rework for the initial CBDOS

src/dos_m65/dos_unitset.s

@@ -0,0 +1,49 @@
+
+;
+; Unit number handling. For detailed description see 'm65dos_bridge.s' file
+;
+
+
+dos_UNITSET:
+
+	; Check if memory content is not damaged
+
+	jsr dos_MEMCHK
+	bcc @1
+	rts
+@1:
+	; Check what kind of device was requested
+
+	cmp #$00
+	beq dos_UNITSET_sdcard
+	; XXX devioces below are not implemented yet
+	; cmp #$01
+	; beq dos_UNITSET_floppy
+	; cmp #$02
+	; beq dos_UNITSET_ramdisk
+
+	sec
+	rts
+
+dos_UNITSET_sdcard:
+
+	stx UNIT_SDCARD
+	+skip_2_bytes_trash_nvz
+
+	; FALLTROUGH
+
+dos_UNITSET_floppy:
+
+	stx UNIT_FLOPPY
+	+skip_2_bytes_trash_nvz
+
+	; FALLTROUGH
+
+dos_UNITSET_ramdisk:
+
+	stx UNIT_RAMDISK
+
+	; FALLTROUGH
+
+	clc
+	rts