1 files changed, 31 insertions, 0 deletions
diff --git a/libmisc/include/libmisc/hash.h b/libmisc/include/libmisc/hash.h
new file mode 100644
index 0000000..5940e64
--- /dev/null
+++ b/libmisc/include/libmisc/hash.h
@@ -0,0 +1,31 @@
+/* libmisc/hash.h - General-purpose hash utilities
+ *
+ * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-Licence-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIBMISC_HASH_H_
+#define _LIBMISC_HASH_H_
+
+#include <stdint.h> /* for uint{n}_t */
+#include <stddef.h> /* for size_t */
+
+/* djb2 hash */
+typedef uint32_t hash_t;
+static inline void hash_init(hash_t *hash) {
+	*hash = 5381;
+}
+static inline void hash_write(hash_t *hash, void *dat, size_t len) {
+	for (size_t i = 0; i < len; i++)
+		*hash = (*hash * 33) + (hash_t)(((unsigned char *)dat)[i]);
+}
+
+/* utilities */
+static inline hash_t hash(void *dat, size_t len) {
+	hash_t h;
+	hash_init(&h);
+	hash_write(&h, dat, len);
+	return h;
+}
+
+#endif /* _LIBMISC_HASH_H_ */