1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73

// Copyright (c) 2018 Colin Finck, RWTH Aachen University
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://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.

use crate::arch;
use crate::synch::spinlock::Spinlock;

static PARK_MILLER_LEHMER_SEED: Spinlock<u32> = Spinlock::new(0);
const RAND_MAX: u64 = 2_147_483_647;

fn generate_park_miller_lehmer_random_number() -> u32 {
	let mut seed = PARK_MILLER_LEHMER_SEED.lock();
	let random = ((u64::from(*seed) * 48271) % RAND_MAX) as u32;
	*seed = random;
	random
}

fn __sys_rand32() -> Option<u32> {
	arch::processor::generate_random_number32()
}

fn __sys_rand64() -> Option<u64> {
	arch::processor::generate_random_number64()
}

fn __sys_rand() -> u32 {
	generate_park_miller_lehmer_random_number()
}

/// Create a cryptographicly secure 32bit random number with the support of
/// the underlying hardware. If the required hardware isn't available,
/// the function returns `None`.
#[cfg(not(feature = "newlib"))]
#[no_mangle]
pub fn sys_secure_rand32() -> Option<u32> {
	kernel_function!(__sys_rand32())
}

/// Create a cryptographicly secure 64bit random number with the support of
/// the underlying hardware. If the required hardware isn't available,
/// the function returns `None`.
#[cfg(not(feature = "newlib"))]
#[no_mangle]
pub fn sys_secure_rand64() -> Option<u64> {
	kernel_function!(__sys_rand64())
}

/// The function computes a sequence of pseudo-random integers
/// in the range of 0 to RAND_MAX
#[no_mangle]
pub extern "C" fn sys_rand() -> u32 {
	kernel_function!(__sys_rand())
}

fn __sys_srand(seed: u32) {
	*(PARK_MILLER_LEHMER_SEED.lock()) = seed;
}

/// The function sets its argument as the seed for a new sequence
/// of pseudo-random numbers to be returned by rand()
#[no_mangle]
pub extern "C" fn sys_srand(seed: u32) {
	kernel_function!(__sys_srand(seed))
}

pub fn random_init() {
	let seed: u32 = arch::processor::get_timestamp() as u32;

	*PARK_MILLER_LEHMER_SEED.lock() = seed;
}