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* Copyright (c) 2002 Fabrice Bellard.
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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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* 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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* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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* FFT/IFFT transforms.
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* The size of the FFT is 2^nbits. If inverse is TRUE, inverse FFT is
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int ff_fft_init(FFTContext *s, int nbits, int inverse)
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float alpha, c1, s1, s2;
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s->exptab = av_malloc((n / 2) * sizeof(FFTComplex));
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s->revtab = av_malloc(n * sizeof(uint16_t));
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s2 = inverse ? 1.0 : -1.0;
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for(i=0;i<(n/2);i++) {
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alpha = 2 * M_PI * (float)i / (float)n;
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s->fft_calc = ff_fft_calc_c;
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/* compute constant table for HAVE_SSE version */
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#if (defined(HAVE_MMX) && (defined(HAVE_BUILTIN_VECTOR) || defined(HAVE_MM3DNOW))) || defined(HAVE_ALTIVEC)
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has_vectors = mm_support() & (MM_3DNOW | MM_3DNOWEXT | MM_SSE | MM_SSE2);
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#if defined(HAVE_ALTIVEC) && !defined(ALTIVEC_USE_REFERENCE_C_CODE)
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has_vectors = mm_support() & MM_ALTIVEC;
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int np, nblocks, np2, l;
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s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
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for(l = 0; l < np2; l += 2 * nblocks) {
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*q++ = s->exptab[l + nblocks];
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q->re = -s->exptab[l].im;
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q->im = s->exptab[l].re;
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q->re = -s->exptab[l + nblocks].im;
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q->im = s->exptab[l + nblocks].re;
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nblocks = nblocks >> 1;
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} while (nblocks != 0);
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if (has_vectors & MM_3DNOWEXT)
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/* 3DNowEx for Athlon(XP) */
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s->fft_calc = ff_fft_calc_3dn2;
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else if (has_vectors & MM_3DNOW)
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/* 3DNow! for K6-2/3 */
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s->fft_calc = ff_fft_calc_3dn;
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#ifdef HAVE_BUILTIN_VECTOR
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if (has_vectors & MM_SSE2)
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s->fft_calc = ff_fft_calc_sse;
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else if ((has_vectors & MM_SSE) &&
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s->fft_calc == ff_fft_calc_c)
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s->fft_calc = ff_fft_calc_sse;
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s->fft_calc = ff_fft_calc_altivec;
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/* compute bit reverse table */
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for(j=0;j<nbits;j++) {
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m |= ((i >> j) & 1) << (nbits-j-1);
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av_freep(&s->revtab);
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av_freep(&s->exptab);
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av_freep(&s->exptab1);
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#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
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FFTSample ax, ay, bx, by;\
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#define MUL16(a,b) ((a) * (b))
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#define CMUL(pre, pim, are, aim, bre, bim) \
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pre = (MUL16(are, bre) - MUL16(aim, bim));\
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pim = (MUL16(are, bim) + MUL16(bre, aim));\
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* Do a complex FFT with the parameters defined in ff_fft_init(). The
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* input data must be permuted before with s->revtab table. No
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* 1.0/sqrt(n) normalization is done.
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void ff_fft_calc_c(FFTContext *s, FFTComplex *z)
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register FFTComplex *p, *q;
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FFTComplex *exptab = s->exptab;
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FFTSample tmp_re, tmp_im;
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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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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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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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for (j = 0; j < nblocks; ++j) {
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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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for(l = nblocks; l < np2; l += nblocks) {
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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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nblocks = nblocks >> 1;
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nloops = nloops << 1;
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} while (nblocks != 0);
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* Do the permutation needed BEFORE calling ff_fft_calc()
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void ff_fft_permute(FFTContext *s, FFTComplex *z)
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const uint16_t *revtab = s->revtab;
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void ff_fft_end(FFTContext *s)
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av_freep(&s->revtab);
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av_freep(&s->exptab);
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av_freep(&s->exptab1);