/* JOrbis
* Copyright (C) 2000 ymnk, JCraft,Inc.
*
* Written by: 2000 ymnk<ymnk@jcraft.com>
*
* Many thanks to
* Monty <monty@xiph.org> and
* The XIPHOPHORUS Company http://www.xiph.org/ .
* JOrbis has been based on their awesome works, Vorbis codec.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public License
* as published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
package com.jcraft.jorbis;
/*
function: LSP (also called LSF) conversion routines
The LSP generation code is taken (with minimal modification) from
"On the Computation of the LSP Frequencies" by Joseph Rothweiler
<rothwlr@altavista.net>, available at:
http://www2.xtdl.com/~rothwlr/lsfpaper/lsfpage.html
********************************************************************/
class Lsp{
static final float M_PI=(float)(3.1415926539);
static void lsp_to_curve(float[] curve,
int[] map, int n, int ln,
float[] lsp, int m,
float amp, float ampoffset){
int i;
float wdel=M_PI/ln;
for(i=0;i<m;i++)lsp[i]=Lookup.coslook(lsp[i]);
int m2=(m/2)*2;
i=0;
while(i<n){
int k=map[i];
float p=.7071067812f;
float q=.7071067812f;
float w=Lookup.coslook(wdel*k);
int ftmp=0;
int c=m>>>1;
for(int j=0;j<m2;j+=2){
q*=lsp[j]-w;
p*=lsp[j+1]-w;
}
if((m&1)!=0){
/* odd order filter; slightly assymetric */
/* the last coefficient */
q*=lsp[m-1]-w;
q*=q;
p*=p*(1.f-w*w);
}
else{
/* even order filter; still symmetric */
q*=q*(1.f+w);
p*=p*(1.f-w);
}
// q=frexp(p+q,&qexp);
q=p+q;
int hx=Float.floatToIntBits(q);
int ix=0x7fffffff&hx;
int qexp=0;
if(ix>=0x7f800000||(ix==0)){
// 0,inf,nan
}
else{
if(ix<0x00800000){ // subnormal
q*=3.3554432000e+07; // 0x4c000000
hx=Float.floatToIntBits(q);
ix=0x7fffffff&hx;
qexp=-25;
}
qexp += ((ix>>>23)-126);
hx=(hx&0x807fffff)|0x3f000000;
q=Float.intBitsToFloat(hx);
}
q=Lookup.fromdBlook(amp*
Lookup.invsqlook(q)*
Lookup.invsq2explook(qexp+m)-ampoffset);
do{curve[i++]*=q;}
// do{curve[i++]=q;}
while(i<n&&map[i]==k);
}
}
}