On 2011-07-14 10:26, Andrew Wiley wrote: > On Thu, Jul 14, 2011 at 9:02 AM, Jonathan M Davis <jmdavisp...@gmx.com>wrote: > > On Thursday 14 July 2011 06:27:47 Andrei Alexandrescu wrote: > > > On 7/14/11 5:51 AM, Regan Heath wrote: > > > > That's my point. I need 8/16/32/64/128 bit versions and it really > > > > would be better if there were general variants. My version are less > > > > than optimal, but do use intrinsics where possible. Someone else can > > > > do a > > > > far > > > > > > better job than I, and it really should be done once, by that person. > > > > Surely we have the infrastructure for someone to add this to phobos? > > > > If something this simple can't or won't be done, what hope do we > > > > have!? > > > > > > I think we should have these functions in std.bitmanip: > > > > > > T toBigEndian(T)(T val) if (isArithmetic!T || isSomeChar!T); > > > T toLittleEndian(T)(T val) if (isArithmetic!T || isSomeChar!T); > > > T bigEndianToNative(T)(T val) if (isArithmetic!T || isSomeChar!T); > > > T littleEndianToNative(T)(T val) if (isArithmetic!T || isSomeChar!T); > > > > > > That means all characters, all integers, and all floating point > > > numbers. The implementations would opportunistically use intrinsics > > > and other specialized means. > > > > Well, it's questionable as to whether there's any point in having such > > functions for 8-bit values, since it would just return the original > > value. And > > I don't think that it should deal with floating point numbers, since > > they're > > not affected by endian-ness. > > I looked this up at one point, and found that (according to Wikipedia, > which may not be perfect) floating point numbers are generally stored > according to the same endianness rules as integers, in which case they > would be affected. I'm not an expert, but why do you think they aren't?
1. I was pretty darn sure of it from what I recalled about looking into it in the past. 2. I misread wikipedia when I went to verify it prior to posting (I just went and reread it after reading your post): http://en.wikipedia.org/wiki/Endian#Floating-point_and_endianness. It discusses the possibility of a little endian machine having big endian floating point values and how that pretty much doesn't happen now and how all x86 machines use little endian floating point. I skimmed it too quickly and thought that it said that all machines today use little endian rather than it saying that all x86 machines use little endian for floating point. So, yes. Unfortunately, floating point values _are_ affected by endianness - though apparently unlike integers, there is no standard way to transmit them over the network. So, I guess that we do need to worry about converting floating point values. Bleh. Why couldn't all computers have been smart and just have used big endian from the beginning and be done with it... - Jonathan M Davis
