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. > > The documentation should specify the relationship to htonl and ntohl. > > If there's a need for converting endianness of larger buffers, we might add: > > ubyte[] toBigEndian(ubyte[] val); > ubyte[] toLittleEndian(ubyte[] val); > ubyte[] bigEndianToNative(ubyte[] val); > ubyte[] littleEndianToNative(ubyte[] val); > > They'd use std.algorithm.reverse internally as needed. > > It's a sweet piece of work. Anyone have the time to prepare a pull request?
I decided to take a crack at it, and it seems to be going pretty well, except that I can't seem to get the floating point values right. Somehow, when I compare a floating point value with the same value except that it's had its endianness swapped twice, they return true for is but false for ==, which makes absolutely no sense to me. There's obviously either something that I don't understand about floating point values (or the relationship between is and ==) or a bug in dmd. It'd be one thing if I couldn't get the values to reverse properly, but when they're equal according to is but not ==, I have no idea how that could even be possible. - Jonathan M Davis
