rust/k210-shared: More helpful panic handler

Try sending the panic message to UARTHS.

rust/accelerometer/Cargo.toml

@@ -5,7 +5,6 @@ authors = ["W.J. van der Laan <laanwj@protonmail.com>"]
 edition = "2018"
 
 [dependencies]
-panic-halt = "0.2.0"
 riscv-rt = "0.5.0"
 k210-hal = "0.1.0"
 riscv = "0.5"

rust/accelerometer/src/main.rs

@@ -4,8 +4,6 @@
 #![no_std]
 #![no_main]
 
-extern crate panic_halt;
-
 use k210_hal::pac;
 use k210_hal::prelude::*;
 use k210_hal::stdout::Stdout;

rust/game-of-life/Cargo.toml

@@ -5,7 +5,6 @@ authors = ["W.J. van der Laan <laanwj@protonmail.com>"]
 edition = "2018"
 
 [dependencies]
-panic-halt = "0.2.0"
 riscv-rt = "0.5.0"
 k210-hal = "0.1.0"
 riscv = "0.5"

rust/game-of-life/src/main.rs

@@ -4,8 +4,6 @@
 #![no_std]
 #![no_main]
 
-extern crate panic_halt;
-
 use k210_hal::pac;
 use k210_hal::prelude::*;
 use k210_hal::stdout::Stdout;

rust/k210-console/Cargo.toml

@@ -5,7 +5,6 @@ authors = ["W.J. van der Laan <laanwj@protonmail.com>"]
 edition = "2018"
 
 [dependencies]
-panic-halt = "0.2.0"
 riscv-rt = "0.5.0"
 k210-hal = "0.1.0"
 riscv = "0.5"

rust/k210-console/src/main.rs

@@ -4,8 +4,6 @@
 #![no_std]
 #![no_main]
 
-extern crate panic_halt;
-
 mod console;
 mod cp437;
 mod cp437_8x8;

rust/k210-shared/src/lib.rs

@@ -4,5 +4,6 @@
 #![no_std]
 
 pub mod board;
+pub mod panic;
 pub mod soc;
 mod util;

rust/k210-shared/src/panic.rs

@@ -0,0 +1,25 @@
+/** Panic handler: based on ARM panic-itm */
+use k210_hal::pac;
+use k210_hal::prelude::*;
+use k210_hal::stdout::Stdout;
+use core::panic::PanicInfo;
+use core::sync::atomic::{self, Ordering};
+
+/** Send panic messages to UARTHS at 115200 baud */
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    // Stealing all peripherals, re-initializing the clocks and serial seems overkill here, but
+    // also, can we really know the state?
+    let p = unsafe { pac::Peripherals::steal() };
+    let clocks = k210_hal::clock::Clocks::new();
+    let serial = p.UARTHS.constrain(115_200.bps(), &clocks);
+    let (mut tx, _) = serial.split();
+    let mut stdout = Stdout(&mut tx);
+    writeln!(stdout, "{}", info).unwrap();
+
+    loop {
+        // add some side effect to prevent this from turning into a UDF instruction
+        // see rust-lang/rust#28728 for details
+        atomic::compiler_fence(Ordering::SeqCst)
+    }
+}

rust/mandelbrot/Cargo.toml

@@ -5,7 +5,6 @@ authors = ["W.J. van der Laan <laanwj@protonmail.com>"]
 edition = "2018"
 
 [dependencies]
-panic-halt = "0.2.0"
 riscv-rt = "0.5.0"
 k210-hal = "0.1.0"
 riscv = "0.5"

rust/mandelbrot/src/main.rs

@@ -4,8 +4,6 @@
 #![no_std]
 #![no_main]
 
-extern crate panic_halt;
-
 mod palette;
 
 use k210_hal::pac;