Re: [libvirt] [PATCH v2] Add virRandom() API to generate numbers with non-power-of-2 limit
On 08/14/2012 05:13 AM, Daniel P. Berrange wrote:
From: "Daniel P. Berrange" <berrange(a)redhat.com>
The current virRandomBits() API is only usable if the caller wants
a random number in the range [0, (n-1)] where n is a power of two.
This adds a virRandom() API which generates a double in the
range [0.0,1.0] with 48 bits of entropy. It then also adds a
virRandomInt(uint32_t max) API which generates an unsigned
in the range [0,@max]
+uint32_t virRandomInt(uint32_t max)
+{
+ double val = virRandom();
+ return val * max;
I just realized this always goes through the slower path of using a
double; it might be worth doing a quick filter for a power of 2, and
forward that directly through virRandomBits(); I'll propose a followup
patch. I find it easier to write virRandomInt(256) than
virRandomBits(8), for example.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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