那个高手看得懂这个复杂的过程，请帮我分析？

procedure Tfmlogin.findlocal;
var localf:file of byte;
    localname:string;
    pcSystemDirectory:pchar;
    dwSDSize : DWORD;
    b:byte;
begin
     dwSDSize := MAX_PATH + 1;
     GetMem( pcSystemDirectory, dwSDSize ); // allocate memory for the string
     try
        if Windows.GetSystemDirectory( pcSystemDirectory, dwSDSize )<>0 then
           localname:=pcSystemDirectory+'\local.dll'
        else
           localname:=extractfilepath(application.exename)+'local.dll';
     except
           localname:=extractfilepath(application.exename)+'local.dll';
     end;
     FreeMem( pcSystemDirectory ); // now free the memory allocated for the string
     if fileexists(localname) then
     begin
          try
             assignfile(localf,localname);
             reset(localf);
             read(localf,b);
             local:=b;
             closefile(localf);
          except
                //选择收银点
                fmselshouyindian:=tfmselshouyindian.Create(application);
                fmselshouyindian.ComboBox1.Clear;
                Q.close;
                Q.sql.text:='select 收银点名称 from 收银点帐单号表';
                Q.open;
                while not Q.eof do
                begin
                     fmselshouyindian.ComboBox1.Items.add(Q.fields[0].asstring);
                     Q.next;
                end;
                Q.close;
                fmselshouyindian.ShowModal;
                Q.sql.text:='select 收银点 from 收银点帐号表 where 收银点名称='''+fmselshouyindian.ComboBox1.Items[fmselshouyindian.combobox1.itemindex]+'''';
                Q.open;
                local:=Q.Fields[0].asinteger;
                Q.close;
                fmselshouyindian.free;
                b:=local;
                try
                   assignfile(localf,localname);
                   rewrite(localf);
                   write(localf,b);
                   closefile(localf);
                except                end;
          end;
     end
     else
     begin
          //选择收银点
                fmselshouyindian:=tfmselshouyindian.Create(application);
                fmselshouyindian.ComboBox1.Clear;
                Q.close;
                Q.sql.text:='select 收银点名称 from 收银点帐单号表';
                Q.open;
                while not Q.eof do
                begin
                     fmselshouyindian.ComboBox1.Items.add(Q.fields[0].asstring);
                     Q.next;
                end;
                Q.close;
                fmselshouyindian.ShowModal;
                Q.sql.text:='select 收银点 from 收银点帐单号表 where 收银点名称='''+fmselshouyindian.ComboBox1.Items[fmselshouyindian.combobox1.itemindex]+'''';
                Q.open;
                local:=Q.Fields[0].asinteger;
                Q.close;
                fmselshouyindian.free;
                b:=local;
                try
                   assignfile(localf,localname);
                   rewrite(localf);
                   write(localf,b);
                   closefile(localf);
                except                end;
     end;
     Q.close;
     Q.sql.text:='select 收银点名称,默认部门ID from 收银点帐单号表 where 收银点='+inttostr(local);
     Q.open;
     potname:=Q.fields[0].asstring;
     bmID:=Q.Fields[1].AsInteger;
     Q.close;
end;