33 lines
1.4 KiB
Zig
33 lines
1.4 KiB
Zig
//! Wall-clock time: the CMOS real-time clock read once at boot and anchored to the
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//! monotonic clock, so a query is a cheap arithmetic offset — no per-call CMOS poll,
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//! no lock, no SMP hazard on the shared 0x70/0x71 ports.
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//!
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//! Wall-clock *seconds* are mechanism the kernel owns, exactly like the monotonic
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//! clock ([[time-architecture]]): reading the hardware's value is not policy.
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//! Calendars, timezones, and formatting layer on top in user space. It exists so the
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//! filesystem can stamp real timestamps (mtime) — see docs/zig-self-hosting.md.
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const architecture = @import("architecture");
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var boot_unix_seconds: u64 = 0;
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var boot_nanos: u64 = 0;
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/// Read the RTC once and anchor it to the monotonic clock. Call at boot, after the
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/// monotonic clock is calibrated.
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pub fn init() void {
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boot_unix_seconds = architecture.readRtcUnixSeconds();
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boot_nanos = architecture.nanos();
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}
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/// The current wall-clock time in Unix epoch seconds (UTC): the boot RTC value plus
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/// the monotonic time elapsed since. Zero until `init` runs.
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pub fn nowSeconds() u64 {
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return boot_unix_seconds + (architecture.nanos() -% boot_nanos) / 1_000_000_000;
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}
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/// The wall-clock time of boot itself (the RTC anchor) — what klog_status hands
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/// the logger service to name a per-boot log directory. Zero until `init` runs.
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pub fn bootSeconds() u64 {
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return boot_unix_seconds;
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}
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