On Wednesday 10 January 2007 21:56, David Anderson wrote:
> Hi,
>
> So, now that the code is reindented, here is the first documentation patch.
>
> On a side-note, I have a couple of questions regarding the code of the
> AIC driver.
>
> The mode passed to aic_set_vector is defined as an U32, with possible
> values #define'd. Is there a reason the API does not use an enum (and
> then cast it to U32 when setting the register, obviously) ?
This is somewhat of a taste issue.
I don't like the use of enums for values with a physical meaning that needs
translation from enum space into physical space because this is wasteful and
confusing and error prone. I think enums are great for abstract values with
no physical meaning eg. state machine states etc.
My absolute pet hate usage of enum that I have seen is
enum{
baud_300,
baud_600,
baud_9600,
...
}
In the called function this then needed some code like
switch(baud_enum_passed_in){
case baud_300:
br = 300;
break;
case baud_600:
.....
}
Unfortunately one of the cases got duplicated (a missing break caused a fall
through) but in all that repeated code it was relatively difficult to spot
Just using 9600 or whatever as a straight value would have been a lot easier!
> Same
> question for the isr parameter: any reason to make the caller cast the
> value, rather than accept a void(*)(void) and cast it to U32 in the
> function?
I have a very good reason for doing this....
I am sometimes a lazy slob!
This code has been stolen from something I wrote in a hurry a few years ago.
It was late at night and my brain was fried and I could remember U32 far
easier than that whole void(*)(void) thing....
Every now and then I see the warning fly past as I compile and I think hey I
should fix that, then that lazy slob that lives inside my body takes over
again!
-- Charles
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