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 int strlen(const char *c);
extern void strcpy(char *a2, const char *a1);
-extern void puts(char *c);
+extern void puts(const 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);