string to char array?

[Kyoji Klyden via Digitalmars-d-learn]

On Saturday, 6 June 2015 at 18:43:08 UTC, Marc Schütz wrote:
>
> _d_arraybounds() always throws an error because that's its 
> purpose. It's implemented here:
> https://github.com/D-Programming-Language/druntime/blob/master/src/core/exception.d#L640
>
> My point was that _d_arraybounds never returns, instead it 
> throws that Error object.
>
> The compiler inserts the checks for the array length whenever 
> you access an array element, _except_ if it can either prove 
> that the array is always long enough (e.g. if its a fixed-size 
> array), in which case it can leave the check out because it's 
> unnecessary, or if it can prove that the array is never long 
> enough, in which case it may already print an error during 
> compilation.
>
Okay I think I roughly get it. Another thing that was on my to-do 
list just moved up in priority I think.. that thing is learning 
everything about the D runtime.


>
> No, the length of the string.
>
> It's roughly the equivalent of this pseudo-code:
>
> extern void _d_arraybounds(void* filename_ptr, size_t 
> filename_len, size_t line);
>
> void f(void* a_ptr, size_t a_length) {
>     if(a_length == 0)
>         goto LBB0_4;
>     *cast(int*) a_ptr = 0;      // line 5
>     if(a_length <= 1)
>         goto LBB0_5;
>     *cast(int*) (a_ptr+4) = 1;  // line 6
>     if(a_length <= 2)
>         goto LBB0_6;
>     *cast(int*) (a_ptr+8) = 1;  // line 7
>     return;
> LBB0_4:
>     // (pretend this filename is 55 chars long)
>     static string __FILE__ = "/path/to/your/source/file.d";
>     _d_arraybounds(__FILE__.ptr, __FILE__.length, 5 /* line 
> number */);
> LBB0_5:
>     _d_arraybounds(__FILE__.ptr, __FILE__.length, 6 /* line 
> number */);
> LBB0_6:
>     _d_arraybounds(__FILE__.ptr, __FILE__.length, 7 /* line 
> number */);
> }
>> ...
> Yes, but it is extremely fast. I'm pretty sure accessing memory 
> at [RSI] and [RSI+4] both take exactly the same time (but can't 
> find a reference now).

Oh I forgot that the path is part of the filename, so it now 
makes a bit more sense on why the names might be so long.
I'm also getting the logic here in a theoretical sense, but in a 
practical sense, not quite yet. That'll probably take doing 
experiments if anything.

Do you perchance have any links to learning resources for the D 
runtime(aside from just the github repository), and also maybe 
x86 architecture stuff? (I know intel has some 1000+ page pdf on 
their site, but I think that's more for hardware and/or OS 
designers..)


Thanks! :)