From 719d57bea98b37d637f0ef0299a426786cc18e2b Mon Sep 17 00:00:00 2001
From: Peter Veenstra <qbix79@users.sourceforge.net>
Date: Thu, 26 May 2005 15:25:29 +0000
Subject: [PATCH] sum of videoROM modules 256 = 0 in VGA mode. Fixes a few koei
 games.

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@2212
---
 src/ints/int10_memory.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/ints/int10_memory.cpp b/src/ints/int10_memory.cpp
index 0ffb3b54..6d391bdf 100644
--- a/src/ints/int10_memory.cpp
+++ b/src/ints/int10_memory.cpp
@@ -108,6 +108,15 @@ void INT10_SetupRomMemory(void) {
 		phys_writeb(PhysMake(0xf000,0xfa6e)+i,int10_font_08[i]);
 	}
 	RealSetVec(0x1F,int10.rom.font_8_second);
+
+	if (machine == MCH_VGA) { //EGA/VGA. Just to be safe
+		/* Sum of all bytes in rom module 256 should be 0 */
+		Bit8u sum = 0;
+		for (i = 0;i < 32 * 1024;i++) //32 KB romsize
+			sum += phys_readb(rom_base + i); //OVERFLOW IS OKAY
+		sum = 256 - sum;
+		phys_writeb(rom_base+int10.rom.used++,sum);
+	}
 };