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Factor out utility method for selecting addressing mode.

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This commit is contained in:
Chris Pressey 2017-12-13 12:14:26 +00:00
parent f87bcf5ee4
commit 75cc1f6b25
1 changed files with 18 additions and 27 deletions
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45
src/sixtypical/compiler.py
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@ -31,6 +31,18 @@ class Compiler(object):
self.labels = {}
self.trampolines = {} # Location -> Label
# helper methods
def addressing_mode_for_index(self, index):
if index == REG_X:
return AbsoluteX
elif index == REG_Y:
return AbsoluteY
else:
raise NotImplementedError(index)
# visitor methods
def compile_program(self, program):
assert isinstance(program, Program)
@ -372,49 +384,28 @@ class Compiler(object):
if src.type == TYPE_WORD and dest.ref.type == TYPE_WORD_TABLE:
src_label = self.labels[src.name]
dest_label = self.labels[dest.ref.name]
addressing_mode = None
if dest.index == REG_X:
addressing_mode = AbsoluteX
elif dest.index == REG_Y:
addressing_mode = AbsoluteY
else:
raise NotImplementedError(dest)
self.emitter.emit(LDA(Absolute(src_label)))
self.emitter.emit(STA(addressing_mode(dest_label)))
self.emitter.emit(STA(self.addressing_mode_for_index(dest.index)(dest_label)))
self.emitter.emit(LDA(Absolute(Offset(src_label, 1))))
self.emitter.emit(STA(addressing_mode(Offset(dest_label, 256))))
self.emitter.emit(STA(self.addressing_mode_for_index(dest.index)(Offset(dest_label, 256))))
else:
raise NotImplementedError
elif isinstance(src, ConstantRef) and isinstance(dest, IndexedRef):
if src.type == TYPE_WORD and dest.ref.type == TYPE_WORD_TABLE:
dest_label = self.labels[dest.ref.name]
addressing_mode = None
if dest.index == REG_X:
addressing_mode = AbsoluteX
elif dest.index == REG_Y:
addressing_mode = AbsoluteY
else:
raise NotImplementedError(dest)
self.emitter.emit(LDA(Immediate(Byte(src.low_byte()))))
self.emitter.emit(STA(addressing_mode(dest_label)))
self.emitter.emit(STA(self.addressing_mode_for_index(dest.index)(dest_label)))
self.emitter.emit(LDA(Immediate(Byte(src.high_byte()))))
self.emitter.emit(STA(addressing_mode(Offset(dest_label, 256))))
self.emitter.emit(STA(self.addressing_mode_for_index(dest.index)(Offset(dest_label, 256))))
else:
raise NotImplementedError
elif isinstance(src, IndexedRef) and isinstance(dest, LocationRef):
if src.ref.type == TYPE_WORD_TABLE and dest.type == TYPE_WORD:
src_label = self.labels[src.ref.name]
dest_label = self.labels[dest.name]
addressing_mode = None
if src.index == REG_X:
addressing_mode = AbsoluteX
elif src.index == REG_Y:
addressing_mode = AbsoluteY
else:
raise NotImplementedError(src)
self.emitter.emit(LDA(addressing_mode(src_label)))
self.emitter.emit(LDA(self.addressing_mode_for_index(src.index)(src_label)))
self.emitter.emit(STA(Absolute(dest_label)))
self.emitter.emit(LDA(addressing_mode(Offset(src_label, 256))))
self.emitter.emit(LDA(self.addressing_mode_for_index(src.index)(Offset(src_label, 256))))
self.emitter.emit(STA(Absolute(Offset(dest_label, 1))))
else:
raise NotImplementedError