From f31f7d5d52ef529797631ab090efda4e85a22fb0 Mon Sep 17 00:00:00 2001
From: David Palm <dvdplm@gmail.com>
Date: Wed, 8 Aug 2018 11:34:28 +0200
Subject: [PATCH 1/2] Remove dep on ethereum-types and make no_std compatible

---
 plain_hasher/Cargo.toml |  6 ++++--
 plain_hasher/src/lib.rs | 17 ++++++-----------
 2 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/plain_hasher/Cargo.toml b/plain_hasher/Cargo.toml
index adc03bb..8fd9cfe 100644
--- a/plain_hasher/Cargo.toml
+++ b/plain_hasher/Cargo.toml
@@ -9,5 +9,7 @@ homepage = "https://github.com/paritytech/plain_hasher"
 
 [dependencies]
 crunchy = "0.1.6"
-ethereum-types = "0.3"
-hashdb = { path = "../hashdb" }
\ No newline at end of file
+
+[features]
+default = ["std"]
+std = []
\ No newline at end of file
diff --git a/plain_hasher/src/lib.rs b/plain_hasher/src/lib.rs
index 4a8a104..3250cd6 100644
--- a/plain_hasher/src/lib.rs
+++ b/plain_hasher/src/lib.rs
@@ -14,20 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
+#![cfg_attr(not(feature = "std"), no_std)]
+
 #[macro_use]
 extern crate crunchy;
-extern crate ethereum_types;
-extern crate hashdb;
 
-use ethereum_types::H256;
-// use hashdb::Hasher;
-use std::hash;
-use std::collections::{HashMap, HashSet};
-/// Specialized version of `HashMap` with H256 keys and fast hashing function.
-pub type H256FastMap<T> = HashMap<H256, T, hash::BuildHasherDefault<PlainHasher>>;
-/// Specialized version of `HashSet` with H256 keys and fast hashing function.
-pub type H256FastSet = HashSet<H256, hash::BuildHasherDefault<PlainHasher>>;
+#[cfg(feature = "std")]
+extern crate core;
 
+use core::hash;
 /// Hasher that just takes 8 bytes of the provided value.
 /// May only be used for keys which are 32 bytes.
 #[derive(Default)]
@@ -50,7 +45,7 @@ impl hash::Hasher for PlainHasher {
 
 		unroll! {
 			for _i in 0..8 {
-				unsafe { 
+				unsafe {
 					*prefix_ptr ^= (*bytes_ptr ^ *bytes_ptr.offset(8)) ^ (*bytes_ptr.offset(16) ^ *bytes_ptr.offset(24));
 					bytes_ptr = bytes_ptr.offset(1);
 					prefix_ptr = prefix_ptr.offset(1);

From d77a5799846fe370b9157fb0e84c906a3f2bc8ad Mon Sep 17 00:00:00 2001
From: David Palm <dvdplm@gmail.com>
Date: Thu, 9 Aug 2018 08:30:07 +0200
Subject: [PATCH 2/2] Add a README, categorize as "no-std", version bump: 0.2

---
 plain_hasher/Cargo.toml               | 5 +++--
 plain_hasher/README.md                | 5 +++++
 test-support/keccak-hasher/Cargo.toml | 2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)
 create mode 100644 plain_hasher/README.md

diff --git a/plain_hasher/Cargo.toml b/plain_hasher/Cargo.toml
index 8fd9cfe..53b8801 100644
--- a/plain_hasher/Cargo.toml
+++ b/plain_hasher/Cargo.toml
@@ -1,11 +1,12 @@
 [package]
 name = "plain_hasher"
 description = "Hasher for 32-bit keys."
-version = "0.1.0"
+version = "0.2.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "MIT"
 keywords = ["hash", "hasher"]
-homepage = "https://github.com/paritytech/plain_hasher"
+homepage = "https://github.com/paritytech/parity-common"
+categories = [ "no-std"]
 
 [dependencies]
 crunchy = "0.1.6"
diff --git a/plain_hasher/README.md b/plain_hasher/README.md
new file mode 100644
index 0000000..2787796
--- /dev/null
+++ b/plain_hasher/README.md
@@ -0,0 +1,5 @@
+# Specialized Hasher for 32-bit keys
+
+Provides `PlainHasher`, a specialized `core::hash::Hasher` that takes just 8 bytes of the provided value and may only be used for keys which are 32 bytes.
+
+The crate is `no_std`-compatible.
\ No newline at end of file
diff --git a/test-support/keccak-hasher/Cargo.toml b/test-support/keccak-hasher/Cargo.toml
index 7c82f17..363d5d7 100644
--- a/test-support/keccak-hasher/Cargo.toml
+++ b/test-support/keccak-hasher/Cargo.toml
@@ -10,4 +10,4 @@ license = "GPL-3.0"
 ethereum-types = "0.3"
 tiny-keccak = "1.4.2"
 hashdb = { version = "0.2.0", path = "../../hashdb" }
-plain_hasher = {  version = "0.1.0", path = "../../plain_hasher" }
\ No newline at end of file
+plain_hasher = {  path = "../../plain_hasher" }
\ No newline at end of file