Op 2020-07-03 om 19:18 schreef Keith Bowes via fpc-devel:
Another thing was the Card function, which
I thought would be easy to do, as surely the code keeps track of how
many elements there are in a set, but if it does, I couldn't find it.
(Just a bit of fun, doesn't really answer your question, since obviously
you'd need it in a ISO compatible mode. Also note that 3.2.0 branched
over an year ago)
But 3.2.0 supports generic functions, and 3.0.0 already supported popcnt
(https://www.freepascal.org/docs-html/rtl/system/popcnt.html).
But the syntax will be CARD<settype>(variable), and there are some minor
things wrong with it: (anyone?)
- needs set type to be defined as type to reuse.
- what to do with a small registerable set, need const ref, but const
[ref] is not yet supported in delphi mode?)
- and alignment requirements for the pointer walking.
- assumes unused bits in the last byte are 0. If that is unsure one
could use the result of the AND 7 to make an and mask to mask out the
unnecessary bits.
{$mode delphi}
{$pointermath on}
Function CARD<T>(const a: T): Integer;
Var bits,dwords,rest,i : Integer;
p: pbyte;
begin
result:=0;
p:=@a;
bits:=(high(t)+1) ;
dwords:=bits div 32;
rest:=(bits mod 32); // bytes
if (rest and 7)>0 then // round rest bits (and 7) up to whole byte (8)
rest:=rest+8;
rest:=rest shr 3; // bits -> bytes.
for i:=0 to dwords-1 do
begin
result:=result +popcnt({unaligned?} pdword(p)^);
inc(pdword(p));
end;
for i:=0 to rest-1 do
begin
result:=result +popcnt({unaligned?} pbyte(p)^);
inc(p);
end;
end;
Type TSettype = set of 0..80;
Var t : TSettype;
i : Integer;
Begin
t:=[];
for i:=0 to 5 do
Include(t,i*13);
Writeln(CARD<tsettype>(t));
End.
I'll probably get back into it eventually, but I might have to redo what
I've already done, because conflicts in the Makefiles are pretty much a
certainty. Personally, I'm nut sure why the Makefiles are included in
SVN; they should be generated `fpcmake -r` before compilation (or being
packed into a source tarball) to avoid this kind of thing.
But that would cause a bootstrap requirement on fpcmake, instead just
the compiler. Note that recently, the generation date has been removed
from the generate file to reduce conflicts.
Anyway, it'll be nice if we can get some more ISO 10206 features. Some
have been popping up here and there over the years (string slices, the
** operator, WriteStr/ReadStr, etc), but a lot of useful features are
missing and seemingly have no equivalent in Borland's proprietary
dialect.
And of course schemata are the proverbial elephant in the room.
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