Merge pull request #71 from groessler/something_to_pull2

Support to create cartridges for the Atari.

libsrc/atari/carthdr.s

@@ -0,0 +1,22 @@
+; Cartridge "header"
+; (In fact, it's at the end of the cartridge, so more a "trailer".)
+;
+; Christian Groessler, 06-Jan-2014
+
+.ifndef __ATARIXL__
+
+.import         __CARTSIZE__, __CARTFLAGS__, cartinit, cartstart
+.export         __CART_HEADER__: absolute = 1
+
+.include        "atari.inc"
+
+.segment        "CARTHDR"
+
+                .word   cartstart       ; start routine
+                .byte   0               ; must be zero
+                .byte   <__CARTFLAGS__
+                .word   cartinit        ; init routine
+
+.assert         (__CARTSIZE__ = $2000 || __CARTSIZE__ = $4000), error, "Cartridge size must either be $2000 or $4000"
+
+.endif  ; .ifndef __ATARIXL__

libsrc/atari/cartinit.s

@@ -0,0 +1,11 @@
+; Cartridge init routine
+;
+; Christian Groessler, 06-Jan-2014
+
+.ifndef __ATARIXL__
+
+.export         cartinit
+
+cartinit:       rts
+
+.endif  ; .ifndef __ATARIXL__

libsrc/atari/cartstart.s

@@ -0,0 +1,21 @@
+; Cartridge start routine
+;
+; Christian Groessler, 06-Jan-2014
+
+.ifndef __ATARIXL__
+
+.export         cartstart
+
+.import         start, copydata
+.importzp       ptr1, ptr2, tmp1, tmp2
+
+.include        "atari.inc"
+
+; start routine of cartridge
+; copy data segment to RAM and chain to entry point of crt0.s
+
+cartstart:      jsr     copydata
+                jsr     start                   ; run program
+                jmp     (DOSVEC)                ; return to DOS
+
+.endif  ; .ifndef __ATARIXL__