txEngine.py

from myhdl import block, always_seq, always_comb, Signal, intbv, enum,\
    ResetSignal
from gemac.crc32 import crc32


txstate = enum('IDLE', 'PREAMBLE', 'SFD', 'FIRSTBYTE', 'INFRAME', 'PADDING',
               'ERROR', 'CRC1', 'CRC2', 'CRC3', 'CRC4', 'SENDPAUSE')


@block
def txengine(txclientintf, txgmii_intf, txflowintf, txconfig, sysreset):

    state = Signal(txstate.IDLE)
    curbyte = Signal(intbv(1, min=0, max=10000))
    pausereq = Signal(bool(0))
    reset = ResetSignal(0, active=0, async=True)
    ifgwait = Signal(intbv(0)[16:])
    data = Signal(intbv(0)[8:])
    dv = Signal(bool(0))

    clearcrc = Signal(bool(0))
    calccrc = Signal(bool(0))
    crcout = Signal(intbv(0xFFFFFFFF)[32:])

    crc32inst = crc32(txclientintf.clk, clearcrc, calccrc, data, crcout, reset)

    @always_comb
    def assign():
        txgmii_intf.clk.next = txclientintf.clk
        txclientintf.ack.next = state == txstate.FIRSTBYTE
        txgmii_intf.err.next = state == txstate.ERROR
        txflowintf.ispaused = state == txstate.IDLE
        clearcrc.next = state == txstate.IDLE
        fcsen = txconfig[29]
        calccrc.next = ((state == txstate.INFRAME) or
                        (state == txstate.PADDING)) and not fcsen
        reseten = txconfig[31]
        reset.next = sysreset or not reseten

    @always_seq(txclientintf.clk.posedge, reset)
    def curbyteinc():
        if state == txstate.IDLE:
            curbyte.next = 1
        else:
            curbyte.next = curbyte + 1

    @always_seq(txclientintf.clk.posedge, reset)
    def pausecntrl():
        if txflowintf.pausereq:
            pausereq.next = 1
        elif state == txstate.SENDPAUSE:
            pausereq.next = 0

    @always_seq(txclientintf.clk.posedge, reset)
    def transmitter():
        txen = txconfig[28]
        if (state == txstate.IDLE) and txen:
            data.next = 0x00
            dv.next = False
            txgmii_intf.data.next = 0x00
            txgmii_intf.dv.next = False
            if ifgwait > 0:
                ifgwait.next = ifgwait - 1
            elif pausereq:
                state.next = txstate.SENDPAUSE
            elif not txflowintf.pauseapply and txclientintf.dv:
                state.next = txstate.PREAMBLE

        elif state == txstate.PREAMBLE:
            data.next = 0x55
            dv.next = True
            txgmii_intf.data.next = data
            txgmii_intf.dv.next = dv
            if curbyte == 7:
                state.next = txstate.SFD

        elif state == txstate.SFD:
            data.next = 0xD5
            txgmii_intf.data.next = data
            state.next = txstate.FIRSTBYTE

        elif state == txstate.FIRSTBYTE:
            ifgen = txconfig[25]
            ifgwait.next = txclientintf.ifgdelay if ifgen else 12
            data.next = txclientintf.data
            txgmii_intf.data.next = data
            state.next = txstate.INFRAME

        elif state == txstate.INFRAME:
            data.next = txclientintf.data
            txgmii_intf.data.next = data
            if not txclientintf.dv:
                jumboen = txconfig[30]
                fcsen = txconfig[29]
                vlanen = txconfig[27]
                if curbyte > (1526 + vlanen*4) and not jumboen:
                    state.next = txstate.ERROR
                elif fcsen:
                    state.next = txstate.IDLE
                elif curbyte < 68:
                    state.next = txstate.PADDING
                else:
                    state.next = txstate.CRC1

        elif state == txstate.PADDING:
            if curbyte == 68:
                state.next = txstate.CRC1

        elif state == txstate.CRC1:
            txgmii_intf.data.next = crcout[32:24]
            state.next = txstate.CRC2

        elif state == txstate.CRC2:
            txgmii_intf.data.next = crcout[24:16]
            state.next = txstate.CRC3

        elif state == txstate.CRC3:
            txgmii_intf.data.next = crcout[16:8]
            state.next = txstate.CRC4

        elif state == txstate.CRC4:
            txgmii_intf.data.next = crcout[8:]
            state.next = txstate.IDLE

        elif state == txstate.ERROR:
            state.next = txstate.IDLE

    return assign, pausecntrl, curbyteinc, transmitter, crc32inst