// c: limited_big_rand
private static IRubyObject randLimitedBignum(
ThreadContext context, RandomType random, RubyBignum limit) {
byte[] buf = limit.getBigIntegerValue().toByteArray();
byte[] bytes = new byte[buf.length];
int len = (buf.length + 3) / 4;
// take care before code cleanup; it might break random sequence compatibility
retry:
while (true) {
long mask = 0;
boolean boundary = true;
for (int idx = len - 1; 0 <= idx; --idx) {
long lim = getIntBigIntegerBuffer(buf, idx) & 0xffffffffL;
mask = (mask != 0) ? 0xffffffffL : makeMask(lim);
long rnd;
if (mask != 0) {
rnd = (random.genrandInt32() & 0xffffffffL) & mask;
if (boundary) {
if (lim < rnd) {
continue retry;
}
if (rnd < lim) {
boundary = false;
}
}
} else {
rnd = 0;
}
setIntBigIntegerBuffer(bytes, idx, (int) rnd);
}
break;
}
return RubyBignum.newBignum(context.runtime, new BigInteger(bytes));
}
// c: rb_random_bytes
@JRubyMethod(name = "bytes")
public IRubyObject bytes(ThreadContext context, IRubyObject arg) {
int n = RubyNumeric.num2int(arg);
byte[] bytes = new byte[n];
int idx = 0;
for (; n >= 4; n -= 4) {
int r = random.genrandInt32();
for (int i = 0; i < 4; ++i) {
bytes[idx++] = (byte) (r & 0xff);
r >>>= 8;
}
}
if (n > 0) {
int r = random.genrandInt32();
for (int i = 0; i < n; ++i) {
bytes[idx++] = (byte) (r & 0xff);
r >>>= 8;
}
}
return context.runtime.newString(new ByteList(bytes));
}
