jorbis/src/com/jcraft/jorbis/Lookup.java

   1 /* JOrbis
   2  * Copyright (C) 2000 ymnk, JCraft,Inc.
   3  *
   4  * Written by: 2000 ymnk<ymnk@jcraft.com>
   5  *
   6  * Many thanks to
   7  *   Monty <monty@xiph.org> and
   8  *   The XIPHOPHORUS Company http://www.xiph.org/ .
   9  * JOrbis has been based on their awesome works, Vorbis codec.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Library General Public License
  13  * as published by the Free Software Foundation; either version 2 of
  14  * the License, or (at your option) any later version.
  15
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU Library General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Library General Public
  22  * License along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  24  */
  25
  26 package com.jcraft.jorbis;
  27
  28 class Lookup{
  29   static final int COS_LOOKUP_SZ=128;
  30   static final float[] COS_LOOKUP={
  31         +1.0000000000000f,+0.9996988186962f,+0.9987954562052f,+0.9972904566787f,
  32         +0.9951847266722f,+0.9924795345987f,+0.9891765099648f,+0.9852776423889f,
  33         +0.9807852804032f,+0.9757021300385f,+0.9700312531945f,+0.9637760657954f,
  34         +0.9569403357322f,+0.9495281805930f,+0.9415440651830f,+0.9329927988347f,
  35         +0.9238795325113f,+0.9142097557035f,+0.9039892931234f,+0.8932243011955f,
  36         +0.8819212643484f,+0.8700869911087f,+0.8577286100003f,+0.8448535652497f,
  37         +0.8314696123025f,+0.8175848131516f,+0.8032075314806f,+0.7883464276266f,
  38         +0.7730104533627f,+0.7572088465065f,+0.7409511253550f,+0.7242470829515f,
  39         +0.7071067811865f,+0.6895405447371f,+0.6715589548470f,+0.6531728429538f,
  40         +0.6343932841636f,+0.6152315905806f,+0.5956993044924f,+0.5758081914178f,
  41         +0.5555702330196f,+0.5349976198871f,+0.5141027441932f,+0.4928981922298f,
  42         +0.4713967368260f,+0.4496113296546f,+0.4275550934303f,+0.4052413140050f,
  43         +0.3826834323651f,+0.3598950365350f,+0.3368898533922f,+0.3136817403989f,
  44         +0.2902846772545f,+0.2667127574749f,+0.2429801799033f,+0.2191012401569f,
  45         +0.1950903220161f,+0.1709618887603f,+0.1467304744554f,+0.1224106751992f,
  46         +0.0980171403296f,+0.0735645635997f,+0.0490676743274f,+0.0245412285229f,
  47         +0.0000000000000f,-0.0245412285229f,-0.0490676743274f,-0.0735645635997f,
  48         -0.0980171403296f,-0.1224106751992f,-0.1467304744554f,-0.1709618887603f,
  49         -0.1950903220161f,-0.2191012401569f,-0.2429801799033f,-0.2667127574749f,
  50         -0.2902846772545f,-0.3136817403989f,-0.3368898533922f,-0.3598950365350f,
  51         -0.3826834323651f,-0.4052413140050f,-0.4275550934303f,-0.4496113296546f,
  52         -0.4713967368260f,-0.4928981922298f,-0.5141027441932f,-0.5349976198871f,
  53         -0.5555702330196f,-0.5758081914178f,-0.5956993044924f,-0.6152315905806f,
  54         -0.6343932841636f,-0.6531728429538f,-0.6715589548470f,-0.6895405447371f,
  55         -0.7071067811865f,-0.7242470829515f,-0.7409511253550f,-0.7572088465065f,
  56         -0.7730104533627f,-0.7883464276266f,-0.8032075314806f,-0.8175848131516f,
  57         -0.8314696123025f,-0.8448535652497f,-0.8577286100003f,-0.8700869911087f,
  58         -0.8819212643484f,-0.8932243011955f,-0.9039892931234f,-0.9142097557035f,
  59         -0.9238795325113f,-0.9329927988347f,-0.9415440651830f,-0.9495281805930f,
  60         -0.9569403357322f,-0.9637760657954f,-0.9700312531945f,-0.9757021300385f,
  61         -0.9807852804032f,-0.9852776423889f,-0.9891765099648f,-0.9924795345987f,
  62         -0.9951847266722f,-0.9972904566787f,-0.9987954562052f,-0.9996988186962f,
  63         -1.0000000000000f,
  64   };
  65   /* interpolated lookup based cos function, domain 0 to PI only */
  66   static float coslook(float a){
  67     double d=a*(.31830989*(float)COS_LOOKUP_SZ);
  68     int i=(int)d;
  69     return COS_LOOKUP[i]+ ((float)(d-i))*(COS_LOOKUP[i+1]-COS_LOOKUP[i]);
  70   }
  71
  72   static final int INVSQ_LOOKUP_SZ=32;
  73   static final float[] INVSQ_LOOKUP={
  74         1.414213562373f,1.392621247646f,1.371988681140f,1.352246807566f,
  75         1.333333333333f,1.315191898443f,1.297771369046f,1.281025230441f,
  76         1.264911064067f,1.249390095109f,1.234426799697f,1.219988562661f,
  77         1.206045378311f,1.192569588000f,1.179535649239f,1.166919931983f,
