From 3fc6d29462a2f3bf6e5c7ecf79ca423e9f5ebb33 Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Sun, 30 Mar 2025 04:53:48 +0200
Subject: [PATCH] JEGA/JVGA: Only update renderer override on master, do not
 update CRTC cursor location unless it's either master or slave, and only
 override the text mode renderer - fixes AX Windows 3.0 386 enhanced mode
 returning from DOS box to full screen.

---
 src/video/vid_ega.c         |  5 +----
 src/video/vid_ega_render.c  |  5 +++++
 src/video/vid_jega.c        | 39 +++++++++++++++++++++++++++----------
 src/video/vid_svga.c        |  6 ++----
 src/video/vid_svga_render.c | 10 ++++++++++
 5 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/src/video/vid_ega.c b/src/video/vid_ega.c
index f002ef999..5b5427b9e 100644
--- a/src/video/vid_ega.c
+++ b/src/video/vid_ega.c
@@ -783,10 +783,7 @@ ega_poll(void *priv)
             ega->y_add *= ega->vres + 1;
             for (y = 0; y <= ega->vres; y++) {
                 /* Render scanline */
-                if (ega->render_override)
-                    ega->render_override(ega->priv_parent);
-                else
-                    ega->render(ega);
+                ega->render(ega);
 
                 /* Render overscan */
                 ega->x_add = (overscan_x >> 1);
diff --git a/src/video/vid_ega_render.c b/src/video/vid_ega_render.c
index 10667084a..8a73ffbbb 100644
--- a/src/video/vid_ega_render.c
+++ b/src/video/vid_ega_render.c
@@ -107,6 +107,11 @@ ega_render_overscan_right(ega_t *ega)
 void
 ega_render_text(ega_t *ega)
 {
+    if (ega->render_override) {
+        ega->render_override(ega->priv_parent);
+        return;
+    }
+
     if ((ega->displine + ega->y_add) < 0)
         return;
 
diff --git a/src/video/vid_jega.c b/src/video/vid_jega.c
index 11c9cbf8d..a238fbff9 100644
--- a/src/video/vid_jega.c
+++ b/src/video/vid_jega.c
@@ -464,21 +464,40 @@ jega_out(uint16_t addr, uint8_t val, void *priv)
         case 0x3d5:
             /* Data */
             if (jega->regs_index != RINVALID_INDEX) {
+                if ((jega->regs_index < 7) && (jega->regs[0x11] & 0x80))
+                    return;
+                if ((jega->regs_index == 7) && (jega->regs[0x11] & 0x80))
+                    val = (jega->regs[7] & ~0x10) | (val & 0x10);
+                /*
+                   Do not allow cursor updates if neither master nor slave is
+                   active - the AX Windows 3.0 386 Enhanced Mode DOS grabber
+                   relies on this for the cursor position to behave correctly.
+                 */
+                if ((jega->regs_index >= 0x0e) && (jega->regs_index <= 0x0f) && !(jega->regs[RMOD1] & 0x0c))
+                    return;
                 jega->regs[jega->regs_index] = val;
                 jega_log("JEGA Out %04X(%02X) %02Xh(%d) %04X:%04X\n", addr, jega->regs_index, val, val, cs >> 4, cpu_state.pc);
                 switch (jega->regs_index) {
                     case RMOD1:
                         /* if the value is changed */
-                        if (jega->is_vga) {
-                            if (val & 0x40)
-                                jega->vga.svga.render_override = NULL;
-                            else
-                                jega->vga.svga.render_override = jega_render_text;
-                        } else {
-                            if (val & 0x40)
-                                jega->ega.render_override = NULL;
-                            else
-                                jega->ega.render_override = jega_render_text;
+                        /*
+                           Do not allow override toggling unless it's on master and
+                           only override the text renderer - the AX Windows 3.0 386
+                           Enhanced Mode DOS grabber relies on this for the grabbing
+                           to behave correctly.
+                         */
+                        if (val & 0x08) {
+                            if (jega->is_vga) {
+                                if (val & 0x40)
+                                    jega->vga.svga.render_override = NULL;
+                                else
+                                    jega->vga.svga.render_override = jega_render_text;
+                            } else {
+                                if (val & 0x40)
+                                    jega->ega.render_override = NULL;
+                                else
+                                    jega->ega.render_override = jega_render_text;
+                            }
                         }
                         break;
                     case RDAGS:
diff --git a/src/video/vid_svga.c b/src/video/vid_svga.c
index 8d1535dda..b4abc18e5 100644
--- a/src/video/vid_svga.c
+++ b/src/video/vid_svga.c
@@ -1176,10 +1176,7 @@ svga_do_render(svga_t *svga)
     }
 
     if (!svga->override) {
-        if (svga->render_override)
-            svga->render_override(svga->priv_parent);
-        else
-            svga->render(svga);
+        svga->render(svga);
 
         svga->x_add = (svga->monitor->mon_overscan_x >> 1);
         svga_render_overscan_left(svga);
@@ -2019,6 +2016,7 @@ svga_doblit(int wx, int wy, svga_t *svga)
 
         /* Block resolution changes while in DPMS mode to avoid getting a bogus
            screen width (320). We're already rendering a blank screen anyway. */
+        pclog("%i + %i, %i + %i\n", svga->monitor->mon_xsize, x_add, svga->monitor->mon_ysize, y_add);
         if (!svga->dpms)
             set_screen_size_monitor(svga->monitor->mon_xsize + x_add, svga->monitor->mon_ysize + y_add, svga->monitor_index);
 
diff --git a/src/video/vid_svga_render.c b/src/video/vid_svga_render.c
index c05d308fa..fbd667a1b 100644
--- a/src/video/vid_svga_render.c
+++ b/src/video/vid_svga_render.c
@@ -147,6 +147,11 @@ svga_render_text_40(svga_t *svga)
     int       bg;
     uint32_t  addr = 0;
 
+    if (svga->render_override) {
+        svga->render_override(svga->priv_parent);
+        return;
+    }
+
     if ((svga->displine + svga->y_add) < 0)
         return;
 
@@ -225,6 +230,11 @@ svga_render_text_80(svga_t *svga)
     int       bg;
     uint32_t  addr = 0;
 
+    if (svga->render_override) {
+        svga->render_override(svga->priv_parent);
+        return;
+    }
+
     if ((svga->displine + svga->y_add) < 0)
         return;