std::rand: move the Isaac implementation to its own file.
This commit is contained in:
Huon Wilson
parent
3a70df1d3c
commit
72bf201d61
198
src/libstd/rand/isaac.rs
Normal file
198
src/libstd/rand/isaac.rs
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@ -0,0 +1,198 @@
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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! The ISAAC random number generator.
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use rand::{seed, Rng};
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use iter::{Iterator, range, range_step};
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use option::{None, Some};
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use cast;
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use cmp;
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use sys;
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use vec;
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static RAND_SIZE_LEN: u32 = 8;
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static RAND_SIZE: u32 = 1 << RAND_SIZE_LEN;
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/// A random number generator that uses the [ISAAC
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/// algorithm](http://en.wikipedia.org/wiki/ISAAC_%28cipher%29).
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///
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/// The ISAAC algorithm is suitable for cryptographic purposes.
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pub struct IsaacRng {
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priv cnt: u32,
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priv rsl: [u32, .. RAND_SIZE],
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priv mem: [u32, .. RAND_SIZE],
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priv a: u32,
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priv b: u32,
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priv c: u32
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}
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impl IsaacRng {
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/// Create an ISAAC random number generator with a random seed.
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pub fn new() -> IsaacRng {
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IsaacRng::new_seeded(seed(RAND_SIZE as uint * 4))
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}
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/// Create an ISAAC random number generator with a seed. This can be any
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/// length, although the maximum number of bytes used is 1024 and any more
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/// will be silently ignored. A generator constructed with a given seed
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/// will generate the same sequence of values as all other generators
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/// constructed with the same seed.
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pub fn new_seeded(seed: &[u8]) -> IsaacRng {
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let mut rng = IsaacRng {
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cnt: 0,
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rsl: [0, .. RAND_SIZE],
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mem: [0, .. RAND_SIZE],
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a: 0, b: 0, c: 0
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};
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let array_size = sys::size_of_val(&rng.rsl);
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let copy_length = cmp::min(array_size, seed.len());
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// manually create a &mut [u8] slice of randrsl to copy into.
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let dest = unsafe { cast::transmute((&mut rng.rsl, array_size)) };
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vec::bytes::copy_memory(dest, seed, copy_length);
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rng.init(true);
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rng
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}
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/// Create an ISAAC random number generator using the default
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/// fixed seed.
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pub fn new_unseeded() -> IsaacRng {
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let mut rng = IsaacRng {
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cnt: 0,
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rsl: [0, .. RAND_SIZE],
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mem: [0, .. RAND_SIZE],
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a: 0, b: 0, c: 0
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};
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rng.init(false);
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rng
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}
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/// Initialises `self`. If `use_rsl` is true, then use the current value
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/// of `rsl` as a seed, otherwise construct one algorithmically (not
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/// randomly).
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fn init(&mut self, use_rsl: bool) {
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let mut a = 0x9e3779b9;
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let mut b = a;
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let mut c = a;
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let mut d = a;
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let mut e = a;
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let mut f = a;
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let mut g = a;
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let mut h = a;
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macro_rules! mix(
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() => {{
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a^=b<<11; d+=a; b+=c;
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b^=c>>2; e+=b; c+=d;
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c^=d<<8; f+=c; d+=e;
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d^=e>>16; g+=d; e+=f;
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e^=f<<10; h+=e; f+=g;
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f^=g>>4; a+=f; g+=h;
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g^=h<<8; b+=g; h+=a;
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h^=a>>9; c+=h; a+=b;
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}}
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);
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do 4.times { mix!(); }
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if use_rsl {
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macro_rules! memloop (
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($arr:expr) => {{
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for i in range_step(0u32, RAND_SIZE, 8) {
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a+=$arr[i ]; b+=$arr[i+1];
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c+=$arr[i+2]; d+=$arr[i+3];
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e+=$arr[i+4]; f+=$arr[i+5];
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g+=$arr[i+6]; h+=$arr[i+7];
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mix!();
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self.mem[i ]=a; self.mem[i+1]=b;
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self.mem[i+2]=c; self.mem[i+3]=d;
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self.mem[i+4]=e; self.mem[i+5]=f;
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self.mem[i+6]=g; self.mem[i+7]=h;
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}
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}}
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);
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memloop!(self.rsl);
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memloop!(self.mem);
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} else {
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for i in range_step(0u32, RAND_SIZE, 8) {
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mix!();
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self.mem[i ]=a; self.mem[i+1]=b;
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self.mem[i+2]=c; self.mem[i+3]=d;
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self.mem[i+4]=e; self.mem[i+5]=f;
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self.mem[i+6]=g; self.mem[i+7]=h;
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}
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}
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self.isaac();
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}
