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


From: Dr. David Alan Gilbert
Subject: Re: [Qemu-devel] [RFC PATCH v2 02/10] Jhash: add linux kernel jhashtable in qemu
Date: Mon, 11 Jan 2016 12:50:10 +0000
User-agent: Mutt/1.5.24 (2015-08-30)

* 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

> 
> 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



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