#
# char find_op(char *s)
# {
#    char op = ‘\0’;
#    while (*s != ‘\0’) { if (*s < ’0’ || *s > ’9’) { op = *s; break; } else { ++s; } }
#    return (op);
# }
#
# char buff[80] = “2*3+4/5”;
#
# main()
# {
#    int a, b, d; double f, g, h; float w, x, y; char c, *p;
#
#    do {
#       switch (c = find_op(p++)) {
#          case ‘+’: a = b + d; break;
#          case ‘*’: f = g / x; break;
#          case ‘/’: w = x * y; break;
#       }
#    } while (c != ‘\0’)
#    h = a * w;
# }
#


.data
buff:	.asciiz "2*3+4/5"
	.space  72
sep:	.asciiz " - "

#parametri ingresso: char *s in $a0

.text
.globl main

#__________________________________BB-BA
find_op:
addi $v1, $v1, 2
addi $s7, $s7, 2
	add	$v0, $0, $0	# op = '\0' 
	add	$t9, $a0, $0	# t9 = s (param. ingresso)

#__________________________________BB-BB
while:
addi $v1, $v1, 8
addi $s7, $s7, 2
	lb	$t0, 0($t9)	# carica il carattere *s
	beq	$t0, $0, end2	# se *s==0 termina il ciclo

#__________________________________BB-BC
addi $v1, $v1, 7
addi $s7, $s7, 5
        slti	$t1, $t0, '0'	# t1 = (t0 <? '0')
        addi	$t2, $0, '9'    #
        slt	$t3, $t2, $t0   # t3 = (t0 >? '9')
        or	$t4, $t1, $t3   # t4 = t1 || t3
	bne	$t4, $0, end1   # se la cond. e' vera ho finito

#__________________________________BB-BD
addi $v1, $v1, 4
addi $s7, $s7, 2
	addi	$t9, $t9, 1	# ...altrimenti s++
	j	while		# e continuo il ciclo while

#__________________________________BB-BE
end1:
addi $v1, $v1, 1
addi $s7, $s7, 1
	add	$v0, $t0, $0	# scrivo in op il risultato

#__________________________________BB-BF
end2:
addi $v1, $v1, 3
addi $s7, $s7, 1
	jr	$ra

# $s3 = a, $s1 = b, $s2 = d
# $f14 = f, $f10 = g, $f12 = h
# $f3 = w, $f1 = x, $f2 = y;

main:
	addi	$s1, $0, 1	# s1  = b = 1
	addi	$s2, $0, 2	# s2  = d = 2
	addi	$t0, $0, 3
	mtc1	$t0, $f10
	cvt.s.w	$f10,$f10
	cvt.d.s	$f10,$f10	# f10 = g = 3
	addi	$t0, $0,4
	mtc1	$t0, $f12
	cvt.s.w	$f12,$f12
	cvt.d.s	$f12,$f12	# f12 = h = 4
	addi	$t0, $0, 5
	mtc1	$t0, $f1
	cvt.s.w	$f1, $f1	# f1  = x = 5
	addi	$t0, $0, 6
	mtc1	$t0, $f2
	cvt.s.w	$f2, $f2	# f2  = y = 6

#Azzeramento variabili per instrumentazione
add $v1, $0, $0	#contatore cicli totali
add $s7, $0, $0	#contatore ncpu
	
#__________________________________BB-B1
addi $v1, $v1, 1
addi $s7, $s7, 1
	la	$a0, buff	# p = buff
	
#__________________________________BB-B2
dowhile:
addi $v1, $v1, 8
addi $s7, $s7, 4
	jal	find_op		# chiamo la find_op
	addi	$a0, $a0, 1	# p++
	addi	$t0, $0, '+'	# case '+' ?
        bne	$t0, $v0, sw2	# se no --> caso successivo

#__________________________________BB-B3
addi $v1, $v1, 4
addi $s7, $s7, 2
	add	$s3, $s1, $s2	# se si', esegui a=b+d
	j	fine_sw		# break

#__________________________________BB-B4
sw2:
addi $v1, $v1, 4
addi $s7, $s7, 2
	addi	$t0, $0, '*'	# case '*' ?
        bne	$t0, $v0, sw3	# se no --> caso successivo

#__________________________________BB-B5
addi $v1, $v1, 5
addi $s7, $s7, 3
	cvt.d.s	$f16, $f1	# se si', esegui f=g/x
	div.d	$f14, $f10, $f16
	j	fine_sw		# break

#__________________________________BB-B6
sw3:
addi $v1, $v1, 4
addi $s7, $s7, 2
	addi	$t0, $0, '/'	# case '/' ?
        bne	$t0, $v0, fine_sw

#__________________________________BB-B7
addi $v1, $v1, 1
addi $s7, $s7, 1
	mul.s	$f3, $f1, $f2	# se si', esegui w=x*y
				# break

#__________________________________BB-B8
fine_sw:
addi $v1, $v1, 3
addi $s7, $s7, 1
	bne	$v0, $0, dowhile # c !=? '\0', se si' do_while

#__________________________________BB-B9
addi $v1, $v1, 4
addi $s7, $s7, 4
	mtc1	$s3, $f7
	cvt.s.w	$f4, $f7
	mul.s	$f5, $f4, $f3	# h = a * w
	cvt.d.s	$f12, $f5

# Stampa risultato instrumentazione
add   $a0, $0, $v1 # cicli totali
addi  $v0, $0, 1
syscall
addi  $v0, $0, 4   # separatore
la    $a0, sep
syscall
add   $a0, $0, $s7 # ncpu
addi  $v0, $0, 1
syscall


# exit (servizio #10)
	li	$v0, 10
	syscall