def translate(self, file):
"""First pass - convert instructions to opcodes"""
program = []
needsarg = False
for line in file:
for word in line.split():
word = word.upper()
if word.startswith("#"):
break
elif needsarg:
if program[-1] == opset.LIT:
program.append(int(word))
else:
program.append(word)
needsarg = False
elif word in opset.name2byte:
byte = opset.name2byte[word]
self.debug("%s -> %s", word, byte)
if opset.unary(byte):
needsarg = True
program.append(byte)
else:
raise SyntaxError("Unrecognized instruction '%s'" % word)
if needsarg:
raise Exception("Missing argument for '%s'" % program[-1])
return program
def run(self, program):
'''Execute list of instructions'''
end = program[0] # First opcode is length
self.memory = [0] * program[1] # Second opcode is memory size requirement
self.pc = 2
while self.pc < end and program[self.pc] != opset.HALT:
instruction = program[self.pc]
self.pc += 1
if opset.nullary(instruction):
self.debug("%02d %s", self.pc, opset.byte2name[instruction])
self.nullary[instruction]()
elif opset.unary(instruction):
argument = program[self.pc]
self.pc += 1
self.debug("%02d %s %s", self.pc, opset.byte2name[instruction], argument)
self.unary[instruction - opset.LIT](argument)
def relabel(self, program, symbols):
"""Replace symbols in program"""
self.debug("Replacing symbols with labels and adresses")
pc = 1
end = len(program)
while pc < end:
instruction = program[pc]
pc += 1
if opset.unary(instruction):
argument = program[pc]
if opset.symbolarg(instruction):
key = opset.LABEL if opset.labelarg(instruction) else opset.MEM
if argument not in symbols[key]:
raise Exception("Cannot use unknown symbol '%s'" % argument)
value = symbols[key][argument]
self.debug("Replace - %s %s -> %s", opset.byte2name[instruction], argument, value)
program[pc] = value
pc += 1
return program
def findsymbols(self, program):
"""Find labels and variables and build symboltable"""
symbols = {opset.LABEL: {}, opset.MEM: {}}
pc = addr = 0
end = len(program)
newprogram = [0, 0]
self.debug("Finding labels and variables")
while pc < end:
instruction = program[pc]
pc += 1
if opset.nullary(instruction):
newprogram.append(instruction)
elif opset.unary(instruction):
argument = program[pc]
pc += 1
if instruction in (opset.LABEL, opset.MEM):
if argument in symbols[instruction]:
raise Exception(
"Cannot declare symbol more than once: %s %s" % (opset.byte2name[instruction], argumet)
)
if instruction == opset.LABEL:
value = len(newprogram)
else:
value = addr
addr += 1
self.debug("Symbol - %s %s -> %s", opset.byte2name[instruction], argument, value)
symbols[instruction][argument] = value
else:
newprogram.append(instruction)
newprogram.append(argument)
# First instruction is length
newprogram[0] = len(newprogram)
# Second instruction is memory requirement
newprogram[1] = addr
return newprogram, symbols
