Commit 67af78d0 authored by Alex Lyon's avatar Alex Lyon

stdlib: make rand()/rand_r() generate from [0, RAND_MAX]

parent 13a10ce7
Pipeline #3946 failed with stages
in 6 minutes and 49 seconds
//! stdlib implementation for Redox, following http://pubs.opengroup.org/onlinepubs/7908799/xsh/stdlib.h.html
use core::{intrinsics, iter, mem, ptr, slice};
use rand::distributions::Alphanumeric;
use rand::distributions::{Alphanumeric, Distribution, Uniform};
use rand::prng::XorShiftRng;
use rand::rngs::JitterRng;
use rand::{Rng, SeedableRng};
......@@ -34,6 +34,10 @@ pub const MB_LEN_MAX: c_int = 4;
static mut ATEXIT_FUNCS: [Option<extern "C" fn()>; 32] = [None; 32];
static mut RNG: Option<XorShiftRng> = None;
lazy_static! {
static ref RNG_SAMPLER: Uniform<c_int> = Uniform::new_inclusive(0, RAND_MAX);
}
#[no_mangle]
pub extern "C" fn _Exit(status: c_int) {
unistd::_exit(status);
......@@ -618,10 +622,10 @@ pub extern "C" fn qsort(
#[no_mangle]
pub unsafe extern "C" fn rand() -> c_int {
match RNG {
Some(ref mut rng) => rng.gen_range(0, RAND_MAX),
Some(ref mut rng) => RNG_SAMPLER.sample(rng),
None => {
let mut rng = XorShiftRng::from_seed([1; 16]);
let ret = rng.gen_range(0, RAND_MAX);
let ret = RNG_SAMPLER.sample(&mut rng);
RNG = Some(rng);
ret
}
......@@ -637,7 +641,7 @@ pub unsafe extern "C" fn rand_r(seed: *mut c_uint) -> c_int {
let seed_arr: [u8; 16] = mem::transmute([*seed; 16 / mem::size_of::<c_uint>()]);
let mut rng = XorShiftRng::from_seed(seed_arr);
let ret = rng.gen_range(0, RAND_MAX);
let ret = RNG_SAMPLER.sample(&mut rng);
*seed = ret as _;
......
......@@ -3,6 +3,6 @@
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