(svn r14636) -Add: DOS port of OpenTTD, without network support though.

21 files changed, 1225 insertions, 29 deletions

diff --git a/Makefile.bundle.in b/Makefile.bundle.in
index 998ffac89..f9625f80c 100644
--- a/Makefile.bundle.in
+++ b/Makefile.bundle.in
@@ -83,6 +83,12 @@ ifeq ($(shell if test -n "`ls -l \"$(BIN_DIR)/scenario/heightmaps/\"* 2>/dev/nul
 endif
 ifeq ($(TTD), openttd.exe)
 	$(Q)unix2dos "$(BUNDLE_DIR)/docs/"* "$(BUNDLE_DIR)/readme.txt" "$(BUNDLE_DIR)/COPYING" "$(BUNDLE_DIR)/changelog.txt" "$(BUNDLE_DIR)/known-bugs.txt"
+ifeq ($(OS), DOS)
+	$(Q)cp "$(ROOT_DIR)/os/dos/cwsdpmi.txt"   "$(BUNDLE_DIR)/docs/"
+ifndef STRIP
+	$(Q)cp "$(ROOT_DIR)/os/dos/cwsdpmi.exe"   "$(TTD_DIR)/"
+endif
+endif
 endif
 
 ### Packing the current bundle into several compressed file formats ###
diff --git a/Makefile.in b/Makefile.in
index 9d004997a..ed9532b48 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -29,6 +29,7 @@ INSTALL_ICON_THEME_DIR = "$(INSTALL_DIR)/$(ICON_THEME_DIR)"
 INSTALL_DATA_DIR = "$(INSTALL_DIR)/"!!DATA_DIR!!
 INSTALL_DOC_DIR = "$(INSTALL_DIR)/"!!DOC_DIR!!
 BINARY_NAME = !!BINARY_NAME!!
+STRIP = !!STRIP!!
 TTD = !!TTD!!
 TTDS = $(SRC_DIRS:%=%/$(TTD))
 OS = !!OS!!
diff --git a/Makefile.src.in b/Makefile.src.in
index 7a1bb7384..d6d268d9a 100644
--- a/Makefile.src.in
+++ b/Makefile.src.in
@@ -259,6 +259,10 @@ else
 endif
 ifdef STRIP
 	$(Q)$(STRIP) $@
+ifeq ($(OS), DOS)
+	$(E) '$(STAGE) Adding CWSDPMI stub to $@'
+	$(Q)$(ROOT_DIR)/os/dos/make_dos_binary_selfcontained.sh $(SRC_OBJS_DIR)/$@
+endif
 endif
 
 # The targets to compile the endian-code
diff --git a/config.lib b/config.lib
index a2352b226..01b41b484 100644
--- a/config.lib
+++ b/config.lib
@@ -446,10 +446,10 @@ check_params() {
 		echo " PREPROCESSOR is only available for OSX"
 		exit 1
 	fi
-	# OS only allows DETECT, UNIX, OSX, FREEBSD, OPENBSD, MORPHOS, BEOS, SUNOS, CYGWIN, MINGW, OS2, WINCE, and PSP
-	if [ -z "`echo $os | egrep '^(DETECT|UNIX|OSX|FREEBSD|OPENBSD|NETBSD|HPUX|MORPHOS|BEOS|SUNOS|CYGWIN|MINGW|OS2|WINCE|PSP)$'`" ]; then
+	# OS only allows DETECT, UNIX, OSX, FREEBSD, OPENBSD, MORPHOS, BEOS, SUNOS, CYGWIN, MINGW, OS2, DOS, WINCE, and PSP
+	if [ -z "`echo $os | egrep '^(DETECT|UNIX|OSX|FREEBSD|OPENBSD|NETBSD|HPUX|MORPHOS|BEOS|SUNOS|CYGWIN|MINGW|OS2|DOS|WINCE|PSP)$'`" ]; then
 		echo "configure: error: invalid option --os=$os"
-		echo " Available options are: --os=[DETECT|UNIX|OSX|FREEBSD|OPENBSD|NETBSD|HPUX|MORPHOS|BEOS|SUNOS|CYGWIN|MINGW|OS2|WINCE|PSP]"
+		echo " Available options are: --os=[DETECT|UNIX|OSX|FREEBSD|OPENBSD|NETBSD|HPUX|MORPHOS|BEOS|SUNOS|CYGWIN|MINGW|OS2|DOS|WINCE|PSP]"
 		exit 1
 	fi
 	# cpu_type can be either 32 or 64
@@ -511,7 +511,7 @@ check_params() {
 	detect_cputype
 
 	if [ "$enable_static" = "1" ]; then
-		if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ] || [ "$os" = "MORPHOS" ]; then
+		if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ] || [ "$os" = "MORPHOS" ] || [ "$os" = "DOS" ]; then
 			enable_static="2"
 		else
 			enable_static="0"
@@ -521,8 +521,8 @@ check_params() {
 	if [ "$enable_static" != "0" ]; then
 		log 1 "checking static... yes"
 
