infernal-interpreter/Emulator.py

import re

import Junk
from opcodes import OPCODES

REGISTERS=["%rax", "%rbx", "%rcx", "%rdx", "%rsp", "%rbp", "%rsi", "%rdi",
			"%r8", "%r9", "%r10", "%r11", "%r12", "%r13", "%r14", "%r15"]

class CodeParseException (BaseException):

	def __init__ (self, line_nr, string):
		self.line_nr = line_nr
		self.string = string

class InternalExecutionException (BaseException):
	pass

class Emulator:

	def __init__ (self, source_text, max_stack_size=1000):
		self.source = source_text
		self.registers = {}
		for reg_name in REGISTERS:
			self.registers[reg_name] = Junk.Junk()
		self.stack = {}
		for i in range(max_stack_size):
			self.stack[i] = Junk.Junk()
		self.code = []
		self.labels = {}
		self.changes = {}
		self.status = {'i':True}
		self.last_sp = 0
		self.max_stack_size = 0
		index = 0
		for line in iter(source_text.splitlines()):
			index = self.processSourceLine(line, index)

	def setStack (self, *stack_list, **kwargs):
		"""
		Sets various stack elements, starting from 0 and going up.
		Automatically sets rsp. This can be disabled by passing set_rsp=False.
		"""
		i = len(self.stack)
		for element in stack_list:
			i -= 1
			self.stack[i] = element
		self.setRegs(rsp=i)
		self.last_sp = i-1

	def setRegs (self, **reg_dict):
		for reg_name, reg_val in reg_dict.iteritems():
			assert(reg_name[0] != '%')
			self.registers["%"+reg_name] = reg_val

	def getVal (self, val_text):
		if val_text[0] == "$":
			return int(val_text[1:])
		elif val_text[0] == "%":
			return self.registers[val_text]
		else:
			raise ValueError('{} is not an usable value name'.format(val_text))

	def compareVal (self, valT1, valT2):
		val1 = self.getVal(valT2)
		val2 = self.getVal(valT1)
		if isinstance(val1,Junk.Junk) or isinstance(val2,Junk.Junk):
			self.status["i"] = (True,)
			return
		self.status["g"] = val1>val2
		self.status["l"] = val1<val2
		self.status["e"] = val1==val2
		self.status["i"] = False

	def changedRegisters (self, *args):
		for reg, val in args:
			self.changes[reg] = val

	def processSourceLine(self, line_text, index):
		tokens = re.findall(r'[^\s,]+', line_text)
		if len(tokens) <= 0 or tokens[0][0] == '#':
			return index
		if tokens[0][-1] == ':':
			self.labels[tokens[0][:-1]] = index
			tokens = tokens[1:]
		for i in range(len(tokens)):
			if tokens[i][0] == "#":
				tokens = tokens[:i]
				break
		self.code.append(tokens)
		return index + 1

	def regState (self, reg_name):
		if reg_name in self.changes:
			return self.changes[reg_name]
		else:
			return "none"

	def getLineSignature (self, line_nr):
		return [ "\\"+token if token[0]=="$" or token[0]=="%" else token for token in self.code[line_nr] ]

	def pushToStack (self, new_element):
		self.registers['%rsp'] -= 1
		self.stack[self.registers['%rsp']] = new_element
		self.changedRegisters(('%rsp',"change"), ("m"+str(self.registers['%rsp']),"insert"))
		self.max_stack_size = max(self.registers['%rsp'], self.max_stack_size)

	def popFromStack (self):
		temp = self.stack[self.registers['%rsp']]
		self.changedRegisters(('%rsp',"change"),("m"+str(self.registers['%rsp']),"remove"))
		self.registers['%rsp'] += 1
		return temp

	def jump (self, label, cond_op="or", **conditions):
		if len(conditions)>0 and self.status["i"]:
			raise Junk.JunkComparisonException(*self.status['i'])
		and_, or_ = True, False
		for cnd_name, cnd_val in conditions.iteritems():
			if self.status[cnd_name] == cnd_val:
				or_ = True
			else:
				and_ = False
		if or_ if cond_op=="or" else and_:
			self.registers['%rip'] = self.labels[label]
			return True
		else:
			return False

	def iterate (self):
		old_rip = self.registers['%rip']
		self.last_sp = self.registers['%rsp']
		if self.registers['%rip'] >= len(self.code) or isinstance(self.registers['%rip'], Junk.Junk):
			return None
		if not isinstance(self.registers['%rip'], (int, long)):
			raise InternalExecutionException("Register %rip should be integer, but was "+str(self.registers['%rip']))
		instruct = self.code[self.registers['%rip']]
		opcode = instruct[0]
		self.changes = {}

		OPCODES[opcode](self, *instruct[1:])

		if self.registers['%rip'] == old_rip:
			self.registers['%rip'] += 1
		else:
			self.changedRegisters(('%rip',"jump"))

		return old_rip

	def __iter__(self):
		return self

	def next(self):
		output = self.iterate()
		if output is None:
			raise StopIteration()
		else:
			return output

	def getUsedRegisters (self):
		return [reg_name for reg_name, reg_val in self.registers.iteritems() if not isinstance(reg_val, Junk.Junk)]