Delphi-Projects

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unit BICLSKey;
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interface
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function CalcLSKey(const BIC, LS: string): Char;
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function CalcKSKey(const BIC, KS: string): Char;
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function ValidLSKey(const BIC, LS: string): Boolean;
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function ValidKSKey(const BIC, KS: string): Boolean;
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function IsRKC(const BIC: string): Boolean;
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implementation
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uses
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  SysUtils, StrUtils;
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function InternalCalcLSKey(const BICLS: string): Char;
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var
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  B: array[1..23] of Byte;
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  I: Integer;
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  Sum: Integer;
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begin
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  for I := 1 to 23 do
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    B[I] := Byte(BICLS[I]) - 48; //Asc('0')
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  B[12] := 0; //default key = 0 for recalculation
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  Sum := 0;
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  for I := 1 to 23 do
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  begin
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    if (I mod 3) = 1 then
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      Inc(Sum, B[I] * 7 mod 10)
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    else if (I mod 3) = 2 then
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      Inc(Sum, B[I] {* 1} mod 10)
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    else {I mod 3 = 0}
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      Inc(Sum, B[I] * 3 mod 10);
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  end;
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  Result := Char(Sum * 3 mod 10 + 48);
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end;
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function CalcLSKey(const BIC, LS: string): Char;
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begin
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  if IsRKC(BIC) then
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    Result := InternalCalcLSKey('0' + Copy(BIC, 5, 2) + LS)
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  else
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    Result := InternalCalcLSKey(Copy(BIC, 7, 3) + LS);
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end;
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function CalcKSKey(const BIC, KS: string): Char;
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begin
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  if not IsRKC(BIC) then //inverted to LS
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    Result := InternalCalcLSKey('0' + Copy(BIC, 5, 2) + KS)
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  else
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    Result := InternalCalcLSKey(Copy(BIC, 7, 3) + KS);
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end;
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function ValidLSKey(const BIC, LS: string): Boolean;
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begin
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  if IsRKC(BIC) then
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    Result := (InternalCalcLSKey('0' + Copy(BIC, 5, 2) + LS) = LS[9])
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  else
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    Result := (InternalCalcLSKey(Copy(BIC, 7, 3) + LS) = LS[9]);
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end;
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function ValidKSKey(const BIC, KS: string): Boolean;
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begin
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  if not IsRKC(BIC) then
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    Result := (InternalCalcLSKey('0' + Copy(BIC, 5, 2) + KS) = KS[9])
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  else
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    Result := (InternalCalcLSKey(Copy(BIC, 7, 3) + KS) = KS[9]);
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end;
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function IsRKC(const BIC: string): Boolean;
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begin
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  Result := StrToInt(AnsiRightStr(BIC, 3)) < 5;
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end;
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end.
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