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# d69f9ef6bbac retro-remote-debug-controller / client / emu_control.py
6.5 KiB · Python · last changed Contract 0.3.0: memory write (POST /mem) + audio drain (GET /audio) 3 months ago source blame history raw
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"""emu_control.py — shared client for the Retro Remote Debug Controller.
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One client for every port's pytest suite. Speaks the HTTP contract in
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../SPEC.md (0.3.x). Depends only on the stdlib; Pillow is optional and only
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needed for .screenshot().
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    from emu_control import EmuControl
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    emu = EmuControl(port=8080)      # emulator started with -controlport 8080
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    emu.wait_ready()
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    emu.step(frames=120)
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    assert emu.regs()["a"] == 0
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    data = emu.mem(0x0400, 256, bank=1)
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    img = emu.screenshot()           # PIL.Image (requires Pillow)
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"""
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from __future__ import annotations
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import io
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import json
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import time
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import urllib.error
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import urllib.request
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CONTRACT_MAJOR = 0
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class EmuControlError(RuntimeError):
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    pass
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def parse_ppm_header(data: bytes):
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    """Parse a binary PPM (P6) header. Returns (width, height, maxval, offset)
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    where offset is the index of the first pixel byte. Raises on malformed
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    input. Stdlib-only — no Pillow needed."""
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    if data[:2] != b"P6":
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        raise EmuControlError(f"not a P6 PPM (magic {data[:2]!r})")
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    fields, i, n = [], 2, len(data)
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    while len(fields) < 3 and i < n:
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        while i < n and data[i:i + 1].isspace():
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            i += 1
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        if i < n and data[i:i + 1] == b"#":            # comment to end of line
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            while i < n and data[i:i + 1] not in (b"\n", b"\r"):
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                i += 1
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            continue
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        start = i
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        while i < n and not data[i:i + 1].isspace():
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            i += 1
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        fields.append(int(data[start:i]))
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    if len(fields) < 3:
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        raise EmuControlError("truncated PPM header")
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    return fields[0], fields[1], fields[2], i + 1        # +1: single whitespace
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class EmuControl:
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    def __init__(self, port: int, host: str = "127.0.0.1", timeout: float = 5.0):
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        self.base = f"http://{host}:{port}"
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        self.timeout = timeout
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    # -- transport ---------------------------------------------------------
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    def _get(self, path: str) -> tuple[bytes, str]:
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        try:
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            with urllib.request.urlopen(self.base + path, timeout=self.timeout) as r:
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                return r.read(), r.headers.get_content_type()
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        except urllib.error.HTTPError as e:
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            raise EmuControlError(f"GET {path} -> {e.code}: {e.read()!r}") from e
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    def _post(self, path: str, body: bytes = b"") -> bytes:
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        req = urllib.request.Request(self.base + path, method="POST", data=body)
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        try:
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            with urllib.request.urlopen(req, timeout=self.timeout) as r:
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                return r.read()
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        except urllib.error.HTTPError as e:
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            raise EmuControlError(f"POST {path} -> {e.code}: {e.read()!r}") from e
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    # -- endpoints ---------------------------------------------------------
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    def status(self) -> dict:
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        body, _ = self._get("/status")
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        st = json.loads(body)
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        major = int(str(st.get("contract", "0")).split(".")[0])
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        if major != CONTRACT_MAJOR:
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            raise EmuControlError(
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                f"contract major mismatch: emulator {st.get('contract')} "
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                f"vs client {CONTRACT_MAJOR}.x"
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            )
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        return st
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    def frame(self) -> int:
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        return int(self.status()["frame"])
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    def regs(self) -> dict:
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        body, _ = self._get("/regs")
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        return json.loads(body)
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    def mem(self, addr: int, length: int, bank: int | None = None) -> bytes:
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        path = f"/mem?addr={addr}&len={length}"
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        if bank is not None:
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            path += f"&bank={bank}"
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        body, _ = self._get(path)
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        return body
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    def step(self, frames: int = 1) -> int:
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        body = self._post(f"/step?frames={frames}")
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        return int(json.loads(body)["frame"])
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    def pause(self) -> None:
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        self._post("/pause")
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    def resume(self) -> None:
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        self._post("/resume")
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    def key(self, text: str | None = None, code: int | None = None,
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            down: bool | None = None) -> None:
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        """Inject a key (contract 0.2). Provide `text` (a single character) or
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        `code` (a raw platform key code). down=True presses/holds, False
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        releases, None taps (press then release). Hold across step() frames for
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        a program that samples input each frame."""
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        parts = []
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        if text is not None:
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            parts.append(f"text={text}")
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        if code is not None:
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            parts.append(f"code={code}")
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        if down is not None:
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            parts.append(f"down={1 if down else 0}")
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        if not parts:
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            raise EmuControlError("key() needs text= or code=")
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        self._post("/key?" + "&".join(parts))
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    def reset(self) -> None:
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        """Soft/cold reset the machine (contract 0.2)."""
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        self._post("/reset")
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    def mem_write(self, addr: int, data: bytes, bank: int | None = None) -> int:
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        """Write/poke bytes at addr (contract 0.3). Returns the number written."""
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        path = f"/mem?addr={addr}"
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        if bank is not None:
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            path += f"&bank={bank}"
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        return int(json.loads(self._post(path, bytes(data)))["written"])
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    def audio(self) -> bytes:
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        """Raw WAV (PCM) of audio synthesized since the last call (contract 0.3).
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        Drain regularly (e.g. after each step) so the ring doesn't overflow."""
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        body, _ = self._get("/audio")
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        return body
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    def screenshot_ppm(self) -> bytes:
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        """Return the live screen as raw PPM (P6) bytes. Stdlib-only."""
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        body, _ = self._get("/screenshot")
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        return body
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    def screenshot(self):
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        """Return the live screen as a PIL.Image (requires Pillow)."""
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        body = self.screenshot_ppm()
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        try:
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            from PIL import Image
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        except ImportError as e:  # pragma: no cover
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            raise EmuControlError("screenshot() needs Pillow (pip install pillow)") from e
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        return Image.open(io.BytesIO(body))
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    # -- helpers -----------------------------------------------------------
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    def wait_ready(self, tries: int = 100, delay: float = 0.05) -> dict:
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        """Poll /status until the server answers (emulator boot race)."""
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        last = None
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        for _ in range(tries):
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            try:
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                return self.status()
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            except (EmuControlError, urllib.error.URLError, ConnectionError) as e:
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                last = e
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                time.sleep(delay)
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        raise EmuControlError(f"emulator control port never came up: {last}")
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    def run_to_frame(self, target: int) -> int:
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        """Step until the frame counter reaches >= target."""
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        cur = self.frame()
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        if target > cur:
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            self.step(frames=target - cur)
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        return self.frame()