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+# Building SWI-Prolog using Emscripten for WebAssembly (WASM)
+
+As  of  version  8.1.2,  building  an executable  for  WASM  is  fully
+supported by the standard build process.  The initial port is the work
+of  Raivo  Laanemets.   Currently  Jesse  Wright  is  most  active  in
+maintaining  the  port.  Jesse  maintains  the  npm build  process  on
+[github](https://github.com/SWI-Prolog/npm-swipl-wasm).
+
+(Infrequent) status updates and various hints on using the WASM version
+are on [this Discourse wiki page](https://swi-prolog.discourse.group/t/swi-prolog-in-the-browser-using-wasm/5650/1)
+
+The  remainder of  this  page  guides you  through  building the  WASM
+version yourself.
+
+
+## Preparation
+
+You need to  download the Emscripten compiler.  Follow the instruction
+on                                                                 its
+[homepage](http://kripken.github.io/emscripten-site/docs/getting_started/downloads.html).
+
+After the successful installation load the Emscripten environment into
+the current terminal session (adjust path):
+
+    source ./emsdk_env.sh
+
+We  currently (May  3, 2023)  use version  3.1.37 of  Emscripten.  The
+build  process also  requires [Node.js](https://nodejs.org/).   Recent
+versions  of Emscripten  require recent  version of  Node.js.  We  use
+v18.16.   We build  using the  [ninja](https://ninja-build.org/) build
+tool.  This is not necessary, but speeds up the build considerably.
+
+The build process assumes
+
+  - A directory `~/wasm` for the Emscripten tools and dependencies
+  - Emscripten installed in `~/wasm/emsdk`.  We installed from the
+    git at https://github.com/emscripten-core/emsdk.git.  That
+	allows to switch versions easily.
+  - SWI-Prolog sources, typically [from git](https://github.com/SWI-Prolog/swipl-devel)
+
+
+## Dependencies
+
+We need several  dependencies.  [zlib](https://zlib.net/) is required,
+the others  are optional.  We  install the dependencies  with _prefix_
+`~/wasm` We assume running the commands from `~/wasm`.  We also assume
+you  setup the  environment  from Emscripten  as  described above,  so
+`emcc` is in our `$PATH`.
+
+### Installing zlib
+
+This is __mandatory__
+
+    wget https://zlib.net/zlib-1.2.13.tar.gz
+    tar -xf "zlib-1.2.13.tar.gz"
+    cd zlib-1.2.13
+    emconfigure ./configure --static --prefix=$HOME/wasm
+    emmake make
+	emmake make install
+
+### Installing pcre
+
+The  [pcre](https://www.pcre.org/)   library  adds   _Perl  Compatible
+Regular Expressions_ to the WASM version.  This is __optional__.
+
+    git clone https://github.com/PCRE2Project/pcre2
+	cd pcre2
+	git checkout pcre2-10.42
+	emcmake cmake -DCMAKE_INSTALL_PREFIX=$HOME/wasm -DPCRE2GREP_SUPPORT_JIT=OFF -G Ninja ..
+	ninja
+	ninja install
+
+### Installing GMPlib
+
+The  [GMP](https://gmplib.org/)  library  brings  unbounded  integers,
+rational numbers and good random  numbers to SWI-Prolog.  The price is
+its size and for  some users the LGPL license.  As  all code is linked
+statically this effectively makes  the resulting system LGPL.  Without
+GMP,     the      build     falls     back     to      the     bundled
+[LibBF](https://bellard.org/libbf/) by Fabrice Bellard.  This provides
+all the same functionality thanks to a compatibility wrapper developed
+by Jan Wielemaker  and Rick Workman.  Notably  performance on rational
+number arithmetic is considerably worse though.  But, the LibBF verion
+is smaller and causes all code  to be covered by _permissive_ licenses
+(MIT, BSD, Apache).   This is __optional__
+
+    wget https://gmplib.org/download/gmp/gmp-6.1.2.tar.lz
+	tar xf gmp-6.1.2.tar.lz
+	cd gmp-6.1.2
+	emconfigure ./configure --disable-assembly --prefix=${HOME}/wasm
+	make -j
+	make install
+
+
+### Sources
+
+The  Emscripten/WASM  build  is   fully  supported  from  the  default
+SWI-Prolog sources.  You find the  WASM specific code in the directory
+`src/wasm` of the source tree.   This contains the JavaScript wrapper,
+several examples and a Prolog web server for the examples.
