From 89432abf12b403eee44ceb62382381312daf3c92 Mon Sep 17 00:00:00 2001
From: Romain Dolbeau <romain@dolbeau.org>
Date: Tue, 1 Aug 2023 10:26:10 +0200
Subject: [PATCH] preliminary RAM expansion patch

---
 RomPatcher/IIsiExtraMemory/Makefile   | 41 +++++++++++++++++++++
 RomPatcher/IIsiExtraMemory/input.txt  |  3 ++
 RomPatcher/IIsiExtraMemory/rompatch.s | 51 +++++++++++++++++++++++++++
 3 files changed, 95 insertions(+)
 create mode 100644 RomPatcher/IIsiExtraMemory/Makefile
 create mode 100644 RomPatcher/IIsiExtraMemory/input.txt
 create mode 100644 RomPatcher/IIsiExtraMemory/rompatch.s

diff --git a/RomPatcher/IIsiExtraMemory/Makefile b/RomPatcher/IIsiExtraMemory/Makefile
new file mode 100644
index 0000000..01a2f08
--- /dev/null
+++ b/RomPatcher/IIsiExtraMemory/Makefile
@@ -0,0 +1,41 @@
+RETRO68=/home/dolbeau/Retro68/build/toolchain
+AS=${RETRO68}/bin/m68k-apple-macos-as
+CC=${RETRO68}/bin/m68k-apple-macos-gcc
+LD=${RETRO68}/bin/m68k-apple-macos-ld
+STRIP=${RETRO68}/bin/m68k-apple-macos-strip
+OBJCOPY=${RETRO68}/bin/m68k-apple-macos-objcopy
+NM=${RETRO68}/bin/m68k-apple-macos-nm
+
+HOSTCC=gcc
+HOSTCFLAGS=-O2
+
+ARCHFLAGS=-march=68020 -mcpu=68020
+CFLAGS=-O2 -mpcrel
+
+GENLINK=../patcher/genlink
+PATCHER=../patcher/patcher
+
+all: IIsi.ROM
+
+show: rompatch.elf
+	$(NM) $< | sort
+
+IIsi.ROM: ../IIsiRemoveChecksumCheck/IIsi.ROM rompatch.raw input.txt
+	/bin/cp ../IIsiRemoveChecksumCheck/IIsi.ROM IIsi.ROM
+	${PATCHER} -i rompatch.raw -p IIsi.ROM -d input.txt
+
+linker.ld: input.txt rompatch.s
+	${GENLINK} -d $< >| $@
+	$(shell for X in `grep .section rompatch.s | awk '{ print $$2 }' `; do grep -q $$X linker.ld || echo " $$X has no entry in linker.ld" && /bin/false; done)
+
+rompatch.o: rompatch.s
+	${AS} ${ARCHFLAGS} $< -o $@ -a > rompatch.l
+
+rompatch.elf: linker.ld rompatch.o ${CSRC:.c=.o} # linker script must be first
+	${LD} -o $@ -T $^
+
+rompatch.raw: rompatch.elf
+	${OBJCOPY} $^ $@ --input-target=elf32-m68k --output-target=binary
+
+clean:
+	rm -f res.inc ${CSRC_ASM} *.o rompatch.srec rompatch.raw rompatch.dir rompatch.l VidRom*.s
diff --git a/RomPatcher/IIsiExtraMemory/input.txt b/RomPatcher/IIsiExtraMemory/input.txt
new file mode 100644
index 0000000..368041f
--- /dev/null
+++ b/RomPatcher/IIsiExtraMemory/input.txt
@@ -0,0 +1,3 @@
+0x00396e, 32, raminfo
+0x003cc4, 316, gary
+0x0419e8, 20, findinfopatch
diff --git a/RomPatcher/IIsiExtraMemory/rompatch.s b/RomPatcher/IIsiExtraMemory/rompatch.s
new file mode 100644
index 0000000..1b6e67d
--- /dev/null
+++ b/RomPatcher/IIsiExtraMemory/rompatch.s
@@ -0,0 +1,51 @@
+	MAPBASE=0x20000000
+	MAPSIZE=0x0f000000
+	MAPEND=MAPBASE+MAPSIZE
+
+/* ************************************************************************ */
+	/* updated table */
+	.section .text.raminfo
+	.long MAPBASE
+	.long MAPEND
+	.long 0x04000000
+	.long 0x08000000
+	.long 0x00000000
+	.long 0x04000000
+	.long 0xFFFFFFFF
+	.long 0xFFFFFFFF
+	
+/* ************************************************************************ */
+	.section .text.gary
+fixchunk:			/* 316 bytes available */
+	/*  recreate the table but with one more chunk, as the original code assumes two chunks and turns them into three */
+	
+	move.l %D4,(%A1)+
+	move.l %D5,(%A1)+
+	move.l %D2,(%A1)+
+	move.l %D3,(%A1)+
+	
+	add.l %D5,%D4
+	move.l %D4,(%A1)+
+	move.l %D1,(%A1)+
+	
+	/* here comes the bonus */
+	move.l #MAPBASE,(%A1)+
+	move.l #MAPSIZE,(%A1)+
+	/* here ends the bonus */
+	
+	moveq #-1,%D4
+	move.l %D4,(%A1)+
+	move.l %D4,(%A1)+
+	
+	jmp (%pc,returnfindinfopatch)
+	
+/* ************************************************************************ */
+	.section .text.findinfopatch
+findinfopatch:				/* 20 bytes available */
+	jmp (%pc,fixchunk)
+	
+	.section .text.returnfindinfopatch
+returnfindinfopatch:	
+	/* */
+
+	.end