Re: gawk compl()

[Stepan Kasal]

Hello,

On Mon, Oct 10, 2005 at 09:29:55AM -0400, Andrew J. Schorr wrote:
> On Mon, Oct 10, 2005 at 02:19:49PM +0200, Karel Zak wrote:
> > $ gawk 'BEGIN {printf("%#x\n", compl(0xFFFF0000)) }'
> > 0x1fffff0000ffff
...
> So, in fact, the calculation is being done with 64 bits.
> Therefore ~0xFFFF0000 = 0xFFFFFFFF0000FFFF.  This is
> then converted to floating point and gets truncated
> in the process.

I have to admit I still don't understand how 0xffffffff0000ffff
becomes 0x1fffff0000ffff.

Could you please explain it?

> At the moment, all of the bitwise operators seem to be
> implemented using uintmax_t.  This is not really problematic
> for the other operators, but it is certainly confusing
> for compl()...

Well, it is confusing if you print the result.

But it is useful when used as

        bong_flag = 0x80
        flags = flags & compl(bong_flags)

And I guess this is the reason for compl().

Stepan