first changes for atari5200 target

libsrc/atari5200/crt0.s

@@ -0,0 +1,55 @@
+;
+; Startup code for cc65 (Atari5200 version)
+;
+; by Christian Groessler (chris@groessler.org), 2014
+;
+
+        .export         _exit, start
+        .export         __STARTUP__ : absolute = 1      ; Mark as startup
+	.import		__RAM_START__, __RAM_SIZE__
+	.import		__RESERVED_MEMORY__
+
+        .import         initlib, donelib, callmain
+        .import         zerobss, copydata
+
+        .include        "zeropage.inc"
+        .include        "atari5200.inc"
+
+
+; ------------------------------------------------------------------------
+; Place the startup code in a special segment.
+
+.segment        "STARTUP"
+
+start:
+
+; Clear the BSS data
+
+        jsr     zerobss
+
+; initialize data
+        jsr     copydata
+
+; setup the stack
+
+        lda     #<(__RAM_START__ + __RAM_SIZE__)
+        sta     sp
+        lda     #>(__RAM_START__ + __RAM_SIZE__)
+        sta     sp+1            ; Set argument stack ptr
+
+; Call module constructors
+
+        jsr     initlib
+
+; Push arguments and call main()
+
+        jsr     callmain
+
+; Call module destructors. This is also the _exit entry.
+
+_exit:  jsr     donelib         ; Run module destructors
+
+; Reset the NES
+
+        jmp start
+