5962a73341
Теперь репозиторий очень грязный, но мне правда уже не хочется мучиться с зависимостиями, поэтому пусть будет так
326 lines
12 KiB
Python
326 lines
12 KiB
Python
from dataclasses import dataclass
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from typing import ClassVar, Callable
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from ctypes import c_uint32, c_int32
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import struct
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from optable import OPCODES, OpcodeDescription, OpL, OpA, OpF, OpD
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from enum import IntFlag, Enum, auto
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WORD_SIZE: int = 4
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class VMFlags(IntFlag):
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# if last instruction is big, then you should
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# skip more memory on step
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AFTER_BRANCH = auto()
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EXPANDED_INSTR = auto()
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class Condition:
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def __init__(self, cond: int):
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self.i: bool = bool(cond & (1 << 3))
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self.v: bool = bool(cond & (1 << 2))
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self.n: bool = bool(cond & (1 << 1))
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self.z: bool = bool(cond & (1 << 0))
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class VMCC(IntFlag):
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OVERFLOW = 1 << 2
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NEGATIVE = 1 << 1
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ZERO = 1 << 0
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@dataclass
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class Breakpoint(Exception):
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address: int
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class VMExceptionType(Enum):
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END_OF_MEM = auto()
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INVALID_OPCODE = auto()
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@dataclass
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class VMException(Exception):
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cause: VMExceptionType
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pc: int
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message: str = ""
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@dataclass
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class VM:
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instr_callbacks: ClassVar[dict[OpcodeDescription, Callable]]
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mem: bytearray
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cc: VMCC
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pc: c_uint32
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registers: list[c_int32]
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breakpoints: set[int]
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_vm_flags: VMFlags
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def __init__(self, mem: bytearray):
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self.mem: bytearray = mem
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self.cc: VMCC = VMCC(0)
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self.pc: c_uint32 = c_uint32(0)
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self.registers: list[c_int32] = [c_int32(0) for _ in range(256)]
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self.breakpoints: set[int] = set()
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self._vm_flags: VMFlags = VMFlags(0)
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self.__init_callbacks__()
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def __init_callbacks__(self):
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VM.instr_callbacks = {
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# ariphmetic
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.ADD):
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self._math_callback_gen(lambda lhs, rhs: lhs + rhs),
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OpD(OpF.QUICK, OpL.MATH, OpA.ADD):
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self._math_quick_callback_gen(lambda lhs, rhs: lhs + rhs),
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.SUB):
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self._math_callback_gen(lambda lhs, rhs: lhs - rhs),
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OpD(OpF.QUICK, OpL.MATH, OpA.SUB):
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self._math_quick_callback_gen(lambda lhs, rhs: lhs - rhs),
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.MUL):
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self._math_callback_gen(lambda lhs, rhs: lhs * rhs),
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OpD(OpF.QUICK, OpL.MATH, OpA.MUL):
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self._math_quick_callback_gen(lambda lhs, rhs: lhs * rhs),
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.DIV):
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self._math_callback_gen(lambda lhs, rhs: lhs // rhs),
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OpD(OpF.QUICK, OpL.MATH, OpA.DIV):
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self._math_quick_callback_gen(lambda lhs, rhs: lhs // rhs),
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# logical ops
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.AND):
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self._math_callback_gen(lambda lhs, rhs: lhs & rhs),
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.OR):
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self._math_callback_gen(lambda lhs, rhs: lhs | rhs),
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.XOR):
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self._math_callback_gen(lambda lhs, rhs: lhs ^ rhs),
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OpD(OpF.UNEXPANDED, OpL.MATH, OpA.MASK):
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self._math_callback_gen(
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lambda lhs, rhs: lhs & ((~rhs + (1 << 32)) % (1 << 32))
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),
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# block 2
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OpD(OpF(0), OpL.MEM, OpA.LOAD):
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self._load_callback,
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OpD(OpF.QUICK, OpL.MEM, OpA.LOAD):
