bsd/net/flowhash.h

   1 /*
   2  * Copyright (c) 2011 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #ifndef _NET_FLOWHASH_H_
  30 #define _NET_FLOWHASH_H_
  31
  32 #include <sys/types.h>
  33
  34 #ifdef  __cplusplus
  35 extern "C" {
  36 #endif
  37
  38 /*
  39  * If 32-bit hash value is too large, use this macro to truncate
  40  * it to n-bit; masking is a faster operation than modulus.
  41  */
  42 #define HASHMASK(n)     ((1UL << (n)) - 1)
  43
  44 /*
  45  * Returns 32-bit hash value.  Hashes which are capable of returning
  46  * more bits currently have their results truncated to 32-bit.
  47  */
  48 typedef u_int32_t net_flowhash_fn_t(const void *, u_int32_t, const u_int32_t);
  49
  50 extern net_flowhash_fn_t *net_flowhash;
  51 extern net_flowhash_fn_t net_flowhash_mh3_x86_32;
  52 extern net_flowhash_fn_t net_flowhash_mh3_x64_128;
  53 extern net_flowhash_fn_t net_flowhash_jhash;
  54 #ifdef  __cplusplus
  55 }
  56 #endif
  57
  58 #endif /* _NET_FLOWHASH_H_ */