📄 fftsg.cpp
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xr = a[j1];
xi = -a[j1 + 1];
yr = a[k1];
yi = -a[k1 + 1];
a[j1] = yr;
a[j1 + 1] = yi;
a[k1] = xr;
a[k1 + 1] = xi;
}
k1 = 2 * k + ip[k];
a[k1 + 1] = -a[k1 + 1];
j1 = k1 + m2;
k1 = j1 + m2;
xr = a[j1];
xi = -a[j1 + 1];
yr = a[k1];
yi = -a[k1 + 1];
a[j1] = yr;
a[j1 + 1] = yi;
a[k1] = xr;
a[k1 + 1] = xi;
k1 += m2;
a[k1 + 1] = -a[k1 + 1];
}
} else {
a[1] = -a[1];
a[m2 + 1] = -a[m2 + 1];
for (k = 1; k < m; k++) {
for (j = 0; j < k; j++) {
j1 = 2 * j + ip[k];
k1 = 2 * k + ip[j];
xr = a[j1];
xi = -a[j1 + 1];
yr = a[k1];
yi = -a[k1 + 1];
a[j1] = yr;
a[j1 + 1] = yi;
a[k1] = xr;
a[k1 + 1] = xi;
j1 += m2;
k1 += m2;
xr = a[j1];
xi = -a[j1 + 1];
yr = a[k1];
yi = -a[k1 + 1];
a[j1] = yr;
a[j1 + 1] = yi;
a[k1] = xr;
a[k1 + 1] = xi;
}
k1 = 2 * k + ip[k];
a[k1 + 1] = -a[k1 + 1];
a[k1 + m2 + 1] = -a[k1 + m2 + 1];
}
}
}
static void bitrv216(REAL *a)
{
REAL x1r, x1i, x2r, x2i, x3r, x3i, x4r, x4i,
x5r, x5i, x7r, x7i, x8r, x8i, x10r, x10i,
x11r, x11i, x12r, x12i, x13r, x13i, x14r, x14i;
x1r = a[2];
x1i = a[3];
x2r = a[4];
x2i = a[5];
x3r = a[6];
x3i = a[7];
x4r = a[8];
x4i = a[9];
x5r = a[10];
x5i = a[11];
x7r = a[14];
x7i = a[15];
x8r = a[16];
x8i = a[17];
x10r = a[20];
x10i = a[21];
x11r = a[22];
x11i = a[23];
x12r = a[24];
x12i = a[25];
x13r = a[26];
x13i = a[27];
x14r = a[28];
x14i = a[29];
a[2] = x8r;
a[3] = x8i;
a[4] = x4r;
a[5] = x4i;
a[6] = x12r;
a[7] = x12i;
a[8] = x2r;
a[9] = x2i;
a[10] = x10r;
a[11] = x10i;
a[14] = x14r;
a[15] = x14i;
a[16] = x1r;
a[17] = x1i;
a[20] = x5r;
a[21] = x5i;
a[22] = x13r;
a[23] = x13i;
a[24] = x3r;
a[25] = x3i;
a[26] = x11r;
a[27] = x11i;
a[28] = x7r;
a[29] = x7i;
}
static void bitrv216neg(REAL *a)
{
REAL x1r, x1i, x2r, x2i, x3r, x3i, x4r, x4i,
x5r, x5i, x6r, x6i, x7r, x7i, x8r, x8i,
x9r, x9i, x10r, x10i, x11r, x11i, x12r, x12i,
x13r, x13i, x14r, x14i, x15r, x15i;
x1r = a[2];
x1i = a[3];
x2r = a[4];
x2i = a[5];
x3r = a[6];
x3i = a[7];
x4r = a[8];
x4i = a[9];
x5r = a[10];
x5i = a[11];
x6r = a[12];
x6i = a[13];
x7r = a[14];
x7i = a[15];
x8r = a[16];
x8i = a[17];
x9r = a[18];
x9i = a[19];
x10r = a[20];
x10i = a[21];
x11r = a[22];
x11i = a[23];
x12r = a[24];
x12i = a[25];
x13r = a[26];
x13i = a[27];
x14r = a[28];
x14i = a[29];
x15r = a[30];
x15i = a[31];
a[2] = x15r;
a[3] = x15i;
a[4] = x7r;
