diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
new file mode 100644
index 0000000..489c766
--- /dev/null
+++ b/.github/workflows/rust.yml
@@ -0,0 +1,25 @@
+name: build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+
+    runs-on: ${{matrix.os}}
+    strategy:
+      fail-fast: true
+      matrix: 
+        os: [macos-latest, ubuntu-latest, windows-latest]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Check formatting
+      run: |
+        rustup component add rustfmt
+        rustup component add clippy
+        cargo fmt -- --check
+        cargo clippy --all-features --verbose -- -Dwarnings
+    - name: Build
+      run: cargo build --verbose
+    - name: Run tests
+      run: cargo test --all-features
diff --git a/Cargo.lock b/Cargo.lock
index c58c710..a222611 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -8,7 +8,7 @@ checksum = "7bbb73db36c1246e9034e307d0fba23f9a2e251faa47ade70c1bd252220c8311"
 
 [[package]]
 name = "esaxx-rs"
-version = "0.1.1"
+version = "0.1.2"
 dependencies = [
  "cc",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 54de2a3..52713e2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "esaxx-rs"
-version = "0.1.1"
+version = "0.1.2"
 authors = ["Nicolas Patry <patry.nicolas@protonmail.com>"]
 edition = "2018"
 description = "Wrapping around sentencepiece's esaxxx library."
diff --git a/README.md b/README.md
index 6bacfa2..c3aa382 100644
--- a/README.md
+++ b/README.md
@@ -1,33 +1,25 @@
+![](https://github.com/Narsil/esaxx-rs/workflows/build/badge.svg)
+
 # esaxx-rs
 
+This code implements a fast suffix tree / suffix array.
+
+This code is taken from ![sentencepiece](https://github.com/google/sentencepiece) 
+and to be used by ![hugging face](https://github.com/huggingface/tokenizers/).
+
+
 Small wrapper around sentencepiece's esaxx suffix array C++ library.
 Usage
 
 ```rust
-let string = "abracadabra".to_string();
+let string = "abracadabra";
+let suffix = esaxx_rs::suffix(string).unwrap();
 let chars: Vec<_> = string.chars().collect();
-let n = chars.len();
-let mut sa = vec![0; n];
-let mut l = vec![0; n];
-let mut r = vec![0; n];
-let mut d = vec![0; n];
-let mut node_num = 0;
-
-let alphabet_size = 0x110000; // All UCS4 range.
-unsafe {
-    esaxx_int32(
-        chars.as_ptr() as *mut u32,
-        sa.as_mut_ptr(),
-        l.as_mut_ptr(),
-        r.as_mut_ptr(),
-        d.as_mut_ptr(),
-        n.try_into().unwrap(),
-        alphabet_size,
-        &mut node_num,
-    );
-}
+let mut iter = suffix.iter();
+assert_eq!(iter.next().unwrap(), (&chars[..4], 2)); // abra
+assert_eq!(iter.next(), Some((&chars[..1], 5))); // a
+assert_eq!(iter.next(), Some((&chars[1..4], 2))); // bra
+assert_eq!(iter.next(), Some((&chars[2..4], 2))); // ra
+assert_eq!(iter.next(), Some((&chars[..0], 11))); // ''
+assert_eq!(iter.next(), None);
 ```
-
-Current version: 0.1.0
-
-License: Apache
diff --git a/README.tpl b/README.tpl
index ee3febb..a972eef 100644
--- a/README.tpl
+++ b/README.tpl
@@ -1,7 +1,12 @@
+![](https://github.com/Narsil/esaxx-rs/workflows/build/badge.svg)
+
 # {{crate}}
 
+This code implements a fast suffix tree / suffix array.
+
+This code is taken from ![sentencepiece](https://github.com/google/sentencepiece) 
+and to be used by ![hugging face](https://github.com/huggingface/tokenizers/).
+
+
 {{readme}}
 
