Jhash: add linux kernel jhashtable in qemu

Jhash will be used by colo-compare and filter-rewriter
to save and lookup net connection info

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/include/qemu/jhash.h b/include/qemu/jhash.h
new file mode 100644
index 0000000000..7222242615
--- /dev/null
+++ b/include/qemu/jhash.h
@@ -0,0 +1,59 @@
+/* jhash.h: Jenkins hash support.
+  *
+  * Copyright (C) 2006. Bob Jenkins (bob_jenkins@burtleburtle.net)
+  *
+  * http://burtleburtle.net/bob/hash/
+  *
+  * These are the credits from Bob's sources:
+  *
+  * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
+  *
+  * These are functions for producing 32-bit hashes for hash table lookup.
+  * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
+  * are externally useful functions.  Routines to test the hash are included
+  * if SELF_TEST is defined.  You can use this free for any purpose. It's in
+  * the public domain.  It has no warranty.
+  *
+  * Copyright (C) 2009-2010 Jozsef Kadlecsik (kadlec@blackhole.kfki.hu)
+  *
+  * I've modified Bob's hash to be useful in the Linux kernel, and
+  * any bugs present are my fault.
+  * Jozsef
+  */
+
+#ifndef QEMU_JHASH_H__
+#define QEMU_JHASH_H__
+
+#include "qemu/bitops.h"
+
+/*
+ * hashtable relation copy from linux kernel jhash
+ */
+
+/* __jhash_mix -- mix 3 32-bit values reversibly. */
+#define __jhash_mix(a, b, c)                \
+{                                           \
+    a -= c;  a ^= rol32(c, 4);  c += b;     \
+    b -= a;  b ^= rol32(a, 6);  a += c;     \
+    c -= b;  c ^= rol32(b, 8);  b += a;     \
+    a -= c;  a ^= rol32(c, 16); c += b;     \
+    b -= a;  b ^= rol32(a, 19); a += c;     \
+    c -= b;  c ^= rol32(b, 4);  b += a;     \
+}
+
+/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
+#define __jhash_final(a, b, c)  \
+{                               \
+    c ^= b; c -= rol32(b, 14);  \
+    a ^= c; a -= rol32(c, 11);  \
+    b ^= a; b -= rol32(a, 25);  \
+    c ^= b; c -= rol32(b, 16);  \
+    a ^= c; a -= rol32(c, 4);   \
+    b ^= a; b -= rol32(a, 14);  \
+    c ^= b; c -= rol32(b, 24);  \
+}
+
+/* An arbitrary initial parameter */
+#define JHASH_INITVAL           0xdeadbeef
+
+#endif /* QEMU_JHASH_H__ */