MIPS: Write AND read a file

问题:

I'm trying to merge two different programs in MIPS in order to write something on a file and then read it through a simple menu. Writing is done good and smooth. Reading is a bit more problematic, since I can't see any output. The reading part itself works, if separated from the writing part. Can someone enlight me on what I'm doing wrong? thanks!

<pre>

.data

fout: .asciiz "test.txt"
reservedspace: .space 1024
cont: .asciiz "reading file... "

buffer: .asciiz "some text to test the program."
##################################################

.text 

main:

menu:

getinput:   

li $v0, 5
syscall
move $s0, $v0

beq $s0, 0, create  
beq $s0, 1, read    
beq $s0, 2, delete
beq $s0, 3, show
beq $s0, 4, exit

j getinput

#######################################

create:
    #write on file
    #open
    li $v0, 13
    la $a0, fout
    li $a1, 1
    li $a2, 0
    syscall
    move $s6, $v0

    #write
    li $v0, 15
    move $a0, $s6
    la $a1, buffer
    li $a2, 30
    syscall

    #close
    li $v0, 16
    move $a0, $s6
    syscall
j menu

search:
    li $v0, 13
    la $a0, fout
    li $a1, 0
    li $a2, 0
    syscall
    move $s6, $v0

    li $v0, 14
    move $a0, $s6
    la $a1, reservedspace
    li $a2, 1024
    syscall

    li  $v0, 4
    la  $a0, cont
    syscall

    close:
    li $v0, 16
    move $a0, $s6
    syscall
j menu

delete:
show:
exit:

    li $v0, 10          #Terminate Program
    syscall

<code>

回答1:

You are not seeing any output because you are not printing what you have read. After reading the text from the file it should be stored in the buffer you provided (reservedspace). So, you can for example print the contents of that buffer with

  la $a0, reservedspace
  li  $v0, 4
  syscall