27 Feb
2015
27 Feb
'15
10:27 a.m.
On 02/27/2015 06:29 AM, Peter Corlett wrote:
C does support bitfields, but can't take the
address of one. The latter is a
fairly uncommon requirement though, and so algorithms that require it will have
to roll their own using mask and shift operations. Given that x86 doesn't have
bitfield instructions and has to fake it with mask and shift, this is no great
loss in practice. It wouldn't surprise me if there was a bitfield_ptr<> in
Boost which did this.
Well, the 386+ CPUs have bit manipulation instructions and *almost* had
bit string/field instructions. There are still books out there that
describe in detail the function of the BFxxx instructions.
I suppose that it's unreasonable for a language to support processor
instruction set extensions. But APL does a great job of supporting
vectors; has a syntax for things such as dot-product, etc. So it can't
be that K&R weren't aware of such things.
It seems to me to be very strange that today we're coding in a language
that was developed for a PDP-11 minicomputer.
--Chuck