On Jul 17, 11 15:44, Jonathan M Davis wrote:
On Sunday 17 July 2011 15:31:36 KennyTM~ wrote:
On Jul 17, 11 05:51, Jonathan M Davis wrote:
On Saturday 16 July 2011 15:38:29 Andrei Alexandrescu wrote:
Just paste the code here.
This is what I have at the moment:
import core.bitop;
[snip]
private T swapEndianImpl(T)(T val)
if(is(Unqual!T == ulong))
{
return ((val& 0xff00000000000000UL)>> 56) |
((val& 0x00ff000000000000UL)>> 40) |
((val& 0x0000ff0000000000UL)>> 24) |
((val& 0x000000ff00000000UL)>> 8) |
((val& 0x00000000ff000000UL)<< 8) |
((val& 0x0000000000ff0000UL)<< 24) |
((val& 0x000000000000ff00UL)<< 40) |
((val& 0x00000000000000ffUL)<< 56);
}
Why not just 'bswap' the two uint parts?
If that will work sure, but thinking about it, I couldn't think of how you
could use bswap like that. bswap swaps the 4 bytes that it's given. But you
have to swap each end with each end, not an end with the middle. So, it's not
like you can use bswap on half of it and then on the other half. I suppose
that you could use bswap for the middle 4 bytes and then bitshifts for the 2
bytes on each side, and that would probably be faster. But I don't see how you
could use bswap to swap any two pieces of a 64-bit integer and properly swap
it. Now, it may very well be possible and I just don't see it, but I don't see
it. So, if you know how, please tell me.
- Jonathan M Davis
import core.bitop;
private ulong swapEndianImpl(ulong val) {
ulong res = bswap(val & 0xffff_ffff);
return res << 32 | bswap(val >> 32);
}
unittest {
assert(swapEndianImpl(0xfedcba98_76543210UL) == 0x10325476_98badcfeUL);
}
