5253f58c36
Add a generic facility for generating perfect string hashes, where all that is needed is an enum and a string table. The existing mechanism using a custom Perl script wrapped around a module continues to be available for any use case where this particular approach isn't sophisticated enough. Much of this patch comes from renaming "enum directives" to "enum directive" as a result of the string hash generator expecting a set of uniform naming conventions. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
55 lines
2.2 KiB
C
55 lines
2.2 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2017 The NASM Authors - All Rights Reserved
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* See the file AUTHORS included with the NASM distribution for
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* the specific copyright holders.
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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
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* conditions are met:
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*
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* * 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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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* ----------------------------------------------------------------------- */
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#include "perfhash.h"
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#include "hashtbl.h" /* For crc64i() */
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int perfhash_find(const struct perfect_hash *hash, const char *str)
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{
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uint32_t k1, k2;
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uint64_t crc;
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uint16_t ix;
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crc = crc64i(hash->crcinit, str);
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k1 = (uint32_t)crc & hash->hashmask;
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k2 = (uint32_t)(crc >> 32) & hash->hashmask;
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ix = hash->hashvals[k1] + hash->hashvals[k2 + hash->hashmask + 1];
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if (ix >= hash->tbllen ||
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!hash->strings[ix] ||
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nasm_stricmp(str, hash->strings[ix]))
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return hash->errval;
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return hash->tbloffs + ix;
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}
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