Follow C calling convention (futureproofing) and utilize macros

src/serial.asm

@@ -1,9 +1,14 @@
 SERIAL_PORT equ 0x3f8
 serialinitialized db 0
 
-serialinit:
-	push ax
+; Write null terminated string in address str_pointer to serial
+macro serw str_pointer {
+	push str_pointer
+	call serialwrite
+	add esp, 4
+}
 
+serialinit:
 	;Disable ints
 	mov dx, SERIAL_PORT+1
 	mov al, 0x00
@@ -54,7 +59,6 @@ serialinit:
 	out dx, al
 	mov [serialinitialized], 1
 .end:
-	pop ax
 	ret
 .errormsg db "Serial init failed", 0
 
@@ -64,7 +68,6 @@ serialwrite:
 	push ebp
 	mov ebp, esp
 	push esi
-	push ax
 	cld
 	mov esi, [ebp+8]
 .loop:
@@ -80,7 +83,6 @@ serialwrite:
 	out dx, al
 	jmp .loop
 .done:
-	pop ax
 	pop esi
 	pop ebp
 	ret