using System;
using System.Collections.Generic;
namespace OggVorbisEncoder.Lookups
{
public class DrftLookup
{
private readonly IList<int> _splitCache;
private readonly IList<float> _trigCache;
public DrftLookup(int n)
{
N = n;
_trigCache = new float[3*n];
_splitCache = new int[32];
fdrffti(n);
}
public int N;
private void fdrffti(int n)
{
if (n == 1)
return;
drfti1(n);
}
private void drfti1(int n)
{
int[] ntryh = {4, 2, 3, 5};
const float tpi = 6.28318530717958648f;
int ntry = 0, i, j = -1;
var nl = n;
var nf = 0;
int nr;
do
{
j++;
if (j < 4)
ntry = ntryh[j];
else
ntry += 2;
do
{
var nq = nl/ntry;
nr = nl - ntry*nq;
if (nr != 0)
break;
nf++;
_splitCache[nf + 1] = ntry;
nl = nq;
if ((ntry != 2) || (nf == 1))
continue;
for (i = 1; i < nf; i++)
{
var ib = nf - i + 1;
_splitCache[ib + 1] = _splitCache[ib];
}
_splitCache[2] = 2;
} while (nl != 1);
} while (nr != 1);
_splitCache[0] = n;
_splitCache[1] = nf;
var argh = tpi/n;
var setting = n;
var nfm1 = nf - 1;
var l1 = 1;
if (nfm1 == 0)
return;
for (var k1 = 0; k1 < nfm1; k1++)
{
var ip = _splitCache[k1 + 2];
var ld = 0;
var l2 = l1*ip;
var ido = n/l2;
var ipm = ip - 1;
for (j = 0; j < ipm; j++)
{
ld += l1;
i = setting;
var argld = ld*argh;
var fi = 0f;
int ii;
for (ii = 2; ii < ido; ii += 2)
{
fi += 1f;
var arg = fi*argld;
_trigCache[i++] = (float) Math.Cos(arg);
_trigCache[i++] = (float) Math.Sin(arg);
}
setting += ido;
}
l1 = l2;
}
}
public void Forward(IList<float> data)
{
if (N == 1)
return;
var nf = _splitCache[1];
var na = 1;
var l2 = N;
var iw = N;
for (var k1 = 0; k1 < nf; k1++)
{
var kh = nf - k1;
var ip = _splitCache[kh + 1];
var l1 = l2/ip;
var ido = N/l2;
var idl1 = ido*l1;
iw -= (ip - 1)*ido;
na = 1 - na;
if (ip != 4)
{
if (ip != 2)
{
if (ido == 1)
na = 1 - na;
if (na != 0)
{
dradfg(ido, ip, l1, idl1, _trigCache, _trigCache, _trigCache, data, data, N + iw - 1);
na = 0;
}
else
{
dradfg(ido, ip, l1, idl1, data, data, data, _trigCache, _trigCache, N + iw - 1);
na = 1;
}
}
else
{
if (na != 0)
dradf2(ido, l1, _trigCache, data, N + iw - 1);
else
dradf2(ido, l1, data, _trigCache, N + iw - 1);
}
}
else
{
var ix2 = iw + ido;
var ix3 = ix2 + ido;
if (na != 0)
dradf4(ido, l1, _trigCache, data, N + iw - 1, N + ix2 - 1, N + ix3 - 1);
else
dradf4(ido, l1, data, _trigCache, N + iw - 1, N + ix2 - 1, N + ix3 - 1);
}
l2 = l1;
}
if (na == 1)
return;
for (var i = 0; i < N; i++)
data[i] = _trigCache[i];
}
private void dradf4(int ido, int l1, IList<float> cc, IList<float> ch, int wa1, int wa2, int wa3)
