37 lines
1.1 KiB
Python
37 lines
1.1 KiB
Python
from nmigen import *
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from ..isa import Funct3
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__all__ = ["CompareUnit"]
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class CompareUnit(Elaboratable):
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def __init__(self):
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self.op = Signal(3)
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self.zero = Signal()
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self.negative = Signal()
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self.overflow = Signal()
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self.carry = Signal()
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self.condition_met = Signal()
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def elaborate(self, platform):
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m = Module()
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with m.Switch(self.op):
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with m.Case(Funct3.BEQ):
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m.d.comb += self.condition_met.eq(self.zero)
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with m.Case(Funct3.BNE):
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m.d.comb += self.condition_met.eq(~self.zero)
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with m.Case(Funct3.BLT):
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m.d.comb += self.condition_met.eq(~self.zero & (self.negative != self.overflow))
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with m.Case(Funct3.BGE):
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m.d.comb += self.condition_met.eq(self.negative == self.overflow)
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with m.Case(Funct3.BLTU):
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m.d.comb += self.condition_met.eq(~self.zero & self.carry)
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with m.Case(Funct3.BGEU):
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m.d.comb += self.condition_met.eq(~self.carry)
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return m
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