Implement RFC 66: Simulation time.

amaranth/hdl/__init__.py

@@ -10,6 +10,7 @@
 from ._ir import Instance, IOBufferInstance
 from ._mem import MemoryData, MemoryInstance
 from ._nir import CombinationalCycle
+from ._time import Period
 from ._xfrm import DomainRenamer, ResetInserter, EnableInserter
 
 
@@ -32,6 +33,8 @@
     "CombinationalCycle",
     # _mem
     "MemoryData", "MemoryInstance",
+    # _time
+    "Period",
     # _xfrm
     "DomainRenamer", "ResetInserter", "EnableInserter",
 ]

amaranth/hdl/_time.py

@@ -0,0 +1,252 @@
+import numbers
+import re
+
+
+__all__ = ["Period"]
+
+
+_TIME_UNITS = {
+    "s":  1_000_000_000_000_000,
+    "ms": 1_000_000_000_000,
+    "us": 1_000_000_000,
+    "ns": 1_000_000,
+    "ps": 1_000,
+    "fs": 1,
+}
+
+
+_FREQUENCY_UNITS = {
+    "Hz":  1_000_000_000_000_000,
+    "kHz": 1_000_000_000_000,
+    "MHz": 1_000_000_000,
+    "GHz": 1_000_000,
+}
+
+
+class Period:
+    def __init__(self, **kwargs):
+        if not kwargs:
+            self._femtoseconds = 0
+            return
+
+        if len(kwargs) > 1:
+            raise TypeError("Period accepts at most one argument")
+
+        (unit, value), = kwargs.items()
+
+        if not isinstance(value, numbers.Real):
+            raise TypeError(f"{unit} value must be a real number")
+
+        if unit in _TIME_UNITS:
+            self._femtoseconds = round(value * _TIME_UNITS[unit])
+
+        elif unit in _FREQUENCY_UNITS:
+            if value == 0:
+                raise ZeroDivisionError("Frequency can't be zero")
+            elif value < 0:
+                raise ValueError("Frequency can't be negative")
+
+            self._femtoseconds = round(_FREQUENCY_UNITS[unit] / value)
+
+        else:
+            raise TypeError(f"{unit} is not a valid unit")
+
+    @property
+    def seconds(self):
+        return self._femtoseconds / 1_000_000_000_000_000
+
+    @property
+    def milliseconds(self):
+        return self._femtoseconds / 1_000_000_000_000
+
+    @property
+    def microseconds(self):
+        return self._femtoseconds / 1_000_000_000
+
+    @property
+    def nanoseconds(self):
+        return self._femtoseconds / 1_000_000
+
+    @property
+    def picoseconds(self):
+        return self._femtoseconds / 1_000
+
+    @property
+    def femtoseconds(self):
+        return self._femtoseconds
+
+    def _check_reciprocal(self):
+        if self._femtoseconds == 0:
+            raise ZeroDivisionError("Can't calculate the frequency of a zero period")
+        elif self._femtoseconds < 0:
+            raise ValueError("Can't calculate the frequency of a negative period")
+
+    @property
+    def hertz(self):
+        self._check_reciprocal()
+        return 1_000_000_000_000_000 / self._femtoseconds
+
+    @property
+    def kilohertz(self):
+        self._check_reciprocal()
+        return 1_000_000_000_000 / self._femtoseconds
+
+    @property
+    def megahertz(self):
+        self._check_reciprocal()
+        return 1_000_000_000 / self._femtoseconds
+
+    @property
+    def gigahertz(self):
+        self._check_reciprocal()
+        return 1_000_000 / self._femtoseconds
+
+    def __lt__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return self._femtoseconds < other._femtoseconds
+
+    def __le__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return self._femtoseconds <= other._femtoseconds
+
+    def __eq__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return self._femtoseconds == other._femtoseconds
+
+    def __ne__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return self._femtoseconds != other._femtoseconds
+
+    def __gt__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return self._femtoseconds > other._femtoseconds
+
+    def __ge__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return self._femtoseconds >= other._femtoseconds
+
+    def __hash__(self):
+        return hash(self._femtoseconds)
+
+    def __bool__(self):
+        return bool(self._femtoseconds)
+
+    def __neg__(self):
+        return Period(fs=-self._femtoseconds)
+
+    def __pos__(self):
+        return self
+
+    def __abs__(self):
+        return Period(fs=abs(self._femtoseconds))
+
