diff --git a/glide2x/h3/glide/src/xos.inc b/glide2x/h3/glide/src/xos.inc
new file mode 100644
index 0000000..9b37101
--- /dev/null
+++ b/glide2x/h3/glide/src/xos.inc
@@ -0,0 +1,145 @@
+;
+; compulsory header for glide3/xdraw* assembly specializations (NASM)
+;
+; $Header$
+; $Log$
+; Revision 1.1.2.3  2004/10/04 08:57:52  dborca
+; supporting DOS/OpenWatcom in Assembly files
+;
+;
+; Revision 1.1.2.1  2003/06/07 09:53:25  dborca
+; initial checkin for NASM sources
+;
+
+;---------------------------------------
+; platform defines
+;---------------------------------------
+%define XOS_DJGPP 1
+%define XOS_LINUX 2
+%define XOS_WIN32 4
+%define XOS_WATCD 8
+
+%define STDCALL   0
+%define ELFTYPE   0
+
+;---------------------------------------
+; pick up the right OS
+;---------------------------------------
+%ifdef __DJGPP__
+%define XOS XOS_DJGPP
+%elifdef __linux__
+%define XOS XOS_LINUX
+%define ELFTYPE 1
+%elifdef __WIN32__
+%define XOS XOS_WIN32
+%define STDCALL 1
+%elifdef __WATCOMD__
+%define XOS XOS_WATCD
+%define STDCALL 1
+%else
+%error Unknown OS
+%endif
+
+;---------------------------------------
+; general purpose macros
+;---------------------------------------
+%macro	extrn	1-2 0
+	%if STDCALL && (%2 > 0)
+		%define %1 %1@%2
+	%endif
+		extern	%1
+%endmacro
+
+%macro	globl	1-2 0
+	%if STDCALL && (%2 > 0)
+		%define %1 %1@%2
+	%endif
+		global	%1
+%endmacro
+
+%macro		proc	1-2 0
+	%push	proc
+	%if STDCALL && (%2 > 0)
+		%define	%$ret	RET %2
+	%else
+		%define	%$ret	RET
+	%endif
+	%if ELFTYPE
+		globl	%1:function, %2
+	%else
+		globl	%1, %2
+	%endif
+%1:
+%endmacro
+
+%macro		endp	0
+	%ifnctx	proc
+		%error	Mismatched `endp'/`proc'
+	%else
+		%pop
+	%endif
+%endmacro
+
+%macro		ret	0
+	%ifnctx	proc
+		RET
+	%else
+		%$ret
+	%endif
+%endmacro
+
+%macro invoke 1-*
+	%rep	%0 - 1
+	%rotate -1
+	push	%1
+	%endrep
+	%rotate -1
+	call	%1
+%if (STDCALL == 0) && (%0 > 1)
+	add	esp, 4 * (%0 - 1)
+%endif
+%endmacro
+
+;---------------------------------------
+; Windows
+;---------------------------------------
+%if XOS == XOS_WIN32
+
+%define TEXT  .text   align=32
+%define DATA  .data   align=32
+%define CONST .rdata  align=32
+
+%endif
+
+;---------------------------------------
+; DJGPP
+;---------------------------------------
+%if XOS == XOS_DJGPP
+
+%define TEXT  .text
+%define DATA  .data
+%define CONST .rodata
+
+%endif
+
+;---------------------------------------
+; Linux
+;---------------------------------------
+%if XOS == XOS_LINUX
+
+%define TEXT  .text   align=32
+%define DATA  .data   align=32
+%define CONST .rodata align=32
+
+%endif
+
+;---------------------------------------
+; WATCOM/DOS
+;---------------------------------------
+%if XOS == XOS_WATCD
+
+%define TEXT  _TEXT	align=1 public use32 class=CODE FLAT
+%define DATA  _DATA	align=4 public use32 class=DATA FLAT
+%define CONST CONST2	align=4 public use32 class=DATA FLAT
+
+%endif