axlibc/
rand.rs

1//! Random number generator.
2
3use core::{
4    ffi::{c_int, c_long, c_uint},
5    sync::atomic::{AtomicU64, Ordering::SeqCst},
6};
7
8static SEED: AtomicU64 = AtomicU64::new(0xa2ce_a2ce);
9
10/// Sets the seed for the random number generator.
11#[unsafe(no_mangle)]
12pub unsafe extern "C" fn srand(seed: c_uint) {
13    SEED.store(seed.wrapping_sub(1) as u64, SeqCst);
14}
15
16/// Returns a 32-bit unsigned pseudo random interger.
17#[unsafe(no_mangle)]
18pub unsafe extern "C" fn rand() -> c_int {
19    let new_seed = SEED.load(SeqCst).wrapping_mul(6364136223846793005) + 1;
20    SEED.store(new_seed, SeqCst);
21    (new_seed >> 33) as c_int
22}
23
24/// Returns a 64-bit unsigned pseudo random number.
25#[unsafe(no_mangle)]
26pub unsafe extern "C" fn random() -> c_long {
27    let new_seed = SEED.load(SeqCst).wrapping_mul(6364136223846793005) + 1;
28    SEED.store(new_seed, SeqCst);
29    new_seed as c_long
30}
axlibc/rand.rs

axlibc/
rand.rs
