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comparison: media/libvorbis/lib/vorbis_lookup.c
media/libvorbis/lib/vorbis_lookup.c
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| -1:000000000000 | 0:d7b59d13ff7f |
|---|---|
| 1 /******************************************************************** | |
| 2 * * | |
| 3 * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. * | |
| 4 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * | |
| 5 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * | |
| 6 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * | |
| 7 * * | |
| 8 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 * | |
| 9 * by the Xiph.Org Foundation http://www.xiph.org/ * | |
| 10 * * | |
| 11 ******************************************************************** | |
| 12 | |
| 13 function: lookup based functions | |
| 14 last mod: $Id: lookup.c 16227 2009-07-08 06:58:46Z xiphmont $ | |
| 15 | |
| 16 ********************************************************************/ | |
| 17 | |
| 18 #include <math.h> | |
| 19 #include "lookup.h" | |
| 20 #include "lookup_data.h" | |
| 21 #include "os.h" | |
| 22 #include "misc.h" | |
| 23 | |
| 24 #ifdef FLOAT_LOOKUP | |
| 25 | |
| 26 /* interpolated lookup based cos function, domain 0 to PI only */ | |
| 27 float vorbis_coslook(float a){ | |
| 28 double d=a*(.31830989*(float)COS_LOOKUP_SZ); | |
| 29 int i=vorbis_ftoi(d-.5); | |
| 30 | |
| 31 return COS_LOOKUP[i]+ (d-i)*(COS_LOOKUP[i+1]-COS_LOOKUP[i]); | |
| 32 } | |
| 33 | |
| 34 /* interpolated 1./sqrt(p) where .5 <= p < 1. */ | |
| 35 float vorbis_invsqlook(float a){ | |
| 36 double d=a*(2.f*(float)INVSQ_LOOKUP_SZ)-(float)INVSQ_LOOKUP_SZ; | |
| 37 int i=vorbis_ftoi(d-.5f); | |
| 38 return INVSQ_LOOKUP[i]+ (d-i)*(INVSQ_LOOKUP[i+1]-INVSQ_LOOKUP[i]); | |
| 39 } | |
| 40 | |
| 41 /* interpolated 1./sqrt(p) where .5 <= p < 1. */ | |
| 42 float vorbis_invsq2explook(int a){ | |
| 43 return INVSQ2EXP_LOOKUP[a-INVSQ2EXP_LOOKUP_MIN]; | |
| 44 } | |
| 45 | |
| 46 #include <stdio.h> | |
| 47 /* interpolated lookup based fromdB function, domain -140dB to 0dB only */ | |
| 48 float vorbis_fromdBlook(float a){ | |
| 49 int i=vorbis_ftoi(a*((float)(-(1<<FROMdB2_SHIFT)))-.5f); | |
| 50 return (i<0)?1.f: | |
| 51 ((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.f: | |
| 52 FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]); | |
| 53 } | |
| 54 | |
| 55 #endif | |
| 56 | |
| 57 #ifdef INT_LOOKUP | |
| 58 /* interpolated 1./sqrt(p) where .5 <= a < 1. (.100000... to .111111...) in | |
| 59 16.16 format | |
| 60 | |
| 61 returns in m.8 format */ | |
| 62 long vorbis_invsqlook_i(long a,long e){ | |
| 63 long i=(a&0x7fff)>>(INVSQ_LOOKUP_I_SHIFT-1); | |
| 64 long d=(a&INVSQ_LOOKUP_I_MASK)<<(16-INVSQ_LOOKUP_I_SHIFT); /* 0.16 */ | |
| 65 long val=INVSQ_LOOKUP_I[i]- /* 1.16 */ | |
| 66 (((INVSQ_LOOKUP_I[i]-INVSQ_LOOKUP_I[i+1])* /* 0.16 */ | |
| 67 d)>>16); /* result 1.16 */ | |
| 68 | |
| 69 e+=32; | |
| 70 if(e&1)val=(val*5792)>>13; /* multiply val by 1/sqrt(2) */ | |
| 71 e=(e>>1)-8; | |
| 72 | |
| 73 return(val>>e); | |
| 74 } | |
| 75 | |
| 76 /* interpolated lookup based fromdB function, domain -140dB to 0dB only */ | |
| 77 /* a is in n.12 format */ | |
| 78 float vorbis_fromdBlook_i(long a){ | |
| 79 int i=(-a)>>(12-FROMdB2_SHIFT); | |
| 80 return (i<0)?1.f: | |
| 81 ((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.f: | |
| 82 FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]); | |
| 83 } | |
| 84 | |
| 85 /* interpolated lookup based cos function, domain 0 to PI only */ | |
| 86 /* a is in 0.16 format, where 0==0, 2^^16-1==PI, return 0.14 */ | |
| 87 long vorbis_coslook_i(long a){ | |
| 88 int i=a>>COS_LOOKUP_I_SHIFT; | |
| 89 int d=a&COS_LOOKUP_I_MASK; | |
| 90 return COS_LOOKUP_I[i]- ((d*(COS_LOOKUP_I[i]-COS_LOOKUP_I[i+1]))>> | |
| 91 COS_LOOKUP_I_SHIFT); | |
| 92 } | |
| 93 | |
| 94 #endif |
