use custom stripped-down crt0 for cartridge, save 65 bytes

1 files changed, 72 insertions, 0 deletions

diff --git a/crt0_cart.s b/crt0_cart.s
new file mode 100644
index 0000000..ec3e423
--- /dev/null
+++ b/crt0_cart.s
@@ -0,0 +1,72 @@
+;
+; Startup code for cc65 (ATARI version)
+;
+; Contributing authors:
+;       Mark Keates
+;       Freddy Offenga
+;       Christian Groessler
+;       Stefan Haubenthal
+;
+
+        .export         __STARTUP__ : absolute = 1      ; Mark as startup
+        .export         _exit, start
+
+        .import         initlib, donelib
+        .import         callmain, zerobss
+        .import         __RESERVED_MEMORY__
+        .import         __RAM_START__, __RAM_SIZE__
+        .include        "zeropage.inc"
+        .include        "atari.inc"
+
+; ------------------------------------------------------------------------
+
+.segment        "STARTUP"
+
+        rts     ; fix for SpartaDOS / OS/A+
+                ; They first call the entry point from AUTOSTRT; and
+                ; then, the load address (this rts here).
+                ; We point AUTOSTRT directly after the rts.
+
+; Real entry point:
+
+start:
+
+; Clear the BSS data.
+
+        jsr     zerobss
+
+; Setup arg stack
+        lda MEMTOP
+        sta sp
+        lda MEMTOP+1
+        sta sp+1
+
+; Call the module constructors.
+
+        jsr     initlib
+
+; Set the left margin to 0.
+
+        ldy     #0
+        sty     LMARGN
+
+; Set the keyboard to upper-/lower-case mode.
+
+        ldx     SHFLOK
+        sty     SHFLOK
+
+; Push the command-line arguments; and, call main().
+
+        jsr     callmain
+
+; Call the module destructors. This is also the exit() entry.
+
+_exit:  jsr     donelib         ; Run module destructors
+
+; Back to DOS.
+
+        rts
+
+; *** end of main startup code
+
+; ------------------------------------------------------------------------