Introduced getcurrentdevice() and implemented it for CBM and Apple.

git-svn-id: svn://svn.cc65.org/cc65/trunk@5863 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/apple2/curdevice.s

@@ -0,0 +1,27 @@
+;
+; Oliver Schmidt, 2012-10-21
+;
+; unsigned char getcurrentdevice (void);
+;
+
+        .export         _getcurrentdevice
+        .import         __dos_type
+
+        .include        "mli.inc"
+
+_getcurrentdevice:
+
+        ; Use unit number of most recent accessed device
+        lda     DEVNUM
+        lsr
+        lsr
+        lsr
+        lsr
+
+        ; Check for ProDOS 8
+        ldx     __dos_type
+        bne     :+
+        lda     #$FF            ; INVALID_DEVICE
+
+:       ldx     #$00
+        rts