Byte Order Swapping Function

[Regan Heath]

On Thu, 14 Jul 2011 08:14:10 +0100, Jonathan M Davis <jmdavisProg at gmx.com>  
wrote:

> On Thursday 14 July 2011 00:03:23 Andrew Wiley wrote:
>> On Wed, Jul 13, 2011 at 11:59 PM, Jonathan M Davis
> <jmdavisProg at gmx.com>wrote:
>> > On Wednesday 13 July 2011 23:37:02 Andrew Wiley wrote:
>> > > Hey, does anyone else thing a function like this belongs in Phobos,
>> > > and
>> >
>> > if
>> >
>> > > so, where do you think it should go?
>> > >
>> > > T ntoh(T)(T val) if (__traits(isArithmetic, T)) {
>> > > version(BigEndian) {
>> > >
>> > >  return val;
>> > >
>> > > }
>> > > else version (LittleEndian) {
>> > >
>> > >  ubyte[] arr = (cast(ubyte*)&val)[0 .. T.sizeof];
>> > >
>> > > ubyte temp;
>> > > for(int i = 0; i < T.sizeof/2; i++) {
>> > >
>> > >  temp = arr[i];
>> > >
>> > > arr[i] = arr[T.sizeof - i - 1];
>> > > arr[T.sizeof - i - 1] = temp;
>> > >
>> > >  }
>> > >
>> > > return val;
>> > > }
>> > >
>> > >  else static assert(0, "Are you sure you're using a computer?");
>> > >  }
>> > >
>> > > I was looking for something along these lines in the docs today and
>> >
>> > couldn't
>> >
>> > > find it. It looks like there's a stream in std.stream to do this,
>> > > but,
>> > > well, I think we've all been pretending std.stream doesn't exist for
>> > > a
>> > > while now.
>> >
>> > core.sys.posix.arpa.inet.d
>> > std.c.windows.winsock.d
>>
>> Both of those are platform specific, and neither of them is general  
>> enough
>> to handle longs.
>
> They're only platform-specific in that you have to import one in Posix  
> and
> another in Windows. Other than that, they're completely  
> platform-independent.
> They're the standard functions for it in C/C++. Now, it's true that there
> isn't one for ulong (since there is no standard one for 64-bit in  
> C/C++), and
> there would definitely be some value in having a function which was  
> overloaded
> on the type so that you could just use the one function for ushort,  
> uint, and
> ulong, but ntohs and ntohl _are_ provided by druntime and Phobos. So,  
> it's not
> like nothing is there.
>
> I did have to create a 64-bit version for std.datetime, so it has a  
> private
> function called endianSwap64 to do the job. So, it's not like I'm saying  
> that
> the situation couldn't be improved, but druntime and Phobos do currently  
> give
> you the exact same thing that C and C++ do.

The crypto library I have been meaning to polish up and submit for  
inclusion into phobos needs these functions in several variants.  I was  
hoping they could/would be included somewhere more 'general' at some  
stage, and any duplicates like those already mentioned removed..

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