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/// Refills the output buffer (`self.rsl`)
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#[inline]
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fn isaac(&mut self) {
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self.c += 1;
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// abbreviations
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let mut a = self.a;
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let mut b = self.b + self.c;
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static MIDPOINT: uint = RAND_SIZE as uint / 2;
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macro_rules! ind (($x:expr) => {
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self.mem[($x >> 2) & (RAND_SIZE - 1)]
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});
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macro_rules! rngstep(
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($j:expr, $shift:expr) => {{
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let base = $j;
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let mix = if $shift < 0 {
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a >> -$shift as uint
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} else {
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a << $shift as uint
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};
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let x = self.mem[base + mr_offset];
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a = (a ^ mix) + self.mem[base + m2_offset];
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let y = ind!(x) + a + b;
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self.mem[base + mr_offset] = y;
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b = ind!(y >> RAND_SIZE_LEN) + x;
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self.rsl[base + mr_offset] = b;
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}}
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);
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let r = [(0, MIDPOINT), (MIDPOINT, 0)];
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for &(mr_offset, m2_offset) in r.iter() {
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for i in range_step(0u, MIDPOINT, 4) {
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rngstep!(i + 0, 13);
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rngstep!(i + 1, -6);
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rngstep!(i + 2, 2);
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rngstep!(i + 3, -16);
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}
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}
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self.a = a;
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self.b = b;
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self.cnt = RAND_SIZE;
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}
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}
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impl Rng for IsaacRng {
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#[inline]
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fn next(&mut self) -> u32 {
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if self.cnt == 0 {
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// make some more numbers
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self.isaac();
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}
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self.cnt -= 1;
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self.rsl[self.cnt]
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}
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}
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@ -58,7 +58,10 @@ use uint;
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use vec;
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use libc::size_t;
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pub use self::isaac::IsaacRng;
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pub mod distributions;
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pub mod isaac;
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/// A type that can be randomly generated using an Rng
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pub trait Rand {
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@ -576,184 +579,6 @@ pub fn weak_rng() -> XorShiftRng {
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XorShiftRng::new()
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}
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static RAND_SIZE_LEN: u32 = 8;
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static RAND_SIZE: u32 = 1 << RAND_SIZE_LEN;
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/// A random number generator that uses the [ISAAC
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/// algorithm](http://en.wikipedia.org/wiki/ISAAC_%28cipher%29).
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///
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/// The ISAAC algorithm is suitable for cryptographic purposes.
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pub struct IsaacRng {
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priv cnt: u32,
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priv rsl: [u32, .. RAND_SIZE],
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priv mem: [u32, .. RAND_SIZE],
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priv a: u32,
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priv b: u32,
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priv c: u32
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}
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impl IsaacRng {
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/// Create an ISAAC random number generator with a random seed.
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pub fn new() -> IsaacRng {
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IsaacRng::new_seeded(seed())
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}
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/// Create an ISAAC random number generator with a seed. This can be any
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/// length, although the maximum number of bytes used is 1024 and any more
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/// will be silently ignored. A generator constructed with a given seed
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/// will generate the same sequence of values as all other generators
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/// constructed with the same seed.
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pub fn new_seeded(seed: &[u8]) -> IsaacRng {
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let mut rng = IsaacRng {
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cnt: 0,
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rsl: [0, .. RAND_SIZE],
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mem: [0, .. RAND_SIZE],
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a: 0, b: 0, c: 0
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};
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let array_size = sys::size_of_val(&rng.rsl);
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let copy_length = cmp::min(array_size, seed.len());
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// manually create a &mut [u8] slice of randrsl to copy into.
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let dest = unsafe { cast::transmute((&mut rng.rsl, array_size)) };
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vec::bytes::copy_memory(dest, seed, copy_length);
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rng.init(true);
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rng
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}
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/// Create an ISAAC random number generator using the default
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/// fixed seed.
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pub fn new_unseeded() -> IsaacRng {
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let mut rng = IsaacRng {
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cnt: 0,
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rsl: [0, .. RAND_SIZE],
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mem: [0, .. RAND_SIZE],
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a: 0, b: 0, c: 0
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};
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rng.init(false);
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rng
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}
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/// Initialises `self`. If `use_rsl` is true, then use the current value
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/// of `rsl` as a seed, otherwise construct one algorithmically (not
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/// randomly).
