1 files changed, 34 insertions, 0 deletions
diff --git a/src/mergesort.c b/src/mergesort.c
new file mode 100644
index 0000000..2562d9d
--- /dev/null
+++ b/src/mergesort.c
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: LGPL-2.1-only */
+
+/* Copyright (C) 2020 Gediminas Jakutis */
+
+#include <errno.h>
+#include <stdlib.h>
+#include "defs.h"
+#include "mergesort.h"
+
+int merge(struct stream * const dest, struct stream * const A, struct stream * const B)
+{
+	int ret;
+	struct entry_l *a;
+	struct entry_l *b;
+
+	try(A->parent != B->parent, err, EINVAL, "cannot merge blocks: uncommon parent!");
+
+	a = get(A);
+	b = get(B);
+
+	while (a || b) {
+		if (a && (!b || a->val <= b->val)) {
+			put(dest, a);
+			a = get(A);
+		} else {
+			put(dest, b);
+			b = get(B);
+		}
+	}
+
+err:
+	return ret;
+}
+