little/big endian conversions

[Regan Heath]

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