汇编语言 字母的大小写转换

大小写转换问题

A     41H  0100  0001B        or  0010  0000B   转换为小写

B   42H  0100  0010B

C     43H  0100  0011B

D     44H  0100  0100B

a     61H  0110  0001B         and  1101  1111B   转换为大写

b     62H  0110  0010B

c     63H  0110  0011B

d     64H  0110  0100B

方法一：

assume cs:code

data segment

db 'ABcDEF'      ; 将ABcDEF全部转换为小写

db 'abCdef'      ; 将abCdef全部转换为大写 

data ends

stack segment stack

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

stack ends

code segment

start:

mov ax, data

mov ds, ax

mov bx, 0

mov ax, data

mov es, ax

mov cx, 6

downLetter: mov dl, ds:[bx]

or dl, 00100000B 

mov es:[bx], dl

inc bx

loop downLetter

mov cx, 6

mov bx, 6

UpLetter:  mov dl, ds:[bx]

and dl, 11011111B

mov es:[bx], dl

inc bx

loop UpLetter

mov ax, 4C00H

int 21H

code ends

end start

方法二：

assume cs:code

data segment

db 'ABcDEF'      ;单引号

db 'abCdef'

data ends

stack segment stack

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

stack ends

code segment

start:

mov ax, data

mov ds, ax

mov bx, 0

mov ax, data

mov es, ax

mov cx, 6

setLetter: mov dl, ds:[bx]

or dl, 00100000B 

mov es:[bx], dl

mov dl, ds:[bx + 6]

and dl, 11011111B

mov es:[bx + 6], dl

inc bx

loop setLetter

mov ax, 4C00H

int 21H

code ends

end start

代码执行结果：

data 段中每个单词的头一个字母改为大写

assume cs:code, ds:data

data segment 

db  '1. file         '

db  '2. edit         '

db  '3. search       '

db  '4. view         '

db  '5. options      '

db  '6. help         '

data ends

code segment

start:

mov ax, data

mov ds, ax

mov es, ax

mov bx, 0

mov si, 3

mov cx, 6

upLetter: mov dl, ds:[bx + si]

and dl, 11011111B

mov es:[bx + si], dl

add bx, 16

loop upLetter

mov ax, 4C00H

int 21

code ends

end start

代码执行结果：

data 段中每个单词都改为大写

assume cs:code, ds:data

data segment 

db  '1. ibm          '

db  '2. dec          '

db  '3. dos          '

db  '4. vax          '

data ends

stack segment

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

stack ends

code segment

start:

mov ax, stack

mov ss, ax

mov sp, 32

mov ax, data

mov ds, ax

mov es, ax

mov cx, 4

mov bx, 0

mov si, 3

upLetter:   push cx

push si

mov cx, 3

upRow: mov dl, ds:[bx + si]

and dl, 11011111B

mov es:[bx + si], dl

inc si

loop upRow

pop si

pop cx

add bx, 16

loop upLetter

mov ax, 4C00H

int 21

code ends

end start

代码执行结果：

data 段中每个单词前4个字母都改为大写

assume cs:code, ds:data

data segment 

db  '1. display      '

db  '2. brows        '

db  '3. replace      '

db  '4. modify       '

data ends

stack segment

dw 0, 0, 0, 0, 0, 0, 0, 0

dw 0, 0, 0, 0, 0, 0, 0, 0

stack ends

code segment

start:

mov ax, stack

mov ss, ax

mov sp, 32

mov ax, data

mov ds, ax

mov es, ax

mov cx, 4

mov bx, 0

mov si, 3

upRow:    push cx

push si

mov cx, 4

upCol: mov dl, ds:[bx + si]

and dl, 11011111B

mov es:[bx + si], dl

inc si

loop upCol

pop si

pop cx

add bx, 16

loop upRow

mov ax, 4C00H

int 21

code ends

end start