{
const float hsqt2 = .70710678118654752f;
int k, t5, t6;
float ti1;
float tr1, tr2;
var t0 = l1*ido;
var t1 = t0;
var t4 = t1 << 1;
var t2 = t1 + (t1 << 1);
var t3 = 0;
for (k = 0; k < l1; k++)
{
tr1 = cc[t1] + cc[t2];
tr2 = cc[t3] + cc[t4];
ch[t5 = t3 << 2] = tr1 + tr2;
ch[(ido << 2) + t5 - 1] = tr2 - tr1;
ch[(t5 += ido << 1) - 1] = cc[t3] - cc[t4];
ch[t5] = cc[t2] - cc[t1];
t1 += ido;
t2 += ido;
t3 += ido;
t4 += ido;
}
if (ido < 2)
return;
if (ido > 2)
{
t1 = 0;
for (k = 0; k < l1; k++)
{
t2 = t1;
t4 = t1 << 2;
t5 = (t6 = ido << 1) + t4;
for (var i = 2; i < ido; i += 2)
{
t3 = t2 += 2;
t4 += 2;
t5 -= 2;
t3 += t0;
var cr2 = _trigCache[wa1 + i - 2]*cc[t3 - 1] + _trigCache[wa1 + i - 1]*cc[t3];
var ci2 = _trigCache[wa1 + i - 2]*cc[t3] - _trigCache[wa1 + i - 1]*cc[t3 - 1];
t3 += t0;
var cr3 = _trigCache[wa2 + i - 2]*cc[t3 - 1] + _trigCache[wa2 + i - 1]*cc[t3];
var ci3 = _trigCache[wa2 + i - 2]*cc[t3] - _trigCache[wa2 + i - 1]*cc[t3 - 1];
t3 += t0;
var cr4 = _trigCache[wa3 + i - 2]*cc[t3 - 1] + _trigCache[wa3 + i - 1]*cc[t3];
var ci4 = _trigCache[wa3 + i - 2]*cc[t3] - _trigCache[wa3 + i - 1]*cc[t3 - 1];
tr1 = cr2 + cr4;
var tr4 = cr4 - cr2;
ti1 = ci2 + ci4;
var ti4 = ci2 - ci4;
var ti2 = cc[t2] + ci3;
var ti3 = cc[t2] - ci3;
tr2 = cc[t2 - 1] + cr3;
var tr3 = cc[t2 - 1] - cr3;
ch[t4 - 1] = tr1 + tr2;
ch[t4] = ti1 + ti2;
ch[t5 - 1] = tr3 - ti4;
ch[t5] = tr4 - ti3;
ch[t4 + t6 - 1] = ti4 + tr3;
ch[t4 + t6] = tr4 + ti3;
ch[t5 + t6 - 1] = tr2 - tr1;
ch[t5 + t6] = ti1 - ti2;
}
t1 += ido;
}
if ((ido & 1) != 0)
return;
}
t2 = (t1 = t0 + ido - 1) + (t0 << 1);
t3 = ido << 2;
t4 = ido;
t5 = ido << 1;
t6 = ido;
for (k = 0; k < l1; k++)
{
ti1 = -hsqt2*(cc[t1] + cc[t2]);
tr1 = hsqt2*(cc[t1] - cc[t2]);
ch[t4 - 1] = tr1 + cc[t6 - 1];
ch[t4 + t5 - 1] = cc[t6 - 1] - tr1;
ch[t4] = ti1 - cc[t1 + t0];
ch[t4 + t5] = ti1 + cc[t1 + t0];
t1 += ido;
t2 += ido;
t4 += t3;
t6 += ido;
}
}
private void dradf2(int ido, int l1, IList<float> cc, IList<float> ch, int wa1)
{
var t1 = 0;
var t2 = l1*ido;
var t0 = t2;
var t3 = ido << 1;
for (var k = 0; k < l1; k++)
{
ch[t1 << 1] = cc[t1] + cc[t2];
ch[(t1 << 1) + t3 - 1] = cc[t1] - cc[t2];
t1 += ido;
t2 += ido;
}
if (ido < 2)
return;
if (ido > 2)
{
t1 = 0;
t2 = t0;
for (var k = 0; k < l1; k++)
{
t3 = t2;
var t4 = (t1 << 1) + (ido << 1);
var t5 = t1;
var t6 = t1 + t1;
for (var i = 2; i < ido; i += 2)
{
t3 += 2;
t4 -= 2;
t5 += 2;
t6 += 2;
var tr2 = _trigCache[wa1 + i - 2]*cc[t3 - 1] + _trigCache[wa1 + i - 1]*cc[t3];
