From 76cd7607628dbf9dc39465aadef083242e715640 Mon Sep 17 00:00:00 2001 From: Stjepan Glavina Date: Wed, 27 May 2020 18:18:29 +0200 Subject: [PATCH] Initial commit --- .gitignore | 2 + CHANGELOG.md | 3 + Cargo.toml | 13 +++ LICENSE-APACHE | 201 +++++++++++++++++++++++++++++++++++++++ LICENSE-MIT | 23 +++++ README.md | 62 ++++++++++++ examples/foo.rs | 5 + src/lib.rs | 245 ++++++++++++++++++++++++++++++++++++++++++++++++ 8 files changed, 554 insertions(+) create mode 100644 .gitignore create mode 100644 CHANGELOG.md create mode 100644 Cargo.toml create mode 100644 LICENSE-APACHE create mode 100644 LICENSE-MIT create mode 100644 README.md create mode 100644 examples/foo.rs create mode 100644 src/lib.rs diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..96ef6c0 --- /dev/null +++ b/.gitignore @@ -0,0 +1,2 @@ +/target +Cargo.lock diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 index 0000000..af42cea --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,3 @@ +# Version 1.0.0 + +- Initial version diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..1c3d899 --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,13 @@ +[package] +name = "fastrand" +version = "1.0.0" +authors = ["Stjepan Glavina "] +edition = "2018" +description = "A simple random number generator" +license = "Apache-2.0 OR MIT" +repository = "https://github.com/stjepang/fastrand" +homepage = "https://github.com/stjepang/fastrand" +documentation = "https://docs.rs/fastrand" +keywords = ["easy", "simple", "rand", "random", "xorshift"] +Categories = ["algorithms"] +readme = "README.md" diff --git a/LICENSE-APACHE b/LICENSE-APACHE new file mode 100644 index 0000000..16fe87b --- /dev/null +++ b/LICENSE-APACHE @@ -0,0 +1,201 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + +TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + +1. 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IN NO EVENT +SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY +CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR +IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +DEALINGS IN THE SOFTWARE. diff --git a/README.md b/README.md new file mode 100644 index 0000000..78a1e7e --- /dev/null +++ b/README.md @@ -0,0 +1,62 @@ +# fastrand + +[![Build](https://github.com/stjepang/fastrand/workflows/Build%20and%20test/badge.svg)]( +https://github.com/stjepang/fastrand/actions) +[![License](https://img.shields.io/badge/license-MIT%2FApache--2.0-blue.svg)]( +https://github.com/stjepang/fastrand) +[![Cargo](https://img.shields.io/crates/v/fastrand.svg)]( +https://crates.io/crates/fastrand) +[![Documentation](https://docs.rs/fastrand/badge.svg)]( +https://docs.rs/fastrand) + +A simple random number generator. + +Easy to use but not cryptographically secure. + +## Examples + +Flip a coin: + +``` +if fastrand::bool() { + println!("heads"); +} else { + println!("tails"); +} +``` + +Generate a random `i32`: + +``` +let num = fastrand::i32(..); +``` + +Choose a random element in an array: + +``` +let v = vec![1, 2, 3, 4, 5]; +let i = fastrand::usize(..v.len()); +let elem = v[i]; +``` + +Shuffle an array: + +``` +let mut v = vec![1, 2, 3, 4, 5]; +fastrand::shuffle(&mut v); +``` + +## 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. diff --git a/examples/foo.rs b/examples/foo.rs new file mode 100644 index 0000000..4fa2654 --- /dev/null +++ b/examples/foo.rs @@ -0,0 +1,5 @@ +fn main() { + for _ in 0..30 { + println!("{}", fastrand::u8(..)); + } +} diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..1996579 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,245 @@ +//! A simple random number generator. +//! +//! Easy to use but not cryptographically secure. +//! +//! # Examples +//! +//! Flip a coin: +//! +//! ``` +//! if fastrand::bool() { +//! println!("heads"); +//! } else { +//! println!