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self._load_callback,
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OpD(OpF(0), OpL.MEM, OpA.STORE):
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self._store_callback,
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OpD(OpF.QUICK, OpL.MEM, OpA.STORE):
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self._store_callback,
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# block 3
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OpD(OpF(0), OpL.BRANCH, OpA.BRANCH):
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self._branch_callback,
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OpD(OpF.QUICK, OpL.BRANCH, OpA.BRANCH):
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self._branch_callback,
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OpD(OpF(0), OpL.BRANCH, OpA.IND_BRANCH):
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self._branch_indexed_callback
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}
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def step(self) -> None:
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"""
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Make one step (only step into)
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"""
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if self._to_raw_bytes_offset(self.pc) > len(self.mem) - WORD_SIZE:
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raise VMException(
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VMExceptionType.END_OF_MEM,
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self.pc.value,
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"couldn't perform step because end of memory occured"
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)
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opcode, *_ = instr = self._fetch_instr()
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opdesc = self._get_opcode_desc(opcode)
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args: tuple[int, ...] = self._parse_instr_fields(bytes(instr))
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if not (OpF.UNEXPANDED in opdesc.flags or
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OpF.QUICK in opdesc.flags):
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extra = struct.unpack(">i", self._fetch_instr())[0]
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args = (*args, extra)
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self._run_callback(opdesc, args)
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self._vm_flags &= ~(VMFlags.EXPANDED_INSTR)
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self._vm_flags &= ~(VMFlags.AFTER_BRANCH)
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def continue_(self) -> None:
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"""
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Continue from current breakpoint
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"""
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while self._to_raw_bytes_offset(self.pc.value) < len(self.mem):
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if self.pc.value in self.breakpoints:
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raise Breakpoint(self.pc.value)
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self.step()
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def run(self) -> None:
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"""
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Run from very beginning
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"""
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self.pc = c_uint32(0)
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while (self._to_raw_bytes_offset(self.pc.value) < len(self.mem)):
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self.continue_()
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def _fetch_instr(self) -> bytearray:
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"""
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Берет из памяти следущее слово, возвращает его
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ВАЖНО: инкрементирует счетчик команд на каждом вызове
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"""
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addr = self._to_raw_bytes_offset(self.pc)
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instr = self.mem[addr:addr+WORD_SIZE]
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self._increment_pc()
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return instr
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def _get_opcode_desc(self, opcode: int):
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"""
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Обертка над обращением к таблице опкодов из файлика optable.py.
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Нужна чтобы прокидывать исключения виртуальной машины, а не
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KeyError
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"""
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if not opcode in OPCODES:
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raise VMException(
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VMExceptionType.INVALID_OPCODE,
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self.pc.value,
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f"Couldn't resolve an opcode {hex(opcode)}"
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)
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return OPCODES[opcode]
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def _to_raw_bytes_offset(self, pointer: int | c_uint32 | c_int32) -> int:
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"""
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Переводит адресс из указателей в рамках процессора, которые
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являются 32-битными, в формат смещения в сырых байтах в памяти
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"""
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if isinstance(pointer, int):
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return pointer * WORD_SIZE
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return pointer.value * WORD_SIZE
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def _parse_instr_fields(
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self,
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instr: bytes
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) -> tuple[int, int, int, int]:
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return struct.unpack(">BBBb", instr)
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def _run_callback(
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self,
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opdesc: OpcodeDescription,
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args: tuple[int, ...]
