void ampegdecoder::decode1()
{
int i,j,q,fr;
for (fr=0; fr<3; fr++)
{
if (fr)
decodehdr(0);
if (!hdrbitrate)
{
for (q=0; q<12; q++)
for (j=0; j<2; j++)
for (i=0; i<32; i++)
fraction[j][12*fr+q][i]=0;
continue;
}
int bitend=mainbufpos-32-(hdrcrc?16:0)+(hdrpadding?32:0)+12*1000*ratetab[hdrlsf?1:0][0][hdrbitrate]/(freqtab[hdrfreq]>>hdrlsf)*32;
int jsbound=(hdrmode==1)?(hdrmodeext+1)*4:(hdrmode==3)?0:32;
int stereo=(hdrmode==3)?1:2;
for (i=0;i<32;i++)
for (j=0;j<((i<jsbound)?2:1);j++)
{
bitalloc1[j][i] = mpgetbits(4);
if (i>=jsbound)
bitalloc1[1][i] = bitalloc1[0][i];
}
for (i=0;i<32;i++)
for (j=0;j<stereo;j++)
if (bitalloc1[j][i])
scale1[j][i]=multiple[mpgetbits(6)]*rangefac[bitalloc1[j][i]];
for (q=0;q<12;q++)
for (i=0;i<32;i++)
for (j=0;j<((i<jsbound)?2:1);j++)
if (bitalloc1[j][i])
{
int s=mpgetbits(bitalloc1[j][i]+1)-(1<<bitalloc1[j][i])+1;
fraction[j][12*fr+q][i]=scale1[j][i]*s;
if (i>=jsbound)
fraction[1][12*fr+q][i]=scale1[1][i]*s;
}
else
{
fraction[j][12*fr+q][i]=0;
if (i>=jsbound)
fraction[1][12*fr+q][i]=0;
}
mpgetbits(bitend-mainbufpos);
}
}
void ampegdecoder::readmain(grsistruct (*si)[2])
{
int stereo=(hdrmode==3)?1:2;
int maindatabegin = mpgetbits(hdrlsf?8:9);
mpgetbits(hdrlsf?(stereo==1)?1:2:(stereo==1)?5:3);
if (!si)
mpgetbits(hdrlsf?(stereo==1)?64:128:(stereo==1)?127:247);
else
{
int ngr=hdrlsf?1:2;
int gr,ch;
for (gr=0; gr<ngr; gr++)
for (ch=0; ch<stereo; ch++)
{
si[ch][gr].ch=ch;
si[ch][gr].gr=gr;
}
for (gr=0; gr<ngr; gr++)
for (ch=0; ch<stereo; ch++)
readsfsi(si[ch][gr]);
int bitpos=0;
for (gr=0; gr<ngr; gr++)
for (ch=0; ch<stereo; ch++)
readgrsi(si[ch][gr], bitpos);
}
int mainslots=(hdrlsf?72:144)*1000*ratetab[hdrlsf?1:0][2][hdrbitrate]/(freqtab[hdrfreq]>>hdrlsf)+(hdrpadding?1:0)-4-(hdrcrc?2:0)-(hdrlsf?(stereo==1)?9:17:(stereo==1)?17:32);
if (huffoffset<maindatabegin)
huffoffset=maindatabegin;
memmove(huffbuf, huffbuf+huffoffset-maindatabegin, maindatabegin);
getbytes(huffbuf+maindatabegin, mainslots);
huffoffset=maindatabegin+mainslots;
bitbuf=huffbuf;
bitbufpos=&huffbit;
}
void ampegdecoder::readhuffman(grsistruct &si, float *xr)
{
int *ro=rotab[(si.blocktype!=2)?0:si.mixedblock?2:1];
int i;
for (i=0; i<si.regionend[2]; i+=2)
{
int t=(i<si.regionend[0])?0:(i<si.regionend[1])?1:2;
int linbits=htablinbits[si.tabsel[t]];
int val=huffmandecoder(htabs[si.tabsel[t]]);
int x;
double v;
x=val>>4;
if (x==15)
x=15+mpgetbits(linbits);
v=pow43tab[x];
if (x)
if (mpgetbit())
v=-v;
xr[ro[i+0]]=v;
x=val&15;
if (x==15)
x=15+mpgetbits(linbits);
v=pow43tab[x];
if (x)
if (mpgetbit())
v=-v;
xr[ro[i+1]]=v;
}
while ((*bitbufpos<si.grend)&&(i<576))
{
int val=huffmandecoder(htabs[si.tabsel[3]]);
int x;
x=(val>>3)&1;
if (x)
if (mpgetbit())
x=-x;
xr[ro[i+0]]=x;
x=(val>>2)&1;
if (x)
if (mpgetbit())
x=-x;
xr[ro[i+1]]=x;
x=(val>>1)&1;
if (x)
if (mpgetbit())
x=-x;
xr[ro[i+2]]=x;
x=val&1;
if (x)
if (mpgetbit())
x=-x;
xr[ro[i+3]]=x;
i+=4;
}
if (*bitbufpos>si.grend)
i-=4;
while (i<576)
xr[ro[i++]]=0;
}
void ampegdecoder::readscalefac(grsistruct &si, int *scalefacl)
{
*bitbufpos=si.grstart;
int newslen[4];
