我需要 MIPS 汇编语言方面的帮助。我正在为我的大学项目做口译员，但遇到了下一个问题：
我需要阅读一个文本文件。我已经为此编写了所有函数。问题是：读取文件的第一行后文件指针没有改变。
代码：
# Get file name from user
jal getFileName
# Open file in read mode
la $a0, szFilename
li $a1, 0 # open for reading
jal fopen
# Save file handler
la $a0, hFile
sw $v0, ($a0)
######### MAIN INTERPRETER CODE ###########
la $a0, hFile
lw $a0, ($a0) # $a0 = file handler
la $a1, line # $a1 = address of line
li $a3, 255 # $a3 = length of line
jal readLine
la $a0, line
jal puts
# try to read next line
la $a0, hFile
lw $a0, ($a0) # $a0 = file handler
la $a1, line # $a1 = address of line
li $a3, 255 # $a3 = length of line
jal readLine
la $a0, line
jal puts
我的文件内容：
vAr A;
var b = false;
输出是：
Enter filename: code.txt
var a;var a;
PS我的函数readLine将文本从大写转换为小写
我怎么解决这个问题？
我的功能代码：
getFileName:
sub $sp, $sp, 4 # allocate memory in stack to strore 4 bytes
sw $ra, ($sp) # save return address to stack
# display message
la $a0, szEnterFilename
jal puts
#############
# get filename from console
la $a0, szFilename
li $a1, 16
jal gets
###############
la $a0, szFilename
li $a1, '\n'
li $a2, 0
jal strrep
###############
lw $ra, ($sp) # get return address from stack
addi $sp, $sp, 4 # clear reserved bytes
jr $ra # return to caller
# Open file for reading
# $a0 - address of filename
# $a1 - mode (flags are 0: read, 1: write)
# Return value: $v0 - file handler
fopen:
li $v0, 13 # system call for open file
li $a2, 0 # mode is ignored
syscall # open a file (file descriptor returned in $v0)
jr $ra
# Reads one line from file
# $a0: file handler
# $a1: address of line
# $a3: line length
# Return value:
# $v0 : number of characters read (0 if EOF, negative if error)
readLine:
li $t0, 0 # we will store here total bytes read before \n
rl_read:
li $a2, 1 # max number of character to read
li $v0, 14 # code to read from file
syscall # read from file
add $t0, $t0, $v0
lb $t1, ($a1)
beq $t1, '\r', rl_end
beq $t1, '\n', rl_end
beq $t1, $zero, rl_end
or $t1, $t1, 0x20
sb $t1, ($a1)
addi $a1, $a1, 1
j rl_read
rl_end:
sb $zero, ($a1)
jr $ra
# Read string from console
# $a0 - address of line
# $a1 - length of line
gets:
li $v0, 8
syscall
jr $ra
