diff options
Diffstat (limited to 'src/libsec/port/nfastrand.c')
-rw-r--r-- | src/libsec/port/nfastrand.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/libsec/port/nfastrand.c b/src/libsec/port/nfastrand.c new file mode 100644 index 00000000..3ba77003 --- /dev/null +++ b/src/libsec/port/nfastrand.c @@ -0,0 +1,23 @@ +#include <u.h> +#include <libc.h> +#include <libsec.h> + +#define Maxrand ((1UL<<31)-1) + +ulong +nfastrand(ulong n) +{ + ulong m, r; + + /* + * set m to the maximum multiple of n <= 2^31-1 + * so we want a random number < m. + */ + if(n > Maxrand) + sysfatal("nfastrand: n too large"); + + m = Maxrand - Maxrand % n; + while((r = fastrand()) >= m) + ; + return r%n; +} |