From 46fbb3bb9ecbb94ad044dcaf9004cef105500222 Mon Sep 17 00:00:00 2001
From: TC1995 <mariogplayer90@gmail.com>
Date: Thu, 22 Feb 2024 13:35:04 +0100
Subject: [PATCH] Video related changes:

IBM/ATI 8514/A side:
Made mode switches more immediate when actually switching from VGA to 8514/A and viceversa.

Tseng ET4000AX/W32 series side:
Actually use bit 2 of index 0x3f for the horizontal blank start bit 8 instead of bit 4 (horizontal retrace start), fixes skew issues with the et4000w32i rev B. card with resolutions like 1024x768 at 15 or 16bpp and others.
---
 src/video/vid_8514a.c     |  2 +-
 src/video/vid_ati_mach8.c |  2 +-
 src/video/vid_et4000.c    | 14 +++++++-------
 src/video/vid_et4000w32.c | 19 ++++++++-----------
 src/video/vid_svga.c      |  6 +++---
 5 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/src/video/vid_8514a.c b/src/video/vid_8514a.c
index a94b974b0..ff1470164 100644
--- a/src/video/vid_8514a.c
+++ b/src/video/vid_8514a.c
@@ -4454,7 +4454,7 @@ ibm8514_init(const device_t *info)
     }
 #endif
 
-    timer_add(&svga->timer8514, ibm8514_poll, svga, 0);
+    timer_add(&svga->timer8514, ibm8514_poll, svga, 1);
 
     return svga;
 }
diff --git a/src/video/vid_ati_mach8.c b/src/video/vid_ati_mach8.c
index b49806177..3888e9c26 100644
--- a/src/video/vid_ati_mach8.c
+++ b/src/video/vid_ati_mach8.c
@@ -6057,7 +6057,7 @@ mach8_init(const device_t *info)
     } else
         ati_eeprom_load_mach8(&mach->eeprom, "mach8.nvr");
 
-    timer_add(&svga->timer8514, ibm8514_poll, svga, 0);
+    timer_add(&svga->timer8514, ibm8514_poll, svga, 1);
 
     return mach;
 }
diff --git a/src/video/vid_et4000.c b/src/video/vid_et4000.c
index fa671e2f6..ae6b7ae82 100644
--- a/src/video/vid_et4000.c
+++ b/src/video/vid_et4000.c
@@ -650,22 +650,22 @@ et4000_recalctimings(svga_t *svga)
 
     svga->ma_latch |= (svga->crtc[0x33] & 3) << 16;
 
-    svga->hblankstart    = (((svga->crtc[0x3f] & 0x10) >> 4) << 8) + svga->crtc[2];
+    svga->hblankstart    = (((svga->crtc[0x3f] & 0x4) >> 2) << 8) + svga->crtc[2];
 
     if (svga->crtc[0x35] & 1)
-        svga->vblankstart += 0x400;
+        svga->vblankstart |= 0x400;
     if (svga->crtc[0x35] & 2)
-        svga->vtotal += 0x400;
+        svga->vtotal |= 0x400;
     if (svga->crtc[0x35] & 4)
-        svga->dispend += 0x400;
+        svga->dispend |= 0x400;
     if (svga->crtc[0x35] & 8)
-        svga->vsyncstart += 0x400;
+        svga->vsyncstart |= 0x400;
     if (svga->crtc[0x35] & 0x10)
-        svga->split += 0x400;
+        svga->split |= 0x400;
     if (!svga->rowoffset)
         svga->rowoffset = 0x100;
     if (svga->crtc[0x3f] & 1)
-        svga->htotal += 256;
+        svga->htotal |= 0x100;
     if (svga->attrregs[0x16] & 0x20) {
         svga->hdisp <<= 1;
         svga->dots_per_clock <<= 1;
diff --git a/src/video/vid_et4000w32.c b/src/video/vid_et4000w32.c
index 7adb6bc89..39b5b9ecc 100644
--- a/src/video/vid_et4000w32.c
+++ b/src/video/vid_et4000w32.c
@@ -432,22 +432,22 @@ et4000w32p_recalctimings(svga_t *svga)
 
     svga->ma_latch |= (svga->crtc[0x33] & 0x7) << 16;
 
-    svga->hblankstart    = (((svga->crtc[0x3f] & 0x10) >> 4) << 8) + svga->crtc[2];
+    svga->hblankstart    = (((svga->crtc[0x3f] & 0x4) >> 2) << 8) + svga->crtc[2];
 
     if (svga->crtc[0x35] & 0x01)
-        svga->vblankstart += 0x400;
+        svga->vblankstart |= 0x400;
     if (svga->crtc[0x35] & 0x02)
-        svga->vtotal += 0x400;
+        svga->vtotal |= 0x400;
     if (svga->crtc[0x35] & 0x04)
-        svga->dispend += 0x400;
+        svga->dispend |= 0x400;
     if (svga->crtc[0x35] & 0x08)
-        svga->vsyncstart += 0x400;
+        svga->vsyncstart |= 0x400;
     if (svga->crtc[0x35] & 0x10)
-        svga->split += 0x400;
+        svga->split |= 0x400;
     if (svga->crtc[0x3F] & 0x80)
-        svga->rowoffset += 0x100;
+        svga->rowoffset |= 0x100;
     if (svga->crtc[0x3F] & 0x01)
-        svga->htotal += 256;
+        svga->htotal |= 0x100;
     if (svga->attrregs[0x16] & 0x20) {
         svga->hdisp <<= 1;
         svga->dots_per_clock <<= 1;
@@ -535,9 +535,6 @@ et4000w32p_recalctimings(svga_t *svga)
         } else {
             switch (svga->gdcreg[5] & 0x60) {
                 case 0x00:
-                    if (et4000->rev == 5)
-                        svga->ma_latch++;
-
                     if (svga->seqregs[1] & 8) /* Low res (320) */
                         svga->render = svga_render_4bpp_lowres;
                     else
diff --git a/src/video/vid_svga.c b/src/video/vid_svga.c
index d60a5de0e..cbb7f12e8 100644
--- a/src/video/vid_svga.c
+++ b/src/video/vid_svga.c
@@ -899,7 +899,7 @@ svga_recalctimings(svga_t *svga)
 
     if (ibm8514_active && (svga->dev8514 != NULL)) {
         if (dev->on[0] || dev->on[1]) {
-            disptime8514 = dev->htotal;
+            disptime8514 = dev->h_total ? dev->h_total : TIMER_USEC;
             _dispontime8514 = dev->hdisped;
         }
     }
@@ -934,10 +934,10 @@ svga_recalctimings(svga_t *svga)
                 dev->dispofftime = TIMER_USEC;
 
             timer_disable(&svga->timer);
-            timer_enable(&svga->timer8514);
+            timer_set_delay_u64(&svga->timer8514, TIMER_USEC);
         } else {
             timer_disable(&svga->timer8514);
-            timer_enable(&svga->timer);
+            timer_set_delay_u64(&svga->timer, TIMER_USEC);
         }
     }