/******************************************************************** * * * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. * * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * * * * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 * * by the Xiph.Org Foundation http://www.xiph.org/ * * * ******************************************************************** function: lookup based functions last mod: \$Id\$ ********************************************************************/ #include #include "lookup.h" #include "lookup_data.h" #include "os.h" #include "misc.h" #ifdef FLOAT_LOOKUP /* interpolated lookup based cos function, domain 0 to PI only */ float vorbis_coslook(float a){ double d=a*(.31830989*(float)COS_LOOKUP_SZ); int i=vorbis_ftoi(d-.5); return COS_LOOKUP[i]+ (d-i)*(COS_LOOKUP[i+1]-COS_LOOKUP[i]); } /* interpolated 1./sqrt(p) where .5 <= p < 1. */ float vorbis_invsqlook(float a){ double d=a*(2.f*(float)INVSQ_LOOKUP_SZ)-(float)INVSQ_LOOKUP_SZ; int i=vorbis_ftoi(d-.5f); return INVSQ_LOOKUP[i]+ (d-i)*(INVSQ_LOOKUP[i+1]-INVSQ_LOOKUP[i]); } /* interpolated 1./sqrt(p) where .5 <= p < 1. */ float vorbis_invsq2explook(int a){ return INVSQ2EXP_LOOKUP[a-INVSQ2EXP_LOOKUP_MIN]; } #include /* interpolated lookup based fromdB function, domain -140dB to 0dB only */ float vorbis_fromdBlook(float a){ int i=vorbis_ftoi(a*((float)(-(1<=(FROMdB_LOOKUP_SZ<>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]); } #endif #ifdef INT_LOOKUP /* interpolated 1./sqrt(p) where .5 <= a < 1. (.100000... to .111111...) in 16.16 format returns in m.8 format */ long vorbis_invsqlook_i(long a,long e){ long i=(a&0x7fff)>>(INVSQ_LOOKUP_I_SHIFT-1); long d=(a&INVSQ_LOOKUP_I_MASK)<<(16-INVSQ_LOOKUP_I_SHIFT); /* 0.16 */ long val=INVSQ_LOOKUP_I[i]- /* 1.16 */ (((INVSQ_LOOKUP_I[i]-INVSQ_LOOKUP_I[i+1])* /* 0.16 */ d)>>16); /* result 1.16 */ e+=32; if(e&1)val=(val*5792)>>13; /* multiply val by 1/sqrt(2) */ e=(e>>1)-8; return(val>>e); } /* interpolated lookup based fromdB function, domain -140dB to 0dB only */ /* a is in n.12 format */ float vorbis_fromdBlook_i(long a){ int i=(-a)>>(12-FROMdB2_SHIFT); return (i<0)?1.f: ((i>=(FROMdB_LOOKUP_SZ<>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]); } /* interpolated lookup based cos function, domain 0 to PI only */ /* a is in 0.16 format, where 0==0, 2^^16-1==PI, return 0.14 */ long vorbis_coslook_i(long a){ int i=a>>COS_LOOKUP_I_SHIFT; int d=a&COS_LOOKUP_I_MASK; return COS_LOOKUP_I[i]- ((d*(COS_LOOKUP_I[i]-COS_LOOKUP_I[i+1]))>> COS_LOOKUP_I_SHIFT); } #endif