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main.py
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main.py
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#################### imports ##################
import sys
import re
############### global variables ###########
global last_register #variable holding last used register
global a #register A
global b #regisrer B
global vars #array with variables
global index_name #dictionary returning name of variable of given index
global name_index #dictionary returning index in vars of given variable's name
global vars_count #number of variables in vars
vars = [] #initialisation of global variables
index_name = {}
name_index = {}
vars_count = 0
last_register = None
a = None
b = None
############## classes #############
class pointer: #pointer class used to access and iterate over arrays
def __init__(self, address, offset):
if not address in name_index:
abort("unknown address: " + address)
self.address = address
self.offset = offset
############## functions' declarations #############
def abort(message):
print("!!!!=======ERROR=======!!!!")
print(message)
print("execution aborted, no further instructions were performed")
print("!!!!=======ERROR=======!!!!")
sys.exit(1)
def abort_compilation(message,line):
print("!!!!=======ERROR=======!!!!")
print("execution aborted at line:\n" + line)
print(message)
print("current state of variables")
print_vars()
print("execution aborted, no further instructions were performed")
print("!!!!=======ERROR=======!!!!")
sys.exit(1)
def uncomment(string): #gets rid of a comment in line
if ";" in string:
return string[:string.find(";")]
else:
return string
def print_vars(): #prints variables
for x in range(len(vars)):
if (type(vars[x]) is pointer):
print(index_name[x] + ": " + vars[x].address + ((" + " + str(vars[x].offset)) if vars[x].offset else ""))
else:
print(index_name[x] + ": " + str(vars[x]))
def segment_declaration(line): #checks if line contains segment declaration.
#Returns True if segment is present and False otherwise
#doesn't include .END !
segments = [".UNIT",".DATA",".CODE"]
for x in segments:
if x in line:
return True
return False
def get_segment(line): #returns string with segment name extracted from line
#doesn't include .END!
index = line.find(".")
return line[index:index+5]
def load(register,value): #loads value to given register
global a
global b
global last_register
if (register=="@A" or register=="@a"):
a=value
last_register = a
elif (register=="@B" or register=="@b"):
b=value
last_register = b
else:
abort("invalid register provided: " + register)
def check_ptrs(a,b): #checks if a or b is pointer
if (type(a) is pointer or type(b) is pointer):
return True
return False
def check_both_ptrs(a,b): #checks if a and b are pointers
if (type(a) is pointer and type(b) is pointer):
return True
return False
def add_values(register,value): #returns new offset which is sum of register and value
if (type(a) is pointer and type(b) is pointer):
abort("cannot perform operation on two pointers")
if (type(value) is pointer and not type(register) is pointer):
return value.offset + register
if (not type(value) is pointer and type(register) is pointer):
return register.offset + value
def add(register,value): #adds value to register
global a
global b
global last_register
if (register=="@A" or register=="@a"): #register A
if (a==None): #check if A is not empty
abort("Nothing was loaded to @A. Cannot perform addition")
if (check_ptrs(a,value)): #check if operation is performed on pointers
if (type(a) is pointer):
a.offset = add_values(a,value)
else:
value.offset = add_values(a,value)
a = value
else: #default case
a+=value
last_register = a
elif (register=="@B" or register=="@b"): #register B (same as A)
if (b==None):
abort("Nothing was loaded to @B. Cannot perform addition")
if (check_ptrs(b,value)):
if (type(b) is tuple):
b.offset = add_values(b,value)
else:
value.offset = add_values(b,value)
b = value
else:
b+=value
last_register = b
else:
abort("invalid register provided: " + register)
def sub(register,value): #subtracts value from register
global a
global b
global last_register
if (register=="@A" or register=="@a"): #register A
if (a==None): #check if register is empty
abort("Nothing was loaded to @A. Cannot perform sub")
if (check_ptrs(a,value)): #pointers case
if (check_both_ptrs(a,value)):
a = a.offset - value.offset
else:
a.offset = a.offset - value
return
a-=value #int case
last_register = a
elif (register=="@B" or register=="@b"): #register B (same as A)
if (b==None):
abort("Nothing was loaded to @B. Cannot perform sub")
if (check_ptrs(b,value)):
if (check_both_ptrs(b,value)):
b = b.offset - value.offset
else:
b.offset = b.offset - value
return
b-=value
last_register = b
else:
abort("invalid register provided: " + register)
def mult(register,value): #multiplies register by value
global a
global b
global last_register
if (register=="@A" or register=="@a"): #register A
if check_ptrs(a,value): #make sure there are no ptrs
abort("cannot perform multiplication on pointers!")
