extern/ffmpeg/libavcodec/fft.c

   1 /*
   2  * FFT/IFFT transforms
   3  * Copyright (c) 2002 Fabrice Bellard.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 /**
  21  * @file fft.c
  22  * FFT/IFFT transforms.
  23  */
  24
  25 #include "dsputil.h"
  26
  27 /**
  28  * The size of the FFT is 2^nbits. If inverse is TRUE, inverse FFT is
  29  * done
  30  */
  31 int ff_fft_init(FFTContext *s, int nbits, int inverse)
  32 {
  33     int i, j, m, n;
  34     float alpha, c1, s1, s2;
  35
  36     s->nbits = nbits;
  37     n = 1 << nbits;
  38
  39     s->exptab = av_malloc((n / 2) * sizeof(FFTComplex));
  40     if (!s->exptab)
  41         goto fail;
  42     s->revtab = av_malloc(n * sizeof(uint16_t));
  43     if (!s->revtab)
  44         goto fail;
  45     s->inverse = inverse;
  46
  47     s2 = inverse ? 1.0 : -1.0;
  48
  49     for(i=0;i<(n/2);i++) {
  50         alpha = 2 * M_PI * (float)i / (float)n;
  51         c1 = cos(alpha);
  52         s1 = sin(alpha) * s2;
  53         s->exptab[i].re = c1;
  54         s->exptab[i].im = s1;
  55     }
  56     s->fft_calc = ff_fft_calc_c;
  57     s->exptab1 = NULL;
  58
  59     /* compute constant table for HAVE_SSE version */
  60 #if (defined(HAVE_MMX) && (defined(HAVE_BUILTIN_VECTOR) || defined(HAVE_MM3DNOW))) || defined(HAVE_ALTIVEC)
  61     {
  62         int has_vectors = 0;
  63
  64 #if defined(HAVE_MMX)
  65         has_vectors = mm_support() & (MM_3DNOW | MM_3DNOWEXT | MM_SSE | MM_SSE2);
  66 #endif
  67 #if defined(HAVE_ALTIVEC) && !defined(ALTIVEC_USE_REFERENCE_C_CODE)
  68         has_vectors = mm_support() & MM_ALTIVEC;
  69 #endif
  70         if (has_vectors) {
  71             int np, nblocks, np2, l;
  72             FFTComplex *q;
  73
  74             np = 1 << nbits;
  75             nblocks = np >> 3;
  76             np2 = np >> 1;
  77             s->exptab1 = av_malloc(np * 2 * sizeof(FFTComplex));
  78             if (!s->exptab1)
  79                 goto fail;
  80             q = s->exptab1;
  81             do {
  82                 for(l = 0; l < np2; l += 2 * nblocks) {
  83                     *q++ = s->exptab[l];
  84                     *q++ = s->exptab[l + nblocks];
  85
  86                     q->re = -s->exptab[l].im;
  87                     q->im = s->exptab[l].re;
  88                     q++;
  89                     q->re = -s->exptab[l + nblocks].im;
  90                     q->im = s->exptab[l + nblocks].re;
  91                     q++;
  92                 }
  93                 nblocks = nblocks >> 1;
  94             } while (nblocks != 0);
  95             av_freep(&s->exptab);
  96 #if defined(HAVE_MMX)
  97 #ifdef HAVE_MM3DNOW
  98             if (has_vectors & MM_3DNOWEXT)
  99                 /* 3DNowEx for Athlon(XP) */
 100                 s->fft_calc = ff_fft_calc_3dn2;
 101             else if (has_vectors & MM_3DNOW)
 102                 /* 3DNow! for K6-2/3 */
 103                 s->fft_calc = ff_fft_calc_3dn;
 104 #endif
 105 #ifdef HAVE_BUILTIN_VECTOR
 106             if (has_vectors & MM_SSE2)
 107                 /* SSE for P4/K8 */
 108                 s->fft_calc = ff_fft_calc_sse;
 109             else if ((has_vectors & MM_SSE) &&
 110                      s->fft_calc == ff_fft_calc_c)
 111                 /* SSE for P3 */
 112                 s->fft_calc = ff_fft_calc_sse;
 113 #endif
 114 #else /* HAVE_MMX */
 115             s->fft_calc = ff_fft_calc_altivec;
 116 #endif
 117         }
 118     }
 119 #endif
 120
 121     /* compute bit reverse table */
 122
 123     for(i=0;i<n;i++) {
 124         m=0;
 125         for(j=0;j<nbits;j++) {
 126             m |= ((i >> j) & 1) << (nbits-j-1);
 127         }
 128         s->revtab[i]=m;
 129     }
 130     return 0;
 131  fail:
 132     av_freep(&s->revtab);
 133     av_freep(&s->exptab);
 134     av_freep(&s->exptab1);
 135     return -1;
 136 }
 137
 138 /* butter fly op */
 139 #define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \
 140 {\
 141   FFTSample ax, ay, bx, by;\
 142   bx=pre1;\
 143   by=pim1;\
 144   ax=qre1;\
 145   ay=qim1;\
 146   pre = (bx + ax);\
 147   pim = (by + ay);\
 148   qre = (bx - ax);\
 149   qim = (by - ay);\
 150 }
 151
 152 #define MUL16(a,b) ((a) * (b))
 153
 154 #define CMUL(pre, pim, are, aim, bre, bim) \
 155 {\
 156    pre = (MUL16(are, bre) - MUL16(aim, bim));\
 157    pim = (MUL16(are, bim) + MUL16(bre, aim));\
 158 }
 159
 160 /**
 161  * Do a complex FFT with the parameters defined in ff_fft_init(). The
 162  * input data must be permuted before with s->revtab table. No
 163  * 1.0/sqrt(n) normalization is done.
