src/devices/dev_le.c

/*
 *  Copyright (C) 2003-2006  Anders Gavare.  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright  
 *     notice, this list of conditions and the following disclaimer in the 
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE   
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 *  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *   
 *
 *  $Id: dev_le.c,v 1.51 2006/07/14 16:33:28 debug Exp $
 *  
 *  LANCE ethernet, as used in DECstations.
 *
 *  This is based on "PMAD-AA TURBOchannel Ethernet Module Functional
 *  Specification". I've tried to keep symbol names in this file to what
 *  the specs use.
 *
 *  This is what the memory layout looks like on a DECstation 5000/200:
 *
 *      0x000000 - 0x0fffff     Ethernet SRAM buffer  (should be 128KB)
 *      0x100000 - 0x17ffff     LANCE registers
 *      0x1c0000 - 0x1fffff     Ethernet Diagnostic ROM and Station
 *                              Address ROM
 *
 *  The length of the device is set to 0x1c0200, however, because Sprite
 *  tries to read TURBOchannel rom data from 0x1c03f0, and that is provided
 *  by the turbochannel device, not this device.
 *
 *
 *  TODO:  Error conditions (such as when there are not enough receive
 *         buffers) are not emulated yet.
 *
 *         (Old bug, but probably still valid:  "UDP packets that are too 
 *         large are not handled well by the Lance device.")
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "cpu.h"
#include "devices.h"
#include "emul.h"
#include "machine.h"
#include "memory.h"
#include "misc.h"
#include "net.h"

#include "if_lereg.h"


#define LE_TICK_SHIFT           14

/*  #define LE_DEBUG  */
/*  #define debug fatal  */

extern int quiet_mode;

#define LE_MODE_LOOP            4
#define LE_MODE_DTX             2
#define LE_MODE_DRX             1


#define N_REGISTERS             4
#define SRAM_SIZE               (128*1024)
#define ROM_SIZE                32


struct le_data {
        int             irq_nr;

        uint64_t        buf_start;
        uint64_t        buf_end;
        int             len;

        uint8_t         rom[ROM_SIZE];

        int             reg_select;
        uint16_t        reg[N_REGISTERS];

        unsigned char   *sram;

        /*  Initialization block:  */
        uint32_t        init_block_addr;

        uint16_t        mode;
        uint64_t        padr;   /*  MAC address  */
        uint64_t        ladrf;
        uint32_t        rdra;   /*  receive descriptor ring address  */
        int             rlen;   /*  nr of rx descriptors  */
        uint32_t        tdra;   /*  transmit descriptor ring address  */
        int             tlen;   /*  nr ot tx descriptors  */

        /*  Current rx and tx descriptor indices:  */
        int             rxp;
        int             txp;

        unsigned char   *tx_packet;
        int             tx_packet_len;

        unsigned char   *rx_packet;
        int             rx_packet_len;
        int             rx_packet_offset;
        int             rx_middle_bit;
};


/*
 *  le_read_16bit():
 *
 *  Read a 16-bit word from the SRAM.
 */
static uint64_t le_read_16bit(struct le_data *d, int addr)
{
        /*  TODO: This is for little endian only  */
        int x = d->sram[addr & (SRAM_SIZE-1)] +
               (d->sram[(addr+1) & (SRAM_SIZE-1)] << 8);
        return x;
}


/*
 *  le_write_16bit():
 *
 *  Write a 16-bit word to the SRAM.
 */
static void le_write_16bit(struct le_data *d, int addr, uint16_t x)
{
        /*  TODO: This is for little endian only  */
        d->sram[addr & (SRAM_SIZE-1)] = x & 0xff;
        d->sram[(addr+1) & (SRAM_SIZE-1)] = (x >> 8) & 0xff;
}


/*
 *  le_chip_init():
 *
 *  Initialize data structures by reading an 'initialization block' from the
 *  SRAM.
 */
static void le_chip_init(struct le_data *d)
{
        d->init_block_addr = (d->reg[1] & 0xffff) + ((d->reg[2] & 0xff) << 16);
        if (d->init_block_addr & 1)
                fatal("[ le: WARNING! initialization block address "
                    "not word aligned? ]\n");

        debug("[ le: d->init_block_addr = 0x%06x ]\n", d->init_block_addr);

        d->mode = le_read_16bit(d, d->init_block_addr + 0);
        d->padr = le_read_16bit(d, d->init_block_addr + 2);
        d->padr += (le_read_16bit(d, d->init_block_addr + 4) << 16);
        d->padr += (le_read_16bit(d, d->init_block_addr + 6) << 32);
        d->ladrf = le_read_16bit(d, d->init_block_addr + 8);
        d->ladrf += (le_read_16bit(d, d->init_block_addr + 10) << 16);
        d->ladrf += (le_read_16bit(d, d->init_block_addr + 12) << 32);
        d->ladrf += (le_read_16bit(d, d->init_block_addr + 14) << 48);
        d->rdra = le_read_16bit(d, d->init_block_addr + 16);
        d->rdra += ((le_read_16bit(d, d->init_block_addr + 18) & 0xff) << 16);
        d->rlen = 1 << ((le_read_16bit(d, d->init_block_addr + 18) >> 13) & 7);
        d->tdra = le_read_16bit(d, d->init_block_addr + 20);
        d->tdra += ((le_read_16bit(d, d->init_block_addr + 22) & 0xff) << 16);
        d->tlen = 1 << ((le_read_16bit(d, d->init_block_addr + 22) >> 13) & 7);

        debug("[ le: DEBUG: mode              %04x ]\n", d->mode);
        debug("[ le: DEBUG: padr  %016llx ]\n", (long long)d->padr);
        debug("[ le: DEBUG: ladrf %016llx ]\n", (long long)d->ladrf);
        debug("[ le: DEBUG: rdra            %06llx ]\n", d->rdra);
        debug("[ le: DEBUG: rlen               %3i ]\n", d->rlen);
        debug("[ le: DEBUG: tdra            %06llx ]\n", d->tdra);
        debug("[ le: DEBUG: tlen               %3i ]\n", d->tlen);

        /*  Set TXON and RXON, unless they are disabled by 'mode':  */
        if (d->mode & LE_MODE_DTX)
                d->reg[0] &= ~LE_TXON;
        else
                d->reg[0] |= LE_TXON;

        if (d->mode & LE_MODE_DRX)
                d->reg[0] &= ~LