1 files changed, 73 insertions, 0 deletions
diff --git a/src/exception.rs b/src/exception.rs
index 7046080..fad3ea9 100644
--- a/src/exception.rs
+++ b/src/exception.rs
@@ -1,3 +1,7 @@
+//! Exceptions
+
+use {Handler, Reserved, StackFrame};
+
 /// Kind of exception
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum Exception {
@@ -41,7 +45,76 @@ impl Exception {
             15 => Exception::Systick,
             n if n >= 16 => Exception::Interrupt(n - 16),
             _ => Exception::Reserved,
+        }
+    }
+}
 
+/// Exception handlers
+#[repr(C)]
+pub struct Handlers {
+    /// Non-maskable interrupt
+    pub nmi: Handler,
+    /// All class of fault
+    pub hard_fault: Handler,
+    /// Memory management
+    pub mem_manage: Handler,
+    /// Pre-fetch fault, memory access fault
+    pub bus_fault: Handler,
+    /// Undefined instruction or illegal state
+    pub usage_fault: Handler,
+    /// Reserved spots in the vector table
+    pub _reserved0: [Reserved; 4],
+    /// System service call via SWI instruction
+    pub svcall: Handler,
+    /// Reserved spots in the vector table
+    pub _reserved1: [Reserved; 2],
+    /// Pendable request for system service
+    pub pendsv: Handler,
+    /// System tick timer
+    pub sys_tick: Handler,
+}
+
+/// Default exception handlers
+pub const DEFAULT_HANDLERS: Handlers = Handlers {
+    _reserved0: [Reserved::Vector; 4],
+    _reserved1: [Reserved::Vector; 2],
+    bus_fault: default_handler,
+    hard_fault: default_handler,
+    mem_manage: default_handler,
+    nmi: default_handler,
+    pendsv: default_handler,
+    svcall: default_handler,
+    sys_tick: default_handler,
+    usage_fault: default_handler,
+};
+
+/// The default exception handler
+///
+/// This handler triggers a breakpoint (`bkpt`) and gives you access, within a
+/// GDB session, to the stack frame (`_sf`) where the exception occurred.
+// This needs asm!, #[naked] and unreachable() to avoid modifying the stack
+// pointer (MSP), that way it points to the previous stack frame
+#[naked]
+pub unsafe extern "C" fn default_handler() {
+    // This is the actual exception handler. `_sf` is a pointer to the previous
+    // stack frame
+    extern "C" fn handler(_sf: &StackFrame) -> ! {
+        #[cfg(feature = "semihosting")]
+        hprintln!("EXCEPTION {:?} @ PC=0x{:08x}", Exception::current(), _sf.pc);
+
+        unsafe {
+            bkpt!();
         }
+
+        loop {}
     }
+
+    // "trampoline" to get to the real exception handler.
+    asm!("mrs r0, MSP
+          ldr r1, [r0, #20]
+          b $0"
+         :
+         : "i"(handler as extern "C" fn(&StackFrame) -> !) :: "volatile");
+
+    ::core::intrinsics::unreachable()
 }