Write Documentation and add CI for no_std

.travis.yml

@@ -7,6 +7,8 @@ matrix:
   include:
     - rust: 1.34.0
     - rust: stable
+    - rust: stable
+      env: TARGET="--target thumbv6m-none-eabi" FEATURES="--features alloc"
     - rust: beta
     - rust: nightly
       addons:
@@ -26,9 +28,10 @@ env:
   - TERM=dumb
 
 script:
-  - cargo build --verbose
-  - cargo test --verbose
-  - cargo doc --verbose
+  - cargo build --verbose $TARGET --no-default-features
+  - cargo build --verbose $TARGET $FEATURES
+  - 'if [[ -z "$TARGET" ]]; then cargo test --verbose; fi'
+  - 'if [[ -z "$TARGET" ]]; then cargo doc --verbose; fi'
   - 'if [[ "$TRAVIS_RUST_VERSION" = nightly ]]; then cargo bench --no-run; fi'
   # run for just a second to confirm that it can build and run ok
   - 'if [[ "$TRAVIS_RUST_VERSION" = nightly ]]; then cargo fuzz list | xargs -L 1 -I FUZZER cargo fuzz run FUZZER -- -max_total_time=1; fi'

README.md

@@ -50,6 +50,11 @@ Decoding is aided by some pre-calculated tables, which are generated by:
 cargo run --example make_tables > src/tables.rs.tmp && mv src/tables.rs.tmp src/tables.rs
 ```
 
+no_std
+---
+
+This crate supports no_std. By default the crate targets std via the `std` feature. You can deactivate the `default-features` to target core instead. In that case you lose out on all the functionality revolving around `std::io`, `std::error::Error` and heap allocations. There is an additional `alloc` feature that you can activate to bring back the support for heap allocations.
+
 Profiling
 ---