MIPS程序设计实例

Posted 2021-01-07 lfri

第一题：用系统功能调用实现简单输入输出

题目要求

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，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

　　4、支持反复输入，直到按“?”键结束程序

MIPS代码

  1 .data
  2    alphabetU: .asciiz " Alpha
"," Bravo
"," China
"," Delta
"," Echo
"," Foxtrot
"," Golf
"," Hotel
",
  3         " India
"," Juliet
"," Kilo
"," Lima
"," Mary
"," November
"," Oscar
"," Paper
"," Quebec
",
  4         " Research
"," Sierra
"," Tango
"," Uniform
"," Victor
"," Whisky
"," X-ray
"," Yankee
"," Zulu
"
  5    alphabetL: .asciiz  " alpha
"," bravo
"," china
"," delta
"," echo
"," foxtrot
"," golf
"," hotel
"," india
",
  6         " juliet
"," kilo
"," lima
"," mary
"," november
"," oscar
"," paper
"," quebec
"," research
",
  7         " sierra
"," tango
"," uniform
"," victor
"," whisky
"," x-ray
"," yankee
"," zulu
"
  8    al_offset: .word 0,8,16,24,32,39,49,56,64,72,81,88,95,102,113,121,129,138,149,158,166,176,185,194,202,211
  9    number:  .asciiz  " Zero
"," First
"," Second
"," Third
"," Fourth
"," Fifth
"," Sixth
"," Seventh
"," Eighth
"," Ninth
"
 10    n_offset:  .word    0,7,15,24,32,41,49,57,67,76
 11    exit_str: .asciiz "#Stop program#"
 12    
 13 .text
 14 .globl  main
 15 main:
 16     li $v0,12                #$v0 contian character read
 17     syscall
 18     beq $v0,‘?‘,exit         #if(v0 == ‘?‘),exit
 19 
 20     #is symble?
 21     sub $t1,$v0,‘0‘
 22     blt $t1,0,symble
 23     
 24     #is number?
 25     sub $t2,$t1,10           #$t2 = $t1 - 10
 26     blt $t2,0,getnum
 27     
 28     #is upper case?
 29     sub $t0,$v0,92
 30     slt $s2,$t0,$0      #if (v0 < ‘Z‘) then s2 = 1
 31     sub $t0,$v0,64
 32     sgt $s3,$t0,$0      #if(v0 > ‘A‘)  then  s3 = 1
 33     and $s1,$s2,$s3     #$s1 = ($s2 && s3)
 34     beq $s1,1,getuword
 35     
 36     #is lower case?
 37     sub $t0,$v0,123
 38     slt $s2,$t0,$0      #if (v0 < ‘Z‘) then s2 = 1
 39     sub $t0,$v0,96
 40     sgt $s3,$t0,$0      #if(v0 > ‘A‘)  then  s3 = 1
 41     and $s1,$s2,$s3     #$s1 = ($s2 && s3)
 42     beq $s1,1,getlword
 43     
 44 symble:
 45     li  $v0,11
 46     add $a0,$0,32        #load value 32 into argument register $a0
 47     syscall              #print space
 48     
 49     add $a0,$a0,10       #32 + 10 = ‘*‘
 50     syscall 
 51     
 52     sub,$a0,$a0,32        #‘*‘ - 32 = ‘
‘
 53     syscall
 54     j main
 55 
 56 getnum:
 57     add $t2,$t2,10        #add 10
 58     sll $t2,$t2,2         #every word use 1 byte (no.9 at address of 9<<2)
 59    
 60    la $s0,n_offset        #load address to $s0
 61    add $s0,$s0,$t2        #$s0 = $s0 + offset
 62    lw  $s1,($s0)  
 63    
 64    la $a0,number
 65    add $a0,$a0,$s1        #$a0 = number + offset
 66    li $v0,4
 67    syscall
 68    j main
 69 
 70 getuword:
 71     sub,$t0,$t0,1
 72     sll $t0,$t0,2
 73     la $s0,al_offset
 74     add $s0,$s0,$t0
 75     lw  $s1,($s0)
 76     la $a0,alphabetU
 77     add $a0,$a0,$s1
 78     li $v0,4
 79     syscall
 80     j main
 81 
 82 getlword:
 83     sub,$t0,$t0,1
 84     sll $t0,$t0,2
 85     la $s0,al_offset
 86     add $s0,$s0,$t0
 87     lw  $s1,($s0)
 88     la $a0,alphabetL
 89     add $a0,$a0,$s1
 90     li $v0,4
 91     syscall
 92     j main
 93 
 94 exit:
 95     add $a0,$0,‘
‘
 96     li $v0,11
 97     syscall
 98     
 99     la $a0,exit_str
100     li $v0,4
101     syscall
102     

第二题：字符串查找比较

题目要求

利用系统功能调用从键盘输入一个字符串，然后输入单个字符，查找该字符串中是否有该字符（区分大小写）。具体要求如下：

　　1、如果找到，则在屏幕上显示：

       Success! Location: X

　　　 其中，X为该字符在字符串中第一次出现的位置

 

　　2、如果没找到，则在屏幕上显示

　　　　Fail!

 

　　3、输入一个字符串后，可以反复输入希望查询的字符，直到按“?”键结束程序

　　4、每个输入字符独占一行，输出查找结果独占一行，位置编码从1开始。

提示：为避免歧义，字符串内不包含”?”符号

MIPS代码

 

 1 #https://ehye.github.io/2017/10/10/MIPS-program-design0/
 2 .data 
 3     success_str: .asciiz  "
Success! Location: "
 4     fail_str:  .asciiz  "
Fail!
 5     buffer: .space 20
 6     exit_str: .asciiz "
#Stop program#"
 7    str1:  .asciiz "Enter string: "
 8    str2:  .asciiz "Enter char: 
 9    
10 .text
11 .globl  main
12 main:
13     #init
14     # a0 = input/result string
15    # a1 = input string length
16    # a2 = input char
17    # a3 = loop donefail
18    li $a3,0
19    li $t0,0
20    
21    #take string
22    la $a0,buffer
23    li $a1,20
24    li $v0,8
25    syscall
26    
27 takechar:
28     li $v0,12
29     syscall
30     beq $v0,‘?‘,exit
31     move  $a2,$v0
32     
33 search:
34     beq $t0,$a1,fail       #if (i == length) then donefail
35     la $a0,buffer                #else load byte
36     add $t2,$a0,$t0            #$t2 = $a0 + offset
37     lb  $s1,($t2)                #$s1 = *$t2
38     beq $s1,$a2,success        #if($s1 == $a2),thne sucess
39     add $t0,$t0,1                #i++
40     j search
41 
42 fail:
43     add $a3,$zero,1            # flag donefail = 1
44     add $t0,$zero,$zero        # reset int i = 0
45     
46     la $a0,fail_str
47     li $v0,4
48     syscall
49     
50     add $a0,$zero,‘
‘
51     li $v0,11
52     syscall
53     j takechar
54     
55 success:
56     la $a0,success_str
57     li $v0,4
58     syscall
59     
60     li $v0,1
61     add $a0,$t0,1            #print index begin from 1 
62     syscall
63     
64     add $a0,$zero,‘
‘
65     li $v0,11
66     syscall
67     add $t0,$zero,0          #reset int i = 0
68     j takechar
69     
70 exit:
71     la  $a0,exit_str    #print exit
72     li  $v0,4
73     syscall
74     
75     li  $v0,10                #exit
76     syscall

 

解释一下，由于这个编辑器插入代码不能选择MIPS，所以没有语法高亮，额，哎哎，水平太菜，知道好的解决方法得大佬请留言啊！