-Current version: {{version}}
-
-License: {{license}}
diff --git a/src/esa.rs b/src/esa.rs
index 5cf557f..2ebf5dc 100644
--- a/src/esa.rs
+++ b/src/esa.rs
@@ -75,7 +75,7 @@ fn suffixtree(
     node_num
 }
 
-pub fn esaxx_rs(
+pub(crate) fn esaxx_rs(
     t: &StringT,
     sa: &mut SArray,
     l: &mut SArray,
diff --git a/src/lib.rs b/src/lib.rs
index 3115755..fd69d71 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,6 +13,25 @@
 //! assert_eq!(iter.next(), Some((&chars[..0], 11))); // ''
 //! assert_eq!(iter.next(), None);
 //! ```
+//!
+//! The previous version uses unsafe optimized c++ code.
+//! There exists another implementation a bit slower (~2x slower) that uses
+//! safe rust. It's a bit slower because it uses usize (mostly 64bit) instead of i32 (32bit).
+//! But it does seems to fix a few OOB issues in the cpp version
+//! (which never seemed to cause real problems in tests but still.)
+//!
+//! ```rust
+//! let string = "abracadabra";
+//! let suffix = esaxx_rs::suffix_rs(string).unwrap();
+//! let chars: Vec<_> = string.chars().collect();
+//! let mut iter = suffix.iter();
+//! assert_eq!(iter.next().unwrap(), (&chars[..4], 2)); // abra
+//! assert_eq!(iter.next(), Some((&chars[..1], 5))); // a
+//! assert_eq!(iter.next(), Some((&chars[1..4], 2))); // bra
+//! assert_eq!(iter.next(), Some((&chars[2..4], 2))); // ra
+//! assert_eq!(iter.next(), Some((&chars[..0], 11))); // ''
+//! assert_eq!(iter.next(), None);
+//! ```
 #![feature(test)]
 extern crate test;
 
@@ -21,11 +40,11 @@ mod esa;
 mod sais;
 mod types;
 
-pub use esa::esaxx_rs;
+use esa::esaxx_rs;
 use types::SuffixError;
 
 extern "C" {
-    pub fn esaxx_int32(
+    fn esaxx_int32(
         // This is char32
         T: *const u32,
         SA: *mut i32,
@@ -38,7 +57,7 @@ extern "C" {
     ) -> i32;
 }
 
-pub fn esaxx(
+fn esaxx(
     chars: &[char],
     sa: &mut [i32],
     l: &mut [i32],
@@ -83,6 +102,8 @@ pub struct Suffix<T> {
     node_num: usize,
 }
 
+/// Creates the suffix array and provides an iterator over its items (Rust version)
+/// See [suffix](fn.suffix.html)
 pub fn suffix_rs(string: &str) -> Result<Suffix<usize>, SuffixError> {
     let chars: Vec<_> = string.chars().collect();
     let n = chars.len();
@@ -102,6 +123,22 @@ pub fn suffix_rs(string: &str) -> Result<Suffix<usize>, SuffixError> {
     })
 }
 
+/// Creates the suffix array and provides an iterator over its items (c++ unsafe version)
+///
+/// Gives you an iterator over the suffixes of the input array and their count within
+/// the input srtring.
+/// ```rust
+/// let string = "abracadabra";
+/// let suffix = esaxx_rs::suffix(string).unwrap();
+/// let chars: Vec<_> = string.chars().collect();
+/// let mut iter = suffix.iter();
+/// assert_eq!(iter.next().unwrap(), (&chars[..4], 2)); // abra
+/// assert_eq!(iter.next(), Some((&chars[..1], 5))); // a
+/// assert_eq!(iter.next(), Some((&chars[1..4], 2))); // bra
+/// assert_eq!(iter.next(), Some((&chars[2..4], 2))); // ra
+/// assert_eq!(iter.next(), Some((&chars[..0], 11))); // ''
+/// assert_eq!(iter.next(), None);
+/// ```
 pub fn suffix(string: &str) -> Result<Suffix<i32>, SuffixError> {
     let chars: Vec<_> = string.chars().collect();
     let n = chars.len();