var ti2 = _trigCache[wa1 + i - 2]*cc[t3] - _trigCache[wa1 + i - 1]*cc[t3 - 1];
ch[t6] = cc[t5] + ti2;
ch[t4] = ti2 - cc[t5];
ch[t6 - 1] = cc[t5 - 1] + tr2;
ch[t4 - 1] = cc[t5 - 1] - tr2;
}
t1 += ido;
t2 += ido;
}
if (ido%2 == 1)
return;
}
t3 = t2 = (t1 = ido) - 1;
t2 += t0;
for (var k = 0; k < l1; k++)
{
ch[t1] = -cc[t2];
ch[t1 - 1] = cc[t3];
t1 += ido << 1;
t2 += ido;
t3 += ido;
}
}
private void dradfg(int ido, int ip, int l1, int idl1, IList<float> cc, IList<float> c1, IList c2,
IList<float> ch, IList<float> ch2, int wa)
{
const float tpi = 6.283185307179586f;
var arg = tpi/ip;
var dcp = (float) Math.Cos(arg);
var dsp = (float) Math.Sin(arg);
var ipph = (ip + 1) >> 1;
var ipp2 = ip;
var idp2 = ido;
var nbd = (ido - 1) >> 1;
var t0 = l1*ido;
var t10 = ip*ido;
int i, j, k, l, ik, t1, t2, t3, t4, t5, t6, t7, t8, t9;
if (ido != 1)
{
for (ik = 0; ik < idl1; ik++)
ch2[ik] = c2[ik];
t1 = 0;
for (j = 1; j < ip; j++)
{
t1 += t0;
t2 = t1;
for (k = 0; k < l1; k++)
{
ch[t2] = c1[t2];
t2 += ido;
}
}
var setting = -ido;
t1 = 0;
if (nbd > l1)
for (j = 1; j < ip; j++)
{
t1 += t0;
setting += ido;
t2 = -ido + t1;
for (k = 0; k < l1; k++)
{
var idij = setting - 1;
t2 += ido;
t3 = t2;
for (i = 2; i < ido; i += 2)
{
idij += 2;
t3 += 2;
ch[t3 - 1] = _trigCache[wa + idij - 1]*c1[t3 - 1] + _trigCache[wa + idij]*c1[t3];
ch[t3] = _trigCache[wa + idij - 1]*c1[t3] - _trigCache[wa + idij]*c1[t3 - 1];
}
}
}
else
for (j = 1; j < ip; j++)
{
setting += ido;
var idij = setting - 1;
t1 += t0;
t2 = t1;
for (i = 2; i < ido; i += 2)
{
idij += 2;
t2 += 2;
t3 = t2;
for (k = 0; k < l1; k++)
{
ch[t3 - 1] = _trigCache[wa + idij - 1]*c1[t3 - 1] + _trigCache[wa + idij]*c1[t3];
ch[t3] = _trigCache[wa + idij - 1]*c1[t3] - _trigCache[wa + idij]*c1[t3 - 1];
t3 += ido;
}
}
}
t1 = 0;
t2 = ipp2*t0;
if (nbd < l1)
for (j = 1; j < ipph; j++)
{
t1 += t0;
t2 -= t0;
t3 = t1;
t4 = t2;
for (i = 2; i < ido; i += 2)
{
t3 += 2;
t4 += 2;
t5 = t3 - ido;
t6 = t4 - ido;
for (k = 0; k < l1; k++)
{
t5 += ido;
t6 += ido;
c1[t5 - 1] = ch[t5 - 1] + ch[t6 - 1];
c1[t6 - 1] = ch[t5] - ch[t6];
c1[t5] = ch[t5] + ch[t6];
c1[t6] = ch[t6 - 1] - ch[t5 - 1];
}
}
}
else
for (j = 1; j < ipph; j++)
{
t1 += t0;
t2 -= t0;
t3 = t1;
t4 = t2;
for (k = 0; k < l1; k++)
{
t5 = t3;
t6 = t4;
for (i = 2; i < ido; i += 2)
{
t5 += 2;
t6 += 2;
c1[t5 - 1] = ch[t5 - 1] + ch[t6 - 1];
c1[t6 - 1] = ch[t5] - ch[t6];
c1[t5] = ch[t5] + ch[t6];
c1[t6] = ch[t6 - 1] - ch[t5 - 1];
}
t3 += ido;
