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76 lines
2.5 KiB
Python
76 lines
2.5 KiB
Python
"""
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Programming Language for 6502/6510 microprocessors, codename 'Sick'
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This is the 6502 assembly code generator (directly from the parse tree)
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Written by Irmen de Jong (irmen@razorvine.net) - license: GNU GPL 3.0
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"""
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import contextlib
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import attr
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from typing import Set, Callable
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from ...plyparse import Scope, AstNode
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from ...compile import Zeropage
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@attr.s(repr=False, cmp=False)
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class Context:
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out = attr.ib(type=Callable)
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stmt = attr.ib(type=AstNode)
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scope = attr.ib(type=Scope)
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floats_enabled = attr.ib(type=bool)
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@contextlib.contextmanager
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def preserving_registers(registers: Set[str], scope: Scope, out: Callable, loads_a_within: bool=False, force_preserve: bool=False):
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# this sometimes clobbers a ZP scratch register and is therefore NOT safe to use in interrupts
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# see http://6502.org/tutorials/register_preservation.html
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if not scope.save_registers and not force_preserve:
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yield
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return
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if registers == {'A'}:
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out("\t\tpha")
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yield
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out("\t\tpla")
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elif registers:
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if not loads_a_within:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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if 'A' in registers:
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out("\t\tpha")
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if 'X' in registers:
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out("\t\ttxa\n\t\tpha")
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if 'Y' in registers:
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out("\t\ttya\n\t\tpha")
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if not loads_a_within:
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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yield
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if 'X' in registers and 'Y' in registers:
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if 'A' not in registers:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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out("\t\tpla\n\t\ttay")
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out("\t\tpla\n\t\ttax")
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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else:
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out("\t\tpla\n\t\ttay")
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out("\t\tpla\n\t\ttax")
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else:
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if 'Y' in registers:
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if 'A' not in registers:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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out("\t\tpla\n\t\ttay")
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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else:
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out("\t\tpla\n\t\ttay")
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if 'X' in registers:
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if 'A' not in registers:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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out("\t\tpla\n\t\ttax")
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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else:
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out("\t\tpla\n\t\ttax")
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if 'A' in registers:
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out("\t\tpla")
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else:
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yield
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