PuzzleScript Retroarch Core

In progress

PuzzleScript project: https://github.com/increpare/PuzzleScript

For making retroarch core, looking at tutorial: https://web.archive.org/web/20190219134028/http://www.beardypig.com/2016/01/22/emulator-build-along-2/

Project using V8 to do standalone PuzzleScript games: https://github.com/Narkhos/Puzzlescript-Wrapper

Docs for using V8: https://v8.dev/docs/embed

Linaro toolchain: https://releases.linaro.org/components/toolchain/binaries/

Building

To compile, first install gn. https://gn.googlesource.com/gn/

Build with:

gn gen out/x64
ninja -C out/x64

The output will be out/x64/puzzlescript_libretro.so which can be copied to your RetroArch core folder. Mine is set to ~/.config/retroarch/cores/.

To quickly test output, do:

ninja -C out/x86 && retroarch -L out/x64/puzzlescript_libretro.so

To compile for ARM based mini systems such as SEGA Genesis Mini, use the cross toolchain. Set args:

gn gen out/arm
gn args out/arm

Add in:

target_cpu = "arm"
linaro = "~/linaro"

Download and untar the linaro toolchain and sysroot into ~/linaro:

https://releases.linaro.org/components/toolchain/binaries/7.5-2019.12/arm-linux-gnueabihf/

Build with:

ninja -C out/arm

Babel

I had to convert the PuzzleScript JS sources to older version of JavaScript to make it compatible with Duktape, there were some issues with backtick literals (template strings). I used Babel and the CLI for this. Installed and converted the directory.

npm install --save-dev @babel/core @babel/cli
npm install @babel/preset-env
cd data/PuzzleScript/src
mkdir es5
npx babel js --out-dir es5

The project level .babelrc configures some options to make it work (like turn off the "use strict").

Compatibility

Using the Ubuntu 22.04 default ARM cross compiler has a glibc that is too new for the SEGA Genesis Mini. I got errors like:

[ERROR] Failed to open libretro core: "/opt/project_lunar/opt/retroarch/config/retroarch/cores/puzzlescript_libretro.so"
[ERROR] Error(s): /lib/libm.so.6: version `GLIBC_2.27' not found (required by /opt/project_lunar/opt/retroarch/config/retroarch/cores/puzzlescript_libretro.so)

I switched to using Linaro 7.5, that works fine. I believe it has GLIBC 2.25. https://releases.linaro.org/components/toolchain/binaries/7.5-2019.12/arm-linux-gnueabihf/

Building V8

I did some experiments with building with V8. Main issue is that V8 does a hermetic build, if you try to use local tools and things you will usually encounter errors. So you have to use recent clang, and the sysroot from Debian Bullseye on ARM. In the end that means your app also needs to use those things, which is too new for the SEGA Genesis Mini system I have with Project Lunar.

Some notes:

Download V8 following instructions at: https://v8.dev/docs/build

Cross compile with instructions at: https://v8.dev/docs/embed

Set options using this command:

gn args out/x64.release/

The options I set are:

is_component_build = true
is_debug = false
target_cpu = "x64"
use_goma = false
v8_enable_backtrace = true
v8_enable_disassembler = true
v8_enable_object_print = true
v8_enable_verify_heap = true
dcheck_always_on = false
v8_use_external_startup_data = false
use_sysroot = false

Build with:

ninja -C out/x64.release v8

Similarly for ARM, use options:

is_component_build = true
is_debug = false
target_cpu = "arm"
v8_target_cpu = "arm"
use_goma = false
v8_enable_backtrace = true
v8_enable_disassembler = true
v8_enable_object_print = true
v8_enable_verify_heap = true
dcheck_always_on = false
v8_use_external_startup_data = false

Then build with:

ninja -C out/arm.release v8

Using V8 build

This results in a bunch of .so files in the out/x64.release directory including things related to V8 and a custom libc++.

To build an application using these files, set V8ROOT to point to the base of the V8 project then do something like:

clang++ \
    -std=c++17 \
    -DV8_COMPRESS_POINTERS \
    -I$V8ROOT \
    -I$V8ROOT/buildtools/third_party/libc++ \
    -I$V8ROOT/include \
    -nostdinc++ \
    -isystem $V8ROOT/buildtools/third_party/libc++/trunk/include \
    -c \
    hello-world.cc \
    -o hello-world.o

clang++ \
    -o hello_world \
    hello-world.o \
    -L$V8ROOT/out/x64.release/ \
    -lv8 -lv8_libbase -lv8_libplatform \
    -stdlib=libc++ \
    -Wl,-rpath,$V8ROOT/out/x64.release

NOTES

The is_component_build means the build will generate .so files instead of statically linking. You can theoretically get a monolithic static build but I had trouble using the final monolithic build since it requires linking against the custom libc++ library. I found it easier to build the .so files and then link to them, that avoids the issues of listing lots of random .o files.

Building on ARM

OLD

On Ubuntu you need to install packages with the cross compiler:

sudo apt install gcc make gcc-arm-linux-gnueabihf binutils-arm-linux-gnueabihf g++-arm-linux-gnueabihf

set(CMAKE_C_COMPILER arm-linux-gnueabihf-gcc)
set(CMAKE_CXX_COMPILER arm-linux-gnueabihf-g++)