if (a==None): #check if register is empty
abort("Nothing was loaded to @A. Cannot perform mult")
a*=value #perform multiplication
last_register = a
elif (register=="@B" or register=="@b"): #register B (same as A)
if check_ptrs(b,value):
abort("cannot perform multiplication on pointers!")
if (b==None):
abort("Nothing was loaded to @B. Cannot perform mult")
b*=value
last_register = b
else:
abort("invalid register provided: " + register)
def div(register,value): #divides register by value
global a
global b
global last_register
if (value==0): #check if value != 0
abort("cannot perform division by 0")
if (register=="@A" or register=="@a"): #register A
if check_ptrs(a,value): #make sure there are no pointers
abort("cannot perform division on pointers!")
if (a==None): #make sure A is not empty
abort("Nothing was loaded to @A. Cannot perform div")
a/=value #perform division
last_register = a
elif (register=="@B" or register=="@b"): #register B (same as A)
if check_ptrs(b,value):
abort("cannot perform division on pointers!")
if (b==None):
abort("Nothing was loaded to @B. Cannot perform div")
b/=value
last_register = b
else:
abort("invalid register provided: " + register)
def store(register,address): #saves value from given register to address
global a
global b
global last_register
global vars
if (register=="@A" or register=="@a"): #register A
if (a==None): #check if A is empty
abort("Nothing was loaded to @A. Cannot perform store")
if (type(a) is list): #case 1: save pointer to array
if not address in name_index:
abort("Unknown variable: " + address)
vars[name_index[address]] = pointer(index_name[vars.index(a)],0)
last_register = a
return
if ("(" in address): #case 2: save integer in array
if not address[1:-1] in name_index:
abort("Unknown variable: " + address)
ptr = vars[name_index[address[1:-1]]]
vars[name_index[ptr.address]][ptr.offset] = a
last_register = a
return
if not address in name_index: #case 3: save integer in normal address
abort("Unknown variable: " + address)
vars[name_index[address]] = a
last_register = a
elif (register=="@B" or register=="@b"): #register B (same as A)
if (b==None):
abort("Nothing was loaded to @B. Cannot perform store")
if (type(b) is list):
if not address in name_index:
abort("Unknown variable: " + address)
vars[name_index[address]] = pointer(index_name[vars.index(b)],0)
last_register = b
return
if ("(" in address):
if not address[1:-1] in name_index:
abort("Unknown variable: " + address)
ptr = vars[name_index[address[1:-1]]]
vars[name_index[ptr.address]][ptr.offset] = b
last_register = b
return
if not address in name_index:
abort("Unknown variable: " + address)
vars[name_index[address]] = b
last_register = b
else:
abort("invalid register provided: " + register)
def get_value(string): #extracts value from instruction
if re.match("[-+]?\d+$",string): #case 1: a number
return int(string)
if string.count(")")==2: #case 2: element from array
res = string.replace(")", "")
res = res.replace("(","")
if not res in name_index:
abort("Unknown variable " + string)
return vars[name_index[vars[name_index[res]].address]][vars[name_index[res]].offset]
if string.count(")")==1: #case 3: normal variable
if not (string[string.find("(")+1:string.find(")")]) in name_index:
abort("Unknown variable " + string)
return vars[name_index[(string[string.find("(")+1:string.find(")")])]]
if not string in name_index: #case 4: array (pointer to array)
abort("Unknown variable " + string)
return vars[name_index[string]]
def unhash(string): #converts # to normal input (used in array initialisaion)
res = ""
input = string.split(",")
for cell in input:
if '#' in cell:
value = cell[cell.find("#")+1:]
repeat = int(cell[:cell.find("#")])
for iterator in range(repeat):
res+=value
if (iterator+1!=repeat):
res+=","
else:
res+=cell
res+=','
res =res[:-1]
return res
def initialise_array(string,name): #initialises array
global vars_count
global index_name
global name_index
global vars
array = []
for num in string.split(","):