-		if [ "$os" != "MINGW" ] && [ "$os" != "CYGWIN" ] && [ "$os" != "OSX" ] && [ "$os" != "MORPHOS" ]; then
-			log 1 "WARNING: static is only known to work on Windows, MacOSX and MorphOS"
+		if [ "$os" != "MINGW" ] && [ "$os" != "CYGWIN" ] && [ "$os" != "OSX" ] && [ "$os" != "MORPHOS" ] && [ "$os" != "DOS" ]; then
+			log 1 "WARNING: static is only known to work on Windows, DOS, MacOSX and MorphOS"
 			log 1 "WARNING: use static at your own risk on this platform"
 
 			sleep 5
@@ -532,7 +532,7 @@ check_params() {
 	fi
 
 	if [ "$enable_unicode" = "1" ]; then
-		if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ]; then
+		if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ] || [ "$os" = "DOS" ]; then
 			enable_unicode="2"
 		else
 			enable_unicode="0"
@@ -595,7 +595,10 @@ check_params() {
 		fi
 	fi
 
-	if [ "$enable_network" != "0" ]; then
+	if [ "$enable_network" = "1" ] && [ "$os" = "DOS" ]; then
+		log 1 "checking network... DOS, skipping"
+		enable_network=0
+	elif [ "$enable_network" != "0" ]; then
 		log 1 "checking network... found"
 	else
 		log 1 "checking network... disabled"
@@ -747,6 +750,10 @@ check_params() {
 		log 1 "checking ccache... $ccache"
 	fi
 
+	if [ "$os" = "DOS" ]; then
+		with_threads="0"
+	fi
+
 	if [ "$os" != "OSX" ] && [ "$with_osx_sysroot" != "0" ]; then
 		if [ "$with_osx_sysroot" = "1" ]; then
 			with_osx_sysroot="0"
@@ -897,7 +904,7 @@ check_params() {
 	fi
 
 	if [ "$personal_dir" = "1" ]; then
-		if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ] || [ "$os" = "WINCE" ]; then
+		if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ] || [ "$os" = "WINCE" ] || [ "$os" = "DOS" ]; then
 			personal_dir="OpenTTD"
 		elif [ "$os" = "OSX" ]; then
 			personal_dir="Documents/OpenTTD"
@@ -1120,11 +1127,11 @@ make_cflags_and_ldflags() {
 		fi
 	fi
 
-	if [ "$os" != "CYGWIN" ] && [ "$os" != "FREEBSD" ] && [ "$os" != "OPENBSD" ] && [ "$os" != "MINGW" ] && [ "$os" != "MORPHOS" ] && [ "$os" != "OSX" ] && [ "$os" != "WINCE" ] && [ "$os" != "PSP" ] && [ "$os" != "OS2" ]; then
+	if [ "$os" != "CYGWIN" ] && [ "$os" != "FREEBSD" ] && [ "$os" != "OPENBSD" ] && [ "$os" != "MINGW" ] && [ "$os" != "MORPHOS" ] && [ "$os" != "OSX" ] && [ "$os" != "DOS" ] && [ "$os" != "WINCE" ] && [ "$os" != "PSP" ] && [ "$os" != "OS2" ]; then
 		LIBS="$LIBS -lpthread"
 	fi
 
-	if [ "$os" != "CYGWIN" ] && [ "$os" != "MINGW" ] && [ "$os" != "WINCE" ]; then
+	if [ "$os" != "CYGWIN" ] && [ "$os" != "MINGW" ] && [ "$os" != "DOS" ] && [ "$os" != "WINCE" ]; then
 		LIBS="$LIBS -lc"
 	fi
 	if [ "$os" = "WINCE" ]; then
@@ -1708,7 +1715,7 @@ detect_awk() {
 
 detect_os() {
 	if [ "$os" = "DETECT" ]; then
-		# Detect UNIX, OSX, FREEBSD, OPENBSD, NETBSD, HPUX, MORPHOS, BEOS, SUNOS, CYGWIN, MINGW, OS2, WINCE, and PSP
+		# Detect UNIX, OSX, FREEBSD, OPENBSD, NETBSD, HPUX, MORPHOS, BEOS, SUNOS, CYGWIN, MINGW, OS2, DOS, WINCE, and PSP
 
