documented stdio.h

+// just like the standard printf except it recognises only the
+// following format directives: %i, %u, %x, %s
+
 extern int printf(char *str, ...);
+
+// standard puts
+
 extern int puts(char *s);
+
+// replacement of the standard putchar
+
 extern int putc(char c);
+
+// prints an unsigned int with:
+//  - f == 'x' => as an hex string
+//  - f == 'u' => as a decimal string
+
+extern int putu(int u, char f);
+
+// prints a signed int as decimal string
+
 extern int puti(int i);