psxbios: Add checks to memcpy.

Always returns dst

diff --git a/libpcsxcore/psxbios.c b/libpcsxcore/psxbios.c
index c362a75..b327632 100644 (file)
--- a/libpcsxcore/psxbios.c
+++ b/libpcsxcore/psxbios.c
@@ -788,9 +788,19 @@ void psxBios_bcmp() { // 0x29
 
 void psxBios_memcpy() { // 0x2a
        char *p1 = (char *)Ra0, *p2 = (char *)Ra1;
-       while ((s32)a2-- > 0) *p1++ = *p2++;
-
-       v0 = a0; pc0 = ra;
+       s32 n=0;
+       v0 = a0;
+       if (a0 == 0 || a2 > 0x7FFFFFFF)
+       {
+               pc0 = ra;
+               return;
+       }
+       while ((s32)a2-- > 0) {
+               n++;
+               *p1++ = *p2++;
+       }
+       a2 = 0;
+       pc0 = ra;
 }
 
 void psxBios_memset() { // 0x2b