basic.cm

.include lemmas.cm

.def move a b
    # a = b
    clear a
    copy b a
.end


.def add a b
    # a = a + b
    move counter b
L0:
    jnzdec counter L1
    goto L2
L1:
    inc a
    goto L0
.var counter 0
L2:
.end


.def sub a b
    # a = a - b (if a > b)
    # a = 0     (if a ≤ b)
    move t b
L0:
    jnzdec t L1
    goto L2
L1:
    jnzdec a L0
    goto L2
.var t 0
L2:
.end


.def mul a b
    # a = a * b
    move counter b
    clear result
L0:
    jnzdec counter L1
    goto L2
L1:
    add result a
    goto L0
L2:
    move a result
    goto L3
.var counter 0
.var result 0
L3:
.end


.def div a b c
    # a = a / b
    # c = a % b
    inc a
    clear quotient
    move remainder a
    move c a
L0:
    sub remainder b
    jnzdec remainder L1
    goto L2
L1:
    inc remainder
    inc quotient
    goto L0
L2:
    move a quotient
    move t b
    mul t quotient
    sub c t
    jnzdec c L3
    halt
.var quotient 0
.var remainder 0
.var t 0
L3:
.end


.def jump L
    # program counter = L
    goto L
.end


.def jz a L
    # program counter = L (if a = 0)
    jnzdec a L0
    goto L
L0:
    inc a
.end


.def jnz a L
    # program counter = L (if a ≠ 0)
    jnzdec a L0
    goto L1
L0:
    inc a
    goto L
L1:
.end