# Development
## Project layout
```text
bench/ -- simple benchmarks
build.rs -- build script
no_atomic.rs -- definitions of statics used by build script (auto-generated)
src/imp/atomic128/ -- 128-bit atomic implementation (mainly by asm)
src/imp/core_atomic.rs -- wrapper for core::sync::atomic types
src/imp/fallback/ -- fallback implementation based on global locks
src/imp/interrupt/ -- fallback implementation based on disabling interrupts (for no-std)
src/imp/msp430.rs -- atomic implementation for MSP430 (by asm)
src/imp/riscv.rs -- atomic implementation for RISC-V without A-extension (by asm)
src/lib.rs -- definitions of public APIs
src/tests/ -- unit tests and test helpers
src/utils.rs -- common code
target-specs/ -- specs of custom targets
tests/api-test/ -- API check
tests/cortex-m/ -- tests for cortex-m (thumbv*m)
tests/gba/ -- tests for gba (thumbv4t)
tools/ -- tools for CI or development
```
## Testing powerpc64le using POWER Functional Simulator
We mainly use qemu to test for targets other than x86_64/aarch64, but some instructions do not work well in qemu, so we sometimes use other tools. This section describes testing powerpc64le using IBM [POWER Functional Simulator](https://www.ibm.com/support/pages/node/6491145).
### Setup
Install dependencies.
```sh
# gcc-powerpc64le-linux-gnu and libc6-dev-ppc64el-cross for cross-compiling
# xterm for simulator
# jq for parsing json output from cargo
sudo apt-get install gcc-powerpc64le-linux-gnu libc6-dev-ppc64el-cross xterm jq
```
Download Simulator from [download page](https://www.ibm.com/support/pages/node/6493437).
Install POWER Functional Simulator.
```sh
sudo dpkg -i systemsim-p10-<version>_amd64.deb
```
Download images (see `/opt/ibm/systemsim-p10-<version>/examples/linux/README` for more).
```sh
cd /opt/ibm/systemsim-p10-<version>/examples/linux
./fetch_ubuntu_disk_image.sh
./fetch_vmlinux.sh
./fetch_skiboot.sh
mv deb2004.img ../../images/disk.img
mv vmlinux ../../images
mv skiboot.lid ../../images
```
Start simulator.
```sh
cd /opt/ibm/systemsim-<version>/run/p10/linux
../power10 -f boot-linux-ubuntu-p10.tcl
```
### Run tests
Install Rust target.
```sh
rustup target add powerpc64le-unknown-linux-gnu
```
Build tests for powerpc64le and get path to test binary.
```sh
# Note: Below is a way to get path to unit test binary. If you need to get
# binaries for other tests, you need to adjust the script or copy paths from
# cargo's "Executable ..." output.
binary_path=$(
CARGO_TARGET_POWERPC64LE_UNKNOWN_LINUX_GNU_LINKER=powerpc64le-linux-gnu-gcc \
cargo test --no-run --all-features --target powerpc64le-unknown-linux-gnu --message-format=json --release \
| jq -r "select(.manifest_path == \"$(cargo locate-project --message-format=plain)\") | select(.executable != null) | .executable"
)
```
Copy test binary to `/tmp` (to easily type in simulator's console).
```sh
cp "$binary_path" /tmp/t
```
In simulator's console, copy test binary from host.
```sh
callthru source /tmp/t>t && chmod +x ./t
```
Run test binary in simulator.
```sh
./t --test-threads=1
```
TODO: Automate more processes.