(*
 * GenerateDPB -
 *  Given a string containing a textual representation
 *  of the database parameters, generate a database
 *  parameter buffer, and return it and its length
 *  in DPB and DPBLength, respectively.
 *)
procedure GenerateDPB(sl: TStrings; var DPB: String;
  var DPBLength: Short);
var
  i : integer;
  j, DPBVal:integer;
  param_name, param_value: String;
  pval: Integer;
begin
  (*
   * The DPB is initially empty, with the exception that
   * the DPB version must be the first byte of the string.
   *)
  DPBLength := 1;
  DPB := Char(isc_dpb_version1);
  (*
   * Iterate through the textual database parameters, constructing
   * a DPB on-the-fly.
   *)
  for i := 0 to sl.Count - 1 do
  begin
    (*
     * Get the parameter's name and value from the list,
     * and make sure that the name is all lowercase with
     * no leading 'isc_dpb_' prefix
     *)
    sl[i]:=FastTrim(sl[i]);
    if sl[i]='' then Continue;

    GetNameAndValue(sl[i],param_name,param_value);
    DoLowerCase(param_name);

    if (param_name[1]=DPBPrefix[1]) and (Pos(DPBPrefix, param_name) = 1) then
       param_name:=FastCopy(param_name,Length(DPBPrefix)+1,MaxInt);
//      Delete(param_name, 1, Length(DPBPrefix));
    (*
     * We want to translate the parameter name to some integer
     * value. We do this by scanning through a list of known
     * database parameter names (DPBConstantNames, defined above).
     *)
    if DPBConstants.Find(param_name,j) then
      DPBVal :=Integer(DPBConstants.Objects[j])
    else
      DPBVal := 0;

    (*
     * A database parameter either contains a string value (case 1)
     * or an integer value (case 2)
     * or no value at all (case 3)
     * or an error needs to be generated (case else)
     *)
    case DPBVal of
      isc_dpb_user_name, isc_dpb_password, isc_dpb_password_enc,
      isc_dpb_sys_user_name, isc_dpb_license, isc_dpb_encrypt_key,
      isc_dpb_lc_messages, isc_dpb_lc_ctype,
      isc_dpb_sql_role_name,isc_dpb_sql_dialect,
      isc_dpb_instance_name, isc_dpb_old_file
     :
      begin
        if DPBVal = isc_dpb_sql_dialect then
          param_value[1] := Char(Ord(param_value[1]) - 48);

        DPB := DPB +
               Char(DPBVal) +
               Char(Length(param_value)) +
               param_value;
        Inc(DPBLength, 2 + Length(param_value));
      end;
      isc_dpb_num_buffers, isc_dpb_dbkey_scope, isc_dpb_force_write,
      isc_dpb_no_reserve, isc_dpb_damaged, isc_dpb_verify,
      isc_dpb_dummy_packet_interval, isc_dpb_connect_timeout,
      isc_dpb_online_dump, isc_dpb_overwrite, isc_dpb_old_file_size
      :
      begin
        DPB := DPB +Char(DPBVal) +#1+Char(StrToInt(param_value));
        Inc(DPBLength, 3);
      end;
      isc_dpb_sweep:
      begin
        DPB := DPB +Char(DPBVal) +#1 +Char(isc_dpb_records);
        Inc(DPBLength, 3);
      end;
      isc_dpb_sweep_interval:
      begin
        pval := StrToInt(param_value);
        DPB := DPB +Char(DPBVal) +#4 +
               PChar(@pval)[0] +
               PChar(@pval)[1] +
               PChar(@pval)[2] +
               PChar(@pval)[3];
        Inc(DPBLength, 6);
      end;
      isc_dpb_activate_shadow, isc_dpb_delete_shadow, isc_dpb_begin_log,
      isc_dpb_quit_log:
      begin
        DPB := DPB +Char(DPBVal) +#1#0;
        Inc(DPBLength, 3);
      end;

      //
      isc_dpb_no_garbage_collect,isc_dpb_garbage_collect:
      begin
        DPB := DPB + Char(DPBVal) + #1#0;
        Inc(DPBLength, 3);
      end;
    else
      begin
        if (DPBVal > 0) and (DPBVal <= isc_dpb_last_dpb_constant) then
          FIBError(feDPBConstantNotSupported,[DPBConstantNames[DPBVal]])
        else
          FIBError(feDPBConstantUnknown, [param_name]);
      end;
    end;
  end;
end;

