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Re: [Qemu-devel] [RFC PATCH v2 02/10] Jhash: add linux kernel jhashtable


From: Zhang Chen
Subject: Re: [Qemu-devel] [RFC PATCH v2 02/10] Jhash: add linux kernel jhashtable in qemu
Date: Tue, 12 Jan 2016 09:58:45 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0



On 01/11/2016 08:50 PM, Dr. David Alan Gilbert wrote:
* Zhang Chen (address@hidden) wrote:

On 01/08/2016 08:08 PM, Dr. David Alan Gilbert wrote:
* Zhang Chen (address@hidden) wrote:
From: zhangchen <address@hidden>

Jhash used by colo-proxy to save and lookup
net connection info

Signed-off-by: zhangchen <address@hidden>
Signed-off-by: zhanghailiang <address@hidden>
---
  include/qemu/jhash.h | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 61 insertions(+)
  create mode 100644 include/qemu/jhash.h

diff --git a/include/qemu/jhash.h b/include/qemu/jhash.h
new file mode 100644
index 0000000..5b82d02
--- /dev/null
+++ b/include/qemu/jhash.h
@@ -0,0 +1,61 @@
+/* jhash.h: Jenkins hash support.
+  *
+  * Copyright (C) 2006. Bob Jenkins (address@hidden)
+  *
+  * 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 (address@hidden)
+  *
+  * 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/bitopt.h"
That does not build, the header in qemu is bitop*s*.h.

Dave
I'm very sorry for it, fix it to

#include "qemu/bitopts.h"
No! It's:

#include "qemu/bitops.h"

Please at least build test this code!

Dave

Fix it to #include "qemu/bitops.h"
I have rebuild this code,but qemu makefile did't check the .h
I don't know whether it is a qemu bug.
you can try change it to #include "qemu/bitops.h" and make.
then change it to #include "qemu/bitopts.h" and make.
repeat it twice, now, you can change it to #include "everything"
in jhash.h. gcc don't check the .h and report error.////


Thanks
zhangchen


Thanks
zhangchen


+
+/*
+ * 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__ */
--
1.9.1



--
Dr. David Alan Gilbert / address@hidden / Manchester, UK


.

--
Thanks
zhangchen



--
Dr. David Alan Gilbert / address@hidden / Manchester, UK


.


--
Thanks
zhangchen






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