 		# Try first via dumpmachine, then via uname
 		os=`echo "$host" | tr '[A-Z]' '[a-z]' | $awk '
@@ -1725,6 +1732,7 @@ detect_os() {
 					/cygwin/       { print "CYGWIN";  exit}
 					/mingw/        { print "MINGW";   exit}
 					/os2/          { print "OS2";     exit}
+					/dos/          { print "DOS";     exit}
 					/wince/        { print "WINCE";   exit}
 					/psp/          { print "PSP";     exit}
 		'`
@@ -1749,7 +1757,7 @@ detect_os() {
 		if [ -z "$os" ]; then
 			log 1 "detecting OS... none detected"
 			log 1 "I couldn't detect your OS. Please use --os=OS to force one"
-			log 1 "Allowed values are: UNIX, OSX, FREEBSD, OPENBSD, NETBSD, MORPHOS, HPUX, BEOS, SUNOS, CYGWIN, MINGW, OS2, WINCE, and PSP"
+			log 1 "Allowed values are: UNIX, OSX, FREEBSD, OPENBSD, NETBSD, MORPHOS, HPUX, BEOS, SUNOS, CYGWIN, MINGW, OS2, DOS, WINCE, and PSP"
 			exit 1
 		fi
 
@@ -1789,7 +1797,7 @@ detect_allegro() {
 
 	# By default on OSX we don't use SDL. The rest is auto-detect
 	if [ "$with_allegro" = "1" ] && [ "$os" = "OSX" ] && [ "$with_cocoa" != "0" ]; then
-		log 1 "checking SDL... OSX, skipping"
+		log 1 "checking Allegro... OSX, skipping"
 
 		allegro_config=""
 		return 0
@@ -2021,6 +2029,8 @@ detect_library() {
 			exit 1
 		fi
 
+		eval "with_$2=0"
+
 		return 0
 	fi
 
@@ -2721,7 +2731,7 @@ showhelp() {
 	echo "  --os=OS                        the OS we are compiling for [DETECT]"
 	echo "                                 DETECT/UNIX/OSX/FREEBSD/OPENBSD/NETBSD/"
 	echo "                                 MORPHOS/HPUX/BEOS/SUNOS/CYGWIN/MINGW/OS2/"
-	echo "                                 WINCE/PSP"
+	echo "                                 DOS/WINCE/PSP"
 	echo "  --endian=ENDIAN                set the endian of the HOST (AUTO/LE/BE)"
 	echo "  --revision=rXXXX               overwrite the revision detection."
 	echo "                                 Use with care!"
diff --git a/configure b/configure
index 6e8ff6cd7..60b67373c 100755
--- a/configure
+++ b/configure
@@ -50,7 +50,7 @@ save_params
 make_cflags_and_ldflags
 
 EXE=""
-if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ] || [ "$os" = "OS2" ] || [ "$os" = "WINCE" ]; then
+if [ "$os" = "MINGW" ] || [ "$os" = "CYGWIN" ] || [ "$os" = "OS2" ] || [ "$os" = "DOS" ] || [ "$os" = "WINCE" ]; then
 	EXE=".exe"
 fi
 
