From 53350b35be2053cf2fc86cd22325411f1ac40975 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Strohh=C3=A4cker?=
 <c2woody@users.sourceforge.net>
Date: Sat, 6 Oct 2007 19:46:32 +0000
Subject: [PATCH] fix dcc functions

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3010
---
 src/ints/int10.cpp       | 45 +++++++++++++++++++++++++++++++++-------
 src/ints/int10_modes.cpp |  5 ++---
 2 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/src/ints/int10.cpp b/src/ints/int10.cpp
index 5d653dba..96af9e9b 100644
--- a/src/ints/int10.cpp
+++ b/src/ints/int10.cpp
@@ -399,15 +399,46 @@ graphics_chars:
 		break;
 	case 0x1A:								/* Display Combination */
 		if (!IS_VGA_ARCH) break;
-		if (reg_al==0) {
-			reg_bx=real_readb(BIOSMEM_SEG,BIOSMEM_DCC_INDEX);
+		if (reg_al==0) {	// get dcc
+			// walk the tables...
+			RealPt vsavept=real_readd(BIOSMEM_SEG,BIOSMEM_VS_POINTER);
+			RealPt svstable=real_readd(RealSeg(vsavept),RealOff(vsavept)+0x10);
+			if (svstable) {
+				RealPt dcctable=real_readd(RealSeg(svstable),RealOff(svstable)+0x02);
+				Bit8u entries=real_readb(RealSeg(dcctable),RealOff(dcctable)+0x00);
+				Bit8u idx=real_readb(BIOSMEM_SEG,BIOSMEM_DCC_INDEX);
+				// check if index within range
+				if (idx<entries) {
+					Bit16u dccentry=real_readw(RealSeg(dcctable),RealOff(dcctable)+0x04+idx*2);
+					if ((dccentry&0xff)==0) reg_bx=dccentry>>8;
+					else reg_bx=dccentry;
+				} else reg_bx=0xffff;
+			} else reg_bx=0xffff;
 			reg_al=0x1A;
-			break;
-		}
-		if (reg_al==1) {
-			real_writeb(BIOSMEM_SEG,BIOSMEM_DCC_INDEX,reg_bl);
+		} else if (reg_al==1) {	// set dcc
+			Bit8u newidx=0xff;
+			// walk the tables...
+			RealPt vsavept=real_readd(BIOSMEM_SEG,BIOSMEM_VS_POINTER);
+			RealPt svstable=real_readd(RealSeg(vsavept),RealOff(vsavept)+0x10);
+			if (svstable) {
+				RealPt dcctable=real_readd(RealSeg(svstable),RealOff(svstable)+0x02);
+				Bit8u entries=real_readb(RealSeg(dcctable),RealOff(dcctable)+0x00);
+				if (entries) {
+					Bitu ct;
+					Bit16u swpidx=reg_bh|(reg_bl<<8);
+					// search the ddc index in the dcc table
+					for (ct=0; ct<entries; ct++) {
+						Bit16u dccentry=real_readw(RealSeg(dcctable),RealOff(dcctable)+0x04+ct*2);
+						if ((dccentry==reg_bx) || (dccentry==swpidx)) {
+							newidx=ct;
+							break;
+						}
+					}
+				}
+			}
+
+			real_writeb(BIOSMEM_SEG,BIOSMEM_DCC_INDEX,newidx);
 			reg_al=0x1A;
-			break;
 		}
 		break;
 	case 0x1B:								/* functionality State Information */
diff --git a/src/ints/int10_modes.cpp b/src/ints/int10_modes.cpp
index 5ad4f0b3..4a1687c8 100644
--- a/src/ints/int10_modes.cpp
+++ b/src/ints/int10_modes.cpp
@@ -290,9 +290,8 @@ static void FinishSetMode(bool clearmem) {
 	real_writeb(BIOSMEM_SEG,BIOSMEM_SWITCHES,0x09);
 	real_writeb(BIOSMEM_SEG,BIOSMEM_MODESET_CTL,real_readb(BIOSMEM_SEG,BIOSMEM_MODESET_CTL)&0x7f);
 
-	if (IS_VGA_ARCH) real_writeb(BIOSMEM_SEG,BIOSMEM_DCC_INDEX,0x08);    // 8 is VGA should be ok for now
-	real_writew(BIOSMEM_SEG,BIOSMEM_VS_POINTER,0x00);
-	real_writew(BIOSMEM_SEG,BIOSMEM_VS_POINTER+2,0x00);
+	// this is an index into the dcc table:
+	if (IS_VGA_ARCH) real_writeb(BIOSMEM_SEG,BIOSMEM_DCC_INDEX,0x0b);
 	real_writed(BIOSMEM_SEG,BIOSMEM_VS_POINTER,int10.rom.video_save_pointers);
 
 	// Set cursor shape