int blocknumber;
if (!hdrlsf)
{
newslen[0]=slentab[0][si.sfcompress];
newslen[1]=slentab[0][si.sfcompress];
newslen[2]=slentab[1][si.sfcompress];
newslen[3]=slentab[1][si.sfcompress];
blocknumber=6;
}
else
if ((hdrmode!=1)||!(hdrmodeext&1)||!si.ch)
{
if (si.sfcompress>=500)
{
newslen[0] = ((si.sfcompress-500)/ 3)%4;
newslen[1] = ((si.sfcompress-500)/ 1)%3;
newslen[2] = ((si.sfcompress-500)/ 1)%1;
newslen[3] = ((si.sfcompress-500)/ 1)%1;
blocknumber = 2;
}
else
if (si.sfcompress>=400)
{
newslen[0] = ((si.sfcompress-400)/20)%5;
newslen[1] = ((si.sfcompress-400)/ 4)%5;
newslen[2] = ((si.sfcompress-400)/ 1)%4;
newslen[3] = ((si.sfcompress-400)/ 1)%1;
blocknumber = 1;
}
else
{
newslen[0] = ((si.sfcompress- 0)/80)%5;
newslen[1] = ((si.sfcompress- 0)/16)%5;
newslen[2] = ((si.sfcompress- 0)/ 4)%4;
newslen[3] = ((si.sfcompress- 0)/ 1)%4;
blocknumber = 0;
}
}
else
{
if (si.sfcompress>=244)
{
newslen[0] = ((si.sfcompress-244)/ 3)%4;
newslen[1] = ((si.sfcompress-244)/ 1)%3;
newslen[2] = ((si.sfcompress-244)/ 1)%1;
newslen[3] = ((si.sfcompress-244)/ 1)%1;
blocknumber = 5;
}
else
if (si.sfcompress>=180)
{
newslen[0] = ((si.sfcompress-180)/16)%4;
newslen[1] = ((si.sfcompress-180)/ 4)%4;
newslen[2] = ((si.sfcompress-180)/ 1)%4;
newslen[3] = ((si.sfcompress-180)/ 1)%1;
blocknumber = 4;
}
else
{
newslen[0] = ((si.sfcompress- 0)/36)%5;
newslen[1] = ((si.sfcompress- 0)/ 6)%6;
newslen[2] = ((si.sfcompress- 0)/ 1)%6;
newslen[3] = ((si.sfcompress- 0)/ 1)%1;
blocknumber = 3;
}
}
int i,k;
int *sfb=sfbtab[blocknumber][(si.blocktype!=2)?0:si.mixedblock?2:1];
int *sfp=scalefacl;
for (i=0;i<4;i++)
if (!si.sfsi[i])
for (k=sfb[i]; k<sfb[i+1]; k++)
*sfp++=mpgetbits(newslen[i]);
else
sfp+=sfb[i+1]-sfb[i];
*sfp++=0;
*sfp++=0;
*sfp++=0;
}
void ampegdecoder::readgrsi(grsistruct &si, int &bitpos)
{
int i;
si.grstart=bitpos;
bitpos+=mpgetbits(12);
si.grend=bitpos;
si.regionend[2]=mpgetbits(9)*2;
si.globalgain=mpgetbits(8);
if (hdrlsf&&(hdrmode==1)&&(hdrmodeext&1)&&si.ch)
{
si.sfcompress=mpgetbits(8);
si.ktabsel=mpgetbit();
}
else
{
si.sfcompress=mpgetbits(hdrlsf?9:4);
si.ktabsel=2;
}
if (mpgetbit())
{
si.blocktype = mpgetbits(2);
si.mixedblock = mpgetbit();
for (i=0; i<2; i++)
si.tabsel[i]=mpgetbits(5);
si.tabsel[2]=0;
for (i=0; i<3; i++)
si.subblockgain[i]=4*mpgetbits(3);
if (si.blocktype==2)
si.regionend[0]=sfbands[hdrlsf][hdrfreq][3];
else
si.regionend[0]=sfbandl[hdrlsf][hdrfreq][HUFFMAXLONG];
si.regionend[1]=576;
}
else
{
for (i=0; i<3; i++)
si.tabsel[i]=mpgetbits(5);
int region0count = mpgetbits(4)+1;
int region1count = mpgetbits(3)+1+region0count;
si.regionend[0]=sfbandl[hdrlsf][hdrfreq][region0count];
si.regionend[1]=sfbandl[hdrlsf][hdrfreq][region1count];
si.blocktype = 0;
si.mixedblock = 0;
}
if (si.regionend[0]>si.regionend[2])
si.regionend[0]=si.regionend[2];
if (si.regionend[1]>si.regionend[2])
si.regionend[1]=si.regionend[2];
si.regionend[3]=576;
si.preflag=hdrlsf?(si.sfcompress>=500)?1:0:mpgetbit();
si.sfshift=mpgetbit();
si.tabsel[3]=mpgetbit()?33:32;
if (si.blocktype)
for (i=0; i<4; i++)
si.sfsi[i]=0;
}
