结合两个 MIPS 程序将小写字母转换为大写字母，反之亦然

Question

我正在尝试构建一个基本的 Mips 程序，该程序采用硬编码字符串并将小写字符转换为大写字符，反之亦然。我设法制作了两个程序，一个从上到下，一个从下到上，但我不知道如何将两者结合起来。我相信我的程序中的错误来自于我检查空格并试图跳过它们，但我真的不确定。通过嵌套案例调用，我试图模仿 if-else 逻辑

.data
string: .asciiz "\nThis Is A Test\n"
newline: .asciiz "\n"

.text
main:
    la  $t0, string # $t0 is pointer to first el of str, loading string
    li  $v0, 4      # print the original string
    la  $a0, string
    syscall
    
    li $s2, ' '
    li $v0, 4
    li $t0, 0

loop:
    lb $t1, string($t0)
    beq $t1, 0, exit
    beq $t1, $s2, neither
    
    j caseLower
   
caseLower:
    blt $t1, 'A', caseUpper
    bgt $t1, 'Z', caseUpper
    addi $t1, $t1, 32
    sb $t1, string($t0)
    addi $t0, $t0, 1
    j loop
    
    
caseUpper:
    blt $t1, 'a', neither
    bgt $t1, 'z', neither
    addi $t0, $t0, -32 
    sb $t1, string($t0)
    addi $t0, $t0, 1
    j loop
    
neither:
    addi $t0, $t0, 1
    j loop
    
exit:
    li $t0, 4
    la $a0, string
    syscall

    li $v0, 10
    syscall

这是我得到的输出：


This Is A Test

this Is A Test

-- program is finished running --

第二行输出我想要的输出是：tHIS iS a tEST

Answer 1

addi $t0, $t0, -32 有问题。

应该是addi $t1, $t1, -32 .

.data
string: .asciiz "\nThis Is A Test\n"
newline: .asciiz "\n"

.text
main:
    la  $t0, string # $t0 is pointer to first el of str, loading string
    li  $v0, 4      # print the original string
    la  $a0, string
    syscall
    
    li $s2, ' '
    li $v0, 4
    li $t0, 0

loop:
    lb $t1, string($t0)
    beq $t1, 0, exit
    beq $t1, $s2, neither
    
    j caseLower
   
caseLower:
    blt $t1, 'A', caseUpper
    bgt $t1, 'Z', caseUpper
    addi $t1, $t1, 32
    sb $t1, string($t0)
    addi $t0, $t0, 1
    j loop
    
    
caseUpper:
    blt $t1, 'a', neither
    bgt $t1, 'z', neither
    addi $t1, $t1, -32 
    sb $t1, string($t0)
    addi $t0, $t0, 1
    j loop
    
neither:
    addi $t0, $t0, 1
    j loop
    
exit:
    li $t0, 4
    la $a0, string
    syscall

    li $v0, 10
    syscall

结合两个 MIPS 程序将小写字母转换为大写字母，反之亦然

Combining two MIPS programs to convert lowercase to uppercase and vice versa

assembly

mips

mips32