Fibonacci number program problem(assembly)

anyone can help me to fix my program problem? I can't output the correct number, what's the problem on my code? Help me, thanks.

Code:

---

## Program to computes the value of Fibonacci number.

    .text
    .globl  __start

__start:

    sub    $sp,$sp,4    # push return address
    sw    $ra,($sp)
    sub    $sp,$sp,4    # push caller's frame pointer
    sw    $fp,($sp)
    sub    $fp,$sp,8    # $fp = $sp - space_for_variables
    move    $sp,$fp

    li    $v0,4    # call to print string
    la    $a0,pr1
    syscall

    li    $v0,5    # call to read integer
    syscall
    sw    $v0,0($fp)    # save in $v0
    nop

    lw    $a0,0($fp)    # load variable into $a0
    nop
    jal    fib
    nop

    sw    $v0,4($fp)    # b = fib(a)
    nop

    li    $v0,4    # call to print string
    la    $a0,pr2
    syscall

    lw    $a0,4($fp)
    li    $v0,1    # call to print integer
    syscall

    add    $sp,$fp,8    # $sp = $fp + space_for_variables

    lw    $fp,($sp)    # pop $fp
    add    $sp,$sp,4
    lw    $ra,($sp)    # pop $ra
    add    $sp,$sp,4
    jr    $ra    # return to OS
    nop

    .data
pr1:    .asciiz "Enter an interger:"
pr2:    .asciiz "\nThe Fibonacci number is:"

# int Fib( int n )
# {
#  if( n <= 0 )
#      return 0
#  else if( n == 1 )
#      return 1
#  else
#    x = Fib( n-1 )
#    y = Fib( n-2 )
#    return x + y
#  endif
# }

    .text
    .globl  fib

fib:
    sub    $sp,$sp,4    # push return address
    sw    $ra,($sp)
    sub    $sp,$sp,4    # push caller's frame pointer
    sw    $fp,($sp)
    sub    $sp,$sp,4    # push register $s1
    sw    $s1,($sp)
    sub    $fp,$sp,0    # $fp = $sp - space_for_variables (==0)
    move    $sp,$fp

    move    $s1,$a0    # save argument in $s1
    li    $t1,0    # get a==0
    bgt    $s1,$t1,lo1    # if (n <= 0)
    nop
    li    $v0,0    # return 0
    j    exit
    nop

lo1:
    move    $s1,$a0    # save argument in $s1
    li    $t1,1    # get a==1
    beq    $s1,$t1,lo2    # if (n == 1)
    nop
    bgt    $s1,$t1,lo3    # if (n <=1)
    nop

lo2:    li    $v0,1    # return 1
    j    exit
    nop
lo3:   
    sub    $a0,$s1,1    # param = n-1
    jal    fib    # compute fib(n-1)
    nop
    move    $v0,$s1    # x = Fib( n-1 )

    sub    $a0,$s1,2    # set param to n-2
    jal    fib    # and make recursive call
    nop
    add    $v0,$v0,$s1# add fib(n-2)

exit:
    add    $sp,$fp,0    # $sp = $fp + space_for_variables (==0)
    lw    $s1,($sp)
    add    $sp,$sp,4
    lw    $fp,($sp)    # pop $fp
    add    $sp,$sp,4
    lw    $ra,($sp)    # pop $ra
    add    $sp,$sp,4
    jr    $ra    # return to OS
    nop

---

> what's the problem on my code?
Well it isn't C++
And you didn't state which Processor or OS you're using.
And you didn't describe the symptoms in anything better than "it doesn't work".


Moved.

This is MIPS assembly language program.
Suppose Fibonacci numbers counting from 0, the resule is 0, 1, 1, 2, 3, 5, 8, 13, 21
but my program can not output the correct answer, which it's i input 6, my program cannot output the result is 8.

Why would it output 8, when the first 6 numbers are 0, 1, 1, 2, 3, 5

Fibonacci numbers counting from 0, not 1.

I can't figure out how you got this far, yet can't figure out how to turn say a 'lt' into an 'le' (for example) to make a loop run for one more iteration.

I mean, if it produces the right sequence, but the wrong length of sequence, then that ought to be the easiest thing to diagnose and fix.

this program is ask user input a number, such as 4, and then do the Fibonacci numbers, output the result, suppose is 3. But my program increase the result for 3 each time, so my result is 6. I can't figure out where the problem is.

Why don't you try writing the program in C++ so that half of us can understand what you're writing, and then if you really need to, port it to assembly.