+    def __add__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return Period(fs=self._femtoseconds + other._femtoseconds)
+
+    def __sub__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return Period(fs=self._femtoseconds - other._femtoseconds)
+
+    def __mul__(self, other):
+        if not isinstance(other, numbers.Real):
+            return NotImplemented
+        return Period(fs=self._femtoseconds * other)
+
+    __rmul__ = __mul__
+
+    def __truediv__(self, other):
+        if isinstance(other, Period):
+            return self._femtoseconds / other._femtoseconds
+        elif isinstance(other, numbers.Real):
+            return Period(fs=self._femtoseconds / other)
+        else:
+            return NotImplemented
+
+    def __floordiv__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return self._femtoseconds // other._femtoseconds
+
+    def __mod__(self, other):
+        if not isinstance(other, Period):
+            return NotImplemented
+        return Period(fs=self._femtoseconds % other._femtoseconds)
+
+    def __str__(self):
+        return self.__format__("")
+
+    def __format__(self, format_spec):
+        m = re.match(r"^([1-9]\d*)?(\.\d+)?( ?)(([munpf]?)s|([kMG]?)Hz)?$", format_spec)
+
+        if m is None:
+            raise ValueError(f"Invalid format specifier '{format_spec}' for object of type 'Period'")
+
+        width, precision, space, unit, s_unit, hz_unit = m.groups()
+
+        if unit is None:
+            if abs(self._femtoseconds) >= 1_000_000_000_000_000:
+                s_unit = ""
+            elif abs(self._femtoseconds) >= 1_000_000_000_000:
+                s_unit = "m"
+            elif abs(self._femtoseconds) >= 1_000_000_000:
+                s_unit = "u"
+            elif abs(self._femtoseconds) >= 1_000_000:
+                s_unit = "n"
+            elif abs(self._femtoseconds) >= 1_000:
+                s_unit = "p"
+            else:
+                s_unit = "f"
+
+            unit = f"{s_unit}s"
+
+        if s_unit is not None:
+            div, digits = {
+                "":  (1_000_000_000_000_000, 15),
+                "m": (1_000_000_000_000, 12),
+                "u": (1_000_000_000, 9),
+                "n": (1_000_000, 6),
+                "p": (1_000, 3),
+                "f": (1, 0),
+            }[s_unit]
+            integer, decimal = divmod(self._femtoseconds, div)
+
+            if precision:
+                precision = int(precision[1:])
+                decimal = round(decimal * 10**(precision - digits))
+                digits = precision
+
+            value = f"{integer}.{decimal:0{digits}}"
+
+            if not precision:
+                value = value.rstrip('0')
+            value = value.rstrip('.')
+
+        else:
+            if hz_unit == "":
+                value = f"{self.hertz:{precision or ''}f}"
+            elif hz_unit == "k":
+                value = f"{self.kilohertz:{precision or ''}f}"
+            elif hz_unit == "M":
+                value = f"{self.megahertz:{precision or ''}f}"
+            elif hz_unit == "G":
+                value = f"{self.gigahertz:{precision or ''}f}"
+
+        str = f"{value}{space}{unit}"
+        if width:
+            str = f"{str:>{width}}"
+
+        return str
+
+    def __repr__(self):
+        for unit, div in _TIME_UNITS.items():
+            if self._femtoseconds % div == 0:
+                return f"Period({unit}={self._femtoseconds // div})"

amaranth/sim/__init__.py

@@ -1,11 +1,13 @@
 from .core import Simulator
 from ._async import DomainReset, BrokenTrigger, SimulatorContext, TickTrigger, TriggerCombination
 from ._pycoro import Settle, Delay, Tick, Passive, Active
+from ..hdl import Period
 
 
 __all__ = [
     "DomainReset", "BrokenTrigger",
     "SimulatorContext", "Simulator", "TickTrigger", "TriggerCombination",
+    "Period",
     # deprecated
     "Settle", "Delay", "Tick", "Passive", "Active",
 ]

amaranth/sim/core.py

@@ -17,10 +17,6 @@
 ]
 
 
-def _seconds_to_femtos(delay: float):
-    return int(delay * 1e15) # seconds to femtoseconds
-
-
 class Simulator:
     # Simulator engines aren't yet a part of the public API.
     """Simulator(toplevel)