Skip to content

Latest commit

 

History

History
35 lines (24 loc) · 1.14 KB

README.md

File metadata and controls

35 lines (24 loc) · 1.14 KB
Raw

SW interrupt

Description

This example tests out the use of CPU exceptions. In particular, this example uses the following piece of code to throw a SW interrupt exception.

    .
    .
    .

	svc 0 ;@ Throw a SW interrupt exceptions.

hang:
	b hang

If implemented correctly, the CPU should then fetch the address of the corresponding handler from the IVT (interrupt vector table) and call it. The following snipped of code is the actual handler of a SW interrupt exception.

extern "C" void __attribute__((interrupt("SWI"))) software_interrupt_handler()
{
   int count = 0;
   for (int i = 0; i < 10; ++i)
       count++;
}

In this example, the handler does not do anything useful - it contains a piece of dummy code.

Demo

The proper call of a SW exception can be tested by setting a breakpoint at the address of the svc instruction. Once the code execution stops at this instruction, we can step through the code twice to jump into the exception handler - the first step retrieves the address from the IVT, and the second step performs the jump itself.