/* tmp must have 2*n words */
void bn_sqr_normal(BN_ULONG *r, BN_ULONG *a, int n, BN_ULONG *tmp)
{
int i,j,max;
BN_ULONG *ap,*rp;
max=n*2;
ap=a;
rp=r;
rp[0]=rp[max-1]=0;
rp++;
j=n;
if (--j > 0)
{
ap++;
rp[j]=bn_mul_words(rp,ap,j,ap[-1]);
rp+=2;
}
for (i=n-2; i>0; i--)
{
j--;
ap++;
rp[j]=bn_mul_add_words(rp,ap,j,ap[-1]);
rp+=2;
}
bn_add_words(r,r,r,max);
/* There will not be a carry */
bn_sqr_words(tmp,a,n);
bn_add_words(r,r,tmp,max);
}
// tmp must have 2*n words
static void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, size_t n,
BN_ULONG *tmp) {
if (n == 0) {
return;
}
size_t max = n * 2;
const BN_ULONG *ap = a;
BN_ULONG *rp = r;
rp[0] = rp[max - 1] = 0;
rp++;
// Compute the contribution of a[i] * a[j] for all i < j.
if (n > 1) {
ap++;
rp[n - 1] = bn_mul_words(rp, ap, n - 1, ap[-1]);
rp += 2;
}
if (n > 2) {
for (size_t i = n - 2; i > 0; i--) {
ap++;
rp[i] = bn_mul_add_words(rp, ap, i, ap[-1]);
rp += 2;
}
}
// The final result fits in |max| words, so none of the following operations
// will overflow.
// Double |r|, giving the contribution of a[i] * a[j] for all i != j.
bn_add_words(r, r, r, max);
// Add in the contribution of a[i] * a[i] for all i.
bn_sqr_words(tmp, a, n);
bn_add_words(r, r, tmp, max);
}
