ref: 972518cb05abadad60bd61a454f743ca72042c47
dir: /libmp/mprand.c/
#include "os.h" #include <mp.h> #include <libsec.h> #include "dat.h" mpint* mprand(int bits, void (*gen)(uchar*, int), mpint *b) { int n, m; mpdigit mask; uchar *p; n = DIGITS(bits); if(b == nil) b = mpnew(bits); else mpbits(b, bits); p = malloc(n*Dbytes); if(p == nil) return nil; (*gen)(p, n*Dbytes); betomp(p, n*Dbytes, b); free(p); // make sure we don't give too many bits m = bits%Dbits; n--; if(m > 0){ mask = 1; mask <<= m; mask--; b->p[n] &= mask; } for(; n >= 0; n--) if(b->p[n] != 0) break; b->top = n+1; b->sign = 1; return b; }