array.append(int(num))
vars.append(array)
index_name[vars_count]=name
name_index[name]=vars_count
vars_count+=1
############## main #############
def main():
global vars_count
global index_name
global name_index
global vars
file = open("main.txt", "r") #open file
raw_input = file.readlines()
lab_dict = {} #dictionary with number of lines corresponding to each goto label
input = [] #lines from .CODE segments
segment = None #current segment
line_count = 0 #number of lines of .CODE segments
for line in raw_input:
current_line = line #create copy
current_line = uncomment(current_line) #get rid of unwanted characters
current_line = current_line.replace(" ","")
current_line = current_line.replace("\t","")
current_line = current_line.replace("\n","")
if (segment_declaration(current_line)): #check if line contains new segment
segment = get_segment(current_line)
continue
if (segment == ".DATA"): #DATA segment case
if (current_line.count(",")==1): #creating new variable
index = current_line.find(":")
if (not re.match("^[a-zA-Z_]\\w*$",current_line[:index])): #check if variable name is correct
abort_compilation("invalid variable name: "+ current_line[:index], current_line)
if(re.match("[-+]?\d+$",current_line.split(",")[1])): #case 1: simple number
index_name[vars_count]=current_line[:index] #index -> name
name_index[current_line[:index]]=vars_count #name -> index
vars.append(int(current_line.split(",")[1]))
vars_count+=1
else: #case 2: pointer
vars.append(pointer(current_line.split(",")[1],0))
index_name[vars_count]=current_line[:index] #index -> name
name_index[current_line[:index]]=vars_count #name -> index
vars_count+=1
if (current_line.count(",")>1): #creating new array
initialise_array(unhash(current_line[current_line.find(".WORD")+6:]),current_line[:current_line.find(":")])
if (segment == ".CODE"): #CODE segment
if ((":" in current_line) and (not ".WORD" in current_line)): #create dictionary with labels
label = current_line.split(":")[0]
lab_dict[label] = line_count
current_line = current_line.replace(label + ":","")
line_count+=1
input.append(current_line) #prepare code to be executes
raw_input.clear() #clean up
file.close()
print("exec start: ") #print initial state of variables
print_vars()
x = 0 #variable with information which line are we in
while(True): #exec start
line = input[x] #load line
x += 1 #prepare move to next line
#print(repr(line))
if (len(line)==0): #check if line is empty
continue
split = line.split(",")
if split[0]=="null": #instructions
continue
elif split[0]=="load":
load(split[1],get_value(split[2]))
elif split[0]=="add":
add(split[1],get_value(split[2]))
elif split[0]=="sub":
sub(split[1],get_value(split[2]))
elif split[0]=="div":
div(split[1],get_value(split[2]))
elif split[0]=="mult":
mult(split[1],get_value(split[2]))
elif split[0]=="store":
store(split[1],split[2])
#print_vars()
elif split[0]=="jump":
if not split[1] in lab_dict:
abort_compilation("label: " + split[1] + "not found in code", line)
x=lab_dict[split[1]]
elif split[0]=="jzero":
if not split[1] in lab_dict:
abort_compilation("label: " + split[1] + "not found in code", line)
if last_register==0:
x=lab_dict[split[1]]
else:
continue
elif split[0]=="jnzero":
if not split[1] in lab_dict:
abort_compilation("label: " + split[1] + "not found in code", line)
if last_register!=0:
x=lab_dict[split[1]]
else:
continue
elif split[0]=="jpos":
if not split[1] in lab_dict:
abort_compilation("label: " + split[1] + "not found in code", line)
if last_register>0:
x=lab_dict[split[1]]
else:
continue
elif split[0]=="jneg":
if not split[1] in lab_dict:
abort_compilation("label: " + split[1] + " not found in code", line)
if last_register<0:
x=lab_dict[split[1]]
else:
continue
elif split[0]=="halt":
break
else:
abort_compilation("Inavlid instruction: " + split[0],line)
if (".END" in line):
break
print("final state:") #print final state of variables
print_vars()
print("press enter to quit")
sys.stdin.read(1) #enter to close
if __name__=='__main__':
main()