
427 }
428
429 case 1: {
430 /* linear interpolation between table values: offset=0.5, step=1 */
431 REG_TYPE t0,t1,v0,v1;
432 T = sincos_lookup0;
433 V = sincos_lookup1;
434 t0 = (*T++)>>1;
435 t1 = (*T++)>>1;
436 do{
437 oX1-=4;
438
439 t0 += (v0 = (*V++)>>1);
440 t1 += (v1 = (*V++)>>1);
441 XPROD31( iX[0], -iX[1], t0, t1, &oX1[3], &oX2[0] );
442 v0 += (t0 = (*T++)>>1);
443 v1 += (t1 = (*T++)>>1);
444 XPROD31( iX[2], -iX[3], v0, v1, &oX1[2], &oX2[1] );
445 t0 += (v0 = (*V++)>>1);
446 t1 += (v1 = (*V++)>>1);
447 XPROD31( iX[4], -iX[5], t0, t1, &oX1[1], &oX2[2] );
448 v0 += (t0 = (*T++)>>1);
449 v1 += (t1 = (*T++)>>1);
450 XPROD31( iX[6], -iX[7], v0, v1, &oX1[0], &oX2[3] );
451
452 oX2+=4;
453 iX+=8;
454 }while(iX<oX1);
455 break;
456 }
457
458 case 0: {
459 /* linear interpolation between table values: offset=0.25, step=0.5 */
460 REG_TYPE t0,t1,v0,v1,q0,q1;
461 T = sincos_lookup0;
462 V = sincos_lookup1;
463 t0 = *T++;
464 t1 = *T++;
465 do{
466 oX1-=4;
467
468 v0 = *V++;
469 v1 = *V++;
470 t0 += (q0 = (v0-t0)>>2);
471 t1 += (q1 = (v1-t1)>>2);
472 XPROD31( iX[0], -iX[1], t0, t1, &oX1[3], &oX2[0] );
473 t0 = v0-q0;
474 t1 = v1-q1;
475 XPROD31( iX[2], -iX[3], t0, t1, &oX1[2], &oX2[1] );
476
477 t0 = *T++;
478 t1 = *T++;
479 v0 += (q0 = (t0-v0)>>2);
480 v1 += (q1 = (t1-v1)>>2);
481 XPROD31( iX[4], -iX[5], v0, v1, &oX1[1], &oX2[2] );
482 v0 = t0-q0;
483 v1 = t1-q1;
484 XPROD31( iX[6], -iX[7], v0, v1, &oX1[0], &oX2[3] );
485
486 oX2+=4;
487 iX+=8;
488 }while(iX<oX1);
489 break;
490 }
491 }
492
493 iX=out+n2+n4;
494 oX1=out+n4;
495 oX2=oX1;
496
497 do{
498 oX1-=4;
499 iX-=4;
500
501 oX2[0] = -(oX1[3] = iX[3]);
502 oX2[1] = -(oX1[2] = iX[2]);
503 oX2[2] = -(oX1[1] = iX[1]);
504 oX2[3] = -(oX1[0] = iX[0]);
505
506 oX2+=4;
507 }while(oX2<iX);
508
509 iX=out+n2+n4;
510 oX1=out+n2+n4;
511 oX2=out+n2;
512
513 do{
514 oX1-=4;
515 oX1[0]= iX[3];
516 oX1[1]= iX[2];
517 oX1[2]= iX[1];
518 oX1[3]= iX[0];
519 iX+=4;
520 }while(oX1>oX2);
521 }
522 }
Open Source Jukebox Firmware