t4 += ido;
}
}
}
for (ik = 0; ik < idl1; ik++)
c2[ik] = ch2[ik];
t1 = 0;
t2 = ipp2*idl1;
for (j = 1; j < ipph; j++)
{
t1 += t0;
t2 -= t0;
t3 = t1 - ido;
t4 = t2 - ido;
for (k = 0; k < l1; k++)
{
t3 += ido;
t4 += ido;
c1[t3] = ch[t3] + ch[t4];
c1[t4] = ch[t4] - ch[t3];
}
}
var ar1 = 1f;
var ai1 = 0f;
t1 = 0;
t2 = ipp2*idl1;
t3 = (ip - 1)*idl1;
for (l = 1; l < ipph; l++)
{
t1 += idl1;
t2 -= idl1;
var ar1h = dcp*ar1 - dsp*ai1;
ai1 = dcp*ai1 + dsp*ar1;
ar1 = ar1h;
t4 = t1;
t5 = t2;
t6 = t3;
t7 = idl1;
for (ik = 0; ik < idl1; ik++)
{
ch2[t4++] = c2[ik] + ar1*c2[t7++];
ch2[t5++] = ai1*c2[t6++];
}
var dc2 = ar1;
var ds2 = ai1;
var ar2 = ar1;
var ai2 = ai1;
t4 = idl1;
t5 = (ipp2 - 1)*idl1;
for (j = 2; j < ipph; j++)
{
t4 += idl1;
t5 -= idl1;
var ar2h = dc2*ar2 - ds2*ai2;
ai2 = dc2*ai2 + ds2*ar2;
ar2 = ar2h;
t6 = t1;
t7 = t2;
t8 = t4;
t9 = t5;
for (ik = 0; ik < idl1; ik++)
{
ch2[t6++] += ar2*c2[t8++];
ch2[t7++] += ai2*c2[t9++];
}
}
}
t1 = 0;
for (j = 1; j < ipph; j++)
{
t1 += idl1;
t2 = t1;
for (ik = 0; ik < idl1; ik++)
ch2[ik] += c2[t2++];
}
if (ido < l1)
{
for (i = 0; i < ido; i++)
{
t1 = i;
t2 = i;
for (k = 0; k < l1; k++)
{
cc[t2] = ch[t1];
t1 += ido;
t2 += t10;
}
}
}
else
{
t1 = 0;
t2 = 0;
for (k = 0; k < l1; k++)
{
t3 = t1;
t4 = t2;
for (i = 0; i < ido; i++)
cc[t4++] = ch[t3++];
t1 += ido;
t2 += t10;
}
}
t1 = 0;
t2 = ido << 1;
t3 = 0;
t4 = ipp2*t0;
for (j = 1; j < ipph; j++)
{
t1 += t2;
t3 += t0;
t4 -= t0;
t5 = t1;
t6 = t3;
t7 = t4;
for (k = 0; k < l1; k++)
{
cc[t5 - 1] = ch[t6];
cc[t5] = ch[t7];
t5 += t10;
t6 += ido;
t7 += ido;
}
}
if (ido == 1)
return;
if (nbd >= l1)
{
t1 = -ido;
t3 = 0;
t4 = 0;
t5 = ipp2*t0;
for (j = 1; j < ipph; j++)
{
t1 += t2;
t3 += t2;
t4 += t0;
t5 -= t0;
t6 = t1;
t7 = t3;
t8 = t4;
t9 = t5;
for (k = 0; k < l1; k++)
{
for (i = 2; i < ido; i += 2)
{
var ic = idp2 - i;
cc[i + t7 - 1] = ch[i + t8 - 1] + ch[i + t9 - 1];
cc[ic + t6 - 1] = ch[i + t8 - 1] - ch[i + t9 - 1];
cc[i + t7] = ch[i + t8] + ch[i + t9];
cc[ic + t6] = ch[i + t9] - ch[i + t8];
}
t6 += t10;
t7 += t10;
t8 += ido;
t9 += ido;
}
}
return;
}
t1 = -ido;
t3 = 0;
t4 = 0;
t5 = ipp2*t0;
for (j = 1; j < ipph; j++)
{
t1 += t2;
t3 += t2;
t4 += t0;
t5 -= t0;
for (i = 2; i < ido; i += 2)
{
t6 = idp2 + t1 - i;
t7 = i + t3;
t8 = i + t4;
t9 = i + t5;
for (k = 0; k < l1; k++)
{
cc[t7 - 1] = ch[t8 - 1] + ch[t9 - 1];
cc[t6 - 1] = ch[t8 - 1] - ch[t9 - 1];
cc[t7] = ch[t8] + ch[t9];
cc[t6] = ch[t9] - ch[t8];
t6 += t10;
t7 += t10;
t8 += ido;
t9 += ido;
}
}
}
}
}
} 