little/big endian conversions
Regan Heath
regan at netmail.co.nz
Tue Apr 8 02:29:38 PDT 2008
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
More information about the Digitalmars-d-learn
mailing list