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 one is correct (it could also be written '[0, n)').
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
s/]/)/ (the range includes 0.0, but excludes 1.0)
virRandomInt(uint32_t max) API which generates an unsigned
in the range [0,@max]
s/]/)/ (the range includes 0, but excludes @max; it could also be
written '[0,@max-1]')
Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com>
---
src/libvirt_private.syms | 2 ++
src/util/virrandom.c | 32 ++++++++++++++++++++++++++++++++
src/util/virrandom.h | 2 ++
3 files changed, 36 insertions(+)
+++ b/src/util/virrandom.c
@@ -23,6 +23,7 @@
#include <stdlib.h>
#include <inttypes.h>
+#include <math.h>
Hmm, the gnulib module 'ldexp' is currently LGPLv3+, but then again,
gnulib doesn't document any glaring issues fixed by the module, other
than the module provides $(LDEXP_LIBM) as a handy way to decide in
Makefile.am whether to link against -lm or not (some libc provide ldexp
without -lm, other platforms require the extra library). Gnulib also
provides the module 'ldexp-ieee', to fix platforms with broken handling
of NaN, but we don't care about NaN in our usage.
I'll ask on gnulib about whether the license of 'ldexp' can be relaxed;
if Bruno agrees, then I'll do a followup patch to pull in that module.
In the meantime, I don't have any objections to how you are using
ldexp(), as long as you cross-compiled to mingw without issues.
+/**
+ * virRandom:
+ *
+ * Generate an evenly distributed random number between [0.0,1.0]
Same conversion of ] to ) as in the commit message.
+/**
+ * virRandomInt32:
s/32// - you must have changed the function name between documenting it
and implementing it.
+ * @max: upper limit
+ *
+ * Generate an evenly distributed random integer between [0,@max]
+ *
+ * Return: a random number between [0,@max]
Same conversion of ] to ) as in the commit message.
ACK with those spelling nits fixed.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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