Merge pull request #556 from 86Box/feature/mga

Added Matrox MGA (Mystique) emulation from PCem.

src/video/vid_mga.h

@@ -0,0 +1,17 @@
+/*
+ * 86Box	A hypervisor and IBM PC system emulator that specializes in
+ *		running old operating systems and software designed for IBM
+ *		PC systems and compatibles from 1981 through fairly recent
+ *		system designs based on the PCI bus.
+ *
+ *		This file is part of the 86Box distribution.
+ *
+ *		Matrox MGA graphics card emulation.
+ *
+ * Version:	@(#)vid_mga.h	1.0.0	2020/01/16
+ *
+ * Author:	Sarah Walker, <http://pcem-emulator.co.uk/>
+ *		Copyright 2008-2020 Sarah Walker.
+ */
+
+extern const device_t mystique_device;

src/video/vid_svga.c

@@ -570,6 +570,7 @@ svga_poll(void *p)
     uint32_t x, blink_delay;
     int wx, wy;
     int skip = (svga->crtc[8] >> 5) & 0x03;
+	int ret;
 
     if (!svga->linepos) {
 	if (svga->displine == svga->hwcursor_latch.y && svga->hwcursor_latch.ena) {
@@ -701,11 +702,18 @@ svga_poll(void *p)
 	svga->vc &= 2047;
 
 	if (svga->vc == svga->split) {
-		svga->ma = svga->maback = 0;
-		svga->sc = 0;
-		if (svga->attrregs[0x10] & 0x20) {
-			svga->scrollcache = 0;
-			svga->x_add = (overscan_x >> 1);
+		ret = 1;
+		
+		if (svga->line_compare)
+			ret = svga->line_compare(svga);
+		
+		if (ret) {
+			svga->ma = svga->maback = 0;
+			svga->sc = 0;
+			if (svga->attrregs[0x10] & 0x20) {
+				svga->scrollcache = 0;
+				svga->x_add = (overscan_x >> 1);
+			}
 		}
 	}
 	if (svga->vc == svga->dispend) {

src/video/vid_svga.h

@@ -109,6 +109,11 @@ typedef struct svga_t
     void (*ven_write)(struct svga_t *svga, uint8_t val, uint32_t addr);
     float (*getclock)(int clock, void *p);
 
+	/*Called when VC=R18 and friends. If this returns zero then MA resetting
+	  is skipped. Matrox Mystique in Power mode reuses this counter for
+	  vertical line interrupt*/
+	int (*line_compare)(struct svga_t *svga);    
+
     /*If set then another device is driving the monitor output and the SVGA
       card should not attempt to display anything */
     int override;

src/win/Makefile.mingw

@@ -678,6 +678,7 @@ VIDOBJ		:= video.o \
 		    vid_et4000.o vid_sc1502x_ramdac.o \
 		    vid_et4000w32.o vid_stg_ramdac.o \
 		    vid_ht216.o \
+			vid_mga.o \
 		    vid_oak_oti.o \
 		    vid_paradise.o \
 		    vid_ti_cf62011.o \

src/win/Makefile_ndr.mingw

@@ -684,6 +684,7 @@ VIDOBJ		:= video.o \
 		    vid_et4000.o vid_sc1502x_ramdac.o \
 		    vid_et4000w32.o vid_stg_ramdac.o \
 		    vid_ht216.o \
+			vid_mga.o \
 		    vid_oak_oti.o \
 		    vid_paradise.o \
 		    vid_ti_cf62011.o \