void subg(giant a, giant b)
/* b := b - a, any signs, any result. */
{
int asgn = a->sign, bsgn = b->sign;
if (asgn == 0)
return;
if (bsgn == 0)
{
gtog(a, b);
negg(b);
return;
}
if ((asgn < 0) != (bsgn < 0))
{
if (bsgn > 0)
{
negg(a);
normal_addg(a, b);
negg(a);
return;
}
negg(b);
normal_addg(a, b);
negg(b);
return;
}
if (bsgn > 0)
{
if (gcompg(b, a) >= 0)
{
normal_subg(a, b);
return;
}
reverse_subg(a, b);
negg(b);
return;
}
negg(a);
negg(b);
if (gcompg(b, a) >= 0)
{
normal_subg(a, b);
negg(a);
negg(b);
return;
}
reverse_subg(a, b);
negg(a);
return;
}
void addg(giant a, giant b)
/* b := b + a, any signs any result. */
{ int asgn = a->sign, bsgn = b->sign;
if(asgn == 0) return;
if(bsgn == 0) {
gtog(a,b);
return;
}
if((asgn < 0) == (bsgn < 0)) {
if(bsgn > 0) {
normal_addg(a,b);
return;
}
negg(a); if(a != b) negg(b); normal_addg(a,b); /* Fix REC 1 Dec 98. */
negg(a); if(a != b) negg(b); return; /* Fix REC 1 Dec 98. */
}
if(bsgn > 0) {
negg(a);
if(gcompg(b,a) >= 0) {
normal_subg(a,b);
negg(a);
return;
}
reverse_subg(a,b);
negg(a);
negg(b);
return;
}
negg(b);
if(gcompg(b,a) < 0) {
reverse_subg(a,b);
return;
}
normal_subg(a,b);
negg(b);
return;
}