drawterm/libmp/mpadd.c

55 lines
783 B
C

#include "os.h"
#include <mp.h>
#include "dat.h"
// sum = abs(b1) + abs(b2), i.e., add the magnitudes
void
mpmagadd(mpint *b1, mpint *b2, mpint *sum)
{
int m, n;
mpint *t;
// get the sizes right
if(b2->top > b1->top){
t = b1;
b1 = b2;
b2 = t;
}
n = b1->top;
m = b2->top;
if(n == 0){
mpassign(mpzero, sum);
return;
}
if(m == 0){
mpassign(b1, sum);
return;
}
mpbits(sum, (n+1)*Dbits);
sum->top = n+1;
mpvecadd(b1->p, n, b2->p, m, sum->p);
sum->sign = 1;
mpnorm(sum);
}
// sum = b1 + b2
void
mpadd(mpint *b1, mpint *b2, mpint *sum)
{
int sign;
if(b1->sign != b2->sign){
if(b1->sign < 0)
mpmagsub(b2, b1, sum);
else
mpmagsub(b1, b2, sum);
} else {
sign = b1->sign;
mpmagadd(b1, b2, sum);
if(sum->top != 0)
sum->sign = sign;
}
}