Re: [PATCH v6 0/9] rust: add `register!` macro

[Dirk Behme]

Hi Alexandre,

On 16.02.26 09:04, Alexandre Courbot wrote:
> This new revision took some time because it is (yet another) overhaul.
> ^_^;
> 
> Thanks to a breakthrough by Gary, we found a way to have the I/O type
> perform the actual I/O instead of the register type, which moves us from
> this access pattern:
> 
>     let boot0 = regs::NV_PMC_BOOT_0::read(bar);
> 
> to this arguably more natural one:
> 
>     let boot0 = bar.read(regs::NV_PMC_BOOT_0);
> 
> It also has the benefit of taking advantage of deref coercion for types
> that wrap an `Io`, something the register-based methods couldn't do and
> which would have required extra `AsRef` implementations just for this
> purpose.
> 
> Furthermore, this resolves the inconsistency of the former register API
> that couldn't use the `try_` I/O accessors (and even had methods whose
> names clashed with them). Now if `Io` supports it, it can be done on a
> register.
> 
> Another benefit is that there is less work done within macros, and more
> in generic code, which is (generally) a win for readability. The
> `register!` macro is considerably smaller and easier to work on, and now
> mostly made up of the bitfield accessors that will eventually be moved
> into another macro.
> 
> I decided to remove a couple of tags because the code has changed quite
> a bit since they were obtained.

Last time I gave this a try was with v2. From my aarch64 simple timer
test on that version I have [1] below. Could you give a hint how to
convert this to v6? :)

Many thanks!

Dirk

[1]

register!(TCR(u16) @ 0x10 {
        9:9    icpf;
        8:8    unf;
        7:6    icpe;
	5:5    unie;
	4:3    ckeg;
	2:0    tpsc;
});


impl TCR {
	fn handle_underflow<const SIZE: usize, T>(io: &T)
	where
	    T: Deref<Target = Io<SIZE>>,
	{
	    let tcr = Self::read(io);
	    if tcr.unf().into() {
	        tcr.set_unf(false).write(io);
	    }
	}
}

...

// Reset the underflow flag
TCR::handle_underflow(io);