diff --git a/os/dos/copying b/os/dos/copying
new file mode 100644
index 000000000..a43ea2126
--- /dev/null
+++ b/os/dos/copying
@@ -0,0 +1,339 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+                          675 Mass Ave, Cambridge, MA 02139, USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
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+
+  Also, for each author's protection and ours, we want to make certain
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+  Finally, any free program is threatened constantly by software
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+
+		    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
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+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
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+Activities other than copying, distribution and modification are not
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+Program (independent of having been made by running the Program).
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+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
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+
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+    You should have received a copy of the GNU General Public License
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+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) 19yy name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Library General
+Public License instead of this License.
diff --git a/os/dos/copying.dj b/os/dos/copying.dj
new file mode 100644
index 000000000..8a5504784
--- /dev/null
+++ b/os/dos/copying.dj
@@ -0,0 +1,48 @@
+This is the file "copying.dj".  It does NOT apply to any sources or
+binaries copyrighted by UCB Berkeley, the Free Software Foundation, or
+any other agency besides DJ Delorie and others who have agreed to
+allow their sources to be distributed under these terms.
+
+   Copyright Information for sources and executables that are marked
+   Copyright (C) DJ Delorie
+                 7 Kim Lane
+                 Rochester NH  03867-2954
+
+This document is Copyright (C) DJ Delorie and may be distributed
+verbatim, but changing it is not allowed.
+
+Source code copyright DJ Delorie is distributed under the terms of the
+GNU General Public Licence, with the following exceptions:
+
+* Sources used to build crt0.o, gcrt0.o, libc.a, libdbg.a, and
+  libemu.a are distributed under the terms of the GNU Library General
+  Public License, rather than the GNU GPL.
+
+* Any existing copyright or authorship information in any given source
+  file must remain intact.  If you modify a source file, a notice to that
+  effect must be added to the authorship information in the source file.
+
+* Runtime binaries, as provided by DJ in DJGPP, may be distributed
+  without sources ONLY if the recipient is given sufficient information
+  to obtain a copy of djgpp themselves.  This primarily applies to
+  go32-v2.exe, emu387.dxe, and stubedit.exe.
+
+* Runtime objects and libraries, as provided by DJ in DJGPP, when
+  linked into an application, may be distributed without sources ONLY
+  if the recipient is given sufficient information to obtain a copy of
+  djgpp themselves.  This primarily applies to crt0.o and libc.a.
+
+-----
+
+Changes to source code copyright BSD, FSF, or others, by DJ Delorie
+fall under the terms of the original copyright.  Such files usually
+have multiple copyright notices in them.
+
+A copy of the files "COPYING" and "COPYING.LIB" are included with this
+document.  If you did not receive a copy of these files, you may
+obtain one from whence this document was obtained, or by writing:
+
+      Free Software Foundation
+      59 Temple Place - Suite 330
+      Boston, MA 02111-1307
+      USA
diff --git a/os/dos/copying.lib b/os/dos/copying.lib
new file mode 100644
index 000000000..bbe3fe198
--- /dev/null
+++ b/os/dos/copying.lib
@@ -0,0 +1,481 @@
+		  GNU LIBRARY GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1991 Free Software Foundation, Inc.
+                    675 Mass Ave, Cambridge, MA 02139, USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+[This is the first released version of the library GPL.  It is
+ numbered 2 because it goes with version 2 of the ordinary GPL.]
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
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+  When we speak of free software, we are referring to freedom, not
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+
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+  Note that it is possible for a library to be covered by the ordinary
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+
+		  GNU LIBRARY GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
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+
+     Appendix: How to Apply These Terms to Your New Libraries
+
+  If you develop a new library, and you want it to be of the greatest
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+    Copyright (C) <year>  <name of author>
+
+    This library is free software; you can redistribute it and/or
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+    This library is distributed in the hope that it will be useful,
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+    You should have received a copy of the GNU Library General Public
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+  Yoyodyne, Inc., hereby disclaims all copyright interest in the
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+
+  <signature of Ty Coon>, 1 April 1990
+  Ty Coon, President of Vice
+
+That's all there is to it!
diff --git a/os/dos/cwsdpmi.exe b/os/dos/cwsdpmi.exe
new file mode 100644
index 000000000..17e322002
--- /dev/null
+++ b/os/dos/cwsdpmi.exe
diff --git a/os/dos/cwsdpmi.txt b/os/dos/cwsdpmi.txt
new file mode 100644
index 000000000..14b09c4d7
--- /dev/null
+++ b/os/dos/cwsdpmi.txt
@@ -0,0 +1,173 @@
+CWSDPMI is Copyright (C) 1995-2000  Charles W Sandmann (sandmann@clio.rice.edu)
+                                    1206 Braelinn, Sugar Land, TX 77479
+
+This is release 5.  The files in this binary distribution may be redistributed
+under the GPL (with source) or without the source code provided:
+
+* CWSDPMI.EXE or CWSDPR0.EXE are not modified in any way except via CWSPARAM.
+
+* CWSDSTUB.EXE internal contents are not modified in any way except via
+  CWSPARAM or STUBEDIT.  It may have a COFF image plus data appended to it.
+
+* Notice to users that they have the right to receive the source code and/or
+  binary updates for CWSDPMI.  Distributors should indicate a site for the
+  source in their documentation.
+
+-------------------------------------------------------------------------------
+
+CWSDPMI was written to provide DPMI services for V2 of DJGPP.  It currently
+does not support 16-bit DPMI applications, or DPMI applications requiring a
+built in extender.  It does support virtual memory and hardware interrupt
+reflection from real mode to protected mode.  DJGPP V1.1x and RSX applications
+will also run using this server, which can be used to provide enhanced control
+over hardware interrupts.  Some DPMI 1.0 extensions (0x506, 0x507, 0x508) have
+been implemented.
+
+CWSDPR0.EXE is an alternate version which runs at ring 0 with virtual memory
+disabled.  It may be used if access to ring-0 features are desired.  It
+currently does not switch stacks on HW interrupts, so some DJGPP features
+such as SIGINT and SIGFPE are not supported and will generate a double fault
+or stack fault error (to be fixed someday).
+
+CWSDSTUB.EXE is a stub loader image for DJGPP which includes CWSDPMI.  This
+allows single executable image distributions.  You can use the EXE2COFF
+program and COPY /B CWSDSTUB.EXE+yourimage yourimage.exe to create a
+standalone executable image.
+
+Some of the internal tuning and configuration parameters may be modified
+in the image using CWSPARAM.EXE (see CWSPARAM.DOC).
+
+If you want to use CWSDPMI with DJGPP, you expand the distribution into the
+DJGPP directory tree.  CWSDPMI.EXE will be put in the BIN directory with your
+DJGPP images and it will automatically be loaded when they run.
+
+Directions for use (server can be used in either of two different ways):
+
+1) "cwsdpmi" alone with no parameters will terminate and stay resident
+   FOR A SINGLE DPMI PROCESS.  This means it unloads itself when your
+   DPMI application exits.  This mode is useful in software which needs
+   DPMI services, since CWSDPMI can be exec'ed and then will unload on exit.
+
+2) "cwsdpmi -p" will terminate and stay resident until you remove it.
+   It can be loaded into UMBs with LH.  "cwsdpmi -u" will unload the TSR.
+
+3) The file used for virtual memory swapping, if desired, is controlled
+   by the "-sc:\cwsdpmi.swp" syntax on the command line.  You must specify
+   either a file with full disk/directory syntax, or "-s-" which disables
+   virtual memory.
+
+4) The default swap file name is c:\cwsdpmi.swp, but this can be changed
+   with the CWSPARAM image, as can some other parameters.
+
+5) You can disable the DPMI 1.0 extensions by starting the image with the
+   "cwsdpmi -x" syntax.  This feature allows you to run programs developed
+   under other DPMI providers which do not behave properly with these
+   extensions enabled (typically use of NULL pointers).
+
+I would like to give special thanks to DJ Delorie who wrote the original
+GO32 code on which CWSDPMI is based.  Morten Welinder also provided and
+improved much of the code in this program.
+
+-------------------------------------------------------------------------------
+
+This section contains a list of the error messages you might see out of
+CWSDPMI and some details on what they mean.
+
+Exceptions are only handled by CWSDPMI if the application does not establish
+an exception handler, exceptions nest 5 deep, or the error is particularly bad:
+
+"Page fault" -
+  1) an illegal page fault happens in a RMCB or HW interrupt, (lock all pages!)
+  2) all available pages have been locked,
+  3) the application is using non-committed pages for null pointer protection.
+"Double Fault" - multiple exceptions occurred
+"Invalid TSS" - typically due to RMCB or HW interrupt being called after the
+   selectors/memory have been deallocated (remember to reset the mouse)
+"General Protection Fault" - bad parameter sent to a DPMI call
+
+"80386 required."
+
+Since 80286 and lesser processors don't have the hardware necessary to
+run CWSDPMI.  No workaround, upgrade.
+
+"DOS 3 required."
+
+A few interrupts are used which need DOS 3.0 or higher.  I don't expect to
+ever see this message, since 80386 machines were introduced after DOS 3.0
+and that check is made first.
+
+"CWSDPMI V0.90+ (r5) Copyright (C) 2000 CW Sandmann  ABSOLUTELY NO WARRANTY"
+
+An informational message displayed if the program is not run in one-pass mode.
+
+"Protected mode not accessible."
+
+This message should only be displayed if running CWSDPMI in a protected
+environment with no access to protected mode.  In this case, DPMI should
+already be available and CWSDPMI would not be needed.  This might happen if
+a 16-bit DPMI client is loaded and a DJGPP image attempts to load CWSDPMI
+to provide 32-bit DPMI services under Windows.
+
+"Warning: cannot open swap file c:\cwsdpmi.swp"
+
+Maybe you are out of file handles, or the swap file name is incorrectly
+specified in the image (change the name with cwsparam).
+
+"No swap space!"
+
+This message means you tried to use more paging file than CWSDPMI was
+configured to handle.  Since this is protected against in the memory
+allocation code, you should never see this message.
+
+"Swap disk full!"
+
+This means the paging file could not be expanded when trying to page
+memory out to disk.  This would normally not be seen, unless you are
+writing output to the same disk which holds the paging file.  Decrease
+the amount of memory your DPMI application is using or free up disk space.
+
+"Interrupt 0x??"
+
+Your application tried to call an interrupt from protected mode which
+normally shouldn't be called (something like a data pointer).  If the
+request was allowed to continue it would likely hang your machine.  If you
+see this message and think the interrupt should be allowed to continue, let
+me know.
+
+"Error: Using XMS switched CPU into V86 mode."
+
+This message might be seen if you have your memory manager in AUTO mode.  The
+only workaround in this case is to stop using AUTO mode.
+
+"Error: could not allocate page table memory"
+
+The page table memory (a minimum of 16Kb) is allocated from conventional
+memory (either in the 640Kb region or UMBs).  If CWSDPMI cannot allocate the
+minimum necessary memory, you would see this message.  Free up some
+conventional memory.  You may also see this message if a page directory needs
+to be faulted in, and there are no available pages.  This means too many pages
+have been locked for the allocated page tables available.  While CWSDPMI
+tries to dynamically allocate these if needed, this effort failed.  You need
+to increase the number of page tables with CWSPARAM, or increase the amount
+of free conventional memory if it is low.  If the application which calls
+CWSDPMI internally manages all the DOS memory, the page tables may need to
+be pre-allocated at DPMI startup time (if this is needed, try using the
+run option flag 2 in cwsparam).
+
+"16-bit DPMI unsupported."
+
+CWSDPMI is a 32-bit only DPMI server.  Ideally, on the request to enter DPMI's
+PM with a 16-bit request, we would just fail the call setting the carry bit
+like the DPMI specification describes.  Some buggy 16-bit compiler tools don't
+check the return status and will hang the machine in this case.  So, I issue
+an error message and exit the image instead.
+
+"Descriptors exhausted."
+
+An attempt to nest a DPMI client failed in the setup phase due to insufficient
+free selectors in the LDT.
+
+"CWSDPMI not removed"
+
+When the -u parameter is specified, if DPMI is not detected this message is
+printed.  Informational.
diff --git a/os/dos/cwsdstub.exe b/os/dos/cwsdstub.exe
new file mode 100644
index 000000000..fabaf3bf4
--- /dev/null
+++ b/os/dos/cwsdstub.exe
diff --git a/os/dos/exe2coff.c b/os/dos/exe2coff.c
new file mode 100644
index 000000000..aa072e8e4
--- /dev/null
+++ b/os/dos/exe2coff.c
@@ -0,0 +1,94 @@
+/* Copyright (C) 1998 DJ Delorie, see COPYING.DJ for details */
+/* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
+/* Updated 2008 to use fread/fopen and friends instead of read/open so it compiles with GCC on Unix (Rubidium) */
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+
+
+static void
+exe2aout(char *fname)
+{
+  unsigned short header[3];
+  FILE *ifile;
+  FILE *ofile;
+  char buf[4096];
+  int rbytes;
+  char *dot = strrchr(fname, '.');
+  if (!dot || strlen(dot) != 4
+      || tolower(dot[1]) != 'e'
+      || tolower(dot[2]) != 'x'
+      || tolower(dot[3]) != 'e')
+  {
+    fprintf(stderr, "%s: Arguments MUST end with a .exe extension\n", fname);
+    return;
+  }
+
+  ifile = fopen(fname, "rb");
+  if (!ifile)
+  {
+    perror(fname);
+    return;
+  }
+  fread(header, sizeof(header), 1, ifile);
+  if (header[0] == 0x5a4d)
+  {
+    long header_offset = (long)header[2]*512L;
+    if (header[1])
+      header_offset += (long)header[1] - 512L;
+    fseek(ifile, header_offset, SEEK_SET);
+    header[0] = 0;
+    fread(header, sizeof(header), 1, ifile);
+    if ((header[0] != 0x010b) && (header[0] != 0x014c))
+    {
+      fprintf(stderr, "`%s' does not have a COFF/AOUT program appended to it\n", fname);
+      return;
+    }
+    fseek(ifile, header_offset, SEEK_SET);
+  }
+  else
+  {
+    fprintf(stderr, "`%s' is not an .EXE file\n", fname);
+    return;
+  }
+
+  *dot = 0;
+  ofile = fopen(fname, "w+b");
+  if (!ofile)
+  {
+    perror(fname);
+    return;
+  }
+
+  while ((rbytes=fread(buf, 1, 4096, ifile)) > 0)
+  {
+    int wb = fwrite(buf, 1, rbytes, ofile);
+    if (wb < 0)
+    {
+      perror(fname);
+      break;
+    }
+    if (wb < rbytes)
+    {
+      fprintf(stderr, "`%s': disk full\n", fname);
+      exit(1);
+    }
+  }
+  fclose(ifile);
+  fclose(ofile);
+}
+
+int
+main(int argc, char **argv)
+{
+  int i;
+  if (argc == 1) printf("Usage: %s <exename>", argv[0]);
+  for (i=1; i<argc; i++)
+    exe2aout(argv[i]);
+  return 0;
+}
+
diff --git a/os/dos/make_dos_binary_selfcontained.sh b/os/dos/make_dos_binary_selfcontained.sh
new file mode 100755
index 000000000..de4bdb9dd
--- /dev/null
+++ b/os/dos/make_dos_binary_selfcontained.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+cd `dirname $0`
+cc -o exe2coff exe2coff.c || exit
+cp $1 binary.exe || exit
+./exe2coff binary.exe || exit
+cat cwsdstub.exe binary > binary.exe || exit
+mv binary.exe $1
+rm binary exe2coff
diff --git a/readme.txt b/readme.txt
index bdc6d3d90..31f4fd20b 100644
--- a/readme.txt
+++ b/readme.txt
@@ -73,14 +73,15 @@ OpenTTD has been ported to several platforms and operating systems. It shouldn't
 be very difficult to port it to a new platform. The currently working platforms
 are:
 
