From 9f2054453da5d0a42201348cf04711759388e16c Mon Sep 17 00:00:00 2001
From: Gregor Riepl <onitake@gmail.com>
Date: Mon, 22 Aug 2022 19:00:42 +0200
Subject: [PATCH] Generate a PRG file

---
 .gitignore | 1 +
 Makefile   | 8 ++------
 driver.a65 | 7 +++++++
 mem.cfg    | 3 +++
 4 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/.gitignore b/.gitignore
index 0d54a79..3ae5b13 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@ plot/
 *.bin
 *.map
 *.lst
+*.prg
diff --git a/Makefile b/Makefile
index 591da2a..3a7cf89 100644
--- a/Makefile
+++ b/Makefile
@@ -4,17 +4,13 @@ MEMCFG := mem.cfg
 
 .PHONY: all clean
 
-all: rs232.bin rs232.lst
+all: rs232.prg
 
 clean:
 	rm -f rs232.bin *.o *.lst *.map
 
-rs232.bin: driver.o
+rs232.prg: driver.o
 	cl65 -v -C ${MEMCFG} -m rs232.map -o $@ $^
 
-%.lst: %.bin
-	@# the start address shouldn't be hardcoded here...
-	da65 -o $@ -S 0x7000 $<
-
 %.o: %.a65
 	ca65 -v -l $(patsubst %.o,%.lst,$@) -t ${MACHINE} -o $@ $<
diff --git a/driver.a65 b/driver.a65
index bc3f0e0..60961a0 100644
--- a/driver.a65
+++ b/driver.a65
@@ -40,6 +40,13 @@ BAUD_RATE = 300
 	rs_status: .byte 0
 	; TODO add a state variable that can be monitored by the BASIC WAIT command
 
+; this is load address, for generating PRG files
+; works, as long as the code segment comes right after these two bytes
+.segment "LOADADDR"
+	.export LOADADDR
+	LOADADDR:
+	.word *+2
+
 ; entry points
 .code
 	; these are convenience entry points right at the beginning of the page,
diff --git a/mem.cfg b/mem.cfg
index 01381c0..f35fee7 100644
--- a/mem.cfg
+++ b/mem.cfg
@@ -1,6 +1,8 @@
 MEMORY {
     # $ED-$F7 seems to be an unused area in the zero page according to the BASIC 2.0/4.0 memory map
     ZP:       file = "", define = yes, start = $00ED, size = $000A;
+    # let's create a PRG file - note that you must define this segment in your code
+    LOADADDR: file = %O,               start = $6FFE, size = $0002;
     # we're loading at $7000, max code size $800 bytes
     RAM:      file = %O,               start = $7000, size = $0800;
     # if we reside in ROM instead, we should have more space available
@@ -10,6 +12,7 @@ MEMORY {
 }
 SEGMENTS {
     ZEROPAGE: load = ZP,       type = zp;
+    LOADADDR: load = LOADADDR, type = ro;
     # change these two to "ROM" if you want to put them on a ROM chip
     CODE:     load = RAM,      type = ro;
     RODATA:   load = RAM,      type = ro;