28 lines
768 B
Zig
28 lines
768 B
Zig
const std = @import("index.zig");
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const builtin = @import("builtin");
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const AtomicOrder = builtin.AtomicOrder;
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const AtomicRmwOp = builtin.AtomicRmwOp;
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const assert = std.debug.assert;
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/// TODO use syscalls instead of a spinlock
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pub const Mutex = struct {
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lock: u8, // TODO use a bool
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pub const Held = struct {
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mutex: *Mutex,
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pub fn release(self: Held) void {
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assert(@atomicRmw(u8, &self.mutex.lock, builtin.AtomicRmwOp.Xchg, 0, AtomicOrder.SeqCst) == 1);
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}
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};
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pub fn init() Mutex {
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return Mutex{ .lock = 0 };
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}
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pub fn acquire(self: *Mutex) Held {
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while (@atomicRmw(u8, &self.lock, builtin.AtomicRmwOp.Xchg, 1, AtomicOrder.SeqCst) != 0) {}
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return Held{ .mutex = self };
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}
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};
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