glibc/locale/hashval.h
Paul Eggert 581c785bf3 Update copyright dates with scripts/update-copyrights
I used these shell commands:

../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")

and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.

I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah.  I don't
know why I run into these diagnostics whereas others evidently do not.

remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
2022-01-01 11:40:24 -08:00

43 lines
1.5 KiB
C

/* Implement simple hashing table with string based keys.
Copyright (C) 1994-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef hashval_t
# define hashval_t unsigned long int
#endif
#include <limits.h> /* For CHAR_BIT. */
hashval_t
compute_hashval (const void *key, size_t keylen)
{
size_t cnt;
hashval_t hval;
/* Compute the hash value for the given string. The algorithm
is taken from [Aho,Sethi,Ullman], modified to reduce the number of
collisions for short strings with very varied bit patterns.
See http://www.clisp.org/haible/hashfunc.html. */
cnt = 0;
hval = keylen;
while (cnt < keylen)
{
hval = (hval << 9) | (hval >> (sizeof hval * CHAR_BIT - 9));
hval += (hashval_t) ((const unsigned char *) key)[cnt++];
}
return hval != 0 ? hval : ~((hashval_t) 0);
}