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commit plain_hasher to util

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This commit is contained in:
debris 2017-08-28 12:40:29 +02:00
parent e0c2995f78
commit 752dad6829
5 changed files with 103 additions and 5 deletions
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6
Cargo.lock generated
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@ -548,7 +548,7 @@ dependencies = [
"bigint 4.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
"heapsize 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
"libc 0.2.21 (registry+https://github.com/rust-lang/crates.io-index)",
"plain_hasher 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
"plain_hasher 0.1.0",
"rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
"rustc-hex 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
]
@ -2201,9 +2201,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
[[package]]
name = "plain_hasher"
version = "0.1.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
"crunchy 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
"crunchy 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
]
[[package]]
@ -3394,7 +3393,6 @@ dependencies = [
"checksum phf_generator 0.7.14 (registry+https://github.com/rust-lang/crates.io-index)" = "db005608fd99800c8c74106a7c894cf582055b689aa14a79462cefdcb7dc1cc3"
"checksum phf_shared 0.7.14 (registry+https://github.com/rust-lang/crates.io-index)" = "fee4d039930e4f45123c9b15976cf93a499847b6483dc09c42ea0ec4940f2aa6"
"checksum pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "3a8b4c6b8165cd1a1cd4b9b120978131389f64bdaf456435caa41e630edba903"
"checksum plain_hasher 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "83ae80873992f511142c07d0ec6c44de5636628fdb7e204abd655932ea79d995"
"checksum podio 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e5422a1ee1bc57cc47ae717b0137314258138f38fd5f3cea083f43a9725383a0"
"checksum pretty_assertions 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "2412f3332a07c7a2a50168988dcc184f32180a9758ad470390e5f55e089f6b6e"
"checksum primal 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "0e31b86efadeaeb1235452171a66689682783149a6249ff334a2c5d8218d00a4"

2
util/bigint/Cargo.toml
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@ -13,7 +13,7 @@ rustc-hex = "1.0"
rand = "0.3.12"
libc = "0.2"
heapsize = { version = "0.4", optional = true }
plain_hasher = "0.1"
plain_hasher = { path = "../plain_hasher" }
[features]
x64asm_arithmetic=[]

12
util/plain_hasher/Cargo.toml Normal file
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@ -0,0 +1,12 @@
[package]
name = "plain_hasher"
description = "Hasher for 32-bit keys."
version = "0.1.0"
authors = ["Parity Technologies <admin@parity.io>"]
license = "MIT"
keywords = ["hash", "hasher"]
categories = ["no-std"]
homepage = "https://github.com/paritytech/plain_hasher"
[dependencies]
crunchy = "0.1.6"

33
util/plain_hasher/benches/bench.rs Normal file
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@ -0,0 +1,33 @@
#![feature(test)]
extern crate test;
extern crate plain_hasher;
use std::hash::Hasher;
use std::collections::hash_map::DefaultHasher;
use test::{Bencher, black_box};
use plain_hasher::PlainHasher;
#[bench]
fn write_plain_hasher(b: &mut Bencher) {
b.iter(|| {
let n: u8 = black_box(100);
(0..n).fold(PlainHasher::default(), |mut old, new| {
let bb = black_box([new; 32]);
old.write(&bb as &[u8]);
old
});
});
}
#[bench]
fn write_default_hasher(b: &mut Bencher) {
b.iter(|| {
let n: u8 = black_box(100);
(0..n).fold(DefaultHasher::default(), |mut old, new| {
let bb = black_box([new; 32]);
old.write(&bb as &[u8]);
old
});
});
}

55
util/plain_hasher/src/lib.rs Normal file
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@ -0,0 +1,55 @@
#![no_std]
#[macro_use]
extern crate crunchy;
use core::{hash, mem};
/// Hasher that just takes 8 bytes of the provided value.
/// May only be used for keys which are 32 bytes.
#[derive(Default)]
pub struct PlainHasher {
prefix: u64,
}
impl hash::Hasher for PlainHasher {
#[inline]
fn finish(&self) -> u64 {
self.prefix
}
#[inline]
#[allow(unused_assignments)]
fn write(&mut self, bytes: &[u8]) {
debug_assert!(bytes.len() == 32);
unsafe {
let mut bytes_ptr = bytes.as_ptr();
let prefix_u8: &mut [u8; 8] = mem::transmute(&mut self.prefix);
let mut prefix_ptr = prefix_u8.as_mut_ptr();
unroll! {
for _i in 0..8 {
*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);
}
}
}
}
}
#[cfg(test)]
mod tests {
use core::hash::Hasher;
use super::PlainHasher;
#[test]
fn it_works() {
let mut bytes = [32u8; 32];
bytes[0] = 15;
let mut hasher = PlainHasher::default();
hasher.write(&bytes);
assert_eq!(hasher.prefix, 47);
}
}