Originally Posted by etabeta78
Code
N64TexturePipeT::Fetch
-	return ((this)->*(TexelFetch[index]))(s, t, tbase, tpal, userdata);
+	return ((this)->*(TexelFetch[index & 79]))(s, t, tbase, tpal, userdata);

you probably meant:
Code
+	return ((this)->*(TexelFetch[index % 79]))(s, t, tbase, tpal, userdata);
grin

however, as others pointed out, the problem lies elsewhere, i.e. why does the index get larger than 79 in the first place? And why do the masks contain values larger than 0x0f

-Darkstar