Adds test code for the Atari (xex) linker file format.

testcode/lib/atari/asm-xex.s

@@ -0,0 +1,51 @@
+; Sample using ATARI file format, by "atari-xex.cfg" linker configuration.
+;
+; This is a very simple example, shows a message to the screen, waits and
+; returns to DOS.
+;
+; Compile with:
+;    cl65 -tatari -Catari-xex.cfg asm-xex.s -o prog.xex
+
+        .include        "atari.inc"
+
+; Default RUNAD is "start", export that:
+        .export         start
+
+
+; Write string to screen
+.proc   puts
+        sta     ICBAL
+        stx     ICBAH
+        lda     #PUTREC
+        sta     ICCOM
+        ldx     #$FF
+        stx     ICBLL
+        inx
+        stx     ICBLH
+        jsr     CIOV
+        rts
+.endproc
+
+
+; Write a message and exit
+
+.proc   start
+        lda     #<msg
+        ldx     #>msg
+        jsr     puts
+
+
+        ; Delay before returning to DOS
+        lda     #0
+        tax
+loop:
+        inx
+        cpx     #$FF
+        adc     #0
+        bcc     loop
+
+        rts
+.endproc
+
+msg:    .byte   "Hello world", ATEOL
+