tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

vorbis_lookup.c (3246B)

      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