little/big endian conversions

[lurker]

so i need to put the float/double into an byte array and just swap?

Regan Heath Wrote:

> Bill Baxter wrote:
> > Regan Heath wrote:
> >> lurker wrote:
> >>> does anybody know how to convert float and doubles to little/big endian?
> >>
> >> This is a guess but if you read:
> >> http://en.wikipedia.org/wiki/IEEE_754
> >>
> >> You'll see the internal representation of a float, given that and a 
> >> little guess work I've come up with:
> >>
> >> import std.stdio;
> >>
> >> int extractSign(float f)
> >> {
> >>     return (*(cast(int*)&f) & 0x80000000) ? -1 : 1;
> >> }
> >>
> >> ubyte extractExp(float f)
> >> {
> >>     return (*(cast(int*)&f) << 1) & 0xFF000000;
> >> }
> >>
> >> int extractFraction(float f)
> >> {
> >>     return *(cast(int*)&f) & 0x007FFFFF;
> >> }
> >>
> >> void main()
> >> {
> >>     float f = -1.25f;
> >>         auto   sign     = extractSign(f);
> >>     auto   exp      = extractExp(f);
> >>     auto   fraction = extractFraction(f);
> >>         writefln(f);
> >>     writefln(sign);
> >>     writefln(exp);
> >>     writefln(fraction);   }
> >>
> >> which will extract the various parts of a float.
> >>
> >> Now, I have no idea how they might change on a big/little endian 
> >> system but I suspect each part would have it's byte order swapped.  In 
> >> which case, byte order swapping the extracted parts then re-assembling 
> >> might give you a byte order swapped float.
> >>
> >> Like I said, I'm guessing.
> >>
> >> What you want is 2 systems with different ordering and then you want 
> >> to dump the content of the float like this:
> >>
> >> writefln("%032b", *(cast(int*)&f));
> >>
> >> then compare.
> >>
> >> Regan
> > 
> > 
> > It doesn't matter that it's in IEEE 745 format.  You just swap the bytes 
> > like it was any old kind of data.
> 
> Doh, for some reason I dismissed that as too simple.
> 
> Regan