zx/
counter.rs

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1// Copyright 2025 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//! Type-safe bindings for Zircon cuonter objects.
6
7use crate::{ok, sys, AsHandleRef, Handle, HandleBased, HandleRef, Status};
8
9/// An object representing a Zircon
10/// [counter](https://fuchsia.dev/fuchsia-src/concepts/objects/counter.md).
11///
12/// As essentially a subtype of `Handle`, it can be freely interconverted.
13#[derive(Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
14#[repr(transparent)]
15pub struct Counter(Handle);
16impl_handle_based!(Counter);
17
18impl Counter {
19    pub fn create() -> Result<Counter, Status> {
20        let options = 0;
21        let mut handle = 0;
22        let status = unsafe { sys::zx_counter_create(options, &mut handle) };
23        ok(status)?;
24        unsafe { Ok(Counter::from(Handle::from_raw(handle))) }
25    }
26
27    pub fn add(&self, value: i64) -> Result<(), Status> {
28        let status = unsafe { sys::zx_counter_add(self.raw_handle(), value) };
29        ok(status)
30    }
31
32    pub fn read(&self) -> Result<i64, Status> {
33        let mut value = 0;
34        let status = unsafe { sys::zx_counter_read(self.raw_handle(), &mut value) };
35        ok(status).map(|()| value)
36    }
37
38    pub fn write(&self, value: i64) -> Result<(), Status> {
39        let status = unsafe { sys::zx_counter_write(self.raw_handle(), value) };
40        ok(status)
41    }
42}
43
44// These tests are intended to verify the Rust bindings rather the counter
45// Zircon object.  The tests for the Zircon object are part of the core-tests
46// suite.
47#[cfg(test)]
48mod tests {
49    use super::*;
50
51    #[test]
52    fn counter_create() {
53        let counter = Counter::create().unwrap();
54        assert_eq!(counter.read().unwrap(), 0);
55    }
56
57    #[test]
58    fn counter_add() {
59        let counter = Counter::create().unwrap();
60        assert_eq!(counter.read().unwrap(), 0);
61        assert!(counter.add(i64::max_value()).is_ok());
62        assert_eq!(counter.read().unwrap(), i64::max_value());
63        assert_eq!(counter.add(1), Err(Status::OUT_OF_RANGE));
64    }
65
66    #[test]
67    fn counter_read_write() {
68        let counter = Counter::create().unwrap();
69        assert_eq!(counter.read().unwrap(), 0);
70        assert!(counter.write(i64::min_value()).is_ok());
71        assert_eq!(counter.read().unwrap(), i64::min_value());
72    }
73}
zx/counter.rs

zx/
counter.rs
