Add log on panic feature.

Author: pierre-rouanet

stm32f0_hal/Cargo.toml

@@ -24,7 +24,6 @@ cortex-m = "0.3.1"
 cortex-m-semihosting = "0.2.0"
 
 [dependencies.cortex-m-rt]
-features = ["abort-on-panic"]
 version = "=0.3.7"
 
 [dependencies.stm32f0x2]
@@ -34,6 +33,7 @@ path = "../stm32f0x2"
 [features]
 default = []
 use_alloc = ["alloc-cortex-m"]
+serial_panic = []
 
 [dependencies.alloc-cortex-m]
 git = "https://github.com/pollen-robotics/alloc-cortex-m"

stm32f0_hal/examples/panic.rs

@@ -0,0 +1,15 @@
+#![no_std]
+
+extern crate cortex_m;
+extern crate stm32f0_hal as hal;
+
+use hal::{rcc, uart};
+
+fn main() {
+    rcc::init();
+
+    unsafe {
+        hal::panic::log_on_serial(uart::Uarts::Uart4);
+    }
+    panic!("This will be sent on TX before abort!");
+}

stm32f0_hal/src/lib.rs

@@ -8,15 +8,18 @@
 //! * RCC
 
 #![no_std]
+#![feature(lang_items)]
+#![feature(core_intrinsics)]
 #![cfg_attr(feature = "use_alloc", feature(global_allocator))]
 
 extern crate cortex_m;
 #[macro_use(exception)]
 extern crate cortex_m_rt;
 extern crate stm32f0x2;
 
-pub mod gpio;
 pub mod adc;
+pub mod gpio;
+pub mod panic;
 pub mod pwm;
 pub mod rcc;
 pub mod uart;

stm32f0_hal/src/panic.rs

@@ -0,0 +1,60 @@
+#[cfg(feature = "serial_panic")]
+use core::fmt::Write;
+
+#[lang = "panic_fmt"]
+#[allow(unused_variables)]
+#[no_mangle]
+pub unsafe extern "C" fn panic_fmt(
+    msg: ::core::fmt::Arguments,
+    file: &'static str,
+    line: u32,
+    column: u32,
+) -> ! {
+    #[cfg(feature = "serial_panic")]
+    {
+        if let Some(ref mut log) = serial_panic::LOG {
+            writeln!(
+                log,
+                "*** PANIC *** 'main' panicked at '{}', {}:{}:{}",
+                msg, file, line, column
+            ).unwrap();
+        }
+    }
+
+    ::core::intrinsics::abort()
+}
+
+#[cfg(feature = "serial_panic")]
+mod serial_panic {
+    use core::fmt::{Error, Write};
+
+    use uart;
+
+    /// Setup a serial TX where the panic will be sent
+    pub unsafe fn log_on_serial(uart: uart::Uarts) {
+        let uart = uart::Uart::setup(
+            uart,
+            57_600,
+            uart::NBits::_8bits,
+            uart::StopBits::_1b,
+            uart::Parity::None,
+        );
+        LOG = Some(SerialLog(uart));
+    }
+
+    pub(crate) static mut LOG: Option<SerialLog> = None;
+
+    pub(crate) struct SerialLog(uart::Uart);
+    impl Write for SerialLog {
+        fn write_str(&mut self, s: &str) -> Result<(), Error> {
+            for &b in s.as_bytes() {
+                while !self.0.transmit_complete() {}
+                self.0.send(b);
+            }
+
+            Ok(())
+        }
+    }
+}
+#[cfg(feature = "serial_panic")]
+pub use self::serial_panic::log_on_serial;