系统功能调用实现简单输入输出

实验目的：熟悉MIPS的指令，掌握简单的汇编程序结构。

实验内容：利用系统功能调用从键盘输入，转换后在屏幕上显示，具体要求如下：

(1) 如果输入的是字母(A~Z，不区分大小写)或数字(0~9)，则将其转换成对应的英文单词后在屏幕上显示，对应关系见下表

(2) 若输入的不是字母或数字，则在屏幕上输出字符“*”

(3) 每输入一个字符，即时转换并在屏幕上显示，需考虑显示结果的清晰美观

(4) 支持反复输入，直到按？键结束程序

(5) 程序结束时，在屏幕上显示本人的姓名全拼和学号

例：在键盘上输入“U2011/”，对应输出内容为“Uniform two zero one one *”

A

Alpha

N

November

1

one

B

Bravo

O

Oscar

2

two

C

Charlie

P

Papa

3

three

D

Delta

Q

Quebec

4

four

E

Echo

R

Romeo

5

five

F

Foxtrot

S

Sierra

6

six

G

Golf

T

Tango

7

seven

H

Hotel

U

Uniform

8

eight

I

India

V

Victor

9

nine

J

Juliet

W

Whisky

0

zero

K

Kilo

X

X-ray

L

Lima

Y

Yankee

M

Mike

Z

Zulu

.data

myname:.asciiz "\r\nNAME:locusxt\r\n"

id:.asciiz "ID:locusxt\r\n"

aa:.asciiz "Alpha " #以下是字母对应的字符串

bb:.asciiz "Bravo "

cc:.asciiz "Charlie "

dd:.asciiz "Delta "

ee:.asciiz "Echo "

ff:.asciiz "Foxtrot "

gg:.asciiz "Golf "

hh:.asciiz "Hotel "

ii:.asciiz "India "

jj:.asciiz "Juliet "

kk:.asciiz "Kilo "

lll:.asciiz "Lima "

mm:.asciiz "Mike "

nn:.asciiz "November "

oo:.asciiz "Oscar "

pp:.asciiz "Papa "

qq:.asciiz "Quebec "

rr:.asciiz "Romeo "

ss:.asciiz "Sierra "

tt:.asciiz "Tango "

uu:.asciiz "Uniform "

vv:.asciiz "Victor "

ww:.asciiz "Whisky "

xx:.asciiz "X-ray "

yy:.asciiz "Yankee "

zz:.asciiz "Zulu "

zero:.asciiz "zero " #以下是数字对应的单词

one:.asciiz "one "

two:.asciiz "two "

three:.asciiz "three "

four:.asciiz "four "

five:.asciiz "five "

six:.asciiz "six "

seven:.asciiz "seven "

eight:.asciiz "eight "

nine:.asciiz "nine "

star:.asciiz "* "

alphabet: .word aa, bb, cc, dd, ee, ff, gg, hh, ii, jj, kk, lll, mm, nn, oo, pp ,qq, rr, ss, tt, uu, vv, ww, xx, yy, zz

num: .word zero, one, two, three, four, five, six, seven, eight, nine

backspace:.asciiz "\b"

.text

.globl main

main:

li $s0, 'z'

li $s1, 'a'

li $s2, 'Z'

li $s3, 'A'

li $s4, '9'

li $s5, '0'

getKey:

li $v0, 12

syscall

#addi $t0, $v0, 0

#la $a0, backspace

#li $v0, 4

#syscall

#addi $v0, $t0, 0

compare:

li $t0, '?'

beq $v0, $t0, deal

#判断是不是小写字母

slt $t0, $s0, $v0 #s0 < v0 ?

bne $t0, $0, dispstar

slt $t0, $v0, $s1 #v0 < s1 ?

beq $t0, $0, dispalph

#判断是不是大写字母

slt $t0, $s2, $v0

bne $t0, $0, dispstar

slt $t0, $v0, $s3

beq $t0, $0, dispalphc

#判断是不是数字

slt $t0, $s4, $v0

bne $t0, $0, dispstar

slt $t0, $v0, $s5

beq $t0, $0, dispnum

j dispstar

dispalphc:#大写字母+32变小写

addi $v0, $v0, 32

dispalph:#处理字母

sub $v0, $v0, $s1 #v0 -= 'a'

sll $v0, $v0, 2

la $t0, alphabet

add $t0, $t0, $v0

lw $a0, ($t0)

li $v0, 4

syscall

j getKey

dispnum:#处理数字

sub $v0, $v0, $s5 #v0 -= '0'

sll $v0, $v0, 2

la $t0, num

add $t0, $t0, $v0

lw $a0, ($t0)

li $v0, 4

syscall

j getKey

dispstar:

la $a0, star

li $v0, 4

syscall

j getKey

deal:#处理问号

la $a0, myname

li $v0, 4

syscall

la $a0, id

li $v0, 4

syscall

==================

syscall 里好像没有不回显的从键盘读

输出"退格"也是不行的,好像直接输出了个空格.

也有可能是mars模拟器太弱了.

这里以及另外一道的esc结束，都替换成了'？'结束