获取一个字节的高4位

Question

我正在尝试获取Byte的高4位。

这是我到目前为止的尝试：

function Upper4Bits(const X : Byte): Byte;
type 
   BS = set of 0..7;
var 
   K : Byte; Q: BS;
begin
  Q := [];
  for K := 0 to 3 do {is it right? upper?}
    {what i need here?}
    Include(Q, {what i put here});

  Upper4Bits := Byte(Q)
end;

提前致谢。

Answer 1

根据您对kotlinski答案的评论，您需要result := (byte1 and $F0) or (byte3 and $0F)。

Answer 2

Answer 3

Upper4Bits := X Shr 4;怎么样？