-  BeOS                 - SDL
+  BeOS                 - SDL or Allegro
+  DOS                  - Allegro
   FreeBSD              - SDL
-  Linux                - SDL
+  Linux                - SDL or Allegro
   MacOS X (universal)  - Cocoa video and sound drivers (SDL works too, but not 100% and not as a universal binary)
   MorphOS              - SDL
   OpenBSD              - SDL
   OS/2                 - SDL
-  Windows              - Win32 GDI (faster) or SDL
+  Windows              - Win32 GDI (faster) or SDL or Allegro
 
 
 4.0) Installing and running OpenTTD:
@@ -298,6 +299,16 @@ OS/2:
   A comprehensive GNU build environment is required to build the OS/2 version.
   See the docs/Readme_OS2.txt file for more information.
 
+DOS:
+  A build environment with DJGPP is needed as well as libraries such as
+  Allegro, zlib and libpng, which all can be downloaded from the DJGPP
+  website. Compilation is straight forward: use make, but do a "./configure"
+  before the first build. The build binary will need cwsdpmi.exe to be in
+  the same directory as the openttd executable. cwsdpmi.exe can be found in
+  the os/dos subdirectory. If you compile with stripping turned on a binary
+  will be generated that does not need cwsdpmi.exe by adding the cswdstub.exe
+  to the created OpenTTD binary.
+
 
 8.0) Translating:
 ---- -------------------
diff --git a/source.list b/source.list
index d91f500fa..fa0ba0c56 100644
--- a/source.list
+++ b/source.list
@@ -639,7 +639,10 @@ music/null_m.cpp
 	#else
 		#if PSP
 		#else
-			music/extmidi.cpp
+			#if DOS
+			#else
+				music/extmidi.cpp
+			#end
 		#end
 	#end
 #end
diff --git a/src/fileio.cpp b/src/fileio.cpp
index f7b4a5af2..0e2d4d895 100644
--- a/src/fileio.cpp
+++ b/src/fileio.cpp
@@ -773,6 +773,10 @@ void ChangeWorkingDirectory(const char *exe)
 	char *s = strrchr(exe, PATHSEPCHAR);
 	if (s != NULL) {
 		*s = '\0';
+#if defined(__DJGPP__)
+		/* If we want to go to the root, we can't use cd C:, but we must use '/' */
+		if (s[-1] == ':') chdir("/");
+#endif
 		if (chdir(exe) != 0) DEBUG(misc, 0, "Directory with the binary does not exist?");
 		*s = PATHSEPCHAR;
 	}
@@ -788,7 +792,7 @@ void ChangeWorkingDirectory(const char *exe)
 void DetermineBasePaths(const char *exe)
 {
 	char tmp[MAX_PATH];
-#if defined(__MORPHOS__) || defined(__AMIGA__) || !defined(WITH_PERSONAL_DIR)
+#if defined(__MORPHOS__) || defined(__AMIGA__) || defined(DOS) || !defined(WITH_PERSONAL_DIR)
 	_searchpaths[SP_PERSONAL_DIR] = NULL;
 #else
 	const char *homedir = getenv("HOME");
@@ -826,7 +830,7 @@ void DetermineBasePaths(const char *exe)
 	AppendPathSeparator(tmp, MAX_PATH);
 	_searchpaths[SP_BINARY_DIR] = strdup(tmp);
 
-#if defined(__MORPHOS__) || defined(__AMIGA__)
+#if defined(__MORPHOS__) || defined(__AMIGA__) || defined(DOS)
 	_searchpaths[SP_INSTALLATION_DIR] = NULL;
 #else
 	snprintf(tmp, MAX_PATH, "%s", GLOBAL_DATA_DIR);
diff --git a/src/intro_gui.cpp b/src/intro_gui.cpp
index 0cd4f9598..6cd94aa00 100644
--- a/src/intro_gui.cpp
+++ b/src/intro_gui.cpp
@@ -161,6 +161,8 @@ void AskExitGame()
 		SetDParam(0, STR_OSNAME_OS2);
 #elif defined(SUNOS)
 		SetDParam(0, STR_OSNAME_SUNOS);
+#elif defined(DOS)
+		SetDParam(0, STR_OSNAME_DOS);
 #else
 		SetDParam(0, STR_OSNAME_UNIX);
 #endif
diff --git a/src/lang/english.txt b/src/lang/english.txt
index d77741b02..370e94b31 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -277,6 +277,7 @@ STR_0131_TOO_MANY_NAMES_DEFINED                                 :{WHITE}Too many
 STR_0132_CHOSEN_NAME_IN_USE_ALREADY                             :{WHITE}Chosen name already in use
 
