jpolo1224 b971d81862 Byte-swap four words at a time on ARM64
copy_data_swap_u32 and its compare variant are assembled by asmjit under
ARCH_X64 only. Every ARM64 build fell through to the scalar per-word loop,
reached through a function pointer so it could not be inlined, and LTO is
disabled project-wide so nothing recovered it afterwards.

It is not a cold path: transform constants, transform programs and vertex data
all upload through it, and a Sonic '06 profile on a Snapdragon 8 Gen 2 put 82.5%
of the RSX thread in FIFO decode with thousands of these blocks per frame.

vrev32q_u8 reverses bytes within each 32-bit lane, which is the same swap the
scalar path does per element. The compare variant accumulates differences and
reduces once at the end rather than branching per element. Checked against the
scalar version over 20000 randomised trials at counts 0 to 39, covering every
tail remainder, for both variants: identical output and identical return value.
2026-08-10 00:28:19 -04:00

ARMSX3

Proof of concept Android port of RPCS3.

Uses the latest RPCS3 upstream code (the recent ARM64 improvements included).

Status

From my testing, I only tried Skate 3. It boots, loads and reaches gameplay at roughly 20 to 30 fps on a Snapdragon 8 Gen 2. Rendering, audio, touch controls and physical controllers work. Almost nothing else has been tested. So the main stop gap at the moment is performance/speed.

Differences from upstream RPCS3

Some of the fixes here are not in upstream and affect any ARM64 build, not only Android:

  • Shaders declared runtime sized arrays inside uniform blocks, which requires VK_EXT_shader_uniform_buffer_unsized_array. Adreno does not support that extension, so every game pipeline failed to compile and nothing rendered. Concrete array bounds are emitted when the extension is missing.

  • The ARM64 SPU block verification checksum folded two thirds of every block through an absolute difference. That collides on the near identical job binaries an SPU job manager streams through the same local store address, so a cached block could end up running against another job's code. It sums now.

  • Thread affinity was compiled out on Android, and the core had no ARM big.LITTLE topology, so SPU and RSX threads were never placed on the fast cores.

  • The LLVM JIT target was pinned to cortex-a34, an in order core from 2016. It detects the host now.

Building

Only arm64-v8a is supported. You need the Android SDK with NDK r27 or newer, CMake 3.30 or newer, and a JDK 17. Android Studio ships all of these.

Clone with submodules, then fetch the two third party checkouts that are not submodules:

git clone --recursive https://github.com/ARMSX2/ARMSX3.git
cd ARMSX3
git clone https://github.com/SnowflakePowered/librashader 3rdparty/librashader
git clone https://github.com/bylaws/libadrenotools android/armsx3-ui/app/src/main/cpp/libadrenotools

Build the core. This is the long part and produces an unstripped library of around 1.3 GB:

export ANDROID_HOME=$HOME/Library/Android/sdk
cmake -B build-android -G Ninja \
  -DCMAKE_TOOLCHAIN_FILE=$ANDROID_HOME/ndk/<version>/build/cmake/android.toolchain.cmake \
  -DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=android-31 \
  -DCMAKE_BUILD_TYPE=RelWithDebInfo
cmake --build build-android --target rpcsx-android -j8

Strip it and put it where the app expects it:

llvm-strip --strip-unneeded build-android/android/libarmsx3-core.so
cp build-android/android/libarmsx3-core.so \
   android/armsx3-ui/app/src/main/jniLibs/arm64-v8a/

Then build the app:

cd android/armsx3-ui
export JAVA_HOME="/Applications/Android Studio.app/Contents/jbr/Contents/Home"
./gradlew :app:assembleRelease

The apk lands in app/build/outputs/apk/release/.

Note that the core library has to be rebuilt and copied again whenever anything under rpcs3/ or android/src/ changes. Gradle does not build it for you.

The Discord Social SDK is proprietary and is not redistributed here. Get it from Discord's developer portal and drop it in app/libs/ and app/src/main/cpp/discord_sdk/ if you want that feature. The build skips it otherwise.

Running it needs PS3 firmware, which is not included. License

GPL-2.0-only, the same as RPCS3. See LICENSE. Some files may be licensed differently, check the file headers.

Based on RPCS3, https://github.com/RPCS3/rpcs3

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