unit FunctionUnit;

interface
var
    Port: string;
    Speed: string;
    DataBit:string;
    CheckBit:string;
    StopBit:string;


function CalMoneyCheck(BA : array of byte;ALow,AHigh:smallint):Byte;
function CalCheck(BA : array of byte;ALow,AHigh:smallint):Byte;
function Encrypt(AByte: byte):byte;
function AntiEncrypt(AByte: byte):byte;
function IsArrayValid(AByteAry : array of byte):Boolean;

function ComStrToInt(AComStr:string):smallint;
function EncryptStr(AStr:string):string;
implementation
uses
    Sysutils;

//計算金錢校驗位
function CalMoneyCheck(BA : array of byte;ALow,AHigh:smallint):Byte;
var
    i:smallint;
    mTotal:integer;
begin
    mTotal := $13;
    for i:=ALow to AHigh do
    begin
        mTotal := mTotal + BA[i];
    end;
    Result := mTotal mod $ff;
end;



//檢查報文是否正確。
function IsArrayValid(AByteAry : array of byte):Boolean;
var
    i,mHigh : integer;
    mByte : byte;
begin
    //檢查報文頭部
    if (AByteAry[0] <> $0f)
        or (AByteAry[1] <> $f0) then
    begin
        Result := False;
        Exit;
    end;
    //mLen為AByteAry最后
    mHigh := Length(AByteAry)-1;
    //將$d2和所有報文作異或
    mByte := $d2;
    for i:=0 to mHigh-1 do
    begin
        mByte := mByte xor AByteAry[i];
    end;
    //檢查校驗位
    if mByte <> AByteAry[mHigh] then Result := False
    else Result := True;
end;

function CalCheck(BA : array of byte;ALow,AHigh:smallint):Byte;
var
    mByte:byte;
    i:smallint;
begin
    mByte := $d2;
    for i:=ALow to AHigh do
    begin
        mByte := mByte xor BA[i];
    end;
    Result := mByte;
end;

//加密數據
function Encrypt(AByte: byte):byte;
var
    mByte3,mByte6: byte;
begin
    //取第三位
    mByte3 := AByte and $8;
    //第三位移動第六位
    mByte3 := mByte3 shl 3;
    //取第六位
    mByte6 := AByte and $40;
    //第6位移動第3位
    mByte6 := mByte6 shr 3;
    //第6位\第3位交換位置
    AByte := AByte or mByte3;
    AByte := AByte or mByte6;
    //和$5d異或
    Result := (AByte xor $5d);
end;

//解密數據
function AntiEncrypt(AByte: byte):byte;
var
    mByte3,mByte6: byte;
begin
    //和$5d異或
    AByte := (AByte xor $5d);
    //取第三位
    mByte3 := AByte and $8;
    //第三位移動第六位
    mByte3 := mByte3 shl 3;
    //取第六位
    mByte6 := AByte and $40;
    //第6位移動第3位
    mByte6 := mByte6 shr 3;
    //第6位\第3位交換位置
    AByte := AByte or mByte3;
    AByte := AByte or mByte6;
    Result := AByte;
end;

function ComStrToInt(AComStr:string):smallint;
var
    mLen: integer;
    mResult: string;
begin
    mLen := Length(AComStr);
    mResult := Copy(AComStr,4,mLen-3);
    Result := StrToInt(mResult);
end;

function EncryptStr(AStr:string):string;
begin
    Result := AStr;
end;

end.