 STR_OSNAME_WINDOWS                                              :Windows
+STR_OSNAME_DOS                                                  :DOS
 STR_OSNAME_UNIX                                                 :Unix
 STR_OSNAME_OSX                                                  :OS X
 STR_OSNAME_BEOS                                                 :BeOS
diff --git a/src/os_timer.cpp b/src/os_timer.cpp
index 0166a445c..bf0a171de 100644
--- a/src/os_timer.cpp
+++ b/src/os_timer.cpp
@@ -35,7 +35,7 @@ unsigned __int64 ottd_rdtsc();
 #endif
 
 /* rdtsc for all other *nix-en (hopefully). Use GCC syntax */
-#if defined(__i386__) || defined(__x86_64__) && !defined(RDTSC_AVAILABLE)
+#if (defined(__i386__) || defined(__x86_64__)) && !defined(__DJGPP__) && !defined(RDTSC_AVAILABLE)
 uint64 ottd_rdtsc()
 {
 	uint32 high, low;
diff --git a/src/stdafx.h b/src/stdafx.h
index a0d715ed3..6fdc4fd37 100644
--- a/src/stdafx.h
+++ b/src/stdafx.h
@@ -353,7 +353,7 @@ void NORETURN CDECL usererror(const char *str, ...);
 void NORETURN CDECL error(const char *str, ...);
 #define NOT_REACHED() error("NOT_REACHED triggered at line %i of %s", __LINE__, __FILE__)
 
-#if defined(MORPHOS) || defined(__NDS__)
+#if defined(MORPHOS) || defined(__NDS__) || defined(__DJGPP__)
 	/* MorphOS and NDS don't have C++ conformant _stricmp... */
 	#define _stricmp stricmp
 #elif defined(OPENBSD)
@@ -361,7 +361,7 @@ void NORETURN CDECL error(const char *str, ...);
 	#define _stricmp strcasecmp
 #endif
 
-#if !defined(MORPHOS) && !defined(OPENBSD) && !defined(__NDS__)
+#if !defined(MORPHOS) && !defined(OPENBSD) && !defined(__NDS__) && !defined(__DJGPP__)
 	/* NDS, MorphOS & OpenBSD don't know wchars, the rest does :( */
 	#define HAS_WCHAR
 #endif /* !defined(MORPHOS) && !defined(OPENBSD) && !defined(__NDS__) */
diff --git a/src/video/allegro_v.cpp b/src/video/allegro_v.cpp
index 913411e6e..36581bcaa 100644
--- a/src/video/allegro_v.cpp
+++ b/src/video/allegro_v.cpp
@@ -179,13 +179,19 @@ static bool CreateMainSurface(int w, int h)
 	if (bpp == 0) usererror("Can't use a blitter that blits 0 bpp for normal visuals");
 	set_color_depth(bpp);
 
+#if defined(DOS)
+	/* Force DOS builds to ALWAYS use full screen as
+	 * it can't do windowed. */
+	_fullscreen = true;
+#endif
+
 	GetVideoModes();
 	GetAvailableVideoMode(&w, &h);
 	if (set_gfx_mode(_fullscreen ? GFX_AUTODETECT_FULLSCREEN : GFX_AUTODETECT_WINDOWED, w, h, 0, 0) != 0) return false;
 
-	_allegro_screen = create_bitmap(screen->w, screen->h);
-	_screen.width = screen->w;
-	_screen.height = screen->h;
+	_allegro_screen = create_bitmap(w, h);
+	_screen.width = w;
+	_screen.height = h;
 	_screen.pitch = ((byte*)screen->line[1] - (byte*)screen->line[0]) / (bitmap_color_depth(screen) / 8);
 
 	poll_mouse();
@@ -399,7 +405,7 @@ void VideoDriver_Allegro::Stop()
 	if (--_allegro_instance_count == 0) allegro_exit();
 }
 
-#if defined(UNIX) || defined(__OS2__) || defined(PSP)
+#if defined(UNIX) || defined(__OS2__) || defined(PSP) || defined(DOS)
 # include <sys/time.h> /* gettimeofday */
 
 static uint32 GetTime()
@@ -490,6 +496,9 @@ bool VideoDriver_Allegro::ChangeResolution(int w, int h)
 
 bool VideoDriver_Allegro::ToggleFullscreen(bool fullscreen)
 {
+#ifdef DOS
+	return false;
+#else
 	_fullscreen = fullscreen;
 	GetVideoModes(); // get the list of available video modes
 	if (_num_resolutions == 0 || !this->ChangeResolution(_cur_resolution.width, _cur_resolution.height)) {
@@ -498,6 +507,7 @@ bool VideoDriver_Allegro::ToggleFullscreen(bool fullscreen)
 		return false;
 	}
 	return true;
+#endif
 }
 
 #endif /* WITH_ALLEGRO */