Mechanism for setting exception handlers #127

New issue

Closed

opened 2021-02-13 17:35:57 -06:00 by davidgiven · 3 comments

davidgiven commented

2021-02-13 17:35:57 -06:00

(Migrated from github.com)

I could be wrong, but there doesn't appear to be any way of setting exception handlers from code other than to create specially-named functions such as isr_svcall, which the documentation suggestsnot to do.

The implementation numbers interrupts/exceptions from 0 for IRQ0. As these appear immediately after the vector table, it ought to be possible to use negative numbers to refer to the exceptions --- these are actually documented in the ARM documentation at https://developer.arm.com/documentation/dui0497/a/the-cortex-m0-processor/exception-model/exception-types, so SVCall is interrupt -5. However, calling irq_set_exclusive_handler() doesn't work because you can only use it on vectors which are already pointing at __unhandled_user_irq.

Given how clean the rest of the SDK's design is, it'd be nice to have a blessed-by-the-API way of doing this.

I could be wrong, but there doesn't appear to be any way of setting exception handlers from code other than to create specially-named functions such as `isr_svcall`, which the documentation suggestsnot to do. The implementation numbers interrupts/exceptions from 0 for IRQ0. As these appear immediately after the vector table, it ought to be possible to use negative numbers to refer to the exceptions --- these are actually documented in the ARM documentation at https://developer.arm.com/documentation/dui0497/a/the-cortex-m0-processor/exception-model/exception-types, so `SVCall` is interrupt -5. However, calling `irq_set_exclusive_handler()` doesn't work because you can only use it on vectors which are already pointing at `__unhandled_user_irq`. Given how clean the rest of the SDK's design is, it'd be nice to have a blessed-by-the-API way of doing this.

Rows
Columns