add macros for writing to an ITM port

3 files changed, 64 insertions, 0 deletions

diff --git a/src/itm.rs b/src/itm.rs
new file mode 100644
index 0000000..6022bbe
--- /dev/null
+++ b/src/itm.rs
@@ -0,0 +1,38 @@
+//! Instrumentation Trace Macrocell
+
+use core::fmt;
+
+struct Itm {
+    port: u8,
+}
+
+impl Itm {
+    fn write_all(&self, buffer: &[u8]) {
+        let stim =
+            unsafe { &(*::peripheral::ITM.get()).stim[self.port as usize] };
+
+        for byte in buffer {
+            while !stim.is_fifo_ready() {}
+            stim.write_u8(*byte);
+        }
+    }
+}
+
+impl fmt::Write for Itm {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_all(s.as_bytes());
+        Ok(())
+    }
+}
+
+/// Writes `fmt::Arguments` to the ITM `port`
+pub fn write_fmt(port: u8, args: fmt::Arguments) {
+    use core::fmt::Write;
+
+    Itm { port }.write_fmt(args).ok();
+}
+
+/// Writes a string to the ITM `port`
+pub fn write_str(port: u8, string: &str) {
+    Itm { port }.write_all(string.as_bytes())
+}
diff --git a/src/lib.rs b/src/lib.rs
index 59428ba..9bdd74c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -29,6 +29,7 @@ pub mod asm;
 pub mod ctxt;
 pub mod exception;
 pub mod interrupt;
+pub mod itm;
 pub mod peripheral;
 pub mod register;
 
diff --git a/src/macros.rs b/src/macros.rs
index bd31167..1c39f18 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -27,3 +27,28 @@ macro_rules! hprintln {
     ($fmt:expr) => (hprint!(concat!($fmt, "\n")));
     ($fmt:expr, $($arg:tt)*) => (hprint!(concat!($fmt, "\n"), $($arg)*));
 }
+
+/// Macro for sending a formatted string through an ITM channel
+#[macro_export]
+macro_rules! iprint {
+    ($channel:expr, $s:expr) => {
+        $crate::itm::write_str($channel, $s);
+    };
+    ($channel:expr, $($arg:tt)*) => {
+        $crate::itm::write_fmt($channel, format_args!($($arg)*));
+    };
+}
+
+/// Macro for sending a formatted string through an ITM channel, with a newline.
+#[macro_export]
+macro_rules! iprintln {
+    ($channel:expr) => {
+        iprint!($channel, "\n");
+    };
+    ($channel:expr, $fmt:expr) => {
+        iprint!($channel, concat!($fmt, "\n"));
+    };
+    ($channel:expr, $fmt:expr, $($arg:tt)*) => {
+        iprint!($channel, concat!($fmt, "\n"), $($arg)*);
+    };
+}