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std::rand: move the Isaac implementation to its own file.

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This commit is contained in:
Huon Wilson 2013-09-21 21:32:57 +10:00
parent 3a70df1d3c
commit 72bf201d61
2 changed files with 207 additions and 184 deletions
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198
src/libstd/rand/isaac.rs Normal file
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@ -0,0 +1,198 @@
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! The ISAAC random number generator.
use rand::{seed, Rng};
use iter::{Iterator, range, range_step};
use option::{None, Some};
use cast;
use cmp;
use sys;
use vec;
static RAND_SIZE_LEN: u32 = 8;
static RAND_SIZE: u32 = 1 << RAND_SIZE_LEN;
/// A random number generator that uses the [ISAAC
/// algorithm](http://en.wikipedia.org/wiki/ISAAC_%28cipher%29).
///
/// The ISAAC algorithm is suitable for cryptographic purposes.
pub struct IsaacRng {
priv cnt: u32,
priv rsl: [u32, .. RAND_SIZE],
priv mem: [u32, .. RAND_SIZE],
priv a: u32,
priv b: u32,
priv c: u32
}
impl IsaacRng {
/// Create an ISAAC random number generator with a random seed.
pub fn new() -> IsaacRng {
IsaacRng::new_seeded(seed(RAND_SIZE as uint * 4))
}
/// Create an ISAAC random number generator with a seed. This can be any
/// length, although the maximum number of bytes used is 1024 and any more
/// will be silently ignored. A generator constructed with a given seed
/// will generate the same sequence of values as all other generators
/// constructed with the same seed.
pub fn new_seeded(seed: &[u8]) -> IsaacRng {
let mut rng = IsaacRng {
cnt: 0,
rsl: [0, .. RAND_SIZE],
mem: [0, .. RAND_SIZE],
a: 0, b: 0, c: 0
};
let array_size = sys::size_of_val(&rng.rsl);
let copy_length = cmp::min(array_size, seed.len());
// manually create a &mut [u8] slice of randrsl to copy into.
let dest = unsafe { cast::transmute((&mut rng.rsl, array_size)) };
vec::bytes::copy_memory(dest, seed, copy_length);
rng.init(true);
rng
}
/// Create an ISAAC random number generator using the default
/// fixed seed.
pub fn new_unseeded() -> IsaacRng {
let mut rng = IsaacRng {
cnt: 0,
rsl: [0, .. RAND_SIZE],
mem: [0, .. RAND_SIZE],
a: 0, b: 0, c: 0
};
rng.init(false);
rng
}
/// Initialises `self`. If `use_rsl` is true, then use the current value
/// of `rsl` as a seed, otherwise construct one algorithmically (not
/// randomly).
fn init(&mut self, use_rsl: bool) {
let mut a = 0x9e3779b9;
let mut b = a;
let mut c = a;
let mut d = a;
let mut e = a;
let mut f = a;
let mut g = a;
let mut h = a;
macro_rules! mix(
() => {{
a^=b<<11; d+=a; b+=c;
b^=c>>2; e+=b; c+=d;
c^=d<<8; f+=c; d+=e;
d^=e>>16; g+=d; e+=f;
e^=f<<10; h+=e; f+=g;
f^=g>>4; a+=f; g+=h;
g^=h<<8; b+=g; h+=a;
h^=a>>9; c+=h; a+=b;
}}
);
do 4.times { mix!(); }
if use_rsl {
macro_rules! memloop (
($arr:expr) => {{
for i in range_step(0u32, RAND_SIZE, 8) {
a+=$arr[i ]; b+=$arr[i+1];
c+=$arr[i+2]; d+=$arr[i+3];
e+=$arr[i+4]; f+=$arr[i+5];
g+=$arr[i+6]; h+=$arr[i+7];
mix!();
self.mem[i ]=a; self.mem[i+1]=b;
self.mem[i+2]=c; self.mem[i+3]=d;
self.mem[i+4]=e; self.mem[i+5]=f;
self.mem[i+6]=g; self.mem[i+7]=h;
}
}}
);
memloop!(self.rsl);
memloop!(self.mem);
} else {
for i in range_step(0u32, RAND_SIZE, 8) {
mix!();
self.mem[i ]=a; self.mem[i+1]=b;
self.mem[i+2]=c; self.mem[i+3]=d;
self.mem[i+4]=e; self.mem[i+5]=f;
self.mem[i+6]=g; self.mem[i+7]=h;
}
}
self.isaac();
}
/// Refills the output buffer (`self.rsl`)
#[inline]
fn isaac(&mut self) {
self.c += 1;
// abbreviations
let mut a = self.a;
let mut b = self.b + self.c;
static MIDPOINT: uint = RAND_SIZE as uint / 2;
macro_rules! ind (($x:expr) => {
self.mem[($x >> 2) & (RAND_SIZE - 1)]
});
macro_rules! rngstep(
($j:expr, $shift:expr) => {{
let base = $j;
let mix = if $shift < 0 {
a >> -$shift as uint
} else {
a << $shift as uint
};
let x = self.mem[base + mr_offset];
a = (a ^ mix) + self.mem[base + m2_offset];
let y = ind!(x) + a + b;
self.mem[base + mr_offset] = y;
b = ind!(y >> RAND_SIZE_LEN) + x;
self.rsl[base + mr_offset] = b;
}}
);
let r = [(0, MIDPOINT), (MIDPOINT, 0)];
for &(mr_offset, m2_offset) in r.iter() {
for i in range_step(0u, MIDPOINT, 4) {
rngstep!(i + 0, 13);
rngstep!(i + 1, -6);
rngstep!(i + 2, 2);
rngstep!(i + 3, -16);
}
}
self.a = a;
self.b = b;
self.cnt = RAND_SIZE;
}
}
impl Rng for IsaacRng {
#[inline]
fn next(&mut self) -> u32 {
if self.cnt == 0 {
// make some more numbers
self.isaac();
}
self.cnt -= 1;
self.rsl[self.cnt]
}
}

193
src/libstd/rand/mod.rs
View file

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