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"""PTIMER block (modeled virtual time; not a silicon timing claim).
Evidence kind: **hardware register/field header** (offsets and field layout)
plus a *modeled* time source. The firmware has not yet been observed reading
this block in the 570.144 boot runs (the observed time-like reads were on
falcon MAILBOX1); the device is therefore opt-in: it is registered only when
a profile declares a ``timer`` section, and a section with
``"enabled": false`` is skipped. Its values are explicitly labelled
*modeled*.
Header facts used:
* ``NV_PTIMER`` block base ``0x9000`` in the register aperture.
* ``NV_PTIMER_TIME_0`` at aperture offset ``0x9400``: nanoseconds bits
``31:5``.
* ``NV_PTIMER_TIME_1`` at aperture offset ``0x9410``: nanoseconds bits
``28:0``.
* Reads of TIME_0 latch TIME_1 (paired read), as on the hardware register
pair; the simulator derives nanoseconds from the machine's instruction
count times the profile's ``ns_per_insn`` (default 1.0, i.e. 1 ns/insn --
a placeholder, not calibrated).
Register offsets below are **relative to the block window base** the profile
declares (``PRIV + 0x9000``), i.e. aperture offset minus ``PTIMER_BASE``:
``0x9400 - 0x9000 = 0x400``. Using the aperture-absolute numbers here would
place the registers outside the declared window and serve nothing.
"""
from __future__ import annotations
from .base import Device
PTIMER_BASE = 0x9000
#: Block-relative offsets of NV_PTIMER_TIME_0/1 (aperture 0x9400/0x9410).
TIME_0 = 0x400
TIME_1 = 0x410
class PtimerBlock(Device):
"""Two-register nanosecond timer with a modeled tick source."""
name = "timer"
def __init__(self, *, base: int = 0, size: int = 0x1000,
ns_per_insn: float = 1.0, clock=None):
super().__init__(base=base, size=size)
self.ns_per_insn = float(ns_per_insn)
self.clock = clock # callable returning virtual instruction count
self._latch = 0
self.reads = 0
def _now_ns(self) -> int:
insns = self.clock() if self.clock is not None else 0
return int(insns * self.ns_per_insn) & 0xFFFFFFFFFFFFFFFF
def read(self, offset: int, size: int) -> int | None:
if size != 4:
return None
if offset == TIME_0:
self._latch = self._now_ns()
self.reads += 1
return (self._latch >> 5) & 0xFFFFFFFF # NSEC field 31:5
if offset == TIME_1:
self.reads += 1
return self._latch & 0x1FFFFFFF # NSEC field 28:0
return None
def peek(self, offset: int, size: int) -> int | None:
if size != 4:
return None
if offset == TIME_0:
return (self._now_ns() >> 5) & 0xFFFFFFFF
if offset == TIME_1:
return self._now_ns() & 0x1FFFFFFF
return None
def write(self, offset: int, size: int, value: int) -> bool:
return False
def state(self) -> dict:
return {"ns_per_insn": self.ns_per_insn, "latch": self._latch,
"reads": self.reads}
def load_state(self, data: dict) -> None:
self.ns_per_insn = float(data.get("ns_per_insn", self.ns_per_insn))
self._latch = int(data.get("latch", 0))
self.reads = int(data.get("reads", 0))
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