inline void poly_pointwise(poly* r, const poly* a, const poly* b)
{
for(size_t i = 0; i < PARAM_N; i++)
{
const uint16_t t = montgomery_reduce(3186*b->coeffs[i]); /* t is now in Montgomery domain */
r->coeffs[i] = montgomery_reduce(a->coeffs[i] * t); /* r->coeffs[i] is back in normal domain */
}
}
void mul_coefficients(IntWrapper<uint16_t>* poly, uint16_t* factors)
{
unsigned int i;
for(i = 0; i < PARAM_N; i++)
poly[i] = montgomery_reduce((poly[i] * factors[i]).toInt());
}
/* GS_bo_to_no; omegas need to be in Montgomery domain */
void ntt(IntWrapper<uint16_t> * a, const uint16_t* omega)
{
int i, start, j, jTwiddle, distance;
IntWrapper<uint16_t> temp;
uint16_t W;
for(i=0;i<10;i+=2)
{
// Even level
distance = (1<<i);
for(start = 0; start < distance;start++)
{
jTwiddle = 0;
for(j=start;j<PARAM_N-1;j+=2*distance)
{
W = omega[jTwiddle++];
temp = a[j];
a[j] = (temp + a[j + distance]); // Omit reduction (be lazy)
a[j + distance] = montgomery_reduce((W * (IntWrapper<uint32_t>(temp) + 3*PARAM_Q - IntWrapper<uint32_t>(a[j + distance]))).toInt());
}
}
// Odd level
distance <<= 1;
for(start = 0; start < distance;start++)
{
jTwiddle = 0;
for(j=start;j<PARAM_N-1;j+=2*distance)
{
W = omega[jTwiddle++];
temp = a[j];
a[j] = barrett_reduce((temp + a[j + distance]).toInt());
a[j + distance] = montgomery_reduce((W * (IntWrapper<uint32_t>(temp) + 3*PARAM_Q - IntWrapper<uint32_t>(a[j + distance]))).toInt());
}
}
}
}