("tails"); +//! } +//! ``` +//! +//! Generate a random `i32`: +//! +//! ``` +//! let num = fastrand::i32(..); +//! ``` +//! +//! Choose a random element in an array: +//! +//! ``` +//! let v = vec![1, 2, 3, 4, 5]; +//! let i = fastrand::usize(..v.len()); +//! let elem = v[i]; +//! ``` +//! +//! Shuffle an array: +//! +//! ``` +//! let mut v = vec![1, 2, 3, 4, 5]; +//! fastrand::shuffle(&mut v); +//! ``` + +use std::cell::Cell; +use std::collections::hash_map::DefaultHasher; +use std::hash::{Hash, Hasher}; +use std::ops::{Bound, RangeBounds}; +use std::thread; +use std::time::Instant; + +/// Generates a random `u64`. +fn gen_u64() -> u64 { + thread_local! { + static RNG: Cell<(u64, u64)> = Cell::new((seed(), seed())); + } + + #[cold] + fn seed() -> u64 { + let mut hasher = DefaultHasher::new(); + thread::current().id().hash(&mut hasher); + Instant::now().hash(&mut hasher); + hasher.finish() + } + + // xorshift+: https://en.wikipedia.org/wiki/Xorshift + RNG.try_with(|rng| { + let (mut a, mut b) = rng.get(); + let (mut t, s) = (a, b); + a = s; + t ^= t << 23; + t ^= t >> 17; + t ^= s ^ (s >> 26); + b = t; + rng.set((a, b)); + t.wrapping_add(s) + }) + .unwrap_or_else(|_| seed()) +} + +/// Generates a random `u128`. +fn gen_u128() -> u128 { + ((gen_u64() as u128) << 64) | (gen_u64() as u128) +} + +/// Computes `(a * b) >> 32`. +fn mul_high_u32(a: u32, b: u32) -> u32 { + (((a as u64) * (b as u64)) >> 32) as u32 +} + +/// Computes `(a * b) >> 64`. +fn mul_high_u64(a: u64, b: u64) -> u64 { + (((a as u128) * (b as u128)) >> 64) as u64 +} + +/// Computes `(a * b) >> 128`. +fn mul_high_u128(a: u128, b: u128) -> u128 { + let a_lo = a as u64 as u128; + let a_hi = (a >> 64) as u64 as u128; + + let b_lo = b as u64 as u128; + let b_hi = (b >> 64) as u64 as u128; + + let carry = (a_lo * b_lo) >> 64; + let carry = (a_hi * b_lo + a_lo * b_hi + carry) >> 64; + a_hi * b_hi + carry +} + +/// Generates a random `u32` in `0..n`. +fn gen_mod_u32(n: u32) -> u32 { + mul_high_u32(gen_u64() as u32, n) +} + +/// Generates a random `u64` in `0..n`. +fn gen_mod_u64(n: u64) -> u64 { + mul_high_u64(gen_u64(), n) +} + +/// Generates a random `u128` in `0..n`. +fn gen_mod_u128(n: u128) -> u128 { + mul_high_u128(gen_u128(), n) +} + +macro_rules! code { + ($t:tt, $gen:expr, $mod:ident, $doc:tt) => { + #[doc = $doc] + /// + /// Panics if the range is empty. + pub fn $t(range: impl RangeBounds<$t>) -> $t { + let low = match range.start_bound() { + Bound::Unbounded => $t::MIN, + Bound::Included(&x) => x, + Bound::Excluded(&x) => x + .checked_add(1) + .unwrap_or_else(|| panic!("invalid start bound: {:?}", range.start_bound())), + }; + + let high = match range.end_bound() { + Bound::Unbounded => $t::MAX, + Bound::Included(&x) => x, + Bound::Excluded(&x) => x + .checked_sub(1) + .unwrap_or_else(|| panic!("invalid end bound: {:?}", range.end_bound())), + }; + + if low > high { + panic!( + "empty range: {:?}..{:?}", + range.start_bound(), + range.end_bound() + ); + } + + if low == $t::MIN && high == $t::MAX { + $gen() as $t + } else { + let len = high.wrapping_sub(low).wrapping_add(1); + low.wrapping_add($mod(len as _) as $t) + } + } + }; +} + +code!( + u8, + gen_u64, + gen_mod_u32, + "Generates a random `u8` in the given range." +); +code!( + i8, + gen_u64, + gen_mod_u32, + "Generates a random `i8` in the given range." +); + +code!( + u16, + gen_u64, + gen_mod_u32, + "Generates a random `u16` in the given range." +); +code!( + i16, + gen_u64, + gen_mod_u32, + "Generates a random `i16` in the given range." +); + +code!( + u32, + gen_u64, + gen_mod_u32, + "Generates a random `u32` in the given range." +); +code!( + i32, + gen_u64, + gen_mod_u32, + "Generates a random `i32` in the given range." +); + +code!( + u64, + gen_u64, + gen_mod_u64, + "Generates a random `u64` in the given range." +); +code!( + i64, + gen_u64, + gen_mod_u64, + "Generates a random `i64` in the given range." +); + +code!( + usize, + gen_u64, + gen_mod_u64, + "Generates a random `usize` in the given range." +); +code!( + isize, + gen_u64, + gen_mod_u64, + "Generates a random `isize` in the given range." +); + +code!( + u128, + gen_u128, + gen_mod_u128, + "Generates a random `u128` in the given range." +); +code!( + i128, + gen_u128, + gen_mod_u128, + "Generates a random `i128` in the given range." +); + +/// Generates a random `bool`. +pub fn bool() -> bool { + self::u8(..) % 2 == 0 +} + +/// Shuffles a slice randomly. +pub fn shuffle(slice: &mut [T]) { + for i in 1..slice.len() { + slice.swap(i, self::usize(..=i)); + } +}