From 2f7de1d23d819525772c185ac5f6a00ac9e482cb Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Thu, 14 Aug 2025 13:13:32 +0200
Subject: [PATCH] EGA, MDA, and Sigma: Fix timings.

---
 src/video/vid_ega.c   | 5 +++--
 src/video/vid_mda.c   | 4 ++--
 src/video/vid_sigma.c | 7 +++++--
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/video/vid_ega.c b/src/video/vid_ega.c
index 26bb38991..5a552ab6d 100644
--- a/src/video/vid_ega.c
+++ b/src/video/vid_ega.c
@@ -643,9 +643,10 @@ ega_recalctimings(ega_t *ega)
         crtcconst *= mdiv;
     } else {
         if (ega->vidclock)
-            crtcconst = (ega->seqregs[1] & 1) ? MDACONST : (MDACONST * (9.0 / 8.0));
+            crtcconst = (cpuclock / 16257000.0 * (double) (1ULL << 32));
         else
-            crtcconst = (ega->seqregs[1] & 1) ? CGACONST : (CGACONST * (9.0 / 8.0));
+            crtcconst = (cpuclock / (157500000.0 / 11.0) * (double) (1ULL << 32));
+        crtcconst *= mdiv;
     }
     ega->dot_clock = crtcconst / mdiv;
 
diff --git a/src/video/vid_mda.c b/src/video/vid_mda.c
index be6a8b6b8..1065df8a8 100644
--- a/src/video/vid_mda.c
+++ b/src/video/vid_mda.c
@@ -130,8 +130,8 @@ mda_recalctimings(mda_t *mda)
     double _dispontime;
     double _dispofftime;
     double disptime;
-    disptime     = mda->crtc[MDA_CRTC_HTOTAL] + 1;
-    _dispontime  = mda->crtc[MDA_CRTC_HDISP];
+    disptime     = (mda->crtc[MDA_CRTC_HTOTAL] + 1) << 1;
+    _dispontime  = (mda->crtc[MDA_CRTC_HDISP]) << 1;
     _dispofftime = disptime - _dispontime;
     _dispontime *= MDACONST;
     _dispofftime *= MDACONST;
diff --git a/src/video/vid_sigma.c b/src/video/vid_sigma.c
index d67b13c0d..9f71773ad 100644
--- a/src/video/vid_sigma.c
+++ b/src/video/vid_sigma.c
@@ -234,6 +234,8 @@ sigma_out(uint16_t addr, uint8_t val, void *priv)
 
             case 0x2D8:
                 sigma->sigmamode = val;
+                sigma->fullchange = changeframecount;
+                sigma_recalctimings(sigma);
                 return;
             case 0x2D9:
                 sigma->sigma_ctl = val;
@@ -392,6 +394,7 @@ sigma_recalctimings(sigma_t *sigma)
     double disptime;
     double _dispontime;
     double _dispofftime;
+    double crtcconst = (cpuclock / 22440000.0 * (double) (1ULL << 32)) * 8.0;
 
     if (sigma->sigmamode & MODE_80COLS) {
         disptime    = (sigma->crtc[0] + 1) << 1;
@@ -402,8 +405,8 @@ sigma_recalctimings(sigma_t *sigma)
     }
 
     _dispofftime = disptime - _dispontime;
-    _dispontime *= CGACONST;
-    _dispofftime *= CGACONST;
+    _dispontime *= crtcconst;
+    _dispofftime *= crtcconst;
     sigma->dispontime  = (uint64_t) (_dispontime);
     sigma->dispofftime = (uint64_t) (_dispofftime);
 }