(*
 * GenerateDPB -
 *  Given a string containing a textual representation
 *  of the database parameters, generate a database
 *  parameter buffer, and return it and its length
 *  in DPB and DPBLength, respectively.
 *)
procedure GenerateDPB(sl: TStrings; var DPB: String;
  var DPBLength: Short);
var
  i : integer;
  j, DPBVal:integer;
  param_name, param_value: String;
  pval: Integer;
begin
  (*
   * The DPB is initially empty, with the exception that
   * the DPB version must be the first byte of the string.
   *)
  DPBLength := 1;
  DPB := Char(isc_dpb_version1);
  (*
   * Iterate through the textual database parameters, constructing
   * a DPB on-the-fly.
   *)
  for i := 0 to sl.Count - 1 do
  begin
    (*
     * Get the parameter's name and value from the list,
     * and make sure that the name is all lowercase with
     * no leading 'isc_dpb_' prefix
     *)
    sl[i]:=FastTrim(sl[i]);
    if sl[i]='' then Continue;

    GetNameAndValue(sl[i],param_name,param_value);
    DoLowerCase(param_name);

    if (param_name[1]=DPBPrefix[1]) and (Pos(DPBPrefix, param_name) = 1) then
       param_name:=FastCopy(param_name,Length(DPBPrefix)+1,MaxInt);
//      Delete(param_name, 1, Length(DPBPrefix));
    (*
     * We want to translate the parameter name to some integer
     * value. We do this by scanning through a list of known
     * database parameter names (DPBConstantNames, defined above).
     *)
    if DPBConstants.Find(param_name,j) then
      DPBVal :=Integer(DPBConstants.Objects[j])
    else
      DPBVal := 0;

    (*
     * A database parameter either contains a string value (case 1)
     * or an integer value (case 2)
     * or no value at all (case 3)
     * or an error needs to be generated (case else)
     *)
    case DPBVal of
      isc_dpb_user_name, isc_dpb_password, isc_dpb_password_enc,
      isc_dpb_sys_user_name, isc_dpb_license, isc_dpb_encrypt_key,
      isc_dpb_lc_messages, isc_dpb_lc_ctype,
      isc_dpb_sql_role_name,isc_dpb_sql_dialect,
      isc_dpb_instance_name, isc_dpb_old_file
     :
      begin
        if DPBVal = isc_dpb_sql_dialect then
          param_value[1] := Char(Ord(param_value[1]) - 48);

        DPB := DPB +
               Char(DPBVal) +
               Char(Length(param_value)) +
               param_value;
        Inc(DPBLength, 2 + Length(param_value));
      end;
      isc_dpb_dbkey_scope, isc_dpb_force_write,
      isc_dpb_no_reserve, isc_dpb_damaged, isc_dpb_verify,
      isc_dpb_dummy_packet_interval, isc_dpb_connect_timeout,
      isc_dpb_online_dump, isc_dpb_overwrite, isc_dpb_old_file_size
      :
      begin
        DPB := DPB +Char(DPBVal) +#1+Char(StrToInt(param_value));
        Inc(DPBLength, 3);
      end;
      isc_dpb_sweep:
      begin
        DPB := DPB +Char(DPBVal) +#1 +Char(isc_dpb_records);
        Inc(DPBLength, 3);
      end;
      isc_dpb_num_buffers, isc_dpb_sweep_interval:
      begin
        pval := StrToInt(param_value);
        DPB := DPB +Char(DPBVal) +#4 +
               PChar(@pval)[0] +
               PChar(@pval)[1] +
               PChar(@pval)[2] +
               PChar(@pval)[3];
        Inc(DPBLength, 6);
      end;
      isc_dpb_activate_shadow, isc_dpb_delete_shadow, isc_dpb_begin_log,
      isc_dpb_quit_log:
      begin
        DPB := DPB +Char(DPBVal) +#1#0;
        Inc(DPBLength, 3);
      end;

      //
      isc_dpb_no_garbage_collect,isc_dpb_garbage_collect:
      begin
        DPB := DPB + Char(DPBVal) + #1#0;
        Inc(DPBLength, 3);
      end;
    else
      begin
        if (DPBVal > 0) and (DPBVal <= isc_dpb_last_dpb_constant) then
          FIBError(feDPBConstantNotSupported,[DPBConstantNames[DPBVal]])
        else
          FIBError(feDPBConstantUnknown, [param_name]);
      end;
    end;
  end;
end;