From b5ae11f850212af32a538451ad5700710335916d Mon Sep 17 00:00:00 2001
From: Elaina Claus <elaina.claus@chtm.me>
Date: Fri, 5 Sep 2025 15:43:22 -0400
Subject: [PATCH] set ds/es to a tiny memory model after entering Unreal mode
 ss/fs/gs will all be huge/flat model after

---
 include/cdecl16.inc    | 4 ++--
 src/stage2/stage2.nasm | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/cdecl16.inc b/include/cdecl16.inc
index 2ec017d..0157454 100644
--- a/include/cdecl16.inc
+++ b/include/cdecl16.inc
@@ -69,8 +69,8 @@
 %endmacro
 %endif
 
-%ifnmacro __DEFLAT_DS_ES
-%macro __DEFLAT_DS_ES 0
+%ifnmacro __TINY_DS_ES
+%macro __TINY_DS_ES 0
     mov ax, __STAGE2_SEGMENT
     mov ds, ax
     mov es, ax
diff --git a/src/stage2/stage2.nasm b/src/stage2/stage2.nasm
index 02c0ba7..42974b1 100755
--- a/src/stage2/stage2.nasm
+++ b/src/stage2/stage2.nasm
@@ -162,6 +162,12 @@ main:
 
     ; enter unreal mode (16 bit code, 32 bit flat memory model)
     call EnterUnrealMode
+
+    ; set ds, es to the STAGE2_SEGMENT, for our model (generally) ds == es == cs
+    ; fs, gs & ss are all still huge data model, and the macro "__REFLAT_DS_ES" exists
+    ; to easily access data outside of 64KiB boundries using ds/es addressing
+    __TINY_DS_ES
+
     print_string UnrealMode_OK_info
 
     ; FAT Driver setup