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) -> None:
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if not (OpF.QUICK in opdesc.flags or OpF.UNEXPANDED in opdesc.flags):
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self._vm_flags |= VMFlags.EXPANDED_INSTR
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if opdesc.layout == OpL.MATH:
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assert len(args) == 4
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_, r3, r1, r2_or_i8 = args
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# поскольку этот колбэк сгенерирован,
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# ему необходимо в явном виде указывать
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# аргумент self
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self.instr_callbacks[opdesc](
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self, r3, r1, r2_or_i8
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)
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if opdesc.layout == OpL.MEM:
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if OpF.QUICK in opdesc.flags:
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assert len(args) == 4
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_, r3, r1, i8 = args
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self.instr_callbacks[opdesc](
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r3, r1, i8
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)
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else:
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assert len(args) == 5
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_, r3, r1, _, disp = args
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self.instr_callbacks[opdesc](
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r3, r1, disp
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)
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if opdesc.layout == OpL.BRANCH:
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if OpF.QUICK in opdesc.flags:
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assert len(args) == 4
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_, cond, _, i8 = args
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self.instr_callbacks[opdesc](
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cond, i8
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)
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elif opdesc.action == OpA.IND_BRANCH:
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assert len(args) == 5
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_, cond, r1, _, disp = args
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self.instr_callbacks[opdesc](
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cond, r1, disp
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)
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else:
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assert len(args) == 5
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_, cond, _, _, disp = args
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self.instr_callbacks[opdesc](
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cond, disp
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)
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def _math_callback_gen(
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self,
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operation: Callable[[int, int], int]
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) -> Callable[["VM", int, int ,int], None]:
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"""
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Поскольку математические операции конструируются
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по одному шаблону, я завел функцию высшего порядка,
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которая будет их генерировать
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"""
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def callback(self, r3: int, r1: int, r2: int):
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lhs = self.registers[r1].value
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rhs = self.registers[r2].value
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self.registers[r3] = c_int32(operation(lhs, rhs))
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return callback
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def _math_quick_callback_gen(
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self,
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operation: Callable[[int, int], int]
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) -> Callable[["VM", int, int ,int], None]:
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"""
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Поскольку математические операции конструируются
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по одному шаблону, я завел функцию высшего порядка,
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которая будет их генерировать.
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В отлиие от _math_callback_gen, эта уже предназначена для
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операций с пометкой QUICK
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"""
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def callback(self, r3: int, r1: int, i8: int) -> None:
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self.cc = VMCC(0)
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lhs = self.registers[r1].value
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result = operation(lhs, i8)
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if result < 0:
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self.cc |= VMCC.NEGATIVE
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elif result == 0:
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self.cc |= VMCC.ZERO
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# самая дорогая проверка на переполнение)
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try:
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struct.pack('i', result)
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except struct.error:
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self.cc |= VMCC.OVERFLOW
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self.registers[r3] = c_int32(result)
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return callback
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def _load_callback(self, r3: int, r1: int, disp: int) -> None:
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addr = self._to_raw_bytes_offset(self.registers[r1].value + disp)
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self.registers[r3] = c_int32(
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struct.unpack(
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">i", self.mem[addr:addr+WORD_SIZE])[0]
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)
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def _store_callback(self, r3: int, r1: int, disp: int) -> None:
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addr = self._to_raw_bytes_offset(self.registers[r1].value + disp)
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self.mem[addr:addr+WORD_SIZE] = struct.pack(
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">i",
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self.registers[r3].value
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)
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def _branch_callback(self, cond: int, disp: int) -> None:
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c = Condition(cond)
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vm_c = Condition(self.cc)
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if (c.v & vm_c.v) | (c.n & vm_c.n) | (c.z & vm_c.z) == c.i:
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self._vm_flags = VMFlags.AFTER_BRANCH
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self.pc = c_uint32(self.pc.value + disp)
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def _branch_indexed_callback(self, cond: int, r1: int, disp: int) -> None:
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c = Condition(cond)
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vm_c = Condition(self.cc.value)
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if (c.v & vm_c.v) | (c.n & vm_c.n) | (c.z & vm_c.z) == c.i:
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self._vm_flags = VMFlags.AFTER_BRANCH
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addr = self.registers[r1].value + disp
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self.pc = c_uint32(addr)
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def _increment_pc(self):
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self.pc = c_uint32(self.pc.value + 1)
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