+ lda _tgi_drv ; Check if we have a driver
+ ora _tgi_drv+1
+ beq @L1
+ jsr tgi_geterror ; First call driver
+@L1: ldx #$00 ; Clear high byte
+ ldy _tgi_error ; Test high level error code
+ beq @L2 ; Branch if no high level error code
+ tya ; Use high level code if we have one
+ stx _tgi_error ; Clear high level error code
+@L2: rts
+
+.endproc