Initial commit: Create a simple volatile wrapper type

Author: phil-opp

.gitignore

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+target
+Cargo.lock

Cargo.toml

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+[package]
+name = "volatile"
+version = "0.1.0"
+authors = ["Philipp Oppermann <[email protected]>"]
+license = "MIT OR Apache-2.0"
+keywords = ["volatile"]
+documentation = "https://docs.rs/volatile"
+repository = "https://github.com/phil-opp/volatile"
+
+[dependencies]

src/lib.rs

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+#![no_std]
+
+use core::ptr;
+
+#[derive(Debug)]
+pub struct Volatile<T: Copy>(T);
+
+impl<T: Copy> Volatile<T> {
+    pub fn read(&self) -> T {
+        unsafe { ptr::read_volatile(&self.0) }
+    }
+
+    pub fn write(&mut self, value: T) {
+        unsafe { ptr::write_volatile(&mut self.0, value) };
+    }
+
+    pub fn update<F>(&mut self, f: F)
+        where F: FnOnce(&mut T)
+    {
+        let mut value = self.read();
+        f(&mut value);
+        self.write(value);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Volatile;
+
+    #[test]
+    fn test_read() {
+        assert_eq!(Volatile(42).read(), 42);
+    }
+
+    #[test]
+    fn test_write() {
+        let mut volatile = Volatile(42);
+        volatile.write(50);
+        assert_eq!(volatile.0, 50);
+    }
+
+    #[test]
+    fn test_update() {
+        let mut volatile = Volatile(42);
+        volatile.update(|v| *v += 1);
+        assert_eq!(volatile.0, 43);
+    }
+}