tmpadd.c - plan9port - [fork] Plan 9 from user space
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       ---
       tmpadd.c (792B)
       ---
            1 #include "os.h"
            2 #include <mp.h>
            3 #include "dat.h"
            4 
            5 /* sum = abs(b1) + abs(b2), i.e., add the magnitudes */
            6 void
            7 mpmagadd(mpint *b1, mpint *b2, mpint *sum)
            8 {
            9         int m, n;
           10         mpint *t;
           11 
           12         /* get the sizes right */
           13         if(b2->top > b1->top){
           14                 t = b1;
           15                 b1 = b2;
           16                 b2 = t;
           17         }
           18         n = b1->top;
           19         m = b2->top;
           20         if(n == 0){
           21                 mpassign(mpzero, sum);
           22                 return;
           23         }
           24         if(m == 0){
           25                 mpassign(b1, sum);
           26                 return;
           27         }
           28         mpbits(sum, (n+1)*Dbits);
           29         sum->top = n+1;
           30 
           31         mpvecadd(b1->p, n, b2->p, m, sum->p);
           32         sum->sign = 1;
           33 
           34         mpnorm(sum);
           35 }
           36 
           37 /* sum = b1 + b2 */
           38 void
           39 mpadd(mpint *b1, mpint *b2, mpint *sum)
           40 {
           41         int sign;
           42 
           43         if(b1->sign != b2->sign){
           44                 if(b1->sign < 0)
           45                         mpmagsub(b2, b1, sum);
           46                 else
           47                         mpmagsub(b1, b2, sum);
           48         } else {
           49                 sign = b1->sign;
           50                 mpmagadd(b1, b2, sum);
           51                 if(sum->top != 0)
           52                         sum->sign = sign;
           53         }
           54 }