From 37a0692a0fe5d9b41b65728d496b6856a1152dcc Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Sun, 4 Nov 2018 18:50:42 +0100
Subject: impl Mutex on all shared resources

document how to write generic code that operates on resources
---
 examples/generics.rs | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 examples/generics.rs

(limited to 'examples/generics.rs')

diff --git a/examples/generics.rs b/examples/generics.rs
new file mode 100644
index 0000000..aee7061
--- /dev/null
+++ b/examples/generics.rs
@@ -0,0 +1,74 @@
+//! examples/generics.rs
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+extern crate panic_semihosting;
+
+use cortex_m_semihosting::debug;
+use lm3s6965::Interrupt;
+use rtfm::{app, Mutex};
+
+// NOTE: This convenience macro will appear in all the other examples and
+// will always look the same
+macro_rules! println {
+    ($($tt:tt)*) => {
+        if let Ok(mut stdout) = cortex_m_semihosting::hio::hstdout() {
+            use core::fmt::Write;
+
+            writeln!(stdout, $($tt)*).ok();
+        }
+    };
+}
+
+#[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;
+
+        println!("UART0(STATE = {})", *STATE);
+
+        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;
+
+        println!("UART1(STATE = {})", *STATE);
+
+        // 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)
+    });
+
+    println!("SHARED: {} -> {}", old, new);
+}
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