1.\" 2.\" Copyright (c) 2003, 2004 The DragonFly Project. All rights reserved. 3.\" 4.\" This code is derived from software contributed to The DragonFly Project 5.\" by Hiten Pandya <hmp@backplane.com>. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in 15.\" the documentation and/or other materials provided with the 16.\" distribution. 17.\" 3. Neither the name of The DragonFly Project nor the names of its 18.\" contributors may be used to endorse or promote products derived 19.\" from this software without specific, prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.Dd December 20, 2009 35.Dt HASHINIT 9 36.Os 37.Sh NAME 38.Nm hashinit , 39.Nm hashinit_ext , 40.Nm phashinit , 41.Nm phashinit_ext 42.Nd generic hash table functions for the kernel 43.Sh SYNOPSIS 44.In sys/param.h 45.In sys/systm.h 46.In sys/malloc.h 47.Ft void * 48.Fn hashinit "int count" "struct malloc_type *type" "u_long *hashmask" 49.Ft void * 50.Fn hashinit_ext "int count" "size_t size" "struct malloc_type *type" "u_long *hashmask" 51.Ft void * 52.Fn phashinit "int count" "struct malloc_type *type" "u_long *nentries" 53.Ft void * 54.Fn phashinit_ext "int count" "size_t size" "struct malloc_type *type" "u_long *nentries" 55.Sh DESCRIPTION 56The kernel hash functions are used for creating a generic hash table. 57.Pp 58The 59.Fn hashinit 60function returns a pointer to a hash table which is sized a 61.Dq "power of two" 62greater or equal to the element 63.Fa count 64requested. 65The masking value is stored in 66.Fa hashmask . 67.Pp 68The 69.Fn phashinit 70function returns a pointer to a prime number sized hash table. 71The element 72.Fa count 73requested is used to dictate an upper-bound for the size of the 74hash table. 75The final size of the hash table is stored by the function in 76.Fa nentries . 77.Pp 78The 79.Fa type 80argument to both of the above functions is used for keeping track 81of memory allocated for the hash table. 82See the 83.Xr kmalloc 9 84manual page for more information on memory statistics. 85.Pp 86The 87.Fn hashinit_ext 88and 89.Fn phashinit_ext 90functions are extended versions of 91.Fn hashinit 92and 93.Fn phashinit 94which take the 95.Fa size 96of the structure as an additional argument and will zero the array instead 97of assuming that it is an array of 98.Dv LIST_HEAD Ns s . 99.Sh SEE ALSO 100.Xr tcp 4 , 101.Xr udp 4 , 102.Xr kmalloc 9 , 103.Xr nlookup 9 104.Sh AUTHORS 105This manual page was written by 106.An Hiten Pandya Aq hmp@backplane.com . 107