1: /* Copyright (c) 1997, 1998, 1999, 2004 Free Software Foundation, Inc.
    2:    This file is part of the GNU C Library.
    3:    Contributed by Thorsten Kukuk <kukuk@suse.de>, 1997.
    4: 
    5:    The GNU C Library is free software; you can redistribute it and/or
    6:    modify it under the terms of the GNU Lesser General Public
    7:    License as published by the Free Software Foundation; either
    8:    version 2.1 of the License, or (at your option) any later version.
    9: 
   10:    The GNU C Library is distributed in the hope that it will be useful,
   11:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   12:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   13:    Lesser General Public License for more details.
   14: 
   15:    You should have received a copy of the GNU Lesser General Public
   16:    License along with the GNU C Library; if not, write to the Free
   17:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   18:    02111-1307 USA.  */
   19: 
   20: #include <rpcsvc/nis.h>
   21: 
   22: /* This is from libc/db/hash/hash_func.c, hash3 is static there */
   23: /*
   24:  * This is INCREDIBLY ugly, but fast.  We break the string up into 8 byte
   25:  * units.  On the first time through the loop we get the "leftover bytes"
   26:  * (strlen % 8).  On every other iteration, we perform 8 HASHC's so we handle
   27:  * all 8 bytes.  Essentially, this saves us 7 cmp & branch instructions.  If
   28:  * this routine is heavily used enough, it's worth the ugly coding.
   29:  *
   30:  * OZ's original sdbm hash
   31:  */
   32: uint32_t
   33: __nis_hash (const void *keyarg, register size_t len)
   34: {
   35:   register const u_char *key;
   36:   register size_t loop;
   37:   register uint32_t h;
   38: 
   39: #define HASHC   h = *key++ + 65599 * h
   40: 
   41:   h = 0;
   42:   key = keyarg;
   43:   if (len > 0)
   44:     {
   45:       loop = (len + 8 - 1) >> 3;
   46:       switch (len & (8 - 1))
   47:         {
   48:         case 0:
   49:           do {
   50:             HASHC;
   51:             /* FALLTHROUGH */
   52:           case 7:
   53:             HASHC;
   54:             /* FALLTHROUGH */
   55:           case 6:
   56:             HASHC;
   57:             /* FALLTHROUGH */
   58:           case 5:
   59:             HASHC;
   60:             /* FALLTHROUGH */
   61:           case 4:
   62:             HASHC;
   63:             /* FALLTHROUGH */
   64:           case 3:
   65:             HASHC;
   66:             /* FALLTHROUGH */
   67:           case 2:
   68:             HASHC;
   69:             /* FALLTHROUGH */
   70:           case 1:
   71:             HASHC;
   72:           } while (--loop);
   73:         }
   74:     }
   75:   return h;
   76: }