Error handler, makefile optimisation

examples/file/main.asm

@@ -8,9 +8,14 @@ extrn print.str
 extrn print.nl
 extrn exit
 
+macro nl {
+	call print.nl
+}
+
 
 section '.strtab'
 filename db "makefile", 0
+error db "An error occurred while opening the file", 0
 
 
 section '.bss' writeable
@@ -22,17 +27,26 @@ _start:
 	push filename
 	call file.open
 	pop eax
+
+	cmp eax, 0
+	jne @f
+		push error
+		call print.str
+		nl
+		call exit
+
+	@@:
 	mov [file_], eax
 	
 	push dword [file_]
 	call print.str
-	call print.nl
-	call print.nl
+	nl
+	nl
 
 	push dword [file_]
 	call file.content
 	call print.str
-	call print.nl
+	nl
 
 	push dword [file_]
 	call file.close