-void memmove(void *dest, void *src, int bytes);
-int strcmp(const char *a2, const char *a1);
-void strcpy(char *a2, const char *a1);
-void tohex(char *s, unsigned long l);
+#include <stdarg.h>
+
+extern void memcpy(void *dest, void *src, int bytes);
+extern void memmove(void *dest, void *src, int bytes);
+extern int memcmp(const char *a2, const char *a1, int bytes);
+extern int strcmp(const char *a2, const char *a1);
+extern int strlen(char *c);
+extern void strcpy(char *a2, const char *a1);
+extern void puts(char *c);
+extern void tohex(char *s, unsigned long l);
+extern void puthex(unsigned long l);
+extern int vsprintf(char *s, const char *fmt, va_list args);
+extern int vsnprintf(char *s, int size, const char *fmt, va_list args);
+extern int sprintf(char *s, const char *fmt, ...);
+extern int snprintf(char *s, int size, const char *fmt, ...);