.data
    string1: .space 1000
    string2: .space 1000
    resenie1: .asciiz "Concatenated string:"
    resenie2: .asciiz "\nLength:"
.text




la $a0, string1 #read first
li $a1, 1000
li $v0, 8
syscall

la $a0, string2 #read second
li $a1, 1000
li $v0, 8
syscall


la $a0, string1
sb $0, -1($a0)
la $a1, string2
sb $0, -1($a1)
jal procedure #procedure

move $t0, $v0
move $t1, $v1

#print
la $a0, resenie1
li $v0, 4
syscall

move $a0, $t1
li $v0, 4
syscall


la $a0, resenie2
li $v0, 4
syscall

move $a0, $t0
li $v0, 1
syscall

li $v0, 10 #exit
syscall





procedure:

li $t0, 0
li $t1, 0

L_1:
lb $t2, ($a0)
slti $t2, $t2, 1
beq $t2, 1, exit1
addi $t0, $t0, 1
addi $a0, $a0, 1
j L_1
exit1:

L_2:
lb $t2, ($a1)
slti $t3, $t2, 1
beq $t3, 1, exit2
addi $t1, $t1, 1
addi $a1, $a1, 1
j L_2
exit2:


#removing endl from strings
addi $t0, $t0, -1
addi $t1, $t1, -1
addi $a0, $a0, -1
addi $a1, $a1, -1


add $v0, $t0, $t1 #v0 = length_1 + length_2
slt $t2, $t0, $t1
beq $t2, 1, addfirst #if t0 < t1 concat first to second

#else:

 #concatenate second to first
 la $v1, string1
 la $a1, string2
 li $t3, 0
 conc1:
    slt $t2, $t3, $t1
    beq $t2, 0, cexit1
    lb $t4, ($a1)
    sb $t4, ($a0)
    addi $t3, $t3, 1 #t2++
    addi $a1, $a1, 1 #a1++
    addi $a0, $a0, 1 #a0++
    j conc1
 cexit1:
 sb $0, ($a0) #null
 j end


#concatenate first to second
addfirst:
la $v1, string2
la $a0, string1
li $t2, 0
conc2:
  slt $t3, $t2, $t0
  beq $t3, 0, cexit2
  lb $t4, ($a0)
  sb $t4, ($a1)
  addi $t2, $t2, 1
  addi $a1, $a1, 1
  addi $a0, $a0, 1
  j conc2

cexit2:
sb $0, ($a1) #null

end:

jr $ra