>>>>> "WP" == Walter C Pelissero <[EMAIL PROTECTED]> writes:
WP> I suppose one could compare the generated code (disassembling it) and
WP> see if there is any degradation.
Some further investigation indicates that max-bits really can be
#xffffffff. And the word-offset deftype is wrong. AFAICT,
word-offset really is the word-offset (32-bit words) of a particular
bit. So the type is more like (integer 0 (2^32/32)).
I briefly looked at the disassembly for both functions. There are
only 20 differences and they seem minor. I think the difference is
because the offsets don't fit in a fixnum anymore.
WP> Wouldn't a 32-bit integer be too big to fit in a "simple" Lisp object
WP> thus requiring a further indirection?
That is correct. But bit-bash-copy carefully declares things so that
the compiler knows the bit offsets will remain a 32-bit unsigned
object, and hence no consing is needed. (I think. The disassembly
doesn't show any more consing than the previous version.)
I've done a few more tests (ansi-tests) and it seems ok. Using your
test-string-stream (but with only 15 iterations instead of 17) for
timing, both versions have the same execution times.
I think bit-bash-copy still has some issues since it won't be able to
copy every possible object, but that should only be a problem with
really big heaps and objects.
I'll check this in very shortly.
Thanks,
Ray
