/*O(n^2) cyclic convolution code for testing*/
void slow_cyclic_convolution_1024_40961(FFTSHORT z[1024], FFTSHORT x[1024], FFTSHORT y[1024]) {
FFTSHORT i,j,t;
for (i = 0; i < n; ++i) {
z[i] = 0;
for (j = 0; j <= i; ++j) {
MUL_MOD(t, x[j], y[i-j], q);
ADD_MOD(z[i], z[i], t, q);
}
for (j = i+1; j < n; ++j) {
MUL_MOD(t, x[j], y[n+i-j], q);
ADD_MOD(z[i], z[i], t, q);
}
}
}
static int change(MYLDAP_SESSION *session, const char *userdn,
const char *homedir, const char *shell)
{
#define NUMARGS 2
char *strvals[(NUMARGS + 1) * 2];
LDAPMod mods[(NUMARGS + 1)], *modsp[(NUMARGS + 1)];
int i = 0;
/* build the list of modifications */
ADD_MOD(attmap_passwd_homeDirectory, homedir);
ADD_MOD(attmap_passwd_loginShell, shell);
/* terminate the list of modifications */
modsp[i] = NULL;
/* execute the update */
return myldap_modify(session, userdn, modsp);
}
/*
We use Gentleman-Sande, decimation-in-frequency FFT, for the forward FFT.
We premultiply x by the 2n'th roots of unity to affect a Discrete Weighted Fourier Transform,
so when we apply pointwise multiplication we obtain the negacyclic convolution, i.e. multiplication
modulo x^n+1.
Note that we will not perform the usual scambling / bit-reversal procedure here because we will invert
the fourier transform using decimation-in-time.
*/
void FFT_twisted_forward_1024_40961(FFTSHORT x[1024]) {
FFTSHORT index, step;
FFTSHORT i,j,m;
FFTSHORT t0,t1;
//Pre multiplication for twisted FFT
j = 0;
for (i = 0; i < n>>1; ++i) {
MUL_MOD(x[j], x[j], W[i], q);
j++;
MUL_MOD(x[j], x[j], W_sqrt[i], q);
j++;
}
step = 1;
for (m = n>>1; m >= 1; m=m>>1) {
index = 0;
for (j = 0 ; j < m; ++j) {
for (i = j; i < n; i += (m<<1)) {
ADD_MOD(t0, x[i], x[i+m], q);
ADD(t1, x[i], q - x[i+m]);
MUL_MOD(x[i+m], t1, W[index], q);
x[i] = t0;
}
SUB_MODn(index, index, step);
}
step = step << 1;
}
}
INT X(safe_mulmod)(INT x, INT y, INT p)
{
INT r;
if (y > x)
return X(safe_mulmod)(y, x, p);
A(0 <= y && x < p);
r = 0;
while (y) {
r = ADD_MOD(r, x*(y&1), p); y >>= 1;
x = ADD_MOD(x, x, p);
}
return r;
}
/*
We use Gentleman-Sande, decimation-in-frequency FFT, for the forward FFT.
Note that we will not perform the usual scambling / bit-reversal procedure here because we will invert
the fourier transform using decimation-in-time.
*/
void FFT_forward_1024_40961(FFTSHORT x[1024]) {
FFTSHORT index, step;
FFTSHORT i,j,m;
FFTSHORT t0,t1;
step = 1;
for (m = n>>1; m >= 1; m=m>>1) {
index = 0;
for (j = 0 ; j < m; ++j) {
for (i = j; i < n; i += (m<<1)) {
ADD_MOD(t0, x[i], x[i+m], q);
ADD(t1, x[i], q - x[i+m]);
MUL_MOD(x[i+m], t1, W[index], q);
x[i] = t0;
}
SUB_MODn(index, index, step);
}
step = step << 1;
}
}
