AND: 邏輯與

;該指令會置 CF=OF=0; 其結果影響 SF、ZF、PF

;指令格式:

AND r/m, r/m/i

; Test22_1.asm - 使用 AND 運算將一個數的第二、四位清零

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.code

main proc

mov al, 00001111b

and al, 11110101b

PrintHex al ;05 - 00000101b

ret

main endp

end main

; Test22_2.asm - 使用 AND 運算將字母轉大寫

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.data

szText db "Delphi", 0

.code

main proc

lea esi, szText

mov ecx, lengthof szText - 1

@@: and byte ptr [esi], 11011111b ;大寫字母和小寫字母只有第五位不同

inc esi

loop @B

PrintString szText ;DELPHI

ret

main endp

end main

OR: 邏輯或

;該指令會置 CF=OF=0; 其結果影響 SF、ZF、PF

;指令格式:

OR r/m, r/m/i

; Test22_3.asm - 使用 OR 運算確保一個數的第二、四位是 1

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.code

main proc

mov al, 11110001b

or al, 00001010b

PrintHex al ;FB - 11111011b

ret

main endp

end main

; Test22_4.asm - 使用 OR 運算將字母轉小寫

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.data

szText db "Delphi", 0

.code

main proc

lea esi, szText

mov ecx, lengthof szText - 1

@@: or byte ptr [esi], 00100000b ;大寫字母和小寫字母只有第五位不同

inc esi

loop @B

PrintString szText ;delphi

ret

main endp

end main

XOR: 邏輯異或

;該指令會置 CF=OF=0; 其結果影響 SF、ZF、PF

;指令格式:

XOR r/m, r/m/i

; Test22_5.asm - 兩次和一個相同的數 XOR 恢復到原來的數

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.code

main proc

mov eax, 12345

xor eax, 88888888

PrintDec eax ;88892929

xor eax, 88888888

PrintDec eax ;12345

ret

main endp

end main

; Test22_6.asm - 使用 XOR 加密與解密字串

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.data

szText db "Hello World!", 0

.code

main proc

;加密

lea esi, szText

mov ecx, lengthof szText - 1

@@: xor byte ptr [esi], 123 ;使用 123 做密碼

inc esi

loop @B

PrintString szText ;顯示亂碼

;解密

lea esi, szText

mov ecx, lengthof szText - 1

@@: xor byte ptr [esi], 123

inc esi

loop @B

PrintString szText ;Hello World!

ret

main endp

end main

NOT: 邏輯取反

;該指令不影響 EFlags

;指令格式:

NOT r/m

; Test22_7.asm - 使用 NOT 加密與解密字串

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.data

szText db "Hello World!", 0

.code

main proc

;加密

lea esi, szText

mov ecx, lengthof szText - 1

@@: not byte ptr [esi]

inc esi

loop @B

PrintString szText ;顯示亂碼

;解密

lea esi, szText

mov ecx, lengthof szText - 1

@@: not byte ptr [esi]

inc esi

loop @B

PrintString szText ;Hello World!

ret

main endp

end main

TEST: 測試邏輯與

;該指令會置 CF=OF=0; 其結果影響 SF、ZF、PF

;指令格式:

TEST r/m, r/m/i

;TEST 同 AND, 但它不修改運算數, 只改變標誌暫存器; 也就是嘗試 AND 的結果

;常用到它對 ZF 的影響(結果為0時ZF=1)

;TEST 之後常常跟著條件跳轉指令 JZ、JNZ

; Test22_8.asm - 觀察 TEST 之後的零標誌位(ZF)

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.code

main proc

;判斷字母 A 二進位制(01000001)的其最後一位是否是 0, 如果是 0 那麼 ZF=1

mov al, "A"

test al, 00000001b

lahf

PrintHex ah ;02 - 00000010b (ZF=0)

;判斷字母 B 二進位制(01000010)的其最後一位是否是 0, 如果是 0 那麼 ZF=1

mov al, "B"

test al, 00000001b

lahf

PrintHex ah ;46 - 01000110b (ZF=1)

;判斷 ecx 是否為空

mov ecx, 1

test ecx, ecx

lahf

PrintHex ah ;06 - 00000010b (ZF=0, 不為空)

xor ecx, ecx

test ecx, ecx

lahf

PrintHex ah ;06 - 01000110b (ZF=1, 為空)

ret

main endp

end main

; Test22_9.asm - 判斷字串中每個字元的二進位制位的最後一位是 1 還是 0

.386

.model flat, stdcall

include windows.inc

include kernel32.inc

include masm32.inc

include debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib

.data

szText db "Delphi", 0

.code

main proc

;清空兩個暫存器用於計數

xor eax, eax

xor edx, edx

lea esi, szText ;字串地址

mov ecx, lengthof szText - 1 ;字串長度

L1: test byte ptr [esi], 00000001b ;迴圈測試每個字元的最後一位是 1 還是 0

jz L2 ;如果是 0 則跳到 L2 給 edx+1

inc eax ;反之給 eax+1

jmp L3

L2: inc edx

L3: inc esi

loop L1

PrintDec eax ;2 - 這是最後一位是 1 的字元的個數: e、i

PrintDec edx ;4 - 這是最後一位是 0 的字元的個數: D、l、p、h

ret

main endp

end main