move FourHash into libcitadel.

[citadel.git] / libcitadel / lib / hash.c

diff --git a/libcitadel/lib/hash.c b/libcitadel/lib/hash.c
index c1e8d4d422bc16b81295b2802257d9f29a8b45d2..665e39b304cd43bf81127a26a9f2d9106b14bfa0 100644 (file)
--- a/libcitadel/lib/hash.c
+++ b/libcitadel/lib/hash.c
@@ -657,6 +657,29 @@ long lFlathash(const char *str, long len)
        else return *(long*)str;
 }
 
+/**
+ * @ingroup HashListAlgorithm
+ * @brief another hashing algorithm; accepts exactly 4 characters, convert it to a hash key.
+ * @param str Our pointer to the long value
+ * @param len the length of the data pointed to; needs to be sizeof long, else we won't use it!
+ * @return the calculated hash value
+ */
+long FourHash(const char *key, long length) 
+{
+       int i;
+       int ret = 0;
+       const unsigned char *ptr = (const unsigned char*)key;
+
+       for (i = 0; i < 4; i++, ptr ++) 
+               ret = (ret << 8) | 
+                       ( ((*ptr >= 'a') &&
+                          (*ptr <= 'z'))? 
+                         *ptr - 'a' + 'A': 
+                         *ptr);
+
+       return ret;
+}
+
 /**
  * @ingroup HashListPrivate
  * @brief private abstract wrapper around the hashing algorithm