Add first C user program

src/kernel/fat16.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "src/kernel/fs.h"
+
+#define FAT16 1
+
+fs_node_t *fat16_mount();
+
+fs_node_t *fat16_open_by(const fs_node_t *directory, const char *name);
+
+fs_node_t *fat16_open_at(const fs_node_t *directory, uint64_t index);
+
+fs_node_t *fat16_open_again(const fs_node_t *source);
+
+void fat16_read(const fs_node_t *file, uint64_t offset, uint64_t size, void *to);
+
+void fat16_close(fs_node_t *node);
+
+void fat16_unmount(fs_node_t *fs);