From 277e8210e00d295a064b7a888947ff1cd8d16e8e Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Tue, 5 Mar 2024 05:22:43 +0200
Subject: [PATCH] attempt at building a cd image (failed)

---
 Makefile      |   11 +++++++++++
 cd/cd.xml     |   15 +++++++++++++++
 cd/system.cnf |    4 ++++
 psx.ld        |    2 +-
 src/startup.S |   18 ++++++++----------
 5 files changed, 39 insertions(+), 11 deletions(-)
 create mode 100644 cd/cd.xml
 create mode 100644 cd/system.cnf

diff --git a/Makefile b/Makefile
index 5da7d41..c0a1ea4 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,7 @@ dep = $(csrc:.c=.d) $(ssrc:.S=.d)
 
 elf = test1.elf
 bin = test1.psx
+iso = test1.iso
 
 TCPREFIX = mipsel-linux-gnu-
 
@@ -25,11 +26,17 @@ $(bin): $(elf)
 $(elf): $(obj)
 	$(LD) -o $@ $(obj) -Map link.map $(LDFLAGS)
 
+$(iso): cd/cd.xml cd/system.cnf $(bin)
+	mkpsxiso -o $@ -y $<
+
 -include $(dep)
 
 %.s: %.c
 	$(CC) $(CFLAGS) -S -o $@ $<
 
+.PHONY: iso
+iso: $(iso)
+
 .PHONY: clean
 clean:
 	rm -f $(obj) $(bin) $(elf) link.map
@@ -41,3 +48,7 @@ cleandep:
 .PHONY: run
 run: $(bin)
 	mednafen $<
+
+.PHONY: runiso
+runiso: $(iso)
+	mednafen test1.cue
diff --git a/cd/cd.xml b/cd/cd.xml
new file mode 100644
index 0000000..1ba46d7
--- /dev/null
+++ b/cd/cd.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<iso_project image_name="test1.iso" cue_sheet="test1.cue" no_xa="0">
+	<track type="data">
+		<identifiers system="PLAYSTATION" application="PLAYSTATION" publisher="SCEE"/>
+		<license file="licensee.dat"/>
+		<directory_tree>
+			<file name="system.cnf" source="system.cnf" type="data"/>
+			<file name="psx.exe" source="../test1.psx" type="data"/>
+			<dummy sectors="1024"/>
+		</directory_tree>
+	</track>
+
+	<!--track type="audio" trackid="02" source="myaudio.wav"/-->
+</iso_project>
diff --git a/cd/system.cnf b/cd/system.cnf
new file mode 100644
index 0000000..b5b5d30
--- /dev/null
+++ b/cd/system.cnf
@@ -0,0 +1,4 @@
+BOOT=cdrom:\psx.exe;1
+TCB=4
+EVENT=10
+STACK=801ffff0
diff --git a/psx.ld b/psx.ld
index 4f6d4cd..fc5a306 100644
--- a/psx.ld
+++ b/psx.ld
@@ -5,7 +5,7 @@ MEMORY {
 	dcache : ORIGIN = 0x1f800000, LENGTH = 0x400
 }
 
-_stacktop = ORIGIN(ram) + LENGTH(ram);
+_stacktop = ORIGIN(ram) + LENGTH(ram) - 16;
 _dcache = ORIGIN(dcache);
 _dcache_end = ORIGIN(dcache) + LENGTH(dcache);
 _progsize = _imgend - _start;
diff --git a/src/startup.S b/src/startup.S
index 3df6b83..afce04b 100644
--- a/src/startup.S
+++ b/src/startup.S
@@ -14,8 +14,7 @@ _start:
 	lui a0, REG_BASE
 
 	# setup screen mode
-	li t0, 0
-	sw t0, REG_GP1(a0)	# GP1 0: reset
+	sw zero, REG_GP1(a0)	# GP1 0: reset
 
 	li t0, 0x03000000	# GP1 3: display enable
 	sw t0, REG_GP1(a0)
@@ -38,25 +37,24 @@ _start:
 	# clear screen
 	li t0, 0x02302010	# cmd 2: fill area (BBGGRR)
 	sw t0, REG_GP0(a0)
-	li t0, 0
-	sw t0, REG_GP0(a0)	# ... top left 0,0 (YYYYXXXX)
+	sw zero, REG_GP0(a0)	# ... top left 0,0 (YYYYXXXX)
 	li t0, 0x00ef013f	# ... size 319x239 (HHHHWWWW)
 	sw t0, REG_GP0(a0)
 
 	# draw gouraud triangle
-	li t0, 0x30ff0000
+	li t0, 0x30ff0000	# cmd 30: draw gouraud triangle (+BBGGRR vert0)
 	sw t0, REG_GP0(a0)
-	li t0, 160 | (16 << 16)
+	li t0, 160 | (16 << 16)	# ... vertex(160, 16)
 	sw t0, REG_GP0(a0)
 
-	li t0, 0x0000ff00
+	li t0, 0x0000ff00	# ... color vert1
 	sw t0, REG_GP0(a0)
-	li t0, 32 | (180 << 16)
+	li t0, 32 | (180 << 16)	# ... vertex(32, 180)
 	sw t0, REG_GP0(a0)
 
-	li t0, 0x000000ff
+	li t0, 0x000000ff	# ... color vert2
 	sw t0, REG_GP0(a0)
-	li t0, 280 | (220 << 16)
+	li t0, 280 | (220 << 16) # ... vertex(220, 280)
 	sw t0, REG_GP0(a0)
 
 	#jal main
-- 
1.7.10.4