From d125caf776c837fd2e9da46a4d19d68b8b6ab068 Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Wed, 10 Jan 2024 09:27:07 +0100
Subject: [PATCH] Applied the blanking extensions to S3 Trio64V+ and V2/DX.

---
 src/video/vid_s3.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/video/vid_s3.c b/src/video/vid_s3.c
index dcb251f02..3b3cebe8d 100644
--- a/src/video/vid_s3.c
+++ b/src/video/vid_s3.c
@@ -4018,7 +4018,7 @@ s3_trio64v_recalctimings(svga_t *svga)
         svga->htotal |= 0x100;
     if (svga->crtc[0x5d] & 0x02) {
         svga->hdisp_time |= 0x100;
-        svga->hdisp |= 0x100 * ((svga->seqregs[1] & 8) ? 16 : 8);
+        svga->hdisp |= 0x100 * svga->dots_per_clock;
     }
     if (svga->crtc[0x5e] & 0x01)
         svga->vtotal |= 0x400;
@@ -4146,6 +4146,24 @@ s3_trio64v_recalctimings(svga_t *svga)
                 break;
         }
     }
+
+    if (!svga->scrblank && svga->attr_palette_enable && (svga->crtc[0x43] & 0x80)) {
+        /* TODO: In case of bug reports, disable 9-dots-wide character clocks in graphics modes. */
+        svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
+    }
+
+    if (svga->crtc[0x5d] & 0x04)
+        svga->hblankstart += 0x100;
+
+    /* NOTE: The S3 Trio64V+ datasheet says this is bit 7, but then where is bit 6?
+             The datasheets for the pre-Trio64V+ cards say +64, which implies bit 6,
+             and, contrary to VGADOC, it also exists on Trio32, Trio64, Vision868,
+             and Vision968. */
+    if (svga->crtc[0x5d] & 0x08)
+        svga->hblank_ext = 0x40;
+    svga->hblank_end_len = 0x00000040;
+
+    svga->hblank_overscan = !(svga->crtc[0x33] & 0x20);
 }
 
 static void