FreePascal 64 bit question

[Dann Corbit]

According to this:
http://wiki.freepascal.org/FPC_New_Feat ... intrinsics

FreePascal should have intrinsics:
BsfQWord() and BsrQWord()

However, I can't seem to get the compiler to recognize them.

Do any FreePascal experts frequent this forum and can you tell me how to get them to work? I want to make a 64 bit version of Booot.

If need be, I can use these primitives to build my own versions:
not Bitwise negation (unary)
and Bitwise and
or Bitwise or
xor Bitwise xor
shl Bitwise shift to the left
shr Bitwise shift to the right

but I would much rather use the intrinsics if possible.

[JuLieN]

Dann, this is a quick search answer, as I'm off to bed now, but here is a sample program that use these functions I found. Hopefully it will help :

Code: Select all

program testbitscan;

function test_byte: boolean;
var
  x8,f,r: byte;
  i: integer;
begin
  for i:=0 to 7 do
  begin
    x8:=1 shl i;
    f:=BsfByte(x8);
    if (f<>i) then
    begin
      writeln('BsfByte(',x8,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrByte(x8);
    if r<>i then
    begin
      writeln('BsrByte(',x8,') returned ',f,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

function test_word: boolean;
var
  x16: word;
  i,f,r: integer;
begin
  for i:=0 to 15 do
  begin
    x16:=1 shl i;
    f:=BsfWord(x16);
    if (f<>i) then
    begin
      writeln('BsfWord(',x16,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrWord(x16);
    if r<>i then
    begin
      writeln('BsrWord(',x16,') returned ',f,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

function test_dword: boolean;
var
  x32: cardinal;
  i,f,r: integer;
begin
  for i:=0 to 31 do
  begin
    x32:=1 shl i;
    f:=BsfDWord(x32);
    if (f<>i) then
    begin
      writeln('BsfDWord(',x32,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrDWord(x32);
    if r<>i then
    begin
      writeln('BsrDWord(',x32,') returned ',f,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

function test_qword: boolean;
var
  x64: qword;
  i, f, r: integer;
begin
  for i:=0 to 63 do
  begin
    x64:=uint64(1) shl i;
    f:=BsfQWord(x64);
    if f<>i then begin
      writeln('BsfQWord(',x64,') returned ',f,', should be ',i);
      exit(false);
    end;
    r:=BsrQWord(x64);
    if r<>i then begin
      writeln('BsrQWord(',x64,') returned ',r,', should be ',i);
      exit(false);
    end;
  end;
  result:=true;
end;

begin
  if test_byte then writeln('passed') else writeln('failed');
  if test_word then writeln('passed') else writeln('failed');
  if test_dword then writeln('passed') else writeln('failed');
  if test_qword then writeln('passed') else writeln('failed');
end.

[JuLieN]

Hmmm... ok, so the problem is : in which unit are those functions found, so you can add it to your "uses" clause? Well... I can't find it either
And the documentation about that is just non-existant at all. All I can say is that it's not in the LCL. Weird.
I guess you'll have to emulate them.

EDIT: Yahoo's cache has a reference to these functions in the free pascal. It might save you some time to copy/paste this code :

http://74.6.239.67/search/cache?ei=UTF- ... B3xcFhWA--

For instance :

Code: Select all

function BsfQWord(Const AValue : QWord): cardinal; assembler; nostackframe;
asm
     bsfl    4(%esp),%eax
     jnz     .L2
.L1: bsfl    8(%esp),%eax
     add     $32,%eax
.L2:
end;

function BsrQWord(Const AValue : QWord): cardinal; assembler; nostackframe;
asm
     bsrl    8(%esp),%eax
     jz     .L1
     add     $32,%eax
     jmp     .L2
.L1: bsrl    4(%esp),%eax
.L2:
end;

But that's in asm, and you probably don't want that

[rvida]

Hi,

You probably need a more recent version of freepascal, at least FPC 2.5.1 revision 16174 or newer. The patch implementing bitscan intrinsics was submitted 2010-10-09 and merged to trunk 2010-10-16. More details on freepascal bugtracker. (By the way, I am the author of this patch )

Richard

[JuLieN]

@Richard

I say, this is a small world!

Btw, thanks for Critter, you are the answer to C/C++ programmers looking down at us Pascal lovers

[Dann Corbit]

Where can the most recent versions be downloaded?

[JuLieN]

Where can the most recent versions be downloaded?

There : http://www.hu.freepascal.org/lazarus/

(I always use the daily builds, that way I can blame the FPC/Lazarus team for Prédateur's bugs.)

[Dann Corbit]

Where can the most recent versions be downloaded?

There : http://www.hu.freepascal.org/lazarus/

(I always use the daily builds, that way I can blame the FPC/Lazarus team for Prédateur's bugs.)

The latest one there for Windows 64 bit appears to be 2.4.3 and Richard said I would need FPC 2.5.1 revision 16174 or newer so I am not sure if it will work

[JuLieN]

The latest one there for Windows 64 bit appears to be 2.4.3 and Richard said I would need FPC 2.5.1 revision 16174 or newer so I am not sure if it will work

Oh, sorry, my mistake. A quick search with people having the same concerns points to Code Typhoon, presumably always up to date to the latest betas of FPC and Lazarus :

http://www.pilotlogic.com/sitejoom/inde ... Itemid=147

I didn't try it, as I always download Lazarus from the link I gave you, but as far as I can see it looks big and serious.

Please report how it goes if you try it, so maybe I'll switch to it.

EDIT: I found that FreePascal's official repository is more up to date than Lazaru's one. Weird. here's the link to the latests official win64 Lazarus 0.9.31 + FPC 2.5.1 installer :
http://ftp.freepascal.org/snapshots/Laz ... -win64.exe

[Steve Maughan]

Hi Richard,

I'm a big fan of Delphi. How does FreePascal compare in terms of speed to Delphi. Is FreePascal 64 significantly faster than Delphi 32 bit for bitboard type programs?

Thanks,

Steve