Added initial (and a bit buggy on OS/2, so use 8514/A on it instead) emulation of XGA for both MCA and ISA buses.

src/video/CMakeLists.txt

@@ -24,7 +24,8 @@ add_library(vid OBJECT agpgart.c video.c vid_table.c vid_cga.c vid_cga_comp.c
     vid_stg_ramdac.c vid_ht216.c vid_oak_oti.c vid_paradise.c vid_rtg310x.c
     vid_f82c425.c vid_ti_cf62011.c vid_tvga.c vid_tgui9440.c vid_tkd8001_ramdac.c
     vid_att20c49x_ramdac.c vid_s3.c vid_s3_virge.c vid_ibm_rgb528_ramdac.c
-    vid_sdac_ramdac.c vid_ogc.c vid_nga.c vid_tvp3026_ramdac.c vid_att2xc498_ramdac.c)
+    vid_sdac_ramdac.c vid_ogc.c vid_nga.c vid_tvp3026_ramdac.c vid_att2xc498_ramdac.c
+    vid_xga.c)
 
 if(MGA)
     target_compile_definitions(vid PRIVATE USE_MGA)

src/video/vid_svga.c

@@ -560,6 +560,8 @@ svga_recalctimings(svga_t *svga)
     } else {
         if (ibm8514_on && ibm8514_enabled)
             ibm8514_recalctimings(svga);
+        if (xga_enabled)
+            xga_recalctimings(svga);
     }
 
     svga->y_add = (overscan_y >> 1) - (svga->crtc[8] & 0x1f);
@@ -660,6 +662,9 @@ svga_poll(void *p)
     if (!vga_on && ibm8514_enabled && ibm8514_on) {
         ibm8514_poll(&svga->dev8514, svga);
         return;
+    } else if (!vga_on && xga_enabled && svga->xga.on) {
+        xga_poll(&svga->xga, svga);
+        return;
     }
 
     if (!svga->linepos) {
@@ -1070,6 +1075,23 @@ svga_write_common(uint32_t addr, uint8_t val, uint8_t linear, void *p)
     cycles -= video_timing_write_b;
 
     if (!linear) {
+	if (xga_enabled) {
+        if (((svga->xga.op_mode & 7) == 4) && (svga->xga.aperture_cntl == 1)) {
+            if (val == 0xa5) { /*Memory size test of XGA*/
+                svga->xga.test = val;
+                return;
+            } else if (val == 0x5a) {
+                svga->xga.test = val;
+                return;
+            } else if (val == 0x12 || val == 0x34) {
+                addr += svga->xga.write_bank;
+                svga->xga.vram[addr & svga->xga.vram_mask] = val;
+                svga->xga.op_mode_reset = 1;
+                return;
+            }
+        } else
+            svga->xga.on = 0;
+	}
 	addr = svga_decode_addr(svga, addr, 1);
 
 	if (addr == 0xffffffff)
@@ -1254,6 +1276,21 @@ svga_read_common(uint32_t addr, uint8_t linear, void *p)
     cycles -= video_timing_read_b;
 
     if (!linear) {
+	if (xga_enabled) {
+        if (((svga->xga.op_mode & 7) == 4) && (svga->xga.aperture_cntl == 1)) {
+            if (svga->xga.test == 0xa5) { /*Memory size test of XGA*/
+                svga->xga.on = 1;
+                return svga->xga.test;
+            } else if (svga->xga.test == 0x5a) {
+                svga->xga.on = 1;
+                return svga->xga.test;
+            } else if (addr == 0xa0000 || addr == 0xa0010) {
+                addr += svga->xga.read_bank;
+                return svga->xga.vram[addr & svga->xga.vram_mask];
+            }
+        } else
+            svga->xga.on = 0;
+	}
 	addr = svga_decode_addr(svga, addr, 0);
 
 	if (addr == 0xffffffff)