use core::sync::atomic::{AtomicUsize, Ordering};
pub struct ClockSource {
pub name: &'static str,
pub frequency_hz: u64,
pub read_fn: fn() -> u64,
}
static CURRENT_FREQ: AtomicUsize = AtomicUsize::new(0);
static ACTIVE: crate::common::once::Once<ClockSource> = crate::common::once::Once::new();
pub fn register(cs: ClockSource) -> bool {
CURRENT_FREQ.store(cs.frequency_hz as usize, Ordering::Release);
ACTIVE.set(cs)
}
pub fn read_ticks() -> u64 {
if let Some(cs) = ACTIVE.get() {
(cs.read_fn)()
} else {
0
}
}
pub fn frequency() -> u64 {
CURRENT_FREQ.load(Ordering::Acquire) as u64
}
pub fn tsc_source() -> ClockSource {
ClockSource {
name: "tsc",
frequency_hz: 3_000_000_000,
read_fn: || {
if let Some((max_leaf, vendor_ebx, vendor_ecx, vendor_edx)) =
crate::arch::shim::cpuid_count(0, 0)
{
static TSC_VENDOR: core::sync::atomic::AtomicUsize =
core::sync::atomic::AtomicUsize::new(0);
TSC_VENDOR.store(
(max_leaf as usize)
^ (vendor_ebx as usize)
^ (vendor_ecx as usize)
^ (vendor_edx as usize),
core::sync::atomic::Ordering::Release,
);
let tsc = crate::arch::x86_64::cpu::tsc::read_tsc();
let lo = tsc as u32;
let hi = (tsc >> 32) as u32;
((hi as u64) << 32) | (lo as u64)
} else {
0
}
},
}
}