inline read_duration function

messages.asm

@@ -158,7 +158,14 @@ newline:
 ;; - bx
 ;; - cx
 beep:
-	call    read_duration	; get duration from keyboard (in al)
+	;; Read duration (0-16 supported)
+	mov ah, 0x00	; read keypress
+	int 0x16
+	;; Read ASCII character is in al
+	sub al, 'a' 	; normalise (a=0, b=1, c=...)
+
+	;; interrupt 0x16, ah=0 returns the read scancode in ah
+	;; so ah must be reset
 	mov     ah, 0
 	push    ax	; store on stack
 
@@ -299,15 +306,15 @@ readbyte:
 ;;
 ;; CLOBBERS
 ;; - ax
-read_duration:
-	;; Read duration (0-16 supported)
-	mov ah, 0x00	; read keypress
-	int 0x16
-
-	;; Read character is in al
-	sub al, 'a' 	; normalise
-
-	ret
+;read_duration:
+;	;; Read duration (0-16 supported)
+;	mov ah, 0x00	; read keypress
+;	int 0x16
+;
+;	;; Read character is in al
+;	sub al, 'a' 	; normalise
+;
+;	ret
 
 ;; Variable to store color mode information for writing to the screen
 color_mode: db 0x02