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authorDan McGee <dan@archlinux.org>2010-12-14 11:56:32 -0600
committerDan McGee <dan@archlinux.org>2010-12-14 11:56:32 -0600
commitdbf59a6b141213b0afc962c71347eb83f8bcab73 (patch)
tree924f24750b5c6a9abd32ce349b111714b02748da
parentd1d163c5a3627675e4d063d196ea2b2255507cc8 (diff)
Add hash_sdbm function
This is prepping for the addition of a hash field to each package to greatly speed up the string comparisons we frequently do on package name in _alpm_pkg_find. Signed-off-by: Dan McGee <dan@archlinux.org>
-rw-r--r--lib/libalpm/util.c21
-rw-r--r--lib/libalpm/util.h1
2 files changed, 22 insertions, 0 deletions
diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index e425fa48..8e83bdac 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -845,4 +845,25 @@ int _alpm_splitname(const char *target, pmpkg_t *pkg)
return(0);
}
+/**
+ * Hash the given string to an unsigned long value.
+ * This is the standard sdbm hashing algorithm.
+ * @param str string to hash
+ * @return the hash value of the given string
+ */
+unsigned long _alpm_hash_sdbm(const char *str)
+{
+ unsigned long hash = 0;
+ int c;
+
+ if(!str) {
+ return(hash);
+ }
+ while((c = *str++)) {
+ hash = c + (hash << 6) + (hash << 16) - hash;
+ }
+
+ return(hash);
+}
+
/* vim: set ts=2 sw=2 noet: */
diff --git a/lib/libalpm/util.h b/lib/libalpm/util.h
index 78877a27..0b804205 100644
--- a/lib/libalpm/util.h
+++ b/lib/libalpm/util.h
@@ -78,6 +78,7 @@ int _alpm_lstat(const char *path, struct stat *buf);
int _alpm_test_md5sum(const char *filepath, const char *md5sum);
char *_alpm_archive_fgets(char *line, size_t size, struct archive *a);
int _alpm_splitname(const char *target, pmpkg_t *pkg);
+unsigned long _alpm_hash_sdbm(const char *str);
#ifndef HAVE_STRSEP
char *strsep(char **, const char *);