From b4dbb5093af8dafc9f67ea41130c9ed5d900793c Mon Sep 17 00:00:00 2001
From: Rangi42 <remy.oukaour+rangi42@gmail.com>
Date: Tue, 31 Oct 2023 23:37:55 -0400
Subject: [PATCH] Warn when SGB compatibility is set without old licensee 0x33

---
 src/fix/main.c                  |   4 ++++
 test/fix/sgb-old-licensee.bin   | Bin 0 -> 512 bytes
 test/fix/sgb-old-licensee.err   |   2 ++
 test/fix/sgb-old-licensee.flags |   1 +
 test/fix/sgb.bin                | Bin 512 -> 512 bytes
 test/fix/sgb.gb                 | Bin 512 -> 512 bytes
 6 files changed, 7 insertions(+)
 create mode 100644 test/fix/sgb-old-licensee.bin
 create mode 100644 test/fix/sgb-old-licensee.err
 create mode 100644 test/fix/sgb-old-licensee.flags

diff --git a/src/fix/main.c b/src/fix/main.c
index 1a872c96..dc5a3f3c 100644
--- a/src/fix/main.c
+++ b/src/fix/main.c
@@ -967,6 +967,10 @@ static void processFile(int input, int output, char const *name, off_t fileSize)
 
 	if (oldLicensee != UNSPECIFIED)
 		overwriteByte(rom0, 0x14B, oldLicensee, "old licensee code");
+	else if (sgb && rom0[0x14B] != 0x33)
+		fprintf(stderr,
+			"warning: SGB compatibility enabled, but old licensee was %#x, not 0x33\n",
+			rom0[0x14B]);
 
 	if (romVersion != UNSPECIFIED)
 		overwriteByte(rom0, 0x14C, romVersion, "mask ROM version number");
diff --git a/test/fix/sgb-old-licensee.bin b/test/fix/sgb-old-licensee.bin
new file mode 100644
index 0000000000000000000000000000000000000000..929bea12c6139792b5b133eefcc2e588e39eeca4
GIT binary patch
literal 512
zcmV+b0{{K<HjXIOfNx|<N4H*i>oOvh(fJ}F@{ODPVIdfqF{7hmYnX4XYI%PNmr5P&
z$C;WJk`Pj{sG4SG=1q>!u$Q)1I9b^8gnZEuQdUCj{O>44sk0cU%5x*Ef>6xYaR!h2
zs>kYY&vJ-8_42mINFLf&`fK?+??kPjiTjrGxK~P$DfyVGaP3-;W@uuG|NeEDzXn_Y
z{8<a^tfC@K0!Q5V_ho`^|27_yOwcqxZ_Adzp}`aYlX{1Zo`;#vAy}1y`i2}A0vZ_L
zB6rk!qat=(h8DCivPpk2honTh;-Bc-_dgd&_s8feO5aAv6D+wRyxbrYgUM9%f+tI6
z;7S!%_B}23d$d`!<uEM7k(YkGaC*!6IPiWA^LEex%$y0yMwPID_@W)Vs6UaK!_Y0{
zQTZ*w^j}S$l(j+cx9tx<pN5`*O`9-;*yP1@5R{K_%OJP<9k0J}S1O@-Ep=>aLW!&V
z2$LT-G{Ejgj7)`Z!C$r{;+mnG^zok51wD6m`V2;d-FXok6~>QTo)kHkH<OIr)d8m-
zwu*{PyCmlGnW1jVG8=P9p7t)Wn@(@^DHgklnX_R)A%PCx`sJ!a06J&V@tb>pOQg5@
z47u(W*#Y&KI(_AF(ivJa)Yxq@VML=3@u;>O_p3}ETVPNaC_rD`am!S+9@V*ItWizd
C#0F>p

literal 0
HcmV?d00001

diff --git a/test/fix/sgb-old-licensee.err b/test/fix/sgb-old-licensee.err
new file mode 100644
index 00000000..2edaa257
--- /dev/null
+++ b/test/fix/sgb-old-licensee.err
@@ -0,0 +1,2 @@
+warning: Overwrote a non-zero byte in the SGB flag
+warning: SGB compatibility enabled, but old licensee was 0xc5, not 0x33
diff --git a/test/fix/sgb-old-licensee.flags b/test/fix/sgb-old-licensee.flags
new file mode 100644
index 00000000..5d9af957
--- /dev/null
+++ b/test/fix/sgb-old-licensee.flags
@@ -0,0 +1 @@
+-s
diff --git a/test/fix/sgb.bin b/test/fix/sgb.bin
index 3ab8ec34173c74396cfcc4c5fb1e0f166dbec248..28a680328075752d7c2f22bc33fe89afbd6c285c 100644
GIT binary patch
delta 13
UcmZo*X<*sl&B$mx*@tlp02$u{%>V!Z

delta 13
UcmZo*X<*sl&B%CSvJc}H0365!VgLXD

diff --git a/test/fix/sgb.gb b/test/fix/sgb.gb
index 4cf70bb6adfe0397441ef0a528567428537a898a..7816b245b9d22df569cc34f0cbec189def0b4949 100644
GIT binary patch
delta 13
UcmZo*X<*sl&B$mx*@tlp02$u{%>V!Z

delta 13
UcmZo*X<*sl&B%CSvJc}H0365!VgLXD