/* cr90 compares the values of two multiple precision numbers */
int __cr(const mp_no *x, const mp_no *y, int p) {
int i;
if (X[0] > Y[0]) i= 1;
else if (X[0] < Y[0]) i=-1;
else if (X[0] < ZERO ) i= __acr(y,x,p);
else i= __acr(x,y,p);
return i;
}
/* Subtract *Y from *X and return the result in *Z. X and Y may overlap but
not X and Z or Y and Z. One guard digit is used. The error is less than
one ULP. */
void
SECTION
__sub (const mp_no *x, const mp_no *y, mp_no *z, int p)
{
int n;
if (X[0] == 0)
{
__cpy (y, z, p);
Z[0] = -Z[0];
return;
}
else if (Y[0] == 0)
{
__cpy (x, z, p);
return;
}
if (X[0] != Y[0])
{
if (__acr (x, y, p) > 0)
{
add_magnitudes (x, y, z, p);
Z[0] = X[0];
}
else
{
add_magnitudes (y, x, z, p);
Z[0] = -Y[0];
}
}
else
{
if ((n = __acr (x, y, p)) == 1)
{
sub_magnitudes (x, y, z, p);
Z[0] = X[0];
}
else if (n == -1)
{
sub_magnitudes (y, x, z, p);
Z[0] = -Y[0];
}
else
Z[0] = 0;
}
}
void __add(const mp_no *x, const mp_no *y, mp_no *z, int p) {
int n;
if (X[0] == ZERO) {__cpy(y,z,p); return; }
else if (Y[0] == ZERO) {__cpy(x,z,p); return; }
if (X[0] == Y[0]) {
if (__acr(x,y,p) > 0) {add_magnitudes(x,y,z,p); Z[0] = X[0]; }
else {add_magnitudes(y,x,z,p); Z[0] = Y[0]; }
}
else {
if ((n=__acr(x,y,p)) == 1) {sub_magnitudes(x,y,z,p); Z[0] = X[0]; }
else if (n == -1) {sub_magnitudes(y,x,z,p); Z[0] = Y[0]; }
else Z[0] = ZERO;
}
return;
}
