add CI

.travis.yml

+# Based on the "trust" template v0.1.1
+# https://github.com/japaric/trust/tree/v0.1.1
+
+dist: trusty
+language: rust
+services: docker
+sudo: required
+
+matrix:
+  include:
+    - env: TARGET=x86_64-unknown-linux-gnu
+      rust: nightly
+    - env: TARGET=thumbv6m-none-eabi
+      rust: nightly
+    - env: TARGET=thumbv7m-none-eabi
+      rust: nightly
+    - env: TARGET=thumbv7em-none-eabi
+      rust: nightly
+    - env: TARGET=thumbv7em-none-eabihf
+      rust: nightly
+
+before_install: set -e
+
+install:
+  - sh ci/install.sh
+  - source ~/.cargo/env || true
+
+script:
+  - bash ci/script.sh
+
+after_script: set +e
+
+cache: cargo
+before_cache:
+  # Travis can't cache files that are not readable by "others"
+  - chmod -R a+r $HOME/.cargo
+
+branches:
+  only:
+    # release tags
+    - /^v\d+\.\d+\.\d+.*$/
+    - master
+
+notifications:
+  email:
+    on_success: never

ci/install.sh

+set -ex
+
+main() {
+    local target=
+    if [ $TRAVIS_OS_NAME = linux ]; then
+        target=x86_64-unknown-linux-musl
+        sort=sort
+    else
+        target=x86_64-apple-darwin
+        sort=gsort  # for `sort --sort-version`, from brew's coreutils.
+    fi
+
+    # This fetches latest stable release
+    local tag=$(git ls-remote --tags --refs --exit-code https://github.com/japaric/cross \
+                       | cut -d/ -f3 \
+                       | grep -E '^v[0.1.0-9.]+$' \
+                       | $sort --version-sort \
+                       | tail -n1)
+    curl -LSfs https://japaric.github.io/trust/install.sh | \
+        sh -s -- \
+           --force \
+           --git japaric/cross \
+           --tag $tag \
+           --target $target
+}
+
+main

ci/script.sh

+set -ex
+
+main() {
+    if [ $TARGET = x86_64-unknown-linux-gnu ]; then
+        cargo test
+        return
+    fi
+
+    cross build --target $TARGET
+    cross build --target $TARGET --release
+}
+
+main