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picoarch - a libretro frontend designed for small screens and low power

picoarch uses libpicofe and SDL to create a small frontend to libretro cores. It's designed for small (320x240 2.0-2.4") screen, low-powered devices like the Trimui Model S (PowKiddy A66).

Running

picoarch can be run by specifying the core library and the content to run:

./picoarch /path/to/core_name_libretro.so /path/to/game.gba

If you do not specify core or content, picoarch will have you select a core from the current directory and content using the built-in file browser.

Building

The frontend can currently be built for the TrimUI Model S and Linux (useful for testing and debugging).

First, fetch the repo with submodules:

git clone --recurse-submodules https://git.crowdedwood.com/picoarch

Linux instructions

To build picoarch itself, you need libSDL 1.2, libpng, and libasound. Different cores may need additional dependencies.

After that, make builds picoarch and all supported cores into this directory.

TrimUI instructions

To build for TrimUI, you need to set up the toolchain first.

To build generic binaries:

make platform=trimui

If you want to build for MinUI, you need to install libmmenu into the toolchain. Then:

make platform=trimui MINUI=1

MINUI=1 will change save/config/system paths to match MinUI standards. If you just want to include mmenu, you can run:

make platform=trimui MMENU=1

Other build options

To debug:

make DEBUG=1

To build a specific supported core:

make gpsp_libretro.so

To clean a core so it will be built again:

make clean-gpsp

To completely clean the repo (will delete, pull, and patch all core repos from scratch)

make force-clean

Distribution builds can also be made for gmenunx and MinUI:

make platform=trimui dist-gmenu
make platform=trimui MINUI=1 dist-minui

These will output a directory structure that can be moved onto the SD card into pkg/gmenunx or pkg/MinUI.

To build profiles for profile-guided optimization:

make PROFILE=GENERATE

To apply the generated profiles:

make PROFILE=APPLY

PGO can give noticeable speed improvements with some emulators.

Notes on cores

In order to make development and testing easier, the Makefile will pull and build supported cores.

You will have to make changes when adding a core, since TrimUI is not a supported libretro platform. picoarch has a patches/ directory containing needed changes to make cores work well in picoarch. Patches are applied in order after checking out the repository.

At a minimum, you need to add a platform=trimui section to the core Makefile.

Some features and fixes are also included in patches -- it would be best to try to upstream them.

picoarch keeps the running core name in a global variable. This is used to override defaults and core settings to work more nicely within picoarch. Overrides based on core name are kept in overrides/ and referenced in overrides.c. These are used to:

  • Shorten core option text and change defaults for small screen / low power devices
  • Rename buttons to match the core's system
  • Reference frameskip core options to make fast-forward faster
  • Display extra options or hide unnecessary options