Ichthyostega
9c21164ae6
This changeset fixes a huge pile of problems, as indicated in the error log of the Doxygen run after merging all the recent Doxygen improvements unfortunately, auto-linking does still not work at various places. There is no clear indication what might be the problem. Possibly the rather unstable Sqlite support in this Doxygen version is the cause. Anyway, needs to be investigated further.
156 lines
4.5 KiB
C
156 lines
4.5 KiB
C
/*
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HASH-FNV.h - FNV hash functions
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adapted by Lumiera.org
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2010, 2011 Christian Thaeter <ct@pipapo.org>
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original by chongo <Landon Curt Noll> /\oo/\
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http://www.isthe.com/chongo/
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Please do not copyright this code. This code is in the public domain.
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LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
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EVENT SHALL LANDON CURT NOLL BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
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USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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PERFORMANCE OF THIS SOFTWARE.
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Share and Enjoy! :-)
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*/
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/** @file hash-fnv.h
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** Fowler-Noll-Vo Hashes.
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** FNV is a non-cryptographic hash function created by Glenn Fowler, Landon Curt Noll, and Phong Vo.
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*/
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#ifndef HASH_FNV_H
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#define HASH_FNV_H
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#include <stdlib.h> /* for size_t */
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#include <inttypes.h>
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#define HASH_FNV64_BASE ((uint64_t)14695981039346656037ULL)
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#define HASH_FNV32_BASE ((uint32_t)2166136261UL)
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#define HASH_FNV64_PRIME ((uint64_t)1099511628211ULL)
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#define HASH_FNV32_PRIME ((uint32_t)16777619UL)
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/**
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* FNV-1a 64 bit hash over a buffer.
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* @param buf start of the buffer
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* @param len size of the buffer
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* @param hval previous hash value when incremental hashing or HASH_FNV64_BASE when starting a new hash
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* @return new hash value
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*/
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uint64_t
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hash_fnv64a_buf (const void *buf, size_t len, uint64_t hval);
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/**
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* FNV-1a 64 bit hash over a zero terminated string.
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* @param str start of the buffer
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* @param len maximum size to be processed
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* @param hval previous hash value when incremental hashing or HASH_FNV64_BASE when starting a new hash
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* @return new hash value
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*/
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uint64_t
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hash_fnv64a_strn (const char* str, size_t len, uint64_t hval);
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/**
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* FNV-1a 32 bit hash over a buffer.
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* @param buf start of the buffer
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* @param len size of the buffer
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* @param hval previous hash value when incremental hashing or HASH_FNV32_BASE when starting a new hash
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* @return new hash value
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*/
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uint32_t
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hash_fnv32a_buf (const void *buf, size_t len, uint32_t hval);
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/**
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* FNV-1a 32 bit hash over a zero terminated string.
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* @param str start of the buffer
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* @param len maximum size to be processed
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* @param hval previous hash value when incremental hashing or HASH_FNV32_BASE when starting a new hash
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* @return new hash value
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*/
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uint32_t
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hash_fnv32a_strn (const char* str, size_t len, uint32_t hval);
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/**
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* reduce a hash value to n bits.
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* Uses the xor folding method to stash a hash value together, this preserves unbiased hash distribution
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* @param hash result from one of the 64 bit hash functions above
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* @param bits number of significat bits for the result
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* @result hashvalue with no more than 'bits' significant bits
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*/
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uint64_t
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hash_fnv64_xorfold (uint64_t hash, int bits);
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/**
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* reduce a hash value to n bits.
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* Uses the xor folding method to stash a hash value together, this preserves unbiased hash distribution
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* @param hash result from one of the 32 bit hash functions above
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* @param bits number of significat bits for the result
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* @result hashvalue with no more than 'bits' significant bits
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*/
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uint32_t
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hash_fnv32_xorfold (uint32_t hash, int bits);
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/**
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* reduce hash to be within 0 to limit-1.
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* Uses the retry method to limit a hash value, this preserves unbiased hash distribution.
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* @param hash result from one of the 64 bit hash functions above
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* @param limit upper limit plus one for the result
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* @result hashvalue in the range from 0 to limit-1
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*/
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uint64_t
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hash_fnv64_retry (uint64_t hash, uint64_t limit);
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/**
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* reduce hash to be within 0 to limit-1.
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* Uses the retry method to limit a hash value, this preserves unbiased hash distribution.
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* @param hash result from one of the 32 bit hash functions above
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* @param limit upper limit plus one for the result
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* @result hashvalue in the range from 0 to limit-1
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*/
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uint32_t
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hash_fnv32_retry (uint64_t hash, uint32_t limit);
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/*
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PLANNED? 128 bit and 256bit hashes
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128 bit FNV_prime = 288 + 28 + 0x3b = 309485009821345068724781371
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256 bit FNV_prime = 2168 + 28 + 0x63 = 374144419156711147060143317175368453031918731002211
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128 bit offset_basis = 144066263297769815596495629667062367629
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256 bit offset_basis =
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100029257958052580907070968620625704837092796014241193945225284501741471925557
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*/
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#endif
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/*
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// Local Variables:
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// mode: C
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// c-file-style: "gnu"
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// indent-tabs-mode: nil
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// End:
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*/
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