4 files changed, 59 insertions, 0 deletions
diff --git a/usr/.keep b/usr/.keep
deleted file mode 100644
index e69de29..0000000
--- a/usr/.keep
+++ /dev/null
diff --git a/usr/sdk/Makefile b/usr/sdk/Makefile
new file mode 100644
index 0000000..9a5cc73
--- /dev/null
+++ b/usr/sdk/Makefile
@@ -0,0 +1,21 @@
+#
+# Copyright (c) 2025, Ian Moffett.
+# Provided under the BSD-3 clause.
+#
+
+CFILES = $(shell find common/ -name "*.c")
+OFILES = $(CFILES:.c=.o)
+
+CC =
+LD =
+
+ARCH =
+SYS_CFLAGS =
+CFLAGS = $(SYS_CFLAGS) -Iinc/
+
+.PHONY: all
+all: $(OFILES)
+	$(AR) rcs libmos.a $(OFILES)
+
+%.o: %.c
+	$(CC) -c $(CFLAGS) $< -o $@
diff --git a/usr/sdk/common/string/strlen.c b/usr/sdk/common/string/strlen.c
new file mode 100644
index 0000000..4499512
--- /dev/null
+++ b/usr/sdk/common/string/strlen.c
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2025, Ian Moffett.
+ * Provided under the BSD-3 clause.
+ */
+
+#include <sdk/string.h>
+#include <sdk/types.h>
+
+USIZE
+strlen(const char *str)
+{
+    USIZE len = 0;
+
+    if (str == NULL) {
+        return 0;
+    }
+
+    while (str[len++] != '\0');
+    return len - 1;
+}
diff --git a/usr/sdk/inc/sdk/string.h b/usr/sdk/inc/sdk/string.h
new file mode 100644
index 0000000..f7668fd
--- /dev/null
+++ b/usr/sdk/inc/sdk/string.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2025, Ian Moffett.
+ * Provided under the BSD-3 clause.
+ */
+
+#ifndef _SDK_STRING_H_
+#define _SDK_STRING_H_ 1
+
+ #include <sdk/types.h>
+
+/*
+ * Returns the length of a string
+ *
+ * @str: String to get length of
+ */
+USIZE strlen(const char *str);
+
+#endif  /* !_SDK_STRING_H_ */