uses dwsUtils, SynCommons, Generics.Defaults;

const
   HASH_BITS = 16;
   HASH_MASK = (1 shl HASH_BITS)-1;

var
   values : array of String;
   hashes : array [0.. HASH_MASK] of Word;

type
   THashFunc = function (const s : String) : Cardinal;

function RunHash(func : THashFunc) : String;
var
   i, j, k : Integer;
   mt, t, mx : Cardinal;
begin
   FillChar(hashes, SizeOf(hashes), 0);
   for i:=0 to High(values) do begin
      Inc(hashes[func(values[i]) and HASH_MASK]);
   end;

   mt:=MaxInt;

   for k:=1 to 30 do begin
      t:=GetTickCount;

      for j:=1 to 100 do
         for i:=0 to High(values) do
            func(values[i]);

      t:=GetTickCount-t;
      if t<mt then mt:=t;
   end;

   j:=0;
   mx:=0;
   for i:=0 to HASH_MASK do begin
      if hashes[i]>1 then
         Inc(j, hashes[i]-1);
      if hashes[i]>mx then
         mx:=hashes[i];
   end;

   Result:= 'Duration: '+IntToStr(t)+#13#10
           +'Collisions : '+IntToStr(j)+' ('+IntToStr(mx)+')'+#13#10;
end;

function KR32Hash(const s : String) : Cardinal;
begin
   Result:=kr32(0, Pointer(@s[1]), Length(s)*2);
end;

function CRC32Hash(const s : String) : Cardinal;
begin
   Result:=crc32cfast(0, Pointer(@s[1]), Length(s)*2);
end;

function FNVHash(const s : String) : Cardinal;
begin
   Result:=fnv32(0, Pointer(@s[1]), Length(s)*2);
end;

function BJHash(const s : String) : Cardinal;
begin
   Result:=BobJenkinsHash(s[1], Length(s)*2, 0);
end;

function ShaHash(const s : String) : Cardinal;
begin
   Result:=StrToInt('$'+Copy(SHA256(@s[1], Length(s)*2), 1, 6));
end;

procedure TForm82.FormCreate(Sender: TObject);
var
   i : Integer;
begin
   SetLength(values, 100000);
   for i:=0 to 99999 do
      values[i]:=Format('%.05d', [i]);

   Memo1.Lines.Add(
       'SimpleStringHash'#13#10
      +RunHash(SimpleStringHash)
      +#13#10
      +'FNV32'#13#10
      +RunHash(FNVHash)
      +#13#10
      +'KR32'#13#10
      +RunHash(KR32Hash)
      +#13#10
      +'CRC32'#13#10
      +RunHash(CRC32Hash)
      +#13#10
      +'BobJenkins'#13#10
      +RunHash(BJHash)
      +#13#10
//      +'SHA256'#13#10
//      +RunHash(ShaHash)
      +#13#10
      );

end;