Compiler IRQ/FIQ-Optimization

[rsta2]

Compiler IRQ/FIQ-Optimization

[vanvught]

The attribute ((interrupt ("FIQ"))) or attribute ((interrupt ("IRQ"))) is used when your code is directly called from the CPU interrupt vector. The compiler generates the register saves/restores based on the interrupt type The same code as generated in https://github.com/rsta2/circle/blob/master/lib/exceptionstub.S with lines; 61,62 and 64 for IRQ. In line 63 there is the call to the C code. Hence the C code is omitting this compiler extension.
Moreover, using these kind of compiler extensions makes your code less portable. Hence your code might be restricted to use with specific compilers only.

[rsta2]

There are often different ways to implement such things. I prefer to use assembler code for hardware stubs like the IRQ and FIQ entry and exit code, because it's more flexible.

[MaPePeR]

Thanks for the response!