private void PrepareWindow(int windowSize, WindowType windowType)
{
mWindowType = windowType;
switch (windowType)
{
case WindowType.Bartlett:
mWindow = WWWindowFunc.BartlettWindow(mProcessBlockSize + 1);
break;
case WindowType.Hann:
mWindow = WWWindowFunc.HannWindow(mProcessBlockSize + 1);
break;
default:
System.Diagnostics.Debug.Assert(false);
break;
}
}
/// <summary>
/// 窓関数をかけた周波数ドメイン値X^m(q)を戻す。
/// 同様の処理をWWGoertzel (Stable Goertzel algorithm)で行うこともできるだろう。
/// </summary>
public WWComplex[] FilterWithWindow(double x, WWWindowFunc.WindowType wt)
{
var r = Filter(x);
var rW = new WWComplex[r.Length];
var w = WWWindowFunc.FreqDomainWindowCoeffs(wt);
switch (w.Length)
{
case 2:
for (int i = 0; i < mN; ++i)
{
int il = i - 1;
if (il < 0)
{
il = mN - 1;
}
int ir = i + 1;
if (mN <= ir)
{
ir = 0;
}
rW[i] = WWComplex.Add(
WWComplex.Mul(r[il], w[1] * 0.5),
WWComplex.Mul(r[i], w[0]),
WWComplex.Mul(r[ir], w[1] * 0.5));
}
return(rW);
case 3:
for (int i = 0; i < mN; ++i)
{
var pos = new int[5];
for (int offs = -2; offs <= 2; ++offs)
{
int p = i + offs;
if (p < 0)
{
p += mN;
}
if (mN <= p)
{
p -= mN;
}
pos[offs + 2] = p;
}
rW[i] = WWComplex.Add(
WWComplex.Mul(r[pos[0]], w[2] * 0.5),
WWComplex.Mul(r[pos[1]], w[1] * 0.5),
WWComplex.Mul(r[pos[2]], w[0]),
WWComplex.Mul(r[pos[3]], w[1] * 0.5),
WWComplex.Mul(r[pos[4]], w[2] * 0.5));
}
return(rW);
default:
System.Diagnostics.Debug.Assert(false);
return(null);
}
}