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opr: Add Bob Jenkins's hash functions
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 Reviewed-on: http://gerrit.openafs.org/6095 Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com> Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com> (cherry picked from commit 20448059f02d07eccf7f81fdb55b80e566acfecc) Change-Id: I53f3a78f416d1893b16498f412d9aaa85db78ad3 Reviewed-on: http://gerrit.openafs.org/6106 Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com> Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
This commit is contained in:
Simon Wilkinson
Jeffrey Altman
parent
536cd4c038
commit
8b224986eb
@ -6,6 +6,7 @@ objects = assert.o casestrcpy.o rbtree.o
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all: $(TOP_INCDIR)/afs/opr.h \
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$(TOP_INCDIR)/afs/opr_assert.h \
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$(TOP_INCDIR)/opr/jhash.h \
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$(TOP_INCDIR)/opr/queue.h \
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$(TOP_INCDIR)/opr/rbtree.h \
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$(TOP_LIBDIR)/libopr.a
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@ -24,6 +25,9 @@ $(TOP_INCDIR)/afs/opr.h: opr.h
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$(TOP_INCDIR)/afs/opr_assert.h: opr_assert.h
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$(INSTALL_DATA) opr_assert.h $@
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$(TOP_INCDIR)/opr/jhash.h: jhash.h
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$(INSTALL_DATA) jhash.h $@
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$(TOP_INCDIR)/opr/queue.h: queue.h
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$(INSTALL_DATA) queue.h $@
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@ -13,6 +13,7 @@ INCFILEDIR = $(DESTDIR)\include\afs
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INCFILES = \
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$(INCFILEDIR)\opr.h \
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$(INCFILEDIR)\opr_assert.h \
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$(DESTDIR)\include\opr\jhash.h \
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$(DESTDIR)\include\opr\queue.h \
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$(DESTDIR)\include\opr\rbtree.h
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106
src/opr/jhash.h
Normal file
106
src/opr/jhash.h
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@ -0,0 +1,106 @@
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/*
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* Copyright (c) 2006 Bob Jenkins
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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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/* This is an OPR version of Bob Jenkins' hash routines. His original copyright
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* declaration reads:
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*
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* lookup3.c, by Bob Jenkins, May 2006, Public Domain.
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*
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* You can use this free for any purpose. It's in the public domain.
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* It has no warranty.
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*/
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#ifndef OPENAFS_OPR_JHASH_H
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#define OPENAFS_OPR_JHASH_H 1
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#define opr_jhash_size(n) ((uint32_t)1<<(n))
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#define opr_jhash_mask(n) (opr_jhash_size(n)-1)
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#define opr_jhash_rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
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#define opr_jhash_mix(a,b,c) \
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{ \
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a -= c; a ^= opr_jhash_rot(c, 4); c += b; \
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b -= a; b ^= opr_jhash_rot(a, 6); a += c; \
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c -= b; c ^= opr_jhash_rot(b, 8); b += a; \
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a -= c; a ^= opr_jhash_rot(c,16); c += b; \
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b -= a; b ^= opr_jhash_rot(a,19); a += c; \
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c -= b; c ^= opr_jhash_rot(b, 4); b += a; \
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}
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#define opr_jhash_final(a,b,c) \
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{ \
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c ^= b; c -= opr_jhash_rot(b,14); \
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a ^= c; a -= opr_jhash_rot(c,11); \
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b ^= a; b -= opr_jhash_rot(a,25); \
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c ^= b; c -= opr_jhash_rot(b,16); \
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a ^= c; a -= opr_jhash_rot(c,4); \
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b ^= a; b -= opr_jhash_rot(a,14); \
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c ^= b; c -= opr_jhash_rot(b,24); \
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}
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static_inline uint32_t
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opr_jhash(const uint32_t *k, size_t length, uint32_t initval)
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{
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uint32_t a,b,c;
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/* Set up the internal state */
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a = b = c = 0xdeadbeef + (((uint32_t)length)<<2) + initval;
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while (length > 3) {
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a += k[0];
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b += k[1];
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c += k[2];
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opr_jhash_mix(a, b, c);
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length -= 3;
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k += 3;
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}
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/* All the case statements fall through */
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switch(length) {
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case 3 : c+=k[2];
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case 2 : b+=k[1];
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case 1 : a+=k[0];
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opr_jhash_final(a, b, c);
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case 0: /* case 0: nothing left to add */
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break;
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}
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return c;
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}
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/* Simplified version of the above function to hash just one int */
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static_inline uint32_t
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opr_jhash_int(uint32_t a, uint32_t initval) {
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uint32_t b, c;
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a += 0xdeadbeef + 4 + initval;
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b = c = 0xdeadbeef + 4 + initval;
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opr_jhash_final(a, b, c);
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return c;
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}
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#endif
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@ -4,6 +4,7 @@ auth/keys
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auth/superuser
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auth/authcon
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cmd/command
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opr/jhash
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opr/queues
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opr/rbtree
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ptserver/pt_util
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1
tests/opr/.gitignore
vendored
1
tests/opr/.gitignore
vendored
@ -2,4 +2,5 @@
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# git ls-files -i --exclude-standard
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# to check that you haven't inadvertently ignored any tracked files.
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/jhash-t
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/rbtree-t
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@ -7,7 +7,7 @@ MODULE_CFLAGS = -I$(srcdir)/..
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LIBS=../tap/libtap.a $(abs_top_builddir)/lib/libopr.a
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tests = queues-t rbtree-t
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tests = jhash-t queues-t rbtree-t
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all check test tests: $(tests)
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@ -17,5 +17,8 @@ queues-t: queues-t.o
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rbtree-t: rbtree-t.o $(LIBS)
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$(AFS_LDRULE) rbtree-t.o ../tap/libtap.a $(LIBS) $(XLIBS)
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jhash-t: jhash-t.o
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$(AFS_LDRULE) jhash-t.o ../tap/libtap.a $(XLIBS)
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clean distclean:
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$(RM) -f $(tests) *.o core
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61
tests/opr/jhash-t.c
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61
tests/opr/jhash-t.c
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@ -0,0 +1,61 @@
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/*
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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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