(9)SHL BH,CL (BH)=0F0H CF=0 (10)SAL AX,1 (AX)=4A10H CF=0
(11)RCL BX,1 CF=1,(BX)=1E6DH, CF=0,(BX)=1E6CH CF=0 (12)ROR DX,CL (DX)=4186H CF=0 11. 假设数据定义如下: DATA SEGMENT
STRING DB ‘The Personal Computer & TV’ DATA ENDS
试用字符串操作指令编程完成以下功能:
(1)把该字符串传送到附加段中偏移地址为GET_CHAR开始的内存单元中。 解:程序段如下:
LEA SI,STRING ;置源串偏移地址 LEA DI,GET_CHAR ;置目的串偏移地址 MOV CX,26 ;置串长度 CLD ;方向标志复位 REP MOVSB ;字符串传送
12.编程将AX寄存器中的内容以相反的次序传送到DX寄存器中,并要求AX中的内容不被破坏,然后统计DX寄存器中1的个数是多少。
解:将AX的内容用ROR循环右移,16次之后AX的内容不变(如果用算术/逻辑右移SHL/SAL,则AX的内容破坏,需要用堆栈PUSHU AX/POP AX保护),其最低位移入CF中,再使用RCL循环左移将CF中的值移入DX中。并且,如果CF的值为1,则将BL加1。
MOV CX, 16 XOR BL, BL
LP1: ROR AX, 1
JNC LP2 INC BL
LP2: RCL DX,1
LOOP LP1 HLT
调试程序:
STACK SEGMENT STACK
DB 100 DUP(?) STACK ENDS DATA SEGMENT BUF DW 12
BUF1 DW 100 DUP (?) DATA ENDS CODE SEGMENT
ASSUME CS:CODE,DS:DATA,SS:STACK START: PUSH DS
MOV AX,DATA
MOV DS,AX MOV AX,1234H
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MOV CX, 16 XOR BL, BL LP1: ROR AX, 1 JNC LP2 INC BL LP2: RCL DX,1 LOOP LP1 HLT CODE ENDS
15. 某班有七个同学的英语成绩低于80分,分数存在ARRAY数组中,试编程完成以下工作:给每人加5分,结果存到NEW数组中. 解:
STACK SEGMENT STACK
DB 100 DUP(?) STACK ENDS DATA SEGMENT
ARRAY DB 7 DUP(?)
NEW DB 7 DUP(?) DATA ENDS CODE SEGMENT
ASSUME CS:CODE,DS:DATA,SS:STACK START: MOV CX, 7 MOV BX, 0
LP1: MOV AL, ARRAY[BX] ADD AL, 05H DAA
MOV NEW[BXI], AL INC BX LOOP LP1 HLT CODE ENDS
END START 调试程序:
STACK SEGMENT STACK
DB 100 DUP(?) STACK ENDS DATA SEGMENT
ARRAY DB 65H,76H,78H,54H,90H,85H,68H NEW DB 7 DUP(?) BUF1 DW 100 DUP (?) DATA ENDS CODE SEGMENT
END START
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ASSUME CS:CODE,DS:DATA,SS:STACK START: PUSH DS
MOV AX,DATA
MOV DS,AX MOV CX, 7 MOV BX, 0
LP1: MOV AL, ARRAY[BX] ADD AL, 05H DAA
MOV NEW[BXI], AL INC BX LOOP LP1 HLT CODE ENDS
某班有七个同学的英语成绩低于80分,分数存在ARRAY数组中,试编程完成以下工作: (1)给每人加5分,结果存到NEW数组中 (2)把总分存到SUM单元中 (3)把平均分存到AVERAGE单元中 解:
STACK SEGMENT STACK
DB 100 DUP(?) STACK ENDS DATA SEGMENT
ARRAY DB 7 DUP(?)
NEW DB 7 DUP(?) SUM DW 0 AVG DB 0 DATA ENDS CODE SEGMENT
ASSUME CS:CODE,DS:DATA,SS:STACK START: MOV CX, 7 MOV SI, 0 MOV SUM, 0 MOV AH, 0 LP1: MOV AL, ARRAY[SI] ADD AL, 05H DAA
MOV NEW[SI], AL ADD AL ,SUM DAA
MOV SUM,AL
END START
7
ADC AH, 0 DAA
MOV SUM+1, AH INC SI LOOP LP1 MOV AX, SUM MOV BL,07H DIV BL MOV AVG, AL HLT CODE ENDS
END START 调试程序:
STACK SEGMENT STACK
DB 100 DUP(?) STACK ENDS DATA SEGMENT
ARRAY DB 65H,76H,78H,54H,90H,85H,68H NEW DB 7 DUP(?) SUM DB 00H,00H AVG DB 0
BUF1 DW 100 DUP (?) DATA ENDS CODE SEGMENT
ASSUME CS:CODE,DS:DATA,SS:STACK START: PUSH DS
MOV AX,DATA
MOV DS,AX MOV CX, 7 MOV SI, 0 MOV SUM, 0 MOV AH, 0 LP1: MOV AL, ARRAY[SI] ADD AL, 05H DAA
MOV NEW[SI], AL ADD AL , SUM DAA
MOV SUM,AL ADC AH, 0 MOV SUM+1, AH INC SI LOOP LP1 MOV AL, SUM
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