From 064a0470a540a6e98af12c4bc1d1f98b423b4660 Mon Sep 17 00:00:00 2001 From: Nikos Mavrogiannopoulos Date: Thu, 27 Sep 2012 08:42:07 +0200 Subject: [PATCH] hash-pjw-bare: new module * lib/hash-pjw-bare.c: New file, very much like hash-pjw.c. * lib/hash-pjw-bare.h: Likewise. * modules/hash-pjw-bare: New file. * MODULES.html.sh (Misc): Add it. Copyright-paperwork-exempt: yes --- ChangeLog | 8 ++++++++ MODULES.html.sh | 1 + lib/hash-pjw-bare.c | 42 ++++++++++++++++++++++++++++++++++++++++++ lib/hash-pjw-bare.h | 24 ++++++++++++++++++++++++ modules/hash-pjw-bare | 22 ++++++++++++++++++++++ 5 files changed, 97 insertions(+) create mode 100644 lib/hash-pjw-bare.c create mode 100644 lib/hash-pjw-bare.h create mode 100644 modules/hash-pjw-bare diff --git a/ChangeLog b/ChangeLog index d6a79ecf3..741c48d19 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2012-10-02: Nikos Mavrogiannopoulos (tiny change) + + hash-pjw-bare: new module + * lib/hash-pjw-bare.c: New file, very much like hash-pjw.c. + * lib/hash-pjw-bare.h: Likewise. + * modules/hash-pjw-bare: New file. + * MODULES.html.sh (Misc): Add it. + 2012-10-02 Eric Blake manywarnings: cater to more gcc infelicities diff --git a/MODULES.html.sh b/MODULES.html.sh index baffef33b..dc480ed4b 100755 --- a/MODULES.html.sh +++ b/MODULES.html.sh @@ -2011,6 +2011,7 @@ func_all_modules () func_module obstack-printf func_module obstack-printf-posix func_module hash-pjw + func_module hash-pjw-bare func_module hash func_module readline func_module readtokens diff --git a/lib/hash-pjw-bare.c b/lib/hash-pjw-bare.c new file mode 100644 index 000000000..d413daa3e --- /dev/null +++ b/lib/hash-pjw-bare.c @@ -0,0 +1,42 @@ +/* hash-pjw-bare.c -- compute a hash value from a provided buffer. + + Copyright (C) 2012 Free Software Foundation, Inc. + + This program 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 3 of the License, or + (at your option) any later version. + + This program 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 this program. If not, see . */ + +#include + +#include "hash-pjw-bare.h" + +#include + +#define SIZE_BITS (sizeof (size_t) * CHAR_BIT) + +/* Return a hash of the N bytes of X using the method described by + Bruno Haible in http://www.haible.de/bruno/hashfunc.html. + Note that while many hash functions reduce their result via modulo + to a 0..table_size-1 range, this function does not do that. */ + +size_t +hash_pjw_bare (const void *x, size_t n) +{ + const unsigned char *s = x; + size_t h = 0; + unsigned i; + + for (i = 0; i < n; i++) + h = s[i] + ((h << 9) | (h >> (SIZE_BITS - 9))); + + return h; +} diff --git a/lib/hash-pjw-bare.h b/lib/hash-pjw-bare.h new file mode 100644 index 000000000..17ea755c6 --- /dev/null +++ b/lib/hash-pjw-bare.h @@ -0,0 +1,24 @@ +/* hash-pjw-bare.h -- declaration for a simple hash function + Copyright (C) 2012 Free Software Foundation, Inc. + + This program 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 3 of the License, or + (at your option) any later version. + + This program 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 this program. If not, see . */ + +#include + +/* Compute a hash code for a buffer starting at X and of size N, + and return the hash code. Note that unlike hash_pjw(), it does not + return it modulo a table size. + The result is platform dependent: it depends on the size of the 'size_t' + type and on the signedness of the 'char' type. */ +extern size_t hash_pjw_bare (const void *x, size_t n) _GL_ATTRIBUTE_PURE; diff --git a/modules/hash-pjw-bare b/modules/hash-pjw-bare new file mode 100644 index 000000000..4dc94e3a3 --- /dev/null +++ b/modules/hash-pjw-bare @@ -0,0 +1,22 @@ +Description: +Compute a hash value for a buffer of known size. + +Files: +lib/hash-pjw-bare.h +lib/hash-pjw-bare.c + +Depends-on: + +configure.ac: + +Makefile.am: +lib_SOURCES += hash-pjw-bare.h hash-pjw-bare.c + +Include: +"hash-pjw-bare.h" + +License: +LGPLv2+ + +Maintainer: +Jim Meyering -- 2.11.0