1be7314b39
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14778 a1c6a512-1295-4272-9138-f99709370657
152 lines
3.5 KiB
C
152 lines
3.5 KiB
C
/*
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* WMA compatible decoder
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* Copyright (c) 2002 The FFmpeg Project.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "wmadec.h"
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#include "wmafixed.h"
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FFTComplex exptab0[512] IBSS_ATTR;
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/* butter fly op */
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#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
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{\
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fixed32 ax, ay, bx, by;\
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bx=pre1;\
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by=pim1;\
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ax=qre1;\
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ay=qim1;\
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pre = (bx + ax);\
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pim = (by + ay);\
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qre = (bx - ax);\
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qim = (by - ay);\
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}
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int fft_calc_unscaled(FFTContext *s, FFTComplex *z)
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{
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int ln = s->nbits;
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int j, np, np2;
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int nblocks, nloops;
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register FFTComplex *p, *q;
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// FFTComplex *exptab = s->exptab;
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int l;
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fixed32 tmp_re, tmp_im;
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int tabshift = 10-ln;
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np = 1 << ln;
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/* pass 0 */
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p=&z[0];
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j=(np >> 1);
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do
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{
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BF(p[0].re, p[0].im, p[1].re, p[1].im,
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p[0].re, p[0].im, p[1].re, p[1].im);
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p+=2;
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}
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while (--j != 0);
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/* pass 1 */
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p=&z[0];
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j=np >> 2;
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if (s->inverse)
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{
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do
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{
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BF(p[0].re, p[0].im, p[2].re, p[2].im,
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p[0].re, p[0].im, p[2].re, p[2].im);
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BF(p[1].re, p[1].im, p[3].re, p[3].im,
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p[1].re, p[1].im, -p[3].im, p[3].re);
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p+=4;
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}
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while (--j != 0);
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}
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else
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{
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do
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{
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BF(p[0].re, p[0].im, p[2].re, p[2].im,
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p[0].re, p[0].im, p[2].re, p[2].im);
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BF(p[1].re, p[1].im, p[3].re, p[3].im,
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p[1].re, p[1].im, p[3].im, -p[3].re);
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p+=4;
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}
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while (--j != 0);
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}
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/* pass 2 .. ln-1 */
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nblocks = np >> 3;
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nloops = 1 << 2;
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np2 = np >> 1;
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do
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{
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p = z;
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q = z + nloops;
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for (j = 0; j < nblocks; ++j)
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{
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BF(p->re, p->im, q->re, q->im,
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p->re, p->im, q->re, q->im);
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p++;
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q++;
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for(l = nblocks; l < np2; l += nblocks)
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{
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CMUL(&tmp_re, &tmp_im, exptab0[(l<<tabshift)].re, exptab0[(l<<tabshift)].im, q->re, q->im);
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//CMUL(&tmp_re, &tmp_im, exptab[l].re, exptab[l].im, q->re, q->im);
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BF(p->re, p->im, q->re, q->im,
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p->re, p->im, tmp_re, tmp_im);
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p++;
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q++;
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}
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p += nloops;
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q += nloops;
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}
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nblocks = nblocks >> 1;
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nloops = nloops << 1;
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}
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while (nblocks != 0);
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return 0;
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}
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int fft_init_global(void)
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{
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int i, n;
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fixed32 c1, s1, s2;
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n=1<<10;
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s2 = 1 ? 1 : -1;
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for(i=0;i<(n/2);++i)
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{
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fixed32 ifix = itofix32(i);
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fixed32 nfix = itofix32(n);
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fixed32 res = fixdiv32(ifix,nfix);
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s1 = fsincos(res<<16, &c1);
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exptab0[i].re = c1;
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exptab0[i].im = s1*s2;
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}
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return 0;
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}
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