Warp wrote:
>   Because C allows many types of low-level optimization that are very
> difficult, if not even outright impossible, in higher-level languages.

>   For example, you know how a C struct will map onto memory locations,
> on every possible platform which your kernel can be compiled for.

Not in a portable way. You don't know what kinds of padding happen, or what 
order the integers are in.

> You know
> exactly what assigning one struct instance to another entails as machine
> code. 

That's true of lots of low-level languages too. FORTH and Ada both spring to 
mind, for example. Lots of languages of the same ilk have instructions for 
laying out structures at a per-byte level. (Erlang? Modula-whatever?)

 > If you need a pointer which should point to a raw memory address,
> you can create one. 

Not in C. Only in some language that looks like C but invoked undefined 
behavior.

> You can be sure that something like garbage collection
> will *not* suddenly and unexpectedly kick in during a highly-critical
> operation. 

True, but there are lots of languages I consider better than C (as in, more 
powerful) that don't have GC. Anything with managed memory is going to be a 
mess for writing kernel code in, I'll grant you. :-) At least for a general 
kernel where you can't control what else runs.

 > If needed, you can even write inline-asm for things which cannot
> be done in C directly (eg. write or read from ports, issue some exotic CPU
> commands such as disabling interrupts, etc).

But not in C. That's kind of my point. There's whole bunches of stuff that 
happen in kernels that C just doesn't define, just like this.

>   And of course C allows for programmatical optimizations which can often
> be difficult in higher-level languages. Memory usage optimization would be
> the main example. 

I'm not sure what that means. If I have an array of 12-bit values in C, 
that's a PITA to implement compared to a lot of other languages (including C++).

-- 
   Darren New, San Diego CA, USA (PST)
   "We'd like you to back-port all the changes in 2.0
    back to version 1.0."
   "We've done that already. We call it 2.0."

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