Re: [Qemu-devel] [RFC PATCH V10 3/7] Jhash: add linux kernel jhashtable in qemu

[Jason Wang <jasowang@redhat.com>]

On 2016年07月26日 09:49, Zhang Chen wrote:
> Jhash 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>
> ---
>   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..0fcd875
> --- /dev/null
> +++ b/include/qemu/jhash.h
> @@ -0,0 +1,61 @@
> +/* 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 indentation looks odd here, please check.
> +  * 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__ */