2015-10-17 10:08:25 +00:00
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class Emittable(object):
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def size(self):
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2015-10-17 15:51:35 +00:00
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raise NotImplementedError
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2015-10-17 10:08:25 +00:00
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2015-10-17 15:51:35 +00:00
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def serialize(self, addr):
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2015-10-17 10:08:25 +00:00
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raise NotImplementedError
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class Byte(Emittable):
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2015-10-16 21:59:35 +00:00
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def __init__(self, value):
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2015-10-17 10:08:25 +00:00
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if value < -127 or value > 255:
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raise IndexError(thing)
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if value < 0:
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value += 256
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self.value = value
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def size(self):
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return 1
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2015-10-17 15:51:35 +00:00
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def serialize(self, addr):
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2015-10-17 10:08:25 +00:00
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return chr(self.value)
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def __repr__(self):
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return "%s(%r)" % (self.__class__.__name__, self.value)
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class Word(Emittable):
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def __init__(self, value):
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# TODO: range-checking
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2015-10-16 21:59:35 +00:00
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self.value = value
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def size(self):
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return 2
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2015-10-17 15:51:35 +00:00
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def serialize(self, addr):
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2015-10-16 21:59:35 +00:00
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word = self.value
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low = word & 255
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high = (word >> 8) & 255
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return chr(low) + chr(high)
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2015-10-17 10:08:25 +00:00
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def __repr__(self):
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return "%s(%r)" % (self.__class__.__name__, self.value)
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2015-10-16 21:59:35 +00:00
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2015-10-17 10:08:25 +00:00
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class Label(Emittable):
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2015-10-16 21:59:35 +00:00
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def __init__(self, name, addr=None):
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self.name = name
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self.addr = addr
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def set_addr(self, addr):
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self.addr = addr
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def size(self):
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return 2
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2015-10-17 15:51:35 +00:00
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def serialize(self, addr):
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2015-10-17 10:08:25 +00:00
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assert self.addr is not None, "unresolved label: %s" % self.name
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2015-10-17 15:51:35 +00:00
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return Word(self.addr).serialize(addr)
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2015-10-16 21:59:35 +00:00
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2015-10-17 17:11:23 +00:00
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def serialize_relative_to(self, addr):
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assert self.addr is not None, "unresolved label: %s" % self.name
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return Byte(self.addr - (addr + 2)).serialize(addr)
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2015-10-17 14:06:50 +00:00
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def __repr__(self):
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addrs = ', addr=%r' % self.addr if self.addr is not None else ''
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return "%s(%r%s)" % (self.__class__.__name__, self.name, addrs)
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2015-10-16 21:59:35 +00:00
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class Emitter(object):
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def __init__(self, addr):
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self.accum = []
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self.start_addr = addr
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2015-10-16 21:59:35 +00:00
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self.addr = addr
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self.name_counter = 0
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2015-10-17 10:08:25 +00:00
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def emit(self, *things):
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for thing in things:
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self.accum.append(thing)
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self.addr += thing.size()
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2015-10-16 21:59:35 +00:00
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def serialize(self, stream):
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2015-10-17 15:51:35 +00:00
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addr = self.start_addr
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2015-10-17 10:08:25 +00:00
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for emittable in self.accum:
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2015-10-17 15:51:35 +00:00
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chunk = emittable.serialize(addr)
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stream.write(chunk)
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addr += len(chunk)
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2015-10-16 21:59:35 +00:00
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def make_label(self, name=None):
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if name is None:
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2015-10-17 09:17:44 +00:00
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name = 'label' + str(self.name_counter)
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self.name_counter += 1
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return Label(name, addr=self.addr)
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def resolve_label(self, label):
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label.set_addr(self.addr)
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2015-10-17 14:46:28 +00:00
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def resolve_bss_label(self, label):
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"""Set the given label to be at the current address and
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advance the address for the next label, but don't emit anything."""
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self.resolve_label(label)
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self.addr += label.size()
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