| // 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 |
| } |
| } |