Make serial work more reliably

src/asm.c

-/*
-  asm.c contains x86 specific functions for executing low level code
-*/
-
-#include "asm.h"
-
-// Wrapper for outb
-// Stolen from http://wiki.osdev.org/Inline_Assembly/Examples
-static inline void outb(uint16_t port, uint8_t val) {
-    asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port));
-}
-
-// Wrapper for inb
-static inline uint8_t inb(uint16_t port) {
-    uint8_t ret;
-    asm volatile ("inb %1, %0" : "=a"(ret) : "Nd"(port));
-    return ret;
-}

src/asm.h

 /*
-  asm.h exports archatecture specific functions for hardware interaction
+  asm.h contains x86 specific functions for executing low level code
 */
 
+#pragma once
 #include <stdint.h>
 
-// Functions for reading and writing to/from x86 IO ports
-static inline void outb(uint16_t port, uint8_t val);
-static inline uint8_t inb(uint16_t port);
+// Wrapper for outb
+// Stolen from http://wiki.osdev.org/Inline_Assembly/Examples
+inline void outb(uint16_t port, uint8_t val) {
+    asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port));
+}
+
+// Wrapper for inb
+inline uint8_t inb(uint16_t port) {
+    uint8_t ret;
+    asm volatile ("inb %1, %0" : "=a"(ret) : "Nd"(port));
+    return ret;
+}

src/kern.c

@@ -110,7 +110,8 @@ void kernel_main() {
          * yet, '\n' will produce some VGA specific character instead.
          * This is normal.
          */
-	terminal_writestring("Hello, kernel World!\n");
     serial_init();
-    serial_writestring("Hello, kernel World!\n");    
+    serial_writestring("First Serial Test!\n");
+    terminal_writestring("Hello, kernel World!\n");
+    serial_writestring("Second Serial Test\n");
 }

src/makefile

@@ -6,3 +6,4 @@ all:
 	$C -T linker.ld -o myos.bin -ffreestanding -O2 -nostdlib *.o -lgcc
 
 clean:
+	rm *.o *.bin

src/serial.c

@@ -27,7 +27,7 @@ void serial_writechar(char a) {
 }
 
 void serial_writestring(char* s) {
-    while (s) {
+    while (*s) {
         serial_writechar(*s);
         s++;
     }