nasmlib/perfhash.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2017 The NASM Authors - All Rights Reserved
   4  *   See the file AUTHORS included with the NASM distribution for
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  12  *     notice, this list of conditions and the following disclaimer.
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  14  *     copyright notice, this list of conditions and the following
  15  *     disclaimer in the documentation and/or other materials provided
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  32  * ----------------------------------------------------------------------- */
  33
  34 #include "perfhash.h"
  35 #include "hashtbl.h"            /* For crc64i() */
  36
  37 int perfhash_find(const struct perfect_hash *hash, const char *str)
  38 {
  39     uint32_t k1, k2;
  40     uint64_t crc;
  41     uint16_t ix;
  42
  43     crc = crc64i(hash->crcinit, str);
  44     k1 = (uint32_t)crc & hash->hashmask;
  45     k2 = (uint32_t)(crc >> 32) & hash->hashmask;
  46
  47     ix = hash->hashvals[k1] + hash->hashvals[k2 + hash->hashmask + 1];
  48
  49     if (ix >= hash->tbllen ||
  50         !hash->strings[ix] ||
  51         nasm_stricmp(str, hash->strings[ix]))
  52         return hash->errval;
  53
  54     return hash->tbloffs + ix;
  55 }