-uint16_t read_uint16_bigendian(FILE * file);
-void write_uint16_bigendian(uint16_t x, FILE * file);
-uint32_t read_uint32_bigendian(FILE * file);
-void write_uint32_bigendian(uint32_t x, FILE * file);
+
+#include <stdio.h> /* for FILE typedef */
+#include <stdint.h> /* for uint16_t, uint32_t */
+
+
+
+extern uint16_t read_uint16_bigendian(FILE * file);
+extern uint32_t read_uint32_bigendian(FILE * file);
+extern void write_uint16_bigendian(uint16_t x, FILE * file);
+extern void write_uint32_bigendian(uint32_t x, FILE * file);