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20448059f0
This imports a small subset of Bob Jenkins lookup3.c hash functions into the opr library. At present we only import the subset of this that deals with aligned arrays of integers, as this addresses our immediate need. It seems likely that if we're interested in a hash function for string arrays (or other arbitrary data), that more recent functions such like SpookyHash (from Bob Jenkins, again) or CityHash (from Google) may be a better solution. The immediate use case for this is removing the use of the '%' operator when indexing speed critical hash tables, as well as ensuring fairer distribution of entries across these tables. A short set of test cases is also provided Change-Id: I0ae26382e77da02204a30a95747f7d6de8c4f24a Reviewed-on: http://gerrit.openafs.org/6095 Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com> Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
62 lines
2.4 KiB
C
62 lines
2.4 KiB
C
/*
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* Copyright (c) 2011 Your File System Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <afsconfig.h>
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#include <afs/param.h>
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#include <roken.h>
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#include <tap/basic.h>
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#include <opr/jhash.h>
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/* Bob Jenkins' lookup3.c comes with a load of self test functions, but
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* unfortunately, they all use 'hashlittle' (his unaligned hash function). As
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* we have only got 'hashword' (word aligned arrays) in OpenAFS, we need to roll
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* our own tests.
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*/
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int
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main(int argc, char **argv)
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{
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plan(8);
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uint32_t test[] = {3526055646, 2064483663, 3234460805, 3963629775};
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is_int(256, opr_jhash_size(8), "opr_jhash_size returns expected value");
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is_int(255, opr_jhash_mask(8), "opr_jhash_mask returns expected value");
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is_int(0xdeadbeef, opr_jhash(test, 0, 0), "empty array hashes as expected");
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is_int(766530906, opr_jhash(test, 4, 0), "simple array works");
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is_int(3782684773, opr_jhash(test, 4, 1), "changing initval works");
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test[2]++;
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is_int(1977082159, opr_jhash(test, 4, 0), "modifying value works");
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is_int(1100796964, opr_jhash(test, 1, 0),
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"single value works through jhash");
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is_int(1100796964, opr_jhash_int(test[0], 0),
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"single value works through jhash_int");
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return 0;
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}
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