From 9b6ff8fe490cae56f6a3bc24e0ac19e47b5eaa41 Mon Sep 17 00:00:00 2001
From: Brad Smith <bbbradsmith@users.noreply.github.com>
Date: Tue, 5 Jun 2018 02:17:38 -0400
Subject: [PATCH] Mapper 30 4-screen (#10)

mapper 30 support for both 1-screen and 4-screen configurations (see: Black Box Challenge)
---
 src/boards/unrom512.cpp | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/boards/unrom512.cpp b/src/boards/unrom512.cpp
index 57b2ae7f..ac6bd57b 100644
--- a/src/boards/unrom512.cpp
+++ b/src/boards/unrom512.cpp
@@ -240,8 +240,24 @@ void UNROM512_Init(CartInfo *info) {
 		chrram_mask = 0x20;
 	else
 		chrram_mask = 0x60;
-	
-	SetupCartMirroring(info->mirror,(info->mirror>=MI_0)?0:1,0);
+
+	int mirror = (head.ROM_type & 1) | ((head.ROM_type & 8) >> 2);
+	switch (mirror)
+	{
+	case 0: // hard horizontal, internal
+		SetupCartMirroring(MI_H, 1, NULL);
+		break;
+	case 1: // hard vertical, internal
+		SetupCartMirroring(MI_V, 1, NULL);
+		break;
+	case 2: // switchable 1-screen, internal (flags: 4-screen + horizontal)
+		SetupCartMirroring(MI_0, 0, NULL);
+		break;
+	case 3: // hard four screen, last 8k of 32k RAM (flags: 4-screen + vertical)
+		SetupCartMirroring(   4, 1, VROM + (info->vram_size - 8192));
+		break;
+	}
+
 	bus_conflict = !info->battery;
 	latcheinit = 0;
 	WLSync = UNROM512LSync;