From: gameblabla <gameblabla@users.noreply.github.com>
Date: Mon, 27 Sep 2021 19:09:52 +0000 (+0000)
Subject: psxmem: Writes to PIO Expansion area have no effect. (#220)
X-Git-Tag: r23~120
X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?p=pcsx_rearmed.git;a=commitdiff_plain;h=fa18abb20fe2316f078023ddec6068bafef86014

psxmem: Writes to PIO Expansion area have no effect. (#220)

This is related to the Tetris with Card Captor fix a while back.
However, i forgot to merge this one as well related to writes,
even though it was not really necessary to fix that particular game.

Co-authored-by: senquack <dansilsby@gmail.com>
---

diff --git a/libpcsxcore/psxmem.c b/libpcsxcore/psxmem.c
index 3caf889b..61b14c65 100644
--- a/libpcsxcore/psxmem.c
+++ b/libpcsxcore/psxmem.c
@@ -176,7 +176,11 @@ int psxMemInit() {
 	memcpy(psxMemWLUT + 0x8000, psxMemWLUT, 0x80 * sizeof(void *));
 	memcpy(psxMemWLUT + 0xa000, psxMemWLUT, 0x80 * sizeof(void *));
 
-	psxMemWLUT[0x1f00] = (u8 *)psxP;
+	// Don't allow writes to PIO Expansion region (psxP) to take effect.
+	// NOTE: Not sure if this is needed to fix any games but seems wise,
+	//       seeing as some games do read from PIO as part of copy-protection
+	//       check. (See fix in psxMemReset() regarding psxP region reads).
+	psxMemWLUT[0x1f00] = NULL;
 	psxMemWLUT[0x1f80] = (u8 *)psxH;
 
 	return 0;