csvorbis.Mdct.mdct_kernel C# (CSharp) Method

        internal float[] mdct_kernel(float[] x, float[] w,
			int n, int n2, int n4, int n8)
        {
            // step 2

            int xA=n4;
            int xB=0;
            int w2=n4;
            int A=n2;

            for(int i=0;i<n4;)
            {
                float x0=x[xA] - x[xB];
                float x1;
                w[w2+i]=x[xA++]+x[xB++];

                x1=x[xA]-x[xB];
                A-=4;

                w[i++]=   x0 * trig[A] + x1 * trig[A+1];
                w[i]=     x1 * trig[A] - x0 * trig[A+1];

                w[w2+i]=x[xA++]+x[xB++];
                i++;
            }

            // step 3

            {
            for(int i=0;i<log2n-3;i++)
            {
                int k0=(int)((uint)n >> (i+2));
                int k1=1 << (i+3);
                int wbase=n2-2;

                A=0;
                float[] temp;

                for(int r=0; r<((uint)k0>>2); r++)
                {
                    int w1=wbase;
                    w2=w1-(k0>>1);
                    float AEv= trig[A],wA;
                    float AOv= trig[A+1],wB;
                    wbase-=2;

                    k0++;
                    for(int s=0;s<(2<<i);s++)
                    {
                        wB     =w[w1]   -w[w2];
                        x[w1]  =w[w1]   +w[w2];

                        wA     =w[++w1] -w[++w2];
                        x[w1]  =w[w1]   +w[w2];

                        x[w2]  =wA*AEv  - wB*AOv;
                        x[w2-1]=wB*AEv  + wA*AOv;

                        w1-=k0;
                        w2-=k0;
                    }
                    k0--;
                    A+=k1;
                }

                temp=w;
                w=x;
                x=temp;
            }
            }

            // step 4, 5, 6, 7
            {
            int C=n;
            int bit=0;
            int x1=0;
            int x2=n2-1;

            for(int i=0;i<n8;i++)
            {
                int t1=bitrev[bit++];
                int t2=bitrev[bit++];

                float wA=w[t1]-w[t2+1];
                float wB=w[t1-1]+w[t2];
                float wC=w[t1]+w[t2+1];
                float wD=w[t1-1]-w[t2];

                float wACE=wA* trig[C];
                float wBCE=wB* trig[C++];
                float wACO=wA* trig[C];
                float wBCO=wB* trig[C++];

                x[x1++]=( wC+wACO+wBCE)*.5f;
                x[x2--]=(-wD+wBCO-wACE)*.5f;
                x[x1++]=( wD+wBCO-wACE)*.5f;
                x[x2--]=( wC-wACO-wBCE)*.5f;
            }
            }
            return(x);
        }