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;
;
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.
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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.
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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.
