Source code for hwtLib.mem.cam

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

from hwt.code import If, Concat, log2ceil
from hwt.hdl.typeShortcuts import hBit
from hwt.hdl.types.bits import Bits
from hwt.interfaces.std import Handshaked, VldSynced
from hwt.interfaces.utils import addClkRstn
from hwt.serializer.mode import serializeParamsUniq
from hwt.synthesizer.unit import Unit
from hwt.synthesizer.param import Param
from hwtLib.interfaces.addrDataHs import AddrDataBitMaskHs


[docs]@serializeParamsUniq
class Cam(Unit):
    """
    Content addressable memory

    Simple combinational version

    MATCH_LATENCY = 1
    """

[docs]    def _config(self):
        self.DATA_WIDTH = Param(36)
        self.ITEMS = Param(16)

[docs]    def _declr(self):
        addClkRstn(self)
        with self._paramsShared():
            self.match = Handshaked()
            self.write = AddrDataBitMaskHs()
            self.write.ADDR_WIDTH.set(log2ceil(self.ITEMS - 1))
        self.out = VldSynced()
        self.out._replaceParam("DATA_WIDTH", self.ITEMS)

[docs]    def writeHandler(self, mem):
        w = self.write
        w.rd(1)

        If(self.clk._onRisingEdge() & w.vld,
           mem[w.addr](Concat(w.data, w.mask[0]))
        )

[docs]    def matchHandler(self, mem):
        key = self.match

        out = self._reg("out_reg", self.out.data._dtype, defVal=0)
        outNext = out.next
        outVld = self._reg("out_vld_reg", defVal=0)

        key.rd(1)
        outVld(key.vld)

        for i in range(int(self.ITEMS)):
            outNext[i](mem[i]._eq(Concat(key.data, hBit(1))))

        self.out.data(out)
        self.out.vld(outVld)

[docs]    def _impl(self):
        # +1 bit to validity check
        self._mem = self._sig("cam_mem",
                              Bits(self.DATA_WIDTH + 1)[self.ITEMS],
                              [0 for _ in range(int(self.ITEMS))]
                              )
        self.writeHandler(self._mem)
        self.matchHandler(self._mem)


if __name__ == "__main__":
    from hwt.synthesizer.utils import toRtl
    u = Cam()
    print(toRtl(u))