halo2_poseidon: Initial empty library crate

Cargo.toml

@@ -2,5 +2,6 @@
 members = [
     "halo2",
     "halo2_gadgets",
+    "halo2_poseidon",
     "halo2_proofs",
 ]

halo2_poseidon/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "halo2_poseidon"
+version = "0.0.0"
+authors = [
+    "Jack Grigg <[email protected]>",
+    "Daira Emma Hopwood <[email protected]>",
+    "Ying Tong Lai",
+]
+edition = "2021"
+rust-version = "1.60"
+description = "The Poseidon algebraic hash function for Halo 2"
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/zcash/halo2"
+readme = "README.md"
+categories = ["cryptography"]
+
+[dependencies]

halo2_poseidon/README.md

@@ -0,0 +1,25 @@
+# halo2_poseidon [![Crates.io](https://img.shields.io/crates/v/halo2_poseidon.svg)](https://crates.io/crates/halo2_poseidon) #
+
+Requires Rust 1.60+.
+
+## Documentation
+
+- [The Halo 2 Book](https://zcash.github.io/halo2/)
+- [Crate documentation](https://docs.rs/halo2_gadgets)
+
+## License
+
+Licensed under either of
+
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   http://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally
+submitted for inclusion in the work by you, as defined in the Apache-2.0
+license, shall be dual licensed as above, without any additional terms or
+conditions.