.data
	msgNgay: 	.asciiz "nhap ngay DAY (DD): "
	msgThang: 	.asciiz "nhap thang MONTH (MM): "
	msgNam: 	.asciiz "nhap nam YEAR (YYYY): "
	errMsg: 	.asciiz "Ngay khong hop le !"
	TIME:		.space 11
	buffer: 	.space 32

.text
.globl main
	main:
	jal 	nhapTime

	la $a0, TIME
	li $v0, 4
	syscall

	li 	$v0, 10
	syscall

.globl nhapTime
	#void nhapTime
	nhapTime:
	sw 	$ra, ($sp)
	#nhap ngay luu vao t0
	li 	$2, 4
	la 	$4, msgNgay
	syscall
	li 	$2, 5
	syscall
	move 	$15, $2

	#nhap thang luu vao t6
	li 	$2, 4
	la 	$4, msgThang
	syscall
	li 	$2, 5
	syscall
	move 	$14, $2

	#nhap nam luu vao t2
	li 	$2, 4
	la 	$4, msgNam
	syscall
	li 	$2, 5
	syscall
	move 	$10, $2

	jal 	check

	lw 	$ra, ($sp)
	jr 	$ra

.globl is_leap_year
	#bool is_leap_year(int year)
	#a0 = year
	is_leap_year:
        li      $v0, 0                  # mac dinh k nhuan

        li      $t0, 4                  # t0 = 4
        divu    $a0, $t0                # year/4
        mfhi    $t1                     # tim so du
        bne     $t1, $zero, exit        # khong chia het cho 4

        li      $t0, 100                # $t0 = 100
        div    	$a0, $t0                # year/100
        mfhi    $t1
        bne     $t1, $zero, set_true    # k chia het cho 100 (year < 100)

        # chia het cho 100
        # va chia het cho 400 thi ok
        li      $t0, 400                # $t0 = 400
        divu    $a0, $t0                # year/400
        mfhi    $t1
        bne     $t1, $zero, exit        # k chia het cho 400
set_true:
        addi    $v0, $v0, 1             # true
exit:
        jr      $ra			#return

.globl slNgay
	#int slNgay(int thang, int nam)
	#thang = $14
	#nam = $10

	slNgay:
	move 	$s1, $ra
	beq 	$14, 1, slngay31
	beq 	$14, 3, slngay31
	beq 	$14, 5, slngay31
	beq 	$14, 7, slngay31
	beq 	$14, 8, slngay31
	beq 	$14, 10, slngay31
	beq 	$14, 12, slngay31

	beq 	$14, 4, slngay30
	beq 	$14, 6, slngay30
	beq 	$14, 9, slngay30
	beq 	$14, 11, slngay30

	slngaythang2:
	move 	$a0, $10
	jal 	is_leap_year
	beq 	$v0, 0, thang2khongnhuan

	beq 	$v0, 1, thang2nhuan

	thang2nhuan:
	li 	$a0, 29
	move 	$ra, $s1
	jr 	$ra

	thang2khongnhuan:
	li 	$a0, 28
	move 	$ra, $s1
	jr 	$ra

	slngay31:
	li 	$a0, 31
	jr 	$ra

	slngay30:
	li 	$a0, 30
	jr 	$ra


.globl check
	# check(int ngay, int thang, int nam)
	# false thi exit program
	# true thi bien TIME se mang gia tri cua ngay vua nhap, addr bien time auto gan vao $a0
	check:

	move 	$t9, $ra
	#kiem tra nam 0k
	sgt 	$t1, $10, $zero
	beqz 	$t1, false

	#kiem tra thang 0k
	li 	$t5, 0 #thang > 0
	sgt 	$t1, $14, $t5
	beqz 	$t1, false

	li 	$t5, 13 #thang < 13
	slt 	$t1, $14, $t5
	beqz 	$t1, false

	#kiem tra ngay
	li 	$t5, 0
	sgt 	$t1, $15, $t5 #if ngay > 0 -> t1 = 1
	beqz 	$t1, false #if t1 = 0 -> ngay < 1 -> false

	jal 	slNgay
	#a0 = slngay
	#neu ngay > a0 return false


	ble 	$15, $a0, true

	false:
	la 	$a0, errMsg
	li 	$v0, 4
	syscall

	li 	$v0, 10
	syscall
	#li 	$a0, 0
	#move 	$ra, $s0
	#jr 	$ra
	true:
	# neu true thi bat dau luu vao time
	la 	$s1, TIME

      	move $a0, $15
      	jal itoa

      	lb 	$t4, 0($s0)

      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o

      	lb 	$t4, 1($s0)
      	beq	$t4, '\0', nxt1
      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o

      	nxt1:
      	li 	$t4, '/'
      	sb	$t4, ($s1)
      	add	$s1, $s1, 1

      	move $a0, $14
      	jal itoa

      	lb 	$t4, 0($s0)
      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o

      	lb 	$t4, 1($s0)
      	beq	$t4, '\0', nxt2		# neu gap null thi nex
      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o
      	nxt2:
      	li 	$t4, '/'
      	sb	$t4, ($s1)
      	add	$s1, $s1, 1

      	move $a0, $10
 	jal itoa

 	lb 	$t4, 0($s0)
      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o

      	lb 	$t4, 1($s0)
      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o

 	lb 	$t4, 2($s0)
      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o

      	lb 	$t4, 3($s0)
      	sb   	$t4, ($s1)     		# luu vao time
      	add  	$s1, $s1, 1    		# len 1 o

 	addi 	$s1, $s1, 1
 	li $t4, '\0' 			#null terminator
 	sb $t4, ($s1)

	move 	$ra, $t9
	jr 	$ra

.globl itoa
# a0 = num
# s0 = addr cua return value
# char* itoa(int n)
itoa:
	move 	$s5, $ra
      	la   	$t0, buffer    		# load buf
      	add  	$t0, $t0, 30   		# seek the end
      	sb   	$0, 1($t0)     		# null-terminated str
      	sb   	$t1, ($t0)     		# init. with ascii 0
      	li   	$t3, 10        		# t3 = 10
      	beq  	$a0, $0, end_itoa 	# =0 thi end

	loop_itoa:
      	div  	$a0, $t3       		# a /= 10
      	mflo 	$a0
      	mfhi 	$t4            		# lay mod =
      	add  	$t4, $t4, '0'  		# int -> char
      	sb   	$t4, ($t0)     		# luu vao buf
      	sub  	$t0, $t0, 1    		# lui buf ve 1 o
      	bne  	$a0, $0, loop_itoa  	# neu chua = 0 thi tiep tuc
      	addi 	$t0, $t0, 1    		# len buf 1 o de ve dung' vi tri

	end_itoa:
      	move 	$s0, $t0      		# tra dia chi str ve s0
      	move 	$ra, $s5
      	jr   	$ra