apps/codecs/libwmapro/wmapro_mdct.c

   1 #include <inttypes.h>
   2 #include "wmapro_mdct.h"
   3 #include "mdct_tables.h"    /* for sincos_lookup_wmap */
   4 #include "../lib/mdct_lookup.h" /* for revtab */
   5 #include "../lib/fft.h"     /* for FFT data structures */
   6 #include "codeclib.h"
   7
   8 #include "../lib/codeclib_misc.h" /* for XNPROD31 */
   9 #include "wmapro_math.h"
  10
  11 void imdct_half(unsigned int nbits, int32_t *output, const int32_t *input){
  12     int k, n8, n4, n2, n, j;
  13     const int32_t *in1, *in2;
  14     FFTComplex *z = (FFTComplex *)output;
  15
  16     n = 1 << nbits;
  17     n2 = n >> 1;
  18     n4 = n >> 2;
  19     n8 = n >> 3;
  20
  21     const int32_t *T = sincos_lookup_wmap + ((n2) - (1<<7));
  22
  23     /* pre rotation */
  24     const int revtab_shift = (14- nbits);
  25     in1 = input;
  26     in2 = input + n2 - 1;
  27     for(k = 0; k < n4; k++) {
  28         j=revtab[k]>>revtab_shift;
  29         XNPROD31(*in2<<2, *in1<<2, T[1]<<14, T[0]<<14, &z[j].re, &z[j].im );
  30         in1 += 2;
  31         in2 -= 2;
  32         T += 2;
  33     }
  34
  35     ff_fft_calc_c(nbits-2, z);
  36
  37     /* post rotation + reordering */
  38     T = sincos_lookup_wmap + ((n2) - (1<<7)) + n4;
  39     const int32_t *V = T;
  40     for(k = 0; k < n8; k++) {
  41         int32_t r0, i0, r1, i1;
  42         XNPROD31(z[n8-k-1].im, z[n8-k-1].re, T[0]<<8, T[1]<<8, &r0, &i1 );
  43         XNPROD31(z[n8+k  ].im, z[n8+k  ].re, V[0]<<8, V[1]<<8, &r1, &i0 );
  44         z[n8-k-1].re = r0;
  45         z[n8-k-1].im = i0;
  46         z[n8+k  ].re = r1;
  47         z[n8+k  ].im = i1;
  48         T-=2;
  49         V+=2;
  50     }
  51 }