The anatomy of an SVC call into a Softdevice.

RE: The anatomy of an SVC call into a Softdevice.

Lightfoot — Wed, 22 Aug 2018 09:23:29 GMT

Thank you Einar.

RE: The anatomy of an SVC call into a Softdevice.

Einar Thorsrud — Wed, 22 Aug 2018 08:48:01 GMT

Hi,

The pointers are passed in R0 - R3. There is a brief description in the Application Programming Interface (API) chapter in the SoftDevice specification but I recommend you refer to the ARM's documentation about SVC calls for details, for example here.

RE: The anatomy of an SVC call into a Softdevice.

Lightfoot — Tue, 21 Aug 2018 17:54:37 GMT

Thank you Elias. I appreciate that data pointers and function pointers are passed to the SVC handler in the SoftDevice. I want to know where those pointers should be located at the point when the SVC instruction is executed.

RE: The anatomy of an SVC call into a Softdevice.

Elias — Tue, 21 Aug 2018 17:37:39 GMT

Is this about using the SoftDevice API, or just for your own knowledge on how such an architecture is implemented?

If this is just about use, check out the Nordic examples.

If this is about knowledge, remember that all C functions are just pointers. This line, for example, compiles fine:
((bool (*)(int))0x1234)(56);
It says to execute whatever code is at address 0x1234 on the machine, passing 56 as an int and getting a bool return.