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200
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1 from asmnodes import ASymbol, AInstruction
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2 from ppci import CompilerError
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199
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3
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4 """
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5 Base classes for defining a target
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6 """
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7
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8 # Machine code interface:
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9 class Operand:
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10 """ Single machine operand """
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11 pass
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12
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13 class Register(Operand):
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14 def __init__(self, name):
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15 self.name = name
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16
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17 class Instruction:
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201
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18 def encode(self):
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19 raise NotImplementedError('TODO')
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199
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20
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21 class Target:
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201
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22 def __init__(self, name, desc=''):
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23 self.name = name
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24 self.desc = desc
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25 self.registers = []
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199
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26 self.instructions = []
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27
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28 def instruction(self, cls):
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29 """ Decorator function that registers an instruction to this target """
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30 self.instructions.append(cls)
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31 return cls
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32
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33 def mapOperand(self, operand):
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34 """ Try to map an operand to a target type """
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35 if type(operand) is ASymbol:
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36 # Try to map to register:
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37 regs = {}
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38 for r in self.registers:
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39 regs[r.name] = r
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40 if operand.name in regs:
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41 return regs[operand.name]
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201
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42 raise CompilerError('Cannot map {0}'.format(operand))
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199
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43
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200
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44 def mapInstruction(self, vi):
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45 """ Map ast tree to real instruction for this target """
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46
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200
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47 # map to real operands:
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48 rops = tuple(map(self.mapOperand, vi.operands))
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49 optypes = tuple(map(type, rops))
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50
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51 # look for a suitable instruction
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52 for ic in self.instructions:
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53 if ic.mnemonic == vi.opcode and ic.operands == optypes:
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54 ri = ic(*rops)
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55 return ri
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201
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56 raise CompilerError('No suitable instruction found for "{0}"'.format(vi))
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57
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