Source code for hwtLib.examples.statements.fsm

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

from hwt.code import FsmBuilder, Switch, If
from hwt.hdl.types.bits import HBits
from hwt.hdl.types.enum import HEnum
from hwt.hwIOs.std import HwIOSignal, HwIOVectSignal
from hwt.hwIOs.utils import addClkRstn
from hwt.hwModule import HwModule
from hwt.pyUtils.typingFuture import override




class FsmExample(HwModule):
    """
    .. hwt-autodoc::
    """
    @override
    def hwDeclr(self):
        addClkRstn(self)
        self.a = HwIOSignal()
        self.b = HwIOSignal()
        self.dout = HwIOVectSignal(3)._m()

    @override
    def hwImpl(self):
        # :note: stT member names are colliding with port names and thus
        #     they will be renamed in HDL
        stT = HEnum("st_t", ["a", "b", "aAndB"])

        a = self.a
        b = self.b
        out = self.dout

        st = FsmBuilder(self, stT)\
        .Trans(stT.a,
            (a & b, stT.aAndB),
            (b, stT.b)
        ).Trans(stT.b,
            (a & b, stT.aAndB),
            (a, stT.a)
        ).Trans(stT.aAndB,
            (a & ~b, stT.a),
            (~a & b, stT.b),
        ).stateReg

        Switch(st)\
        .Case(stT.a,
              out(1)
        ).Case(stT.b,
              out(2)
        ).Case(stT.aAndB,
              out(3)
        )





class HadrcodedFsmExample(FsmExample):
    """
    .. hwt-autodoc::
    """
    @override
    def hwImpl(self):
        a = self.a
        b = self.b
        out = self.dout

        st = self._reg("st", HBits(3), 1)

        If(st._eq(1),
            If(a & b,
                st(3)
            ).Elif(b,
                st(2)
            )
        ).Elif(st._eq(2),
            If(a & b,
               st(3)
            ).Elif(a,
                st(1)
            )
        ).Elif(st._eq(3),
            If(a & ~b,
               st(1)
            ).Elif(~a & b,
                st(2)
            )
        ).Else(
            st(1)
        )

        Switch(st)\
        .Case(1,
            out(1)
        ).Case(2,
            out(2)
        ).Case(3,
            out(3)
        ).Default(
            out(None)
        )



if __name__ == "__main__":
    from hwt.synth import to_rtl_str
    
    m = FsmExample()
    print(to_rtl_str(m))