  78         1.154700538379f,1.142857142857f,1.131370849898f,1.120224067222f,
  79         1.109400392450f,1.098884511590f,1.088662107904f,1.078719779941f,
  80         1.069044967650f,1.059625885652f,1.050451462878f,1.041511287847f,
  81         1.032795558989f,1.024295039463f,1.016001016002f,1.007905261358f,
  82         1.000000000000f,
  83   };
  84   /* interpolated 1./sqrt(p) where .5 <= p < 1. */
  85   static float invsqlook(float a){
  86 // System.out.println(a);
  87     double d=a*(2.f*(float)INVSQ_LOOKUP_SZ)-(float)INVSQ_LOOKUP_SZ;
  88     int i=(int)d;
  89     return INVSQ_LOOKUP[i]+ ((float)(d-i))*(INVSQ_LOOKUP[i+1]-INVSQ_LOOKUP[i]);
  90   }
  91
  92   static final int INVSQ2EXP_LOOKUP_MIN=-32;
  93   static final int INVSQ2EXP_LOOKUP_MAX=32;
  94   static final float[] INVSQ2EXP_LOOKUP={
  95                  65536.f,    46340.95001f,         32768.f,    23170.47501f,
  96                  16384.f,     11585.2375f,          8192.f,    5792.618751f,
  97                   4096.f,    2896.309376f,          2048.f,    1448.154688f,
  98                   1024.f,    724.0773439f,           512.f,     362.038672f,
  99                    256.f,     181.019336f,           128.f,    90.50966799f,
 100                     64.f,      45.254834f,            32.f,      22.627417f,
 101                     16.f,     11.3137085f,             8.f,    5.656854249f,
 102                      4.f,    2.828427125f,             2.f,    1.414213562f,
 103                      1.f,   0.7071067812f,            0.5f,   0.3535533906f,
 104                    0.25f,   0.1767766953f,          0.125f,  0.08838834765f,
 105                  0.0625f,  0.04419417382f,        0.03125f,  0.02209708691f,
 106                0.015625f,  0.01104854346f,      0.0078125f, 0.005524271728f,
 107              0.00390625f, 0.002762135864f,    0.001953125f, 0.001381067932f,
 108            0.0009765625f, 0.000690533966f,  0.00048828125f, 0.000345266983f,
 109          0.000244140625f,0.0001726334915f,0.0001220703125f,8.631674575e-05f,
 110         6.103515625e-05f,4.315837288e-05f,3.051757812e-05f,2.157918644e-05f,
 111         1.525878906e-05f,
 112   };
 113   /* interpolated 1./sqrt(p) where .5 <= p < 1. */
 114   static float invsq2explook(int a){
 115     return INVSQ2EXP_LOOKUP[a-INVSQ2EXP_LOOKUP_MIN];
 116   }
 117
 118   static final int FROMdB_LOOKUP_SZ=35;
 119   static final int FROMdB2_LOOKUP_SZ=32;
 120   static final int FROMdB_SHIFT=5;
 121   static final int FROMdB2_SHIFT=3;
 122   static final int FROMdB2_MASK=31;
 123   static final float[] FROMdB_LOOKUP={
 124                      1.f,   0.6309573445f,   0.3981071706f,   0.2511886432f,
 125            0.1584893192f,            0.1f,  0.06309573445f,  0.03981071706f,
 126           0.02511886432f,  0.01584893192f,           0.01f, 0.006309573445f,
 127          0.003981071706f, 0.002511886432f, 0.001584893192f,          0.001f,
 128         0.0006309573445f,0.0003981071706f,0.0002511886432f,0.0001584893192f,
 129                  0.0001f,6.309573445e-05f,3.981071706e-05f,2.511886432e-05f,
 130         1.584893192e-05f,          1e-05f,6.309573445e-06f,3.981071706e-06f,
 131         2.511886432e-06f,1.584893192e-06f,          1e-06f,6.309573445e-07f,
 132         3.981071706e-07f,2.511886432e-07f,1.584893192e-07f,
 133   };
 134   static final float[] FROMdB2_LOOKUP={
 135            0.9928302478f,   0.9786445908f,   0.9646616199f,   0.9508784391f,
 136            0.9372921937f,     0.92390007f,   0.9106992942f,   0.8976871324f,
 137            0.8848608897f,   0.8722179097f,   0.8597555737f,   0.8474713009f,
 138             0.835362547f,   0.8234268041f,   0.8116616003f,   0.8000644989f,
 139            0.7886330981f,   0.7773650302f,   0.7662579617f,    0.755309592f,
 140            0.7445176537f,   0.7338799116f,   0.7233941627f,   0.7130582353f,
 141            0.7028699885f,   0.6928273125f,   0.6829281272f,   0.6731703824f,
 142            0.6635520573f,   0.6540711597f,   0.6447257262f,   0.6355138211f,
 143   };
 144   /* interpolated lookup based fromdB function, domain -140dB to 0dB only */
 145   static float fromdBlook(float a){
 146     int i=(int)(a*((float)(-(1<<FROMdB2_SHIFT))));
 147     return (i<0)?1.f:
 148       ((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.f:
 149        FROMdB_LOOKUP[i>>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]);
 150   }
 151
 152 }
 153
 154