riscv-formal-nmigen/rvfi/cores/minerva/units/compare.py

37 lines
1.1 KiB
Python
Raw Normal View History

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