Move uart into its own translation unit

lib/uart.c

@@ -0,0 +1,9 @@
+/* QEMU memory maps a UART device here. */
+#define UART_BASE ((volatile char *)0x10000000)
+
+void uart_putc(char c) { *UART_BASE = c; }
+
+void uart_puts(const char *s) {
+    while (*s) uart_putc(*s++);
+}
+

lib/uart.h

@@ -0,0 +1,10 @@
+#ifndef UART_KERNEL_H
+#define UART_KERNEL_H
+
+/** Send a single character to the UART device */
+void uart_putc(char c);
+
+/** Send a **NULL TERMINATED** string to the UART device */
+void uart_puts(const char *s);
+
+#endif

start.c

@@ -2,17 +2,7 @@
 #include <riscv.h>
 #include <spinlock.h>
 #include <types.h>
-
+#include <uart.h>
-/* QEMU memory maps a UART device here. */
-#define UART_BASE ((volatile char *)0x10000000)
-
-/** Send a single character to the UART device */
-void uart_putc(char c) { *UART_BASE = c; }
-
-/** Send a **NULL TERMINATED** string to the UART device */
-void uart_puts(const char *s) {
-    while (*s) uart_putc(*s++);
-}
 
 /**
  * Allocate one stack per CPU (hart).