ref: a0d4c5e208405f84076891faaa43235bb2b87fc2
dir: /sys/src/libmp/port/mprand.c/
#include "os.h" #include <mp.h> #include "dat.h" mpint* mprand(int bits, void (*gen)(uchar*, int), mpint *b) { mpdigit mask; int n, m; uchar *p; n = DIGITS(bits); if(b == nil){ b = mpnew(bits); setmalloctag(b, getcallerpc(&bits)); }else mpbits(b, bits); p = malloc(n*Dbytes); if(p == nil) sysfatal("mprand: %r"); (*gen)(p, n*Dbytes); betomp(p, n*Dbytes, b); free(p); // make sure we don't give too many bits m = bits%Dbits; if(m == 0) return b; mask = 1; mask <<= m; mask--; b->p[n-1] &= mask; return mpnorm(b); }