想看看有人能告诉我我的while循环有什么问题。我试图让程序读取用户输入的字符串（罗马数字），然后比较我的if语句到最后总结金额并将其打印为整数。现在它读取了第一个字母M（MXXI），但是当它到达X时就开始了。
.data
buffer: .space 20
onlyCaps: .asciiz "Please enter only Capital Numbers\n"
enter1: .asciiz "Number out of range. Please enter another number\n"
enter2: .asciiz "Please enter your roman numeral: "
debug: .asciiz "reach"
M: .asciiz "1000"
D: .asciiz "500"
C: .asciiz "100"
L: .asciiz "50"
X: .asciiz "10"
V: .asciiz "5"
I: .asciiz "1"
.text
main:
la $a0, onlyCaps # "Enter Only Capital numbers"
li $v0, 4
syscall
la $a0, enter2 #prompt user with "Please enter a roman numeral:"
li $v0, 4
syscall
la $a0, buffer #load byte space into address
li $a1, 3 # allot the byte space for string
li $v0, 8 #read user input, j
syscall
li $t4, 1 #initialized at 1 for the loop
loop:
lb $t0, 0($a0) # Save $v0 value to $t0
add $a0, $a0, $t4 #increment the address
j mCheck
#while loop ends here
mCheck:
beq $t0, 'M', mChar # if $t0 equal M go to mChar
bne $t0, 'M', dCheck # move to see if equals D
dCheck:
beq $t0, 'D', dChar # if $t0 equal D go to dChar
bne $t0, 'D', cCheck
cCheck:
beq $t0, 'C', cChar # if $t0 equal C go to cChar
bne $t0, 'C', lCheck
lCheck:
beq $t0, 'L', lChar # if $t0 equal L go to lChar
bne $t0, 'L', xCheck
xCheck:
beq $t0, 'X', xChar # if $t0 equal X go to xChar
bne $t0, 'X', vCheck
vCheck:
beq $t0, 'V', vChar # if $t0 equal V go to vChar
bne $t0, 'V', iCheck
iCheck:
beq $t0, 'I', iChar # if $t0 equal I go to iChar
bne $t0, 'I', error
mChar:
la $a0, M #puts one hundred in $t3
li $v0, 4
syscall
j loop
dChar:
la $a0, D # prints out 500
li $v0, 4
syscall
j loop
cChar:
la $a0, C # prints out 500
li $v0, 4
syscall
j loop
lChar:
la $a0, L # prints out 500
li $v0, 4
syscall
j loop
xChar:
la $a0, X # prints out 500
li $v0, 4
syscall
j loop
vChar:
la $a0, V # prints out 500
li $v0, 4
syscall
j loop
iChar:
la $a0, I # prints out 500
li $v0, 4
syscall
j loop
error:
la $a0, enter1 # Print error meg. then back to main
li $v0, 4
syscall
j done
done:
li $v0, 10 # Exit
syscall