1 files changed, 15 insertions, 0 deletions
diff --git a/03-refactor/include/printf.h b/03-refactor/include/printf.h
new file mode 100644
index 0000000..ec3eec0
--- /dev/null
+++ b/03-refactor/include/printf.h
@@ -0,0 +1,15 @@
+#ifndef PRINTF_H_
+#define PRINTF_H_
+
+#include <stdarg.h>
+#include <stdlib.h>
+
+typedef void(*printf_callback_t)(volatile void*, char);
+
+void printf_format(
+    const char* fmt,
+    printf_callback_t callback,
+    volatile void* callback_closure,
+    va_list lst);
+
+#endif /* PRINTF_H_ */