求助：MIPS汇编中预定义字符串与用户输入字符串的匹配实现

我需要实现一个可接收命令的控制台程序，但无法通过字符串比较正确解析输入的命令。以下是我当前的MIPS代码，以及我期望实现功能的Java版本示例。我试过网上的各种方法，但都没用——那些方法针对的都是非用户输入的字符串对比场景，不适用于我的情况。

当前MIPS代码 #

.data 
cmdline: .asciiz "> "
helpline: .asciiz "> Commands:\n> help - displays available commands\n> echo - returns text inputted after command\n> exit - exits program\n>\n"
helpcomp: .asciiz "help"
echocomp: .asciiz "echo"
exitcomp: .asciiz "exit"
noRecog: .asciiz "> Command not recognized\n> Input 'help' for a list of commands\n>\n"
tempText: .asciiz "echo found\n"
buffer: .space 21
buffersize: .word 20
.text 

j cmdLoop

cmdLoop:
    li  $v0, 4
    la  $a0, cmdline
    syscall
    
    la      $s2, buffer
    move    $t2, $s2
    syscall
    
    move   $a0,$t2
        la          $a1, buffersize
        li          $v0, 8
        syscall
        
        j help
        
 help:
    la $s3, helpcomp
    move $t2, $s3
compareHelp:

        lb      $t2,($s2)                   # get next char from str1
    lb      $t3,($s3)                   # get next char from str2
    bne     $t2,$t3,compareExit               # are they different? if yes, fly

    beq     $t2,$zero,helpExecute             # at EOS? yes, fly (strings equal)

        addi    $s2,$s2,1                   # point to next char
        addi    $s3,$s3,1                   # point to next char
        j       compareHelp
        
helpExecute:
    li $v0, 4
    la $a0, helpline
    syscall
    
    li $v0, 10
    syscall
    
compareExit:
    li $v0, 4
    la $a0, tempText
    syscall
    
    li $v0, 10
    syscall

期望实现的Java版本 #

public class Console {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        
        System.out.print("> ");
        
        while(true) {
            String command = input.nextLine();
            
            if(command.contains("help")) {
                System.out.print("Commands:"
                        + "\nhelp - displays available commands"
                        + "\necho - prints the text inputted    right after echo"
                        + "\nexit - quits out of the program"
                        + "\n> ");
            } else if (command.contains("echo")) {
                String echo = command.substring(5, command.length());
                System.out.println(echo);
                System.out.print("> ");
            } else if (command.contains("exit")) {
                break;
            }
        }
        input.close();

    }

}

内容的提问来源于stack exchange，提问作者Skyler Van Kleeck