ubytes to ulong problem

[Charles Hixson]

On 12/21/2013 03:52 PM, Ali Çehreli wrote:
> On 12/21/2013 03:13 PM, John Colvin wrote:
>
> > Ideally the compiler will optimise your version to be fast, but you may
> > find you get better performance by doing the bit manipulations 
> eplicitly:
>
> Assuming that the program needs to support only big endian and little 
> endian systems (i.e. excluding systems where no D compiler exists :)), 
> the following is less wordy and should be equally fast:
>
> import std.bitmanip;
> import std.system;
>
> ulong ubytesToUlong(ubyte[] block, size_t n = 0)
> in
> {
>     assert (n >= 0);
>     assert (n + 8 <= block.length);
> }
> body
> {
>     ulong value = *cast(ulong*)(block.ptr + n);
>
>     if (std.system.endian == Endian.littleEndian) {
>         return *cast(ulong*)(value.nativeToBigEndian.ptr);
>
>     } else {
>         return value;
>     }
> }
>
> Ali
>
>
Will that work even when the alignment is to odd bytes?  Because that's 
the case I was really worried about.  The ubyte array is a packed 
mixture of types, some of which are isolated bytes.

-- 
Charles Hixson