From b1015cbf9ef73c6d2d56e0567602c34f88c0fd75 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mat=C3=ADas=20Israelson?=
 <57065102+israpps@users.noreply.github.com>
Date: Thu, 12 Feb 2026 14:56:47 -0300
Subject: [PATCH] [PS2 0x7F] consider only first two bits of parameter

original SCPH-10020 do this, so for example, a parameter 0xF would be as sending 0x0
---
 src/ps2/card_emu/ps2_mc_auth.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ps2/card_emu/ps2_mc_auth.c b/src/ps2/card_emu/ps2_mc_auth.c
index 694a7c4..e5b3e74 100644
--- a/src/ps2/card_emu/ps2_mc_auth.c
+++ b/src/ps2/card_emu/ps2_mc_auth.c
@@ -573,7 +573,7 @@ inline __attribute__((always_inline)) void __time_critical_func(ps2_mc_auth_keyS
     receiveOrNextCmd(&_);
     DPRINTF("KeySelect: requested %d key\n", _);
     if (PS2_VARIANT_RETAIL == settings_get_ps2_variant()) {
-        switch (_) {
+        switch (_ & 0x03) {
             case REQUEST_DEX:
                 keysource = ps2_keysource;
                 key = dex_key;