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 */
26float 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. */
34float 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. */
41float 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 */
47float 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 */
61long 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 */
77float 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 */
86long 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