ref: 261ec9fe0e0b2dbde909da79a93e90220a9ea62c
dir: /sys/src/libc/port/lnrand.c/
#include	<u.h>
#include	<libc.h>
#define	MASK	0x7fffffffL
long
lnrand(long n)
{
	long slop, v;
	if(n < 0)
		return n;
	slop = MASK % n;
	do
		v = lrand();
	while(v <= slop);
	return v % n;
}