From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 library/std/src/sys/itron/mutex.rs | 93 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 library/std/src/sys/itron/mutex.rs

(limited to 'library/std/src/sys/itron/mutex.rs')

diff --git a/library/std/src/sys/itron/mutex.rs b/library/std/src/sys/itron/mutex.rs
new file mode 100644
index 000000000..715e94c3b
--- /dev/null
+++ b/library/std/src/sys/itron/mutex.rs
@@ -0,0 +1,93 @@
+//! Mutex implementation backed by μITRON mutexes. Assumes `acre_mtx` and
+//! `TA_INHERIT` are available.
+use super::{
+    abi,
+    error::{expect_success, expect_success_aborting, fail, ItronError},
+    spin::SpinIdOnceCell,
+};
+
+pub struct Mutex {
+    /// The ID of the underlying mutex object
+    mtx: SpinIdOnceCell<()>,
+}
+
+pub type MovableMutex = Mutex;
+
+/// Create a mutex object. This function never panics.
+fn new_mtx() -> Result<abi::ID, ItronError> {
+    ItronError::err_if_negative(unsafe {
+        abi::acre_mtx(&abi::T_CMTX {
+            // Priority inheritance mutex
+            mtxatr: abi::TA_INHERIT,
+            // Unused
+            ceilpri: 0,
+        })
+    })
+}
+
+impl Mutex {
+    #[inline]
+    pub const fn new() -> Mutex {
+        Mutex { mtx: SpinIdOnceCell::new() }
+    }
+
+    pub unsafe fn init(&mut self) {
+        // Initialize `self.mtx` eagerly
+        let id = new_mtx().unwrap_or_else(|e| fail(e, &"acre_mtx"));
+        unsafe { self.mtx.set_unchecked((id, ())) };
+    }
+
+    /// Get the inner mutex's ID, which is lazily created.
+    fn raw(&self) -> abi::ID {
+        match self.mtx.get_or_try_init(|| new_mtx().map(|id| (id, ()))) {
+            Ok((id, ())) => id,
+            Err(e) => fail(e, &"acre_mtx"),
+        }
+    }
+
+    pub unsafe fn lock(&self) {
+        let mtx = self.raw();
+        expect_success(unsafe { abi::loc_mtx(mtx) }, &"loc_mtx");
+    }
+
+    pub unsafe fn unlock(&self) {
+        let mtx = unsafe { self.mtx.get_unchecked().0 };
+        expect_success_aborting(unsafe { abi::unl_mtx(mtx) }, &"unl_mtx");
+    }
+
+    pub unsafe fn try_lock(&self) -> bool {
+        let mtx = self.raw();
+        match unsafe { abi::ploc_mtx(mtx) } {
+            abi::E_TMOUT => false,
+            er => {
+                expect_success(er, &"ploc_mtx");
+                true
+            }
+        }
+    }
+}
+
+impl Drop for Mutex {
+    fn drop(&mut self) {
+        if let Some(mtx) = self.mtx.get().map(|x| x.0) {
+            expect_success_aborting(unsafe { abi::del_mtx(mtx) }, &"del_mtx");
+        }
+    }
+}
+
+pub(super) struct MutexGuard<'a>(&'a Mutex);
+
+impl<'a> MutexGuard<'a> {
+    #[inline]
+    pub(super) fn lock(x: &'a Mutex) -> Self {
+        unsafe { x.lock() };
+        Self(x)
+    }
+}
+
+impl Drop for MutexGuard<'_> {
+    #[inline]
+    fn drop(&mut self) {
+        unsafe { self.0.unlock() };
+    }
+}
-- 
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