# Assignment: extend this program to reverse the string "intext"
# and write the result to "outtext".

            .text
            .set noreorder
main:       la    $t1, intext   # t1 points to start of intext
            la    $t2, outtext  # t2 points to start of outtext

            li    $t0, 0        # t0 used to count characers
seek_end:   lb    $t3, 0($t1)   # read character
            beq   $t3, 0, seek_end1 # check if 0 (end of string)
            addiu $t0, $t0, 1
            addiu $t1, $t1, 1
            b     seek_end
seek_end1:  addu  $t2, $t2, $t0 # t2 points to end of outtext
            sb    $t3, 0($t2)   # write 0 to terminate string
            la    $t1, intext   # t1 points to start of intext


            la $a0, intext
        move $a1, $t2
        move $a2, $t0
        addiu $a1, $a1, -1 #Fix off-by-1 (temp fix)
        bal rev # call: rev(a0,a1,a2)

stop:       b     stop

       #argument 0, första tecknet att kopiera
       #argument 1, destinationsadressen för den karaktären
       #argument 2, hur många tecken som ska kopieras

rev:    addiu $sp, $sp, -4
    sw    $31, 0($sp) #push return address to stack
    addiu $sp, $sp, -4
    sw    $fp, 0($sp) #push old fp
    move  $fp, $sp  #move fp to sp
    addiu $sp, $sp, -12 #Make room for 3 local variables


    #Entry Sequence complete

save:   sw    $a0, 0($sp)   #We save address of first character as a local variable
    sw    $a1, 4($sp)   #We save the destination address as a local var
    sw    $a2, 8($sp)   #We save the number of characters to copy as a loc var


    #Our variables are now saved on the stack

    #start of reversing function

if: bne   $a2, $zero, else  # if num of char not equal to 0, jump to else
                # otherwise go to then

then:   b     exit


else:   addi  $a0, $a0, 1 # New read-char address
    addi  $a1, $a1, -1 # New destination address
    addi  $a2, $a2, -1 # reduce number of chars to copy
    bal   rev

    lw $t3, -12($fp)    # load address of first letter
    lb $t4, 0($t3)      # load the given letter from the address
    lw $t5, -8($fp)
    sb $t4, 0($t5)


exit:   move $sp, $fp       # destroy local variables
    lw   $fp, 0($sp)    # restore last fp (to move down in the stack)
    addi $sp, $sp, 4    # pop word containing old fp
    lw   $31, 0($sp)    # restore return address
    addi $sp, $sp, 4    # pop word containing return address
    jr   $31        # return




#copy:
#       addi $t2, $t2, -1 # Minskar utstring-index
#       lb $t3, 0($t1) # Laddar byte ur instring till temporärt register t3
#       sb $t3, 0($t2) # Sparar det laddade innehållet från t3 till slutet på utstring
#       addi $t1, $t1, 1 # ökar index på instring
#       addi $t0, $t0, -1 # minskar character count
#       bgtz $t0, copy # branchar om character count > 0



            .data
intext:     .string "!dlroW olleH"
            .align 4
outtext:    .string "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"