63 lines
1.7 KiB
Python
63 lines
1.7 KiB
Python
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#!/usr/bin/env python3
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from dataclasses import dataclass
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from random import choices
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from string import ascii_lowercase, digits
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from typing import List
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from ichor.isa import Opcode
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@dataclass
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class Label(object):
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name: str
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def __hash__(self):
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return hash(self.name)
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class FuncBuilder(object):
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def __init__(self) -> None:
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self._opcodes = []
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def write(self, op: Opcode):
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self._opcodes.append(op)
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def make_label(self, prefix=""):
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frag = ''.join(choices(ascii_lowercase + digits, k=8))
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return Label(f"{prefix or 'gensym'}_{frag}")
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def set_label(self, label: Label):
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self._opcodes.append(label)
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def build(self) -> List[Opcode]:
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"""Assemble the written body into fully resolved opcodes."""
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# The trivial two-pass assembler. First pass removes labels from the
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# opcode stream, marking where they occurred.
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labels = {}
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unassembled = []
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for op in self._opcodes:
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match op:
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case Label(_) as l:
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assert l not in labels # Label marks must be unique.
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labels[l] = len(unassembled)
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case o:
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unassembled.append(o)
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# Second pass rewrites instructions (which can reference forwards OR
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# backwards labels) with real targets instead of labels.
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assembled = []
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for op in unassembled:
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match op:
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case Opcode.GOTO(Label(_) as l):
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assembled.append(Opcode.GOTO(labels[l]))
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case Opcode.VTEST(Label(_) as l):
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assembled.append(Opcode.VTEST(labels[l]))
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case o:
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assembled.append(o)
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return assembled
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