tgenprime.c - plan9port - [fork] Plan 9 from user space
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       ---
       tgenprime.c (544B)
       ---
            1 #include "os.h"
            2 #include <mp.h>
            3 #include <libsec.h>
            4 
            5 /*  generate a probable prime.  accuracy is the miller-rabin interations */
            6 void
            7 genprime(mpint *p, int n, int accuracy)
            8 {
            9         mpdigit x;
           10 
           11         /* generate n random bits with high and low bits set */
           12         mpbits(p, n);
           13         genrandom((uchar*)p->p, (n+7)/8);
           14         p->top = (n+Dbits-1)/Dbits;
           15         x = 1;
           16         x <<= ((n-1)%Dbits);
           17         p->p[p->top-1] &= (x-1);
           18         p->p[p->top-1] |= x;
           19         p->p[0] |= 1;
           20 
           21         /* keep icrementing till it looks prime */
           22         for(;;){
           23                 if(probably_prime(p, accuracy))
           24                         break;
           25                 mpadd(p, mptwo, p);
           26         }
           27 }