XZ Utils on DOS
===============

Introduction

    This document explains how to build XZ Utils for DOS using DJGPP.
    The resulting binaries should run at least on various DOS versions
    and under Windows 95/98/98SE/ME, although the Windows version of
    XZ Utils is recommended under Windows 95 and later.

    This is currently experimental and has got very little testing.

    Note: Makefile and config.h are updated only now and then. This
    means that especially if you checked out a development version,
    building for DOS probably won't work without updating Makefile
    and config.h first.


Getting and Installing DJGPP

    You may use <http://www.delorie.com/djgpp/zip-picker.html> to help
    deciding what to download, but as of writing (2010-10-09) that may
    not be the most convenient way taking into account what components
    are actually required to build XZ Utils. However, using the
    zip-picker can still be worth doing to get nice short summary of
    installation instructions (they can be found from readme.1st too).

    For a more manual method, first select a mirror from
    <http://www.delorie.com/djgpp/getting.html>. You need
    the following files:

        unzip32.exe  (if you don't already have a LFN-capable unzipper)
        beta/v2/djdev204.zip
        v2gnu/bnu219b.zip
        v2gnu/gcc444b.zip
        v2gnu/mak3791b.zip
        v2misc/csdpmi7b.zip

    If newer versions are available, probably you should try them first.
    Note that djdev203.zip is too old to build XZ Utils; you need at
    least djdev204.zip. Also note that you want csdpmi7b.zip even if you
    run under Windows or DOSEMU, because the XZ Utils Makefile will embed
    cwsdstub.exe to the resulting binaries.

    See the instructions in readme.1st found from djdev204.zip. Here's
    a short summary, but you should still read readme.1st.

        C:\> mkdir DJGPP
        C:\> cd DJGPP
        C:\DJGPP> c:\download\unzip32 c:\download\djdev204.zip
        C:\DJGPP> c:\download\unzip32 c:\download\bnu219b.zip
        C:\DJGPP> c:\download\unzip32 c:\download\gcc444b.zip
        C:\DJGPP> c:\download\unzip32 c:\download\mak3791b.zip
        C:\DJGPP> c:\download\unzip32 c:\download\csdpmi7b.zip

        C:\DJGPP> set PATH=C:\DJGPP\BIN;%PATH%
        C:\DJGPP> set DJGPP=C:\DJGPP\DJGPP.ENV

    You may want to add the last two lines into AUTOEXEC.BAT or have,
    for example, DJGPP.BAT which you can run before using DJGPP.

    Make sure you use completely upper case path in the DJGPP environment
    variable. This is not required by DJGPP, but the XZ Utils Makefile is
    a bit stupid and expects that everything in DJGPP environment variable
    is uppercase.


Building

    You need to have an environment that supports long filenames (LFN).
    Once you have built XZ Utils, the resulting binaries can be run
    without long filename support.

    Run "make" in this directory (the directory containing this README).
    You should get xz.exe (and a bunch of temporary files). Other tools
    are not built. Having e.g. xzdec.exe doesn't save much space compared
    to xz.exe, because the DJGPP runtime makes the .exe quite big anyway.


Bugs

    xz doesn't necessarily work in Dosbox. It should work in DOSEMU.

    Pressing Ctrl-c or Ctrl-Break won't remove the incomplete target file
    when running under Windows XP Command Prompt (something goes wrong
    with SIGINT handling). It works correctly under Windows 95/98/98SE/ME.