+@L1: lda (ptr1),y
+ sta XMin,y
+ dey
+ bpl @L1
+
+ cli
+ rts
+
+;----------------------------------------------------------------------------
+; GETBOX: Return the mouse bounding box. The parameters are passed as they
+; come from the C program, that is, a pointer to a mouse_box struct in a/x.
+
+GETBOX: sta ptr1
+ stx ptr1+1 ; Save data pointer
+
+ ldy #.sizeof (MOUSE_BOX)-1
+ sei
+
+@L1: lda XMin,y
+ sta (ptr1),y