From: Willy Tarreau <w@1wt.eu>
Date: Sat, 17 Apr 2021 13:49:34 +0000 (+0200)
Subject: MINOR: tools: add statistical_prng_range() to get a random number over a range
X-Git-Tag: v2.4-dev17~68
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84ebfabf7;p=thirdparty%2Fhaproxy.git

MINOR: tools: add statistical_prng_range() to get a random number over a range

This is simply a multiply and shift from statistical_prng() but it's made
easily accessible.
---

diff --git a/include/haproxy/tools.h b/include/haproxy/tools.h
index 3121fea51a..e09e17e644 100644
--- a/include/haproxy/tools.h
+++ b/include/haproxy/tools.h
@@ -1073,6 +1073,14 @@ static inline unsigned int statistical_prng()
 	return statistical_prng_state = x;
 }
 
+/* returns a random number between 0 and <range> - 1 that is evenly distributed
+ * over the range.
+ */
+static inline uint statistical_prng_range(uint range)
+{
+	return mul32hi(statistical_prng(), range);
+}
+
 /* Update array <fp> with the character transition <prev> to <curr>. If <prev>
  * is zero, it's assumed that <curr> is the first character. If <curr> is zero
  * its assumed to mark the end. Both may be zero. <fp> is a 1024-entries array