void fft_radix2(mp_limb_t ** ii,
mp_size_t n, mp_bitcnt_t w, mp_limb_t ** t1, mp_limb_t ** t2)
{
mp_size_t i;
mp_size_t limbs = (w*n)/GMP_LIMB_BITS;
if (n == 1)
{
fft_butterfly(*t1, *t2, ii[0], ii[1], 0, limbs, w);
SWAP_PTRS(ii[0], *t1);
SWAP_PTRS(ii[1], *t2);
return;
}
for (i = 0; i < n; i++)
{
fft_butterfly(*t1, *t2, ii[i], ii[n+i], i, limbs, w);
SWAP_PTRS(ii[i], *t1);
SWAP_PTRS(ii[n+i], *t2);
}
fft_radix2(ii, n/2, 2*w, t1, t2);
fft_radix2(ii + n, n/2, 2*w, t1, t2);
}
void fmpz_add(fmpz_t coeffs_out, const fmpz_t in1, const fmpz_t in2)
{
fmpz_t coeffs1 = in1;
fmpz_t coeffs2 = in2;
long carry;
unsigned long size1 = ABS(coeffs1[0]);
unsigned long size2 = ABS(coeffs2[0]);
if (size1 < size2)
{
SWAP_PTRS(coeffs1, coeffs2);
size1 = ABS(coeffs1[0]);
size2 = ABS(coeffs2[0]);
}
if (!size1)
{
if (!size2) coeffs_out[0] = 0L;
else
{
if (coeffs_out != coeffs2) F_mpn_copy(coeffs_out, coeffs2, size2+1);
}
} else if (!size2)
{
if (coeffs_out != coeffs1) F_mpn_copy(coeffs_out, coeffs1, size1+1);
} else if ((long) (coeffs1[0] ^ coeffs2[0]) >= 0L)
{
coeffs_out[0] = coeffs1[0];
carry = mpn_add(coeffs_out+1, coeffs1+1, size1, coeffs2+1, size2);
if (carry)
{
coeffs_out[size1+1] = carry;
if ((long) coeffs_out[0] < 0L) coeffs_out[0]--;
else coeffs_out[0]++;
}
} else
{
carry = 0;
if (size1 != size2) carry = 1;
else carry = mpn_cmp(coeffs1+1, coeffs2+1, size1);
if (carry == 0) coeffs_out[0] = 0L;
else if (carry > 0)
{
mpn_sub(coeffs_out+1, coeffs1+1, size1, coeffs2+1, size2);
coeffs_out[0] = coeffs1[0];
NORM(coeffs_out);
}
else
{
mpn_sub_n(coeffs_out+1, coeffs2+1, coeffs1+1, size1);
coeffs_out[0] = -coeffs1[0];
NORM(coeffs_out);
}
}
}
void ifft_negacyclic(mp_limb_t ** ii, mp_size_t n, mp_bitcnt_t w,
mp_limb_t ** t1, mp_limb_t ** t2, mp_limb_t ** temp)
{
mp_size_t i;
mp_size_t limbs = (w*n)/FLINT_BITS;
ifft_radix2(ii, n/2, 2*w, t1, t2);
ifft_radix2(ii+n, n/2, 2*w, t1, t2);
if (w & 1)
{
for (i = 0; i < n; i++)
{
ifft_butterfly(*t1, *t2, ii[i], ii[n+i], i, limbs, w);
SWAP_PTRS(ii[i], *t1);
SWAP_PTRS(ii[n+i], *t2);
fft_adjust(*t1, ii[i], n - i/2, limbs, w);
mpn_neg_n(*t1, *t1, limbs + 1);
SWAP_PTRS(ii[i], *t1);
fft_adjust(*t2, ii[n+i], n - (n+i)/2, limbs, w);
mpn_neg_n(*t2, *t2, limbs + 1);
SWAP_PTRS(ii[n+i], *t2);
i++;
ifft_butterfly(*t1, *t2, ii[i], ii[n+i], i, limbs, w);
SWAP_PTRS(ii[i], *t1);
SWAP_PTRS(ii[n+i], *t2);
fft_adjust_sqrt2(*t1, ii[i], 2*n-i, limbs, w, *temp);
mpn_neg_n(*t1, *t1, limbs + 1);
SWAP_PTRS(ii[i], *t1);
fft_adjust_sqrt2(*t2, ii[n+i], n-i, limbs, w, *temp);
mpn_neg_n(*t2, *t2, limbs + 1);
SWAP_PTRS(ii[n+i], *t2);
}
} else
{
for (i = 0; i < n; i++)
{
ifft_butterfly(*t1, *t2, ii[i], ii[n+i], i, limbs, w);
SWAP_PTRS(ii[i], *t1);
SWAP_PTRS(ii[n+i], *t2);
fft_adjust(*t1, ii[i], 2*n-i, limbs, w/2);
mpn_neg_n(*t1, *t1, limbs + 1);
SWAP_PTRS(ii[i], *t1);
fft_adjust(*t2, ii[n+i], n-i, limbs, w/2);
mpn_neg_n(*t2, *t2, limbs + 1);
SWAP_PTRS(ii[n+i], *t2);
}
}
}