+
+
+## Building
+
+Go to  where you downloaded  the `swipl-devel` source tree.   Create a
+build directory:
+
+    mkdir build.wasm
+	cd build.wasm
+
+Now, create a script `configure` with this content (adjust as required):
+
+```
+WASM_HOME=$HOME/wasm
+source $WASM_HOME/emsdk/emsdk_env.sh
+TOOLCHAIN=$EMSDK/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake
+[ -f $TOOLCHAIN ] || echo "Could not find emscripten toolchain"
+
+cmake -DCMAKE_TOOLCHAIN_FILE=$TOOLCHAIN \
+      -DCMAKE_BUILD_TYPE=Release \
+	  -DCMAKE_FIND_ROOT_PATH=$HOME/wasm \
+	  -DINSTALL_DOCUMENTATION=OFF \
+	  -G Ninja ..
+```
+
+Now configure and build the system using these commands
+
+    bash configure
+	ninja
+
+Optionally you may test the system  by running the command below.  The
+`-j 8` are the number of tests run in paralel.  Choosing the number of
+cores of your system is a good start.
+
+	ctest -j 8
+
+
+## Run the system
+
+You  can  run the  commandline  SWI-Prolog  with  full access  to  the
+filesystem using the command below (from the `build.wasm` directory).
+
+    node src/swipl.js
+
+The build products for deployment are  in `src`.  You can run the demo
+with a native SWI-Prolog using
+
+    swipl ../src/wasm/server.pl [--port=8080]
+
+Now open the URL that is printed  in your browser.  You should get the
+same as https://dev.swi-prolog.org/wasm/
+
+---
+@see https://github.com/SWI-Prolog/npm-swipl-wasm
+@see https://swi-prolog.discourse.group/t/swi-prolog-in-the-browser-using-wasm/5650/1
diff --git a/build/WebAssembly.txt b/build/WebAssembly.txt
deleted file mode 100644
index b57958a..0000000
--- a/build/WebAssembly.txt
+++ /dev/null
@@ -1,37 +0,0 @@
-# Building SWI-Prolog using Emscripten for WebAssembly (WASM)
-
-As of version 8.1.2, building an executable  for WASM is fully supported
-by the standard build process. The port   is the work of Raivo Laanemets
-and  related  material   can   be   found    mostly   on   his   [GitHub
-pages](https://github.com/).
-
-## Preparation
-
-You need to download the Emscripten  compiler. Follow the instruction on
-its
-[homepage](http://kripken.github.io/emscripten-site/docs/getting_started/downloads.html).
-
-After the successful installation load the Emscripten environment into the current terminal session (adjust path):
-
-    source ./emsdk_env.sh
-
-## Dependencies
-
-SWI-Prolog depends on zlib. To compile it to WebAssembly:
-
-    wget https://zlib.net/zlib-1.2.11.tar.gz -O "$HOME/zlib-1.2.11.tar.gz"
-    tar -xf "$HOME/zlib-1.2.11.tar.gz" -C "$HOME"
-    cd "$HOME/zlib-1.2.11"
-    emconfigure ./configure
-    emmake make
-
-This will download and build zlib   into the zlib-1.2.11 subdirectory in
-your home directory.
-
-## Building
-
-See
-[CMAKE.md](https://github.com/SWI-Prolog/swipl-devel/blob/master/CMAKE.md)
-in the top directory of the sources.
-
-@see https://github.com/SWI-Prolog/swipl-wasm