Feature request: #define offsets

[mkahane]

The struct methodology works well for memory mapped registers, however sometimes FPGA registers are not memory mapped to a processor and can only be accessed via indirect addressing.

In this case it would be useful to have #defines with absolute/relative offsets of the registers instead of packed structs.

[amykyta3]

Offset define macros scale pretty poorly since they implicitly assume a flat structure.

In a past tool you may be familiar with, the other option would be to emit defines at each hierarchy, and describe array stride and dimensions. This technically works, but gets incredibly verbose and error-prone.

What about using offsetof() provided by stddef.h?: https://en.cppreference.com/w/c/types/offsetof

offsetof(my_struct_t, foo.bar[3][4].register)`

That lets you reference "addresses" by name, and even in loops if inside an array.

[ahogen]

@amykyta3 What about using offsetof() provided by stddef.h?: https://en.cppreference.com/w/c/types/offsetof

Careful...

If offsetof is applied to a bit-field member, the behavior is undefined, because the address of a bit-field cannot be taken.

[0] https://en.cppreference.com/w/c/types/offsetof

[amykyta3]

Sorry I did not mean to suggest you use it on bit-field members. Use offsetof() to calculate the address offset of a register, or other intermediate nodes as necessary, but not bit fields for exactly the reason you pointed out.