psxbios: Add checks to strcat

Nocash documentation says that function fails if src or dst is 0.
If so, then it must return 0.

This fix is required for fixing crash on bootup in Digimon World.

1 files changed, 6 insertions, 1 deletions

diff --git a/libpcsxcore/psxbios.c b/libpcsxcore/psxbios.c
index 292d80d..4624bf4 100644
--- a/libpcsxcore/psxbios.c
+++ b/libpcsxcore/psxbios.c
@@ -394,7 +394,12 @@ void psxBios_strcat() { // 0x15
 #ifdef PSXBIOS_LOG
 	PSXBIOS_LOG("psxBios_%s: %s, %s\n", biosA0n[0x15], Ra0, Ra1);
 #endif
-
+	if (a0 == 0 || a1 == 0)
+	{
+		v0 = 0;
+		pc0 = ra;
+		return;
+	}
 	while (*p1++);
 	--p1;
 	while ((*p1++ = *p2++) != '\0');