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, which cannot run the Windows version
of XZ Utils.
This is currently experimental and has got very little testing.
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 (2009-02-13) 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 more manual method, first select a mirror from
<http://www.delorie.com/djgpp/getting.html>. You need
the following files:
unzip32.exe
beta/v2/djdev204.zip
v2gnu/bnu219b.zip
v2gnu/gcc432b.zip
v2gnu/mak3791b.zip
v2gnu/sed415b.zip
v2misc/csdpmi5b.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 csdpmi5b.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\gcc432b.zip
C:\DJGPP> c:\download\unzip32 c:\download\mak3791b.zip
C:\DJGPP> c:\download\unzip32 c:\download\sed415b.zip
C:\DJGPP> c:\download\unzip32 c:\download\csdpmi5b.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
Just run "make" in this directory (the directory containing this
README). You should get liblzma.a, xz.exe, xzdec.exe, and
lzmadec.exe. Of these, probably xz.exe is the only interesting one.
Note: You need to have an environment that supports long filenames.
Once you have built XZ Utils, the resulting binaries can be run
without long filename support.
Additional Make Flags and Targets
You may want to try some additional optimizations, which may or
may not make the code faster (and may or may not hit possible
compiler bugs more easily):
make CFLAGS="-O3 -fomit-frame-pointer -funroll-loops"
If you want to enable assertions (the assert() macro), use DEBUG=1.
You may want to disable optimizations too if you plan to actually
debug the code. Never use DEBUG=1 for production builds!
make DEBUG=1 CFLAGS="-g -O0"
Bugs
"make clean" may remove src/xz/hardware.c when it tries to remove
src/xz/hardware-fixed.c. This is probably a bug somewhere in the
DOS environment I use. Maybe it tries truncated 8.3 name first and
since that gives a name of an existing file, it doesn't look for
long filename.
"xz -fc /dev/tty" hangs at least in DOSEMU and cannot be interrupted
by pressing C-c. Maybe xz should never accept non-regular files on
DOS even when --force is used.
Using different memory usage limit for encoding and decoding doesn't
make sense under pure DOS. Maybe it is still OK when running under
Windows.
The progress indicator of "xz -v" doesn't get updated when running
under Dosbox, but it works in DOSEMU. I currently (2009-02-13) don't
know if it works in other environments.
Report bugs to <lasse.collin@tukaani.org> (in English or Finnish).
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