40 lines
1.0 KiB
Python
40 lines
1.0 KiB
Python
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from nmigen import *
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__all__ = ["Shifter"]
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class Shifter(Elaboratable):
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def __init__(self):
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self.x_direction = Signal()
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self.x_sext = Signal()
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self.x_shamt = Signal(5)
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self.x_src1 = Signal(32)
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self.x_stall = Signal()
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self.m_result = Signal(32)
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def elaborate(self, platform):
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m = Module()
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x_operand = Signal(32)
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x_filler = Signal()
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m_direction = Signal()
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m_result = Signal(32)
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m.d.comb += [
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# left shifts are equivalent to right shifts with reversed bits
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x_operand.eq(Mux(self.x_direction, self.x_src1, self.x_src1[::-1])),
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x_filler.eq(Mux(self.x_direction & self.x_sext, self.x_src1[-1], 0))
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]
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with m.If(~self.x_stall):
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m.d.sync += [
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m_direction.eq(self.x_direction),
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m_result.eq(Cat(x_operand, Repl(x_filler, 32)) >> self.x_shamt)
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]
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m.d.comb += self.m_result.eq(Mux(m_direction, m_result, m_result[::-1]))
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return m
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