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fn init(&mut self, use_rsl: bool) {
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let mut a = 0x9e3779b9;
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let mut b = a;
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let mut c = a;
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let mut d = a;
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let mut e = a;
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let mut f = a;
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let mut g = a;
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let mut h = a;
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macro_rules! mix(
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() => {{
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a^=b<<11; d+=a; b+=c;
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b^=c>>2; e+=b; c+=d;
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c^=d<<8; f+=c; d+=e;
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d^=e>>16; g+=d; e+=f;
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e^=f<<10; h+=e; f+=g;
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f^=g>>4; a+=f; g+=h;
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g^=h<<8; b+=g; h+=a;
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h^=a>>9; c+=h; a+=b;
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}}
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);
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do 4.times { mix!(); }
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if use_rsl {
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macro_rules! memloop (
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($arr:expr) => {{
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for i in range_step(0u32, RAND_SIZE, 8) {
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a+=$arr[i ]; b+=$arr[i+1];
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c+=$arr[i+2]; d+=$arr[i+3];
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e+=$arr[i+4]; f+=$arr[i+5];
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g+=$arr[i+6]; h+=$arr[i+7];
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mix!();
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self.mem[i ]=a; self.mem[i+1]=b;
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self.mem[i+2]=c; self.mem[i+3]=d;
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self.mem[i+4]=e; self.mem[i+5]=f;
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self.mem[i+6]=g; self.mem[i+7]=h;
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}
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}}
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);
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memloop!(self.rsl);
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memloop!(self.mem);
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} else {
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for i in range_step(0u32, RAND_SIZE, 8) {
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mix!();
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self.mem[i ]=a; self.mem[i+1]=b;
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self.mem[i+2]=c; self.mem[i+3]=d;
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self.mem[i+4]=e; self.mem[i+5]=f;
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self.mem[i+6]=g; self.mem[i+7]=h;
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}
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}
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self.isaac();
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}
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/// Refills the output buffer (`self.rsl`)
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#[inline]
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fn isaac(&mut self) {
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self.c += 1;
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// abbreviations
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let mut a = self.a;
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let mut b = self.b + self.c;
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static MIDPOINT: uint = RAND_SIZE as uint / 2;
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macro_rules! ind (($x:expr) => {
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self.mem[($x >> 2) & (RAND_SIZE - 1)]
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});
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macro_rules! rngstep(
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($j:expr, $shift:expr) => {{
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let base = $j;
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let mix = if $shift < 0 {
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a >> -$shift as uint
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} else {
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a << $shift as uint
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};
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let x = self.mem[base + mr_offset];
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a = (a ^ mix) + self.mem[base + m2_offset];
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let y = ind!(x) + a + b;
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self.mem[base + mr_offset] = y;
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b = ind!(y >> RAND_SIZE_LEN) + x;
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self.rsl[base + mr_offset] = b;
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}}
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);
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let r = [(0, MIDPOINT), (MIDPOINT, 0)];
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for &(mr_offset, m2_offset) in r.iter() {
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for i in range_step(0u, MIDPOINT, 4) {
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rngstep!(i + 0, 13);
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rngstep!(i + 1, -6);
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rngstep!(i + 2, 2);
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rngstep!(i + 3, -16);
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}
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}
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self.a = a;
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self.b = b;
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self.cnt = RAND_SIZE;
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}
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}
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impl Rng for IsaacRng {
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#[inline]
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fn next(&mut self) -> u32 {
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if self.cnt == 0 {
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// make some more numbers
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self.isaac();
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}
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self.cnt -= 1;
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self.rsl[self.cnt]
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}
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}
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/// An [Xorshift random number
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/// generator](http://en.wikipedia.org/wiki/Xorshift).
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///
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@ -786,7 +611,8 @@ impl XorShiftRng {
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pub fn new() -> XorShiftRng {
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#[fixed_stack_segment]; #[inline(never)];
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// generate seeds the same way as seed(), except we have a spceific size
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// generate seeds the same way as seed(), except we have a
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// specific size, so we can just use a fixed buffer.
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let mut s = [0u8, ..16];
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loop {
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do s.as_mut_buf |p, sz| {
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@ -817,12 +643,11 @@ impl XorShiftRng {
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}
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}
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/// Create a new random seed.
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pub fn seed() -> ~[u8] {
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/// Create a new random seed of length `n`.
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pub fn seed(n: uint) -> ~[u8] {
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#[fixed_stack_segment]; #[inline(never)];
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unsafe {
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let n = RAND_SIZE * 4;
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let mut s = vec::from_elem(n as uint, 0_u8);
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do s.as_mut_buf |p, sz| {
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rustrt::rand_gen_seed(p, sz as size_t)
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@ -844,7 +669,7 @@ pub fn task_rng() -> @mut IsaacRng {
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let r = local_data::get(tls_rng_state, |k| k.map(|&k| *k));
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match r {
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None => {
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let rng = @@mut IsaacRng::new_seeded(seed());
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let rng = @@mut IsaacRng::new();
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local_data::set(tls_rng_state, rng);
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*rng
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}
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@ -877,7 +702,7 @@ mod test {
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#[test]
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fn test_rng_seeded() {
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let seed = seed();
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let seed = seed(400);
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let mut ra = IsaacRng::new_seeded(seed);
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let mut rb = IsaacRng::new_seeded(seed);
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assert_eq!(ra.gen_ascii_str(100u), rb.gen_ascii_str(100u));
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