Better documentation for kprintf/stdio

kern/libkern/stdio.c

@@ -1,16 +1,23 @@
-#include <uart.h>
 #include <mini-printf.h>
 #include <stddef.h>
+#include <uart.h>
 
-int stdout_puts(char *s, int len, void *unused) {
+/** Helper routine to put characters into our uart device */
+static int stdout_puts(char *s, int len, void *unused) {
     (void)unused;
-    // Example: UART write loop
+    for (int i = 0; i < len; i++) uart_putc(s[i]);
-    for (int i = 0; i < len; i++) {
-        uart_putc(s[i]);   // <-- your low-level "put char" routine
-    }
     return len;
 }
 
+/**
+ * Printf-like functionality for the kernel.
+ *
+ * %%       - print '%',
+ * %c       - character,
+ * %s       - string,
+ * %d, %u   - decimal integer,
+ * %x, %X   - hex integer,
+ */
 int kprintf(const char *restrict fmt, ...) {
     va_list ap;
     va_start(ap, fmt);