Cross-compile for armhf (#5)

* Utility script

* Add GitHub action

* Temporarily run on pull requests, too

* Specify output file to use

* Store built application

.github/workflows/build-raspberry.yml

@@ -0,0 +1,39 @@
+name: Build for Raspberry Pi
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Download ARM Toolchain
+        run: |
+          pushd /tmp
+          wget "https://developer.arm.com/-/media/Files/downloads/gnu-a/10.2-2020.11/binrel/gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf.tar.xz?revision=d0b90559-3960-4e4b-9297-7ddbc3e52783&la=en&hash=985078B758BC782BC338DB947347107FBCF8EF6B" \
+            -O gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf.tar.xz
+          tar xf gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf.tar.xz
+        
+      - name: Install Standard Rust library for Raspberry Pi 2/3/4
+        run: |
+          rustup target add armv7-unknown-linux-gnueabihf
+
+      - name: Perform build
+        run: |
+          ./cross-compile-armv7.sh
+        env:
+          ARMHF_TOOLCHAIN_PATH: "/tmp/gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf/"
+
+      - name: Upload application
+        uses: actions/upload-artifact@v2
+        if: github.ref == 'refs/heads/main'
+        with:
+          name: dsmr-rs
+          path: target/armv7-unknown-linux-gnueabihf/release/dsmr-rs

cross-compile-armv7.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+set -euo pipefail
+
+PATH=$ARMHF_TOOLCHAIN_PATH/bin:$PATH \
+	cargo build --target armv7-unknown-linux-gnueabihf --release --features ""