Credit: The initial Web Assembly cross compile was found in a pull request:
https://github.com/NetHack/NetHack/pull/385
by apowers313. The pull request was merged with some accompanying
NetHack source tree integration changes in early October 2020.
Cross-compiler used: emscripten
Cross-compiler url: https://emscripten.org/docs/getting_started/downloads.html
Here's a brief guide to obtaining the cross-compiler sources via git and
building it on your system.
For Ubuntu, the build prerequisite packages for building the compiler can
be easily obtained:
sudo apt-get install python3 cmake default-jre
For macOS, you will need to install Xcode, git, cmake, Python 3.5 or new
(at time of this writing).
After installing the prerequite packages above, obtain the cross-compiler
via git and build it from the directory of your choice using steps similar
to these:
git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
git pull
./emsdk install latest
./emsdk activate latest
source ./emsdk_env.sh
The steps above reflect what was outlined at this url at the time
of writing:
https://emscripten.org/docs/getting_started/downloads.html
That is the definitive source and trumps anything documented here.
On your linux host, prepare to cross-compile NetHack as follows:
cd sys/unix ; sh setup.sh hints/linux.2020 ; cd ../..
make fetch-lua
On your macOS host, prepare to cross-compile NetHack as follows:
cd sys/unix ; sh setup.sh hints/macOS.2020 ; cd ../..
make fetch-lua
Then, cross-compile to targets/wasm as follows:
make CROSS_TO_WASM=1
You can build src/nethacklib.a from pull request 385 as follows:
make WANT_LIBNH=1
Do not add any additional windowport interfaces to your build
(such as WANT_WIN_TTY=1 WANT_WIN_CURSES=1 WANT_WIN_X11=1 or
WANT_WIN_QT=1) as those aren't applicable to the Web Assembly
or nethacklib builds. A "shim" pseudo-windowport is included
from pull request 385.
Result: As mentioned, the wasm cross-compile will end up in
targets/wasm and the nethacklib.a will end up
src.
The cross-compiler hints additions are enclosed inside ifdef sections
and shouldn't interfere with the non-cross-compile builds using
hints/linux.2020 or hints/macOS.2020.
Update the cross-compiling doc at the top.
Remove sys/msdos/Makefile1.cross, sys/msdos/Makefile2.cross, and
sys/msdos/msdos-cross-compile.sh as they are no longer required.
Remove occurrences of CROSSCOMPILE_HOST as the host-side of a
cross-compile can be determined from:
defined(CROSSCOMPILE) && !defined(CROSSCOMPILE_TARGET)
without the additional macro.
