MIPS - How do I store user input and store it in an array dynamically?

Question

Can anyone show me an example of how to first record the size, n, of the integer list from the user, and then store the n integers entered by the user into an array that can hold n integers?

I can't find something similar through google. Any help would be appreciated.

Which part are you having trouble with? What language are you working in? — Oliver Charlesworth
– Oliver Charlesworth, Commented Apr 21, 2014 at 0:26
Indeed, unless you absolutely have to do this in assembly language (which in this day and age, for a problem of this sort, would probably only be a "homework" requirement) your actual question should depend on the details of the user interface subsystem and the run time support environment, not on the processor. — Chris Stratton
– Chris Stratton, Commented Apr 21, 2014 at 0:35

Community · Accepted Answer · 2018-03-18 13:43:26Z

2

You'll want to look at this list of MIPS system calls, the first 17 of which are supported by the spim simulator.

With that list in mind, here's the general approach you should take:

# read n from console
li $v0 5
syscall
move $t0 $v0

# allocate dynamic memory
sll $a0 $v0 2    # sll performs $a0 = $v0 x 2^2
li $v0 9    #9 is the system code for service(sbrk) whoes work is        
syscall     #to allocate dynamic memory

move $t1 $zero
move $t2 $v0

loop:
    bge $t1 $t0 end

    # read in and store int
    li $v0 5
    syscall
    sw $v0 0($t2)

    addi $t1 $t1 1
    addi $t2 $t2 4
    j loop

end:

edited Mar 18, 2018 at 13:43

CommunityBot

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answered Apr 21, 2014 at 19:38

Konrad Lindenbach

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3 Comments

Stack Player Over a year ago

is it more efficient to do sll $a0, $v0, 2 than to li $a0, 20?

Konrad Lindenbach Over a year ago

They are not equivalent. n is stored in $v0 but it needs to be multiplied by 4 to get the number of bytes required hence sll $a0 $v0 2

Stack Player Over a year ago

I forgot he was taking an input from user, my bad

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