 164  */
 165 void ff_fft_calc_c(FFTContext *s, FFTComplex *z)
 166 {
 167     int ln = s->nbits;
 168     int j, np, np2;
 169     int nblocks, nloops;
 170     register FFTComplex *p, *q;
 171     FFTComplex *exptab = s->exptab;
 172     int l;
 173     FFTSample tmp_re, tmp_im;
 174
 175     np = 1 << ln;
 176
 177     /* pass 0 */
 178
 179     p=&z[0];
 180     j=(np >> 1);
 181     do {
 182         BF(p[0].re, p[0].im, p[1].re, p[1].im,
 183            p[0].re, p[0].im, p[1].re, p[1].im);
 184         p+=2;
 185     } while (--j != 0);
 186
 187     /* pass 1 */
 188
 189
 190     p=&z[0];
 191     j=np >> 2;
 192     if (s->inverse) {
 193         do {
 194             BF(p[0].re, p[0].im, p[2].re, p[2].im,
 195                p[0].re, p[0].im, p[2].re, p[2].im);
 196             BF(p[1].re, p[1].im, p[3].re, p[3].im,
 197                p[1].re, p[1].im, -p[3].im, p[3].re);
 198             p+=4;
 199         } while (--j != 0);
 200     } else {
 201         do {
 202             BF(p[0].re, p[0].im, p[2].re, p[2].im,
 203                p[0].re, p[0].im, p[2].re, p[2].im);
 204             BF(p[1].re, p[1].im, p[3].re, p[3].im,
 205                p[1].re, p[1].im, p[3].im, -p[3].re);
 206             p+=4;
 207         } while (--j != 0);
 208     }
 209     /* pass 2 .. ln-1 */
 210
 211     nblocks = np >> 3;
 212     nloops = 1 << 2;
 213     np2 = np >> 1;
 214     do {
 215         p = z;
 216         q = z + nloops;
 217         for (j = 0; j < nblocks; ++j) {
 218             BF(p->re, p->im, q->re, q->im,
 219                p->re, p->im, q->re, q->im);
 220
 221             p++;
 222             q++;
 223             for(l = nblocks; l < np2; l += nblocks) {
 224                 CMUL(tmp_re, tmp_im, exptab[l].re, exptab[l].im, q->re, q->im);
 225                 BF(p->re, p->im, q->re, q->im,
 226                    p->re, p->im, tmp_re, tmp_im);
 227                 p++;
 228                 q++;
 229             }
 230
 231             p += nloops;
 232             q += nloops;
 233         }
 234         nblocks = nblocks >> 1;
 235         nloops = nloops << 1;
 236     } while (nblocks != 0);
 237 }
 238
 239 /**
 240  * Do the permutation needed BEFORE calling ff_fft_calc()
 241  */
 242 void ff_fft_permute(FFTContext *s, FFTComplex *z)
 243 {
 244     int j, k, np;
 245     FFTComplex tmp;
 246     const uint16_t *revtab = s->revtab;
 247
 248     /* reverse */
 249     np = 1 << s->nbits;
 250     for(j=0;j<np;j++) {
 251         k = revtab[j];
 252         if (k < j) {
 253             tmp = z[k];
 254             z[k] = z[j];
 255             z[j] = tmp;
 256         }
 257     }
 258 }
 259
 260 void ff_fft_end(FFTContext *s)
 261 {
 262     av_freep(&s->revtab);
 263     av_freep(&s->exptab);
 264     av_freep(&s->exptab1);
 265 }
 266