#ARRAY Format: ["Command","Argument"],
#Help Format: Command [Argument] => Description

#MEM 8-bit-num => Store a number in a variable
#LD mem_location => Load a variable into RAM
#SUB 8-bit-num => Subtract the RAM by a number
#STO mem_location => Store the current RAM values into a variable
#OUT => Output the current Ram
#JZ mem_location => Jump to memory location IF Zero flag is set
#JMP mem_location => Jump to a memory location
#HLT => Halt the main clock (ALWAYS USE AT END OF PROGRAM)
#JC mem_location => Jump to memory location IF carry flag is set 

#Count down binary values from 00000111 until 00000000

# commands = [
#     ["MEM","00000111"], # 0x00000000
#     ["LD","0x00000000"], # 0x00000001
#     ["SUB","00000001"], # 0x00000010
#     ["STO","0x00000000"], # 0x00000011
#     ["OUT",""], # 0x00000100
#     ["JZ","0x00000111"], # 0x00000101
#     ["JMP","0x00000001"], # 0x00000110
#     ["HLT",""] # 0x00000111
# ]

FILE_CODE = "./test.jas"

#Do not mess with code below.

class Halt(Exception): pass

locations = []
ptr = "0x00000000"
mem_load = "00000000"
flags = [
    False, # Zero Flag
    False # Carry Flag
]
def parseFile(file):
    fileCode = []
    with open(file,"r") as f:
        for line in f.readlines():
            fSplit = line.split(" ")
            if len(fSplit) == 2:
                fileCode.append([fSplit[0],fSplit[1].replace("\n","")])
            else:
                fileCode.append([fSplit[0].replace("\n",""),""])
    return fileCode
commands = parseFile(FILE_CODE)
def countMem():
    num_mem = 0
    for i in xrange(len(commands)):
        if (commands[i][0] == "MEM"):
            num_mem += 1
    return num_mem
def display():
    n = 8
    print("MEMORY:")
    for i in xrange(len(commands)):
        b = bin(i)[2:]
        l = len(b)
        b = str(0) * (n - l) + b
        cmd = commands[i][0]
        subcmd = commands[i][1]
        if (i == countMem()):
            print "\nPROGRAM:"
        if (commands[i][0] == "MEM"):
            print "0x"+b+" "+subcmd
        else:
            print "0x"+b+" "+cmd+" "+subcmd
        locations.append(["0x"+b,commands[i][0],commands[i][1].replace("0x","")])
def getCmdFromPtr(memloc):
    for i in xrange(len(locations)):
        if (locations[i][0] == memloc):
            return locations[i][1]
    return False
def getValFromPtr(memloc):
    for i in xrange(len(locations)):
        if (locations[i][0] == memloc):
            return locations[i][2]
    return False
def setValFromPtr(memloc,val):
    for i in xrange(len(locations)):
        if (locations[i][0] == memloc):
            locations[i][2] = val
            return
def add(x,y):
        maxlen = max(len(x), len(y))

        #Normalize lengths
        x = x.zfill(maxlen)
        y = y.zfill(maxlen)

        result = ''
        carry = 0

        for i in range(maxlen-1, -1, -1):
            r = carry
            r += 1 if x[i] == '1' else 0
            r += 1 if y[i] == '1' else 0

            # r can be 0,1,2,3 (carry + x[i] + y[i])
            # and among these, for r==1 and r==3 you will have result bit = 1
            # for r==2 and r==3 you will have carry = 1

            result = ('1' if r % 2 == 1 else '0') + result
            carry = 0 if r < 2 else 1       

        if carry !=0 : result = '1' + result

        return result.zfill(maxlen)
def sub(s1, s2):
    b = bin(int(s1, 2) - int(s2, 2))[2:]
    l = len(b)
    b = str(0) * (8 - l) + b
    return b  
def runCode(cmd,arg):
    global mem_load
    global ptr
    global flags
    
    if mem_load == "000000b1":
        mem_load = "00000000"
    if mem_load == "00000000":
        flags[0] = True
    else:
        flags[0] = False     
    if len(mem_load) != 8:
        flags[1] = True
    elif len(mem_load) == 8:
        flags[1] = False
    
    if cmd == "JMP":
        ptr = "0x"+arg
    elif cmd == "JZ" and flags[0]:
        ptr = "0x"+arg
    elif cmd == "LD":
        mem_load = getValFromPtr("0x"+arg)
    elif cmd == "OUT":
        print mem_load
    elif cmd == "STO":
        setValFromPtr(arg,mem_load)
    elif cmd == "ADD":
        mem_load = add(mem_load,arg)
    elif cmd == "SUB":
        mem_load = sub(mem_load,arg)
    elif cmd == "HLT":
        raise Halt
    elif cmd == "JC" and flags[1]:
        ptr = "0x"+arg
    ptr = "0x"+add(ptr.replace("0x",""),"00000001")
    return
print("=-=-=-CODE-=-=-=")
display()
print("\nRunning Program...")
try:
    while True:
        runCode(getCmdFromPtr(ptr),getValFromPtr(ptr))
except Halt:
    pass