- 分别指出下列指令中源操作数和目的操作数的寻址方式。
(1)MOV SI, 10
(2)MOV DI, [EAX]
(3)ADD EAX, 4[BX]
(4)SUB DX, 5[BX +DI]
(5)MOV [EDI*4 +2], AX
(6)MOV BH, DS:[10]
(7)ADD [SI], SI
(8)ADD CX, -7[BP +DI] - 已知下列各条指令(实方式下)在执行前有:
(EAX) = 0AAH (EBX) = 0BBH (ECX) = 0CCH (EDX) = 0DDH
(EBP) = 5000H (ESI) = 4000H (EDI) = 6000H (DS) = 1000H
(ES) = 2000H (SS) = 3000H以下存储单元的内容均是按字类型说明的:
(35000H) = 100H (100BBH) = 200H (16000H) = 300H (24000H) = 400H
(35500H) = 355H (13D00H) = 0F13DH (17000H) = 0F13DH (100B3H) = 0F8BBH
(27000H) = 270H (39000H) = 39H (160BBH) = 0 (100AAH) = 2
(1A000H) = 1AH试判断下列各指令是否正确, 对于正确的指令,请填写表2.1 中的后面各项。
表2.1 指令分析表(前后指令间没有关系)
| 指令 | 目的操作数地址 | 本指令执行前目的操作数的值 | 本指令执行后目的操作数的值 |
|---|---|---|---|
| MOV AX, 3 | |||
| SUB WORD PTR [AX], 3 | |||
| ADD WORD PTR [EAX], 3 | |||
| ADD BH, 2 | |||
| SUB EBP, 2 | |||
| SUB [CX], DX | |||
| ADD DI, 2 | |||
| SUB SI, 10 | |||
| MOV [BX], BX | |||
| MOV [DI], DX | |||
| MOV ES: [DX], BX | |||
| MOV ES: [SI], DS | |||
| MOV DX, SS | |||
| MOV EAX, EIP | |||
| SUB 2[DX], AX | |||
| ADD 500H[BP], CX | |||
| SUB [SI -300H], AX | |||
| MOV [AX +2], BX | |||
| MOV [DI +1000H], SI | |||
| MOV [CX -100H], AX | |||
| MOV [DX +60], AX | |||
| MOV -8[BX], CX | |||
| MOV ES: 1000[DI], BP | |||
| MOV [BP +SI], DX | |||
| MOV [DI +SI], DX | |||
| MOV [EDI +ESI], DX | |||
| MOV [BX +DI], 10H | |||
| MOV [BX +DI], DX |
- 阅读下列程序, 并指出程序执行之后, 以BUF2、BUF3、BUF4 为首址的3 个字节存储区中存放的数据。
.386
STACK SEGMENT USE16 STACK
DB 200 DUP(0)
STACK ENDS
DATA SEGMENT USE16
BUF1 DB 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
BUF2 DB 10 DUP(0)
BUF3 DB 10 DUP(0)
BUF4 DB 10 DUP(0)
DATA ENDS
CODE SEGMENT USE16
ASSUME CS: CODE, DS: DATA, SS: STACK
START: MOV AX, DATA
MOV DS, AX
MOV SI, OFFSET BUF1
MOV DI, OFFSET BUF2
MOV BX, OFFSET BUF3
MOV BP, OFFSET BUF4
MOV CX, 10
LOPA: MOV AL, [SI]
MOV [DI], AL
INC AL
MOV [BX], AL
ADD AL, 3
MOV DS:[BP], AL
INC SI
INC DI
INC BP
INC BX
DEC CX
JNZ LOPA
MOV AH, 4CH
INT 21H
CODE ENDS
END START- 试修改上一题中的代码段，改用变址寻址方式访问BUF1、BUF2、BUF3、BUF4四个存储区中的存储单元。