我正在用汇编程序编写一个程序，该程序一次接收一个用户输入字符，并使用递归将其插入按字母顺序排列的字符串中。我已经盯着这个看了很长时间，但它似乎仍然应该工作。对此，其他一些人将不胜感激。
.data
text1: .asciiz "To begin, type a lower case letter.\n"
text2: .asciiz "Any time you are prompted for an input, you may type a 'P' to print the alphabetized string.\n"
text3: .asciiz "You can also type 'Q' to end the program.\n\n"
text4: .asciiz "Input: "
text5: .asciiz "End."
err: .asciiz "Something broke\n"
str: .asciiz "abcdefghijklmnopqrstuvwxyz"
buffer: .space 30
in: .space 4
.text
main: la $a0, text1 #opening statements
li $v0, 4
syscall
la $a0, text2
syscall
la $a0, text3
syscall
input: la $a0, text4
li $v0, 4
syscall
li $v0, 12 #get input character
syscall
move $t0, $v0
li $a0, 0x0a #print new line
li $v0, 11
syscall
beq $t0, 0x50, print #input is 'P'; print out string
beq $t0, 0x51, end #input is 'Q'; end
la $t1, str
search: lb $t2, 0($t1) #search for the starting location
beqz $t2, error
beq $t2, $t0, phase1
addi $t1, $t1, 1
j search
phase1: sw $t2, ($sp) #store the letter on the stack
sub $sp, $sp, 4
sw $t1, ($sp) #store address of the letter on the stack
sub $sp, $sp, 4
addi $t1, $t1, 1 #increment address
lb $t2, 0($t1) #getting next letter to prepare for next loop
beqz $t2, phase2 #if end of string is reached, come out of loop
jal phase1
j input
phase2: lw $ra, ($sp) #pull return location off stack
addi $sp, $sp, 4
lw $t3, ($sp) #pull letter address off stack
addi $sp, $sp 4
lw $t4, ($sp) #pull letter off stack
addi $sp, $sp, 4
addi $t3, $t3, 1 #increment old address to get new address
sw $t4, 0($t3) #store the letter in its new location
jr $ra
error: la $a0, err
li $v0, 4
syscall
j input
print: la $a0, str
li $v0, 4
syscall
li $a0, 0x0a
li $v0, 11
syscall
j input
end: la $a0, text5
li $v0, 4
syscall
li $v0, 10
syscall
具体来说，我在线上遇到错误：
sw $t4, 0($t3)
它说：“存储中未对齐的地址：0x100100e7”
之后，我得到“异常 5 [存储中的地址错误] 发生并被忽略”
随后是“发生并忽略异常 6 [错误指令地址]”的无休止链
我正在使用 QtSpim。