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 https://xiph.org/ * |
10 | * * |
11 | ******************************************************************** |
12 | |
13 | function: lookup based functions |
14 | |
15 | ********************************************************************/ |
16 | |
17 | #include <math.h> |
18 | #include "lookup.h" |
19 | #include "lookup_data.h" |
20 | #include "os.h" |
21 | #include "misc.h" |
22 | |
23 | #ifdef FLOAT_LOOKUP |
24 | |
25 | /* interpolated lookup based cos function, domain 0 to PI only */ |
26 | float vorbis_coslook(float a){ |
27 | double d=a*(.31830989*(float)COS_LOOKUP_SZ); |
28 | int i=vorbis_ftoi(d-.5); |
29 | |
30 | return COS_LOOKUP[i]+ (d-i)*(COS_LOOKUP[i+1]-COS_LOOKUP[i]); |
31 | } |
32 | |
33 | /* interpolated 1./sqrt(p) where .5 <= p < 1. */ |
34 | float vorbis_invsqlook(float a){ |
35 | double d=a*(2.f*(float)INVSQ_LOOKUP_SZ)-(float)INVSQ_LOOKUP_SZ; |
36 | int i=vorbis_ftoi(d-.5f); |
37 | return INVSQ_LOOKUP[i]+ (d-i)*(INVSQ_LOOKUP[i+1]-INVSQ_LOOKUP[i]); |
38 | } |
39 | |
40 | /* interpolated 1./sqrt(p) where .5 <= p < 1. */ |
41 | float vorbis_invsq2explook(int a){ |
42 | return INVSQ2EXP_LOOKUP[a-INVSQ2EXP_LOOKUP_MIN]; |
43 | } |
44 | |
45 | #include <stdio.h> |
46 | /* interpolated lookup based fromdB function, domain -140dB to 0dB only */ |
47 | float vorbis_fromdBlook(float a){ |
48 | int i=vorbis_ftoi(a*((float)(-(1<<FROMdB2_SHIFT)))-.5f); |
49 | return (i<0)?1.f: |
50 | ((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.f: |
51 | FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]); |
52 | } |
53 | |
54 | #endif |
55 | |
56 | #ifdef INT_LOOKUP |
57 | /* interpolated 1./sqrt(p) where .5 <= a < 1. (.100000... to .111111...) in |
58 | 16.16 format |
59 | |
60 | returns in m.8 format */ |
61 | long vorbis_invsqlook_i(long a,long e){ |
62 | long i=(a&0x7fff)>>(INVSQ_LOOKUP_I_SHIFT-1); |
63 | long d=(a&INVSQ_LOOKUP_I_MASK)<<(16-INVSQ_LOOKUP_I_SHIFT); /* 0.16 */ |
64 | long val=INVSQ_LOOKUP_I[i]- /* 1.16 */ |
65 | (((INVSQ_LOOKUP_I[i]-INVSQ_LOOKUP_I[i+1])* /* 0.16 */ |
66 | d)>>16); /* result 1.16 */ |
67 | |
68 | e+=32; |
69 | if(e&1)val=(val*5792)>>13; /* multiply val by 1/sqrt(2) */ |
70 | e=(e>>1)-8; |
71 | |
72 | return(val>>e); |
73 | } |
74 | |
75 | /* interpolated lookup based fromdB function, domain -140dB to 0dB only */ |
76 | /* a is in n.12 format */ |
77 | float vorbis_fromdBlook_i(long a){ |
78 | int i=(-a)>>(12-FROMdB2_SHIFT); |
79 | return (i<0)?1.f: |
80 | ((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.f: |
81 | FROMdB_LOOKUP[i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]); |
82 | } |
83 | |
84 | /* interpolated lookup based cos function, domain 0 to PI only */ |
85 | /* a is in 0.16 format, where 0==0, 2^^16-1==PI, return 0.14 */ |
86 | long vorbis_coslook_i(long a){ |
87 | int i=a>>COS_LOOKUP_I_SHIFT; |
88 | int d=a&COS_LOOKUP_I_MASK; |
89 | return COS_LOOKUP_I[i]- ((d*(COS_LOOKUP_I[i]-COS_LOOKUP_I[i+1]))>> |
90 | COS_LOOKUP_I_SHIFT); |
91 | } |
92 | |
93 | #endif |
94 | |