From 112ed11473e4be6fadf8f1abad08195294e838f4 Mon Sep 17 00:00:00 2001
From: "B. Watson" <yalhcru@gmail.com>
Date: Thu, 18 Feb 2016 05:26:21 -0500
Subject: save a byte in the cart build

---
 Makefile    | 18 ++++--------------
 crt0_cart.s | 11 ++++++-----
 2 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/Makefile b/Makefile
index 74ec7a5..ddcfa5b 100644
--- a/Makefile
+++ b/Makefile
@@ -303,21 +303,11 @@ mkcart: mkcart.c
 	$(HOSTCC) $(HOSTCFLAGS) -o mkcart mkcart.c
 
 # cc65 doc atari.html explains how to produce a raw binary file.
-# we build it for $03ff because cc65-produced atari binaries always
-# have an RTS as the first byte (for compatibility with SpartaDOS).
-# the "tail -c+2" stuff removes the first byte, so we end up with
-# a romable_taimain.raw that's ready to be copied to $0400 and run
-# via "JSR $0400".
-#romable_taimain.raw: $(TAIMAIN_C_SRC) $(TAIMAIN_ASM_SRC) $(TAIMAIN_HDRS)
-#	rm -f taimain.xex
-#	$(MAKE) FONT_ADDR=0x9c00 TAIMAIN_ADDR=0x3ff EXTRACFLAGS="-Wl -D__AUTOSTART__=1 -Wl -D__EXEHDR__=1 -DCART_TARGET=1 --asm-define CART_TARGET=1" taimain.xex
-#	tail -c+2 taimain.xex > romable_taimain.raw
-#	rm -f taimain.xex
-
+# using a custom crt0 to get rid of the extra RTS cc65 puts there for
+# SpartaDOS compatibility (which has no effect on a cartridge image,
+# except to waste 1 byte).
 romable_taimain.raw: $(TAIMAIN_C_SRC) $(TAIMAIN_ASM_SRC) $(TAIMAIN_HDRS) $(BIGNUM_SRC) $(BIGNUM_HDRS) $(TAIMAIN_LIBS) crt0_cart.s
-	cl65 --config cartbank3.cfg -m taipan.map -t atari -T -I. -L. -DFONT_ADDR=0x9c00 --start-addr 0x3ff -Wl -D__STACKSIZE__=0x200 -O -Wl -D__SYSTEM_CHECK__=1 -Wl -D__AUTOSTART__=1 -Wl -D__EXEHDR__=1  -DCART_TARGET=1 --asm-define CART_TARGET=1 -DBIGNUM=BIGFLOAT -o romable_taimain.raw.in $(TAIMAIN_C_SRC) $(TAIMAIN_ASM_SRC) $(BIGNUM_SRC) $(TAIMAIN_LIBS) crt0_cart.s
-	tail -c+2 romable_taimain.raw.in > romable_taimain.raw
-	rm -f romable_taimain.raw.in
+	cl65 --config cartbank3.cfg -m taipan.map -t atari -T -I. -L. -DFONT_ADDR=0x9c00 --start-addr 0x400 -Wl -D__STACKSIZE__=0x200 -O -Wl -D__SYSTEM_CHECK__=1 -Wl -D__AUTOSTART__=1 -Wl -D__EXEHDR__=1  -DCART_TARGET=1 --asm-define CART_TARGET=1 -DBIGNUM=BIGFLOAT -o romable_taimain.raw $(TAIMAIN_C_SRC) $(TAIMAIN_ASM_SRC) $(BIGNUM_SRC) $(TAIMAIN_LIBS) crt0_cart.s
 
 # 256 bytes of $ff filler, for the last page of each code bank. Wasting
 # this little bit of space simplifies the copying code in bank7.s (no
diff --git a/crt0_cart.s b/crt0_cart.s
index ec3e423..7448e9b 100644
--- a/crt0_cart.s
+++ b/crt0_cart.s
@@ -8,6 +8,12 @@
 ;       Stefan Haubenthal
 ;
 
+; Modified for use with Taipan cartridge image:
+; - Removed the RTS at the start of the code
+; - Got rid of __ATARIXL__ conditionals
+; - Don't save stuff like APPMHI and LMARGN, since the cart
+;   never returns.
+
         .export         __STARTUP__ : absolute = 1      ; Mark as startup
         .export         _exit, start
 
@@ -22,11 +28,6 @@
 
 .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:
-- 
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