liba52/resample_altivec.c

   1 // this code is based on a52dec/libao/audio_out_oss.c
   2 // AltiVec support Copyright (c) 2004 Romain Dolbeau <romain@dolbeau.org>
   3
   4 #ifndef SYS_DARWIN
   5 #include <altivec.h>
   6 #endif
   7
   8 const vector signed int magic = {0x43c00000,0x43c00000,0x43c00000,0x43c00000};
   9
  10 static inline vector signed short convert16_altivec(vector signed int v1, vector signed int v2)
  11 {
  12   register vector signed short result;
  13   v1 = vec_subs(v1, magic);
  14   v2 = vec_subs(v2, magic);
  15   result = vec_packs(v1, v2);
  16
  17   return result;
  18 }
  19
  20 static int a52_resample_STEREO_to_2_altivec(float * _f, int16_t * s16){
  21 #if 0
  22   int i;
  23   int32_t * f = (int32_t *) _f;
  24   for (i = 0; i < 256; i++) {
  25     s16[2*i] = convert (f[i]);
  26     s16[2*i+1] = convert (f[i+256]);
  27   }
  28   return 2*256;
  29 #else
  30   int i = 0;
  31   int32_t * f = (int32_t *) _f;
  32   register vector signed int f0, f4, f256, f260;
  33   register vector signed short reven, rodd, r0, r1;
  34
  35   for (i = 0; i < 256; i+= 8) {
  36     f0 = vec_ld(0, f);
  37     f4 = vec_ld(16, f);
  38
  39     f256 = vec_ld(1024, f);
  40     f260 = vec_ld(1040, f);
  41
  42     reven = convert16_altivec(f0, f4);
  43     rodd = convert16_altivec(f256, f260);
  44
  45     r0 = vec_mergeh(reven, rodd);
  46     r1 = vec_mergel(reven, rodd);
  47
  48     vec_st(r0, 0, s16);
  49     vec_st(r1, 16, s16);
  50
  51     f += 8;
  52     s16 += 16;
  53   }
  54   return(2*256);
  55 #endif
  56 }
  57
  58 static void* a52_resample_altivec(int flags, int ch){
  59 fprintf(stderr, "Checking for AltiVec resampler : 0x%08x, %d\n", flags, ch);
  60
  61   switch (flags) {
  62   case A52_CHANNEL:
  63   case A52_STEREO:
  64   case A52_DOLBY:
  65     if(ch==2) return a52_resample_STEREO_to_2_altivec;
  66     break;
  67
  68   default:
  69         fprintf(stderr, "Unsupported flags: 0x%08x (%d channels)\n", flags, ch);
  70         break;
  71   }
  72   return NULL;
  73 }
  74