split sdbm code from hash.c to independent program

hash/hash_sdbm.c

@@ -0,0 +1,49 @@
+/**
+ * @addtogroup hash Hash algorithms
+ * @{
+ * @file hash_sdbm.c
+ * @author [Christian Bender](https://github.com/christianbender)
+ * @brief [SDBM hash algorithm](http://www.cse.yorku.ca/~oz/hash.html)
+ */
+#include <assert.h>
+#include <inttypes.h>
+#include <stdio.h>
+
+/**
+ * @brief SDBM algorithm implementation
+ *
+ * @param s NULL terminated string to hash
+ * @return 64-bit
+ */
+uint64_t sdbm(const char* s)
+{
+    uint64_t hash = 0;
+    int i = 0;
+    while (s[i] != '\0')
+    {
+        hash = s[i] + (hash << 6) + (hash << 16) - hash;
+        i++;
+    }
+    return hash;
+}
+
+/**
+ * @brief Test function for ::sdbm
+ */
+void test_sdbm()
+{
+    assert(sdbm("Hello World") == 12881824461405877380);
+    assert(sdbm("Hello World!") == 7903571203300273309);
+    assert(sdbm("Hello world") == 15154913742888948900);
+    assert(sdbm("Hello world!") == 15254999417003201661);
+    printf("Tests passed\n");
+}
+
+/** @} */
+
+/** Main function */
+int main()
+{
+    test_sdbm();
+    return 0;
+}