a[5] = x7i;
a[6] = x11r;
a[7] = x11i;
a[8] = x3r;
a[9] = x3i;
a[10] = x13r;
a[11] = x13i;
a[12] = x5r;
a[13] = x5i;
a[14] = x9r;
a[15] = x9i;
a[16] = x1r;
a[17] = x1i;
a[18] = x14r;
a[19] = x14i;
a[20] = x6r;
a[21] = x6i;
a[22] = x10r;
a[23] = x10i;
a[24] = x2r;
a[25] = x2i;
a[26] = x12r;
a[27] = x12i;
a[28] = x4r;
a[29] = x4i;
a[30] = x8r;
a[31] = x8i;
}
static void bitrv208(REAL *a)
{
REAL x1r, x1i, x3r, x3i, x4r, x4i, x6r, x6i;
x1r = a[2];
x1i = a[3];
x3r = a[6];
x3i = a[7];
x4r = a[8];
x4i = a[9];
x6r = a[12];
x6i = a[13];
a[2] = x4r;
a[3] = x4i;
a[6] = x6r;
a[7] = x6i;
a[8] = x1r;
a[9] = x1i;
a[12] = x3r;
a[13] = x3i;
}
static void bitrv208neg(REAL *a)
{
REAL x1r, x1i, x2r, x2i, x3r, x3i, x4r, x4i,
x5r, x5i, x6r, x6i, x7r, x7i;
x1r = a[2];
x1i = a[3];
x2r = a[4];
x2i = a[5];
x3r = a[6];
x3i = a[7];
x4r = a[8];
x4i = a[9];
x5r = a[10];
x5i = a[11];
x6r = a[12];
x6i = a[13];
x7r = a[14];
x7i = a[15];
a[2] = x7r;
a[3] = x7i;
a[4] = x3r;
a[5] = x3i;
a[6] = x5r;
a[7] = x5i;
a[8] = x1r;
a[9] = x1i;
a[10] = x6r;
a[11] = x6i;
a[12] = x2r;
a[13] = x2i;
a[14] = x4r;
a[15] = x4i;
}
static void cftf1st(int n, REAL *a, REAL *w)
{
int j, j0, j1, j2, j3, k, m, mh;
REAL wn4r, csc1, csc3, wk1r, wk1i, wk3r, wk3i,
wd1r, wd1i, wd3r, wd3i;
REAL x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i,
y0r, y0i, y1r, y1i, y2r, y2i, y3r, y3i;
mh = n >> 3;
m = 2 * mh;
j1 = m;
j2 = j1 + m;
j3 = j2 + m;
x0r = a[0] + a[j2];
x0i = a[1] + a[j2 + 1];
x1r = a[0] - a[j2];
x1i = a[1] - a[j2 + 1];
x2r = a[j1] + a[j3];
x2i = a[j1 + 1] + a[j3 + 1];
x3r = a[j1] - a[j3];
x3i = a[j1 + 1] - a[j3 + 1];
a[0] = x0r + x2r;
a[1] = x0i + x2i;
a[j1] = x0r - x2r;
a[j1 + 1] = x0i - x2i;
a[j2] = x1r - x3i;
a[j2 + 1] = x1i + x3r;
a[j3] = x1r + x3i;
a[j3 + 1] = x1i - x3r;
wn4r = w[1];
csc1 = w[2];
csc3 = w[3];
wd1r = 1;
wd1i = 0;
wd3r = 1;
wd3i = 0;
k = 0;
for (j = 2; j < mh - 2; j += 4) {
k += 4;
wk1r = csc1 * (wd1r + w[k]);
wk1i = csc1 * (wd1i + w[k + 1]);
wk3r = csc3 * (wd3r + w[k + 2]);
wk3i = csc3 * (wd3i - w[k + 3]);
wd1r = w[k];
wd1i = w[k + 1];
wd3r = w[k + 2];
wd3i = -w[k + 3];
j1 = j + m;
j2 = j1 + m;
j3 = j2 + m;
x0r = a[j] + a[j2];
x0i = a[j + 1] + a[j2 + 1];
x1r = a[j] - a[j2];
x1i = a[j + 1] - a[j2 + 1];
y0r = a[j + 2] + a[j2 + 2];
y0i = a[j + 3] + a[j2 + 3];
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