From: Willy Tarreau <w@1wt.eu>
Date: Sat, 7 Mar 2020 23:41:00 +0000 (+0100)
Subject: MINOR: tools: add 64-bit rotate operators
X-Git-Tag: v2.2-dev4~10
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7a40909c00c13d2733bc1d41ddc7dc1d19e05da9;p=thirdparty%2Fhaproxy.git

MINOR: tools: add 64-bit rotate operators

This adds rotl64/rotr64 to rotate a 64-bit word by an arbitrary number
of bits. It's mainly aimed at being used with constants.
---

diff --git a/include/common/standard.h b/include/common/standard.h
index a78083318d..f9eed961fd 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -66,6 +66,26 @@
  * power of 2, and 0 otherwise */
 #define POWEROF2(x) (((x) & ((x)-1)) == 0)
 
+/* rotate left a 64-bit integer by <bits:[0-5]> bits */
+static inline uint64_t rotl64(uint64_t v, uint8_t bits)
+{
+#if !defined(__ARM_ARCH_8A) && !defined(__x86_64__)
+	bits &= 63;
+#endif
+	v = (v << bits) | (v >> (-bits & 63));
+	return v;
+}
+
+/* rotate right a 64-bit integer by <bits:[0-5]> bits */
+static inline uint64_t rotr64(uint64_t v, uint8_t bits)
+{
+#if !defined(__ARM_ARCH_8A) && !defined(__x86_64__)
+	bits &= 63;
+#endif
+	v = (v >> bits) | (v << (-bits & 63));
+	return v;
+}
+
 /* DEFNULL() returns either the argument as-is, or NULL if absent. This is for
  * use in macros arguments.
  */