>From 14a0d1ac40de4fcd16dff605a0fdf86a8227520f Mon Sep 17 00:00:00 2001
From: Nikos Mavrogiannopoulos <address@hidden>
Date: Thu, 27 Sep 2012 08:42:07 +0200
Subject: [PATCH] Added hash-pjw-s.

---
 lib/hash-pjw-s.c   |   42 ++++++++++++++++++++++++++++++++++++++++++
 lib/hash-pjw-s.h   |   24 ++++++++++++++++++++++++
 modules/hash-pjw-s |   22 ++++++++++++++++++++++
 3 files changed, 88 insertions(+)
 create mode 100644 lib/hash-pjw-s.c
 create mode 100644 lib/hash-pjw-s.h
 create mode 100644 modules/hash-pjw-s

diff --git a/lib/hash-pjw-s.c b/lib/hash-pjw-s.c
new file mode 100644
index 0000000..3765e35
--- /dev/null
+++ b/lib/hash-pjw-s.c
@@ -0,0 +1,42 @@
+/* hash-pjw-s.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 <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "hash-pjw-s.h"
+
+#include <limits.h>
+
+#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_s (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-s.h b/lib/hash-pjw-s.h
new file mode 100644
index 0000000..cf61f8d
--- /dev/null
+++ b/lib/hash-pjw-s.h
@@ -0,0 +1,24 @@
+/* hash-pjw-s.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 <http://www.gnu.org/licenses/>.  */
+
+#include <stddef.h>
+
+/* 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_s (const void *x, size_t n) _GL_ATTRIBUTE_PURE;
diff --git a/modules/hash-pjw-s b/modules/hash-pjw-s
new file mode 100644
index 0000000..d8735ca
--- /dev/null
+++ b/modules/hash-pjw-s
@@ -0,0 +1,22 @@
+Description:
+Compute a hash value for a buffer of known size.
+
+Files:
+lib/hash-pjw-s.h
+lib/hash-pjw-s.c
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += hash-pjw-s.h hash-pjw-s.c
+
+Include:
+"hash-pjw-s.h"
+
+License:
+LGPLv2+
+
+Maintainer:
+Jim Meyering
-- 
1.7.10.4