unsigned long random_bits(random_state *state, int bits)
{
- int ret = 0;
+ unsigned long ret = 0;
int n;
for (n = 0; n < bits; n += 8) {
ret = (ret << 8) | state->databuf[state->pos++];
}
- ret &= (1 << bits) - 1;
+ /*
+ * `(1 << bits) - 1' is not good enough, since if bits==32 on a
+ * 32-bit machine, behaviour is undefined and Intel has a nasty
+ * habit of shifting left by zero instead. We'll shift by
+ * bits-1 and then separately shift by one.
+ */
+ ret &= (1 << (bits-1)) * 2 - 1;
return ret;
}