我正在 MIPS 中制作电话目录，但在获取每次递归时输入的元素时遇到问题。当选择模式 [I]（查询）来检索我之前所做的输入时，将使用 Print_Entry 函数。但是，当我创建新条目时，前一个条目的元素会被我插入的最新元素覆盖。每个元素占用 20 个字符的内存。谁能解释为什么该程序不保留以前条目的元素？
.data
menu: .asciiz "\nPlease determine operation, Entry[E],Inquiry[I] ,Quit[Q]: \n"
get_first: .asciiz "\nPlease enter first name: \n"
get_last: .asciiz "\nPlease enter last name: \n"
get_num: .asciiz "\nPlease enter phone number: \n"
entry_submission: .asciiz "\nThank you, the new entry is the following: "
find_contact: .asciiz "\nPlease enter the entry number you wish to retrieve: "
not_found: .asciiz "\nThere is no such entry in the phonebook"
print_contact: .asciiz "\nThe number is: "
error_message: .asciiz "\nWrong input, please try again\n"
space1: .asciiz "\n"
space2: .asciiz ".\n"
.align 2
last_name: .space 20
first_name: .space 20
phone_num: .space 20
phonebook: .space 600
.text
main:
la $s1,phonebook #Set address to phonebook in $s1
addu $s4, $zero, $s1
ori $s2, $zero, 0 #Index for how many times we have executed Get_Entry
sub_main:
#E=69 I=73 Q=81 (ascii codes)
#Call function Prompt_User
jal Prompt_User
beq $s0,69,x
beq $s0,73,y
beq $s0,81,z
#Print "Wrong input try again" if it isn't one of the 3 letters
ori $v0, $zero, 4
la $a0, error_message
syscall
j sub_main
x:
#Call function Get_Entry
jal Get_Entry
j sub_main
y:
#Call function Print_Entry
jal Print_Entry
j sub_main
z:
#Terminate the programm
ori $v0, $zero, 10
syscall
Prompt_User:
#print "Please determine operation, Entry[E],Inquiry [I] ,Quit [Q]: \n"
ori $v0, $zero, 4
la $a0, menu
syscall
#Get users input
ori $v0, $zero, 12 #call=12=read character
syscall
#Save user's choice in $s0
addu $s0, $zero, $v0
jr $ra
Get_Entry:
addi $sp, $sp, -4 # enlarge the stack, to make room for one word
sw $ra, 0($sp) # save return address to stack
addu $s5, $zero, $s4
jal Last_Name #Asks for the Last Name from user
addi $s4,20
jal First_Name #Asks for the First Name from user
addi $s4,20
jal Phone_Number #Asks for the Phone Number from user
addi $s4,20
#Prints "Thank you, the new entry is the following: "
ori $v0, $zero, 4
la $a0, entry_submission
syscall
ori $v0, $zero, 4
la $a0, space1
syscall
#Prints index
ori $v0, $zero, 1
addu $a0, $zero, $s2
syscall
ori $v0, $zero, 4
la $a0, space2
syscall
#Prints Last Name
ori $v0, $zero, 4
lw $a0, 0($s5)
syscall
#Prints first name
ori $v0, $zero, 4
lw $a0, 20($s5)
syscall
#Prints phone number
ori $v0, $zero, 4
lw $a0, 40($s5)
syscall
addi $s2,$s2,1 #Progress counter of Get_Entry executions
lw $ra, 0($sp) # load return address to stack
addi $sp, $sp, 4 # shrink the stack to its former size
jr $ra
Last_Name:
#Ask for last name
ori $v0, $zero, 4
la $a0, get_last
syscall
#Read user's input
ori $a1, $zero, 20
ori $v0, $zero, 8
la $a0,last_name
syscall
la $t0, last_name #Load address of user's input in $t0
sw $t0, 0($s4) #Store user's string in phonebook
jr $ra
First_Name:
#Ask for first name
ori $v0, $zero, 4
la $a0, get_first
syscall
#Read user's input
ori $a1, $zero, 20
ori $v0, $zero, 8
la $a0,first_name
syscall
la $t0, first_name #Load address of user's input in $t0
sw $t0, 0($s4) #Store user's string in phonebook
jr $ra
Phone_Number:
#Ask for Phone Number
ori $v0, $zero, 4
la $a0, get_num
syscall
#Read user's input
ori $a1, $zero, 20
ori $v0, $zero, 8
la $a0,phone_num
syscall
la $t0,phone_num #Load address of user's input in $t0
sw $t0, 0($s4) #Store user's string in phonebook
jr $ra
Print_Entry:
#Print "Please enter the entry number you wish to retrieve:"
ori $v0, $zero, 4
la $a0, find_contact
syscall
#Get user's choice
ori $v0, $zero, 5
syscall
addu $t8, $zero, $v0
#Check if user's input is less than 0
slt $t7, $t8, $0
bne $t7, $zero, exit
#Check if user's input is greater than the number of entries in the catalog
slt $t7, $s2, $t8
bne $t7, $zero, exit
addi $t1,$zero,60
mul $t9, $t8, $t1
addu $s3, $s1, $t9
#Print "The number is:"
ori $v0, $zero, 4
la $a0, print_contact
syscall
#Print Last name of registration
ori $v0, $zero, 4
lw $a0, 0($s3)
syscall
#Print First name of registration
ori $v0, $zero, 4
lw $a0, 20($s3)
syscall
#Print phone number of registration
ori $v0, $zero, 4
lw $a0, 40($s3)
syscall
jr $ra
exit:
#Print "There is no such entry in the phonebook"
ori $v0, $zero, 4
la $a0, not_found
syscall
jr $ra
图？？？ xreiazomai thn voitheia su