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// Copyright 2018 Developers of the Rand project.
// Copyright 2013-2015 The Rust Project Developers.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#[cfg(not(any(target_os = "macos", target_os = "ios", target_os = "windows")))]
pub fn get_nstime() -> u64 {
use std::time::{SystemTime, UNIX_EPOCH};
let dur = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
// The correct way to calculate the current time is
// `dur.as_secs() * 1_000_000_000 + dur.subsec_nanos() as u64`
// But this is faster, and the difference in terms of entropy is
// negligible (log2(10^9) == 29.9).
dur.as_secs() << 30 | dur.subsec_nanos() as u64
}
#[cfg(any(target_os = "macos", target_os = "ios"))]
pub fn get_nstime() -> u64 {
use libc;
// On Mac OS and iOS std::time::SystemTime only has 1000ns resolution.
// We use `mach_absolute_time` instead. This provides a CPU dependent
// unit, to get real nanoseconds the result should by multiplied by
// numer/denom from `mach_timebase_info`.
// But we are not interested in the exact nanoseconds, just entropy. So
// we use the raw result.
unsafe { libc::mach_absolute_time() }
}
#[cfg(target_os = "windows")]
pub fn get_nstime() -> u64 {
use winapi;
unsafe {
let mut t = super::mem::zeroed();
winapi::um::profileapi::QueryPerformanceCounter(&mut t);
*t.QuadPart() as u64
}
}
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