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112 lines
3.3 KiB
Python
112 lines
3.3 KiB
Python
from operator import attrgetter
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from amaranth import *
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from amaranth.asserts import AnyConst
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from amaranth.hdl.ast import ValueCastable, Value
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__all__ = ["InsnField", "WordInsn"]
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class InsnField:
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def __init__(self, value=None):
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self.value = value
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@property
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def shape(self):
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return self._shape
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@property
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def offset(self):
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return self._offset
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@property
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def name(self):
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return self._name
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@property
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def value(self):
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return self._value
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@value.setter
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def value(self, value):
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if value is not None and not isinstance(value, int):
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raise TypeError("Field value must be an integer, not {!r}"
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.format(value))
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self._value = value
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def as_const(self):
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if self.value is not None:
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return Const(self.value, self.shape)
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else:
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return AnyConst(self.shape)
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class WordInsn(ValueCastable):
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SIZE = 32
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def __init__(self):
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value_map = {}
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field_map = {}
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curr_offset = 0
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for field in sorted(self.fields, key=attrgetter('offset')):
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if not isinstance(field, InsnField):
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raise TypeError("Field must be an instance of InsnField, not {!r}"
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.format(field))
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if field.name in field_map:
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raise ValueError("Duplicate field name '{}'".format(field.name))
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if curr_offset > field.offset:
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raise ValueError("Field '{}' at offset {} overlaps with its predecessor"
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.format(field.name, field.offset))
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# Add undefined bits located between this field and its predecessor.
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if curr_offset < field.offset:
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undef_bits = AnyConst(unsigned(field.offset - curr_offset))
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value_map[curr_offset] = undef_bits
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value_map[field.offset] = field.as_const()
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field_map[field.name ] = field
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curr_offset = field.offset + field.shape.width
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if curr_offset > self.SIZE:
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raise ValueError
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# Add undefined bits located after the last field.
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if curr_offset < self.SIZE:
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undef_bits = AnyConst(unsigned(self.SIZE - curr_offset))
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value_map[curr_offset] = undef_bits
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self.field_map = field_map
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self.value_map = value_map
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@property
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def fields(self):
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return self._fields
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def __getattr__(self, name):
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return self[name]
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def __getitem__(self, item):
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if isinstance(item, str):
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try:
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field = self.field_map[item]
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except KeyError:
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raise AttributeError("WordInsn {!r} does not have a field '{}'"
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.format(self, item))
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value = self.value_map[field.offset]
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return value
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else:
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try:
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return Value.__getitem__(self, item)
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except KeyError:
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raise AttributeError("WordInsn {!r} does not have a field '{}'"
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.format(self, item))
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@ValueCastable.lowermethod
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def as_value(self):
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value = Cat(v for o, v in sorted(self.value_map.items(), reverse=True))
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assert len(value) == self.SIZE
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return value
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