.data
    a: .word 0
    operation: .word 0
    b: .word 0
    result: .word 0
    choice: .word 0

    newLine: .asciiz "\n"

    firstItemMessage: .asciiz "Put first item\n"
    operationMessage: .asciiz "Put operation code\n"
    secondItemMessage: .asciiz "Put second item\n"

    wrongOperationCode: .asciiz "Wrong operation code"

    operations: .asciiz "Operations:\n0 - addition\n1 - subtraction\n2 - division\n3 - multiplication\n"
    resultMessage: .asciiz "Result: "

    choiceMessage: .asciiz "Do you want to invoke next operation? (0 - no, 1 - yes)\n"
.text

    main:

    li $v0, 4
    la $a0, firstItemMessage
    syscall

    jal readInt
    sw $v0, a

    li $v0, 4
    la $a0, operations
    syscall

    li $v0, 4
    la $a0, newLine
    syscall

    li $v0, 4
    la $a0, operationMessage
    syscall

    jal readInt
    sw $v0, operation

    li $v0, 4
    la $a0, secondItemMessage
    syscall

    jal readInt
    sw $v0, b

    lw $t0, operation

    beq $t0, 0, addition
    beq $t0, 1, subtraction
    beq $t0, 2, division
    beq $t0, 3, multiplication

    li $v0, 4
    la $a0, wrongOperationCode
    syscall

    li $v0, 4
    la $a0, newLine
    syscall

    li $v0, 4
    la $a0, newLine
    syscall

    jal main

    endif:

    sw $t3, result

    li $v0, 4
    la $a0, resultMessage
    syscall

    li $v0, 1
    lw $a0, result
    syscall

    li $v0, 4
    la $a0, newLine
    syscall

    li $v0, 4
    la $a0, choiceMessage
    syscall

    jal readInt
    sw $v0, choice

    lw $t0, choice

    li $v0, 4
    la $a0, newLine
    syscall

    beq $t0, 1, main

    end:
    # end of program
    li $v0, 10
    syscall

    readInt:
    li $v0, 5
    syscall
    jr $ra

    addition:
    lw $t4, a
    lw $t5, b

    add $t3, $t4, $t5

    j endif

    subtraction:
    lw $t4, a
    lw $t5, b

    sub $t3, $t4, $t5

    j endif

    division:
    lw $t4, a
    lw $t5, b

    div $t3, $t4, $t5

    j endif

    multiplication:
    lw $t4, a
    lw $t5, b

    mul $t3, $t4, $t5

    j endif