Merge #99

99: impl Mutex on all shared resources r=japaric a=japaric

document how to write generic code that operates on resources

Co-authored-by: Jorge Aparicio <jorge@japaric.io>

1 files changed, 62 insertions, 0 deletions

diff --git a/examples/generics.rs b/examples/generics.rs
new file mode 100644
index 0000000..c8ce839
--- /dev/null
+++ b/examples/generics.rs
@@ -0,0 +1,62 @@
+//! examples/generics.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::{debug, hprintln};
+use lm3s6965::Interrupt;
+use rtfm::{app, Mutex};
+
+#[app(device = lm3s6965)]
+const APP: () = {
+    static mut SHARED: u32 = 0;
+
+    #[init]
+    fn init() {
+        rtfm::pend(Interrupt::UART0);
+        rtfm::pend(Interrupt::UART1);
+    }
+
+    #[interrupt(resources = [SHARED])]
+    fn UART0() {
+        static mut STATE: u32 = 0;
+
+        hprintln!("UART0(STATE = {})", *STATE).unwrap();
+
+        advance(STATE, resources.SHARED);
+
+        rtfm::pend(Interrupt::UART1);
+
+        debug::exit(debug::EXIT_SUCCESS);
+    }
+
+    #[interrupt(priority = 2, resources = [SHARED])]
+    fn UART1() {
+        static mut STATE: u32 = 0;
+
+        hprintln!("UART1(STATE = {})", *STATE).unwrap();
+
+        // just to show that `SHARED` can be accessed directly and ..
+        *resources.SHARED += 0;
+        // .. also through a (no-op) `lock`
+        resources.SHARED.lock(|shared| *shared += 0);
+
+        advance(STATE, resources.SHARED);
+    }
+};
+
+fn advance(state: &mut u32, mut shared: impl Mutex<T = u32>) {
+    *state += 1;
+
+    let (old, new) = shared.lock(|shared| {
+        let old = *shared;
+        *shared += *state;
+        (old, *shared)
+    });
+
+    hprintln!("SHARED: {} -> {}", old, new).unwrap();
+}