初学 Delphi 嵌入汇编[17] - 逻辑运算

AND: 逻辑与指令
OR : 逻辑或指令
XOR: 逻辑异或指令
NOT: 逻辑非指令

这和 Delphi 的逻辑命令完全一致.

---

//逻辑非 Not: 
{
  not 1 = 0; 
  not 0 = 1;
}
var
  ByteNum: Byte;
begin
  //赋值 11111111B (255) 取反:
  asm
    mov al, 11111111B {eax 包含 ax; ax 包含 al; al 是 eax 的低八位}
    not al            {给 11111111 取反会得到 00000000}
    mov ByteNum, al   {把寄存器 al 中的值给变量 ByteNum}
  end;
  ShowMessage(IntToStr(ByteNum)); {0}


  //赋值 00000001B (1) 取反:
  asm
    mov al, 00000001B
    not al            {给 00000001 取反会得到 11111110}
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {254}


  //赋值 10000000B (128) 取反:
  asm
    mov al, 00000001B
    not al            {给 10000000 取反会得到 01111111}
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {127}
end;

---

//逻辑或 Or: 
{
  1 or 0 = 1; 
  0 or 1 = 1; 
  1 or 1 = 1; 
  0 or 0 = 0;
}
var
  ByteNum: Byte;
begin
  asm
    mov al, 10101010B {170}
    mov cl, 01010101B {85}
    or  al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {255}
end;

---

//逻辑与 And:
{
  1 and 1 = 1;
  1 and 0 = 0;
  0 and 1 = 0;
  0 and 0 = 0;
}
var
  ByteNum: Byte;
begin
  //例1
  asm
    mov al, 11111111B {255}
    mov cl, 11111111B {255}
    and al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {255}

  //例2
  asm
    mov al, 00000000B {0}
    mov cl, 00000000B {0}
    and al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {0}

  //例3
  asm
    mov al, 11111111B {255}
    mov cl, 00000000B {0}
    and al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {0}

  //例4
  asm
    mov al, 10101010B {170}
    mov cl, 01010101B {85}
    and al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {0}
end;

---

//逻辑异或 Xor:
{
  1 Xor 0 = 1;
  0 Xor 1 = 1;
  1 Xor 1 = 0;
  0 Xor 0 = 0;
}
var
  ByteNum: Byte;
begin
  //例1
  asm
    mov al, 11111111B {255}
    mov cl, 11111111B {255}
    xor al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {0}

  //例2
  asm
    mov al, 11111111B {255}
    mov cl, 00000000B {0}
    xor al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {255}

  //例3
  asm
    mov al, 10101010B {170}
    mov cl, 01010101B {85}
    xor al, cl
    mov ByteNum, al
  end;
  ShowMessage(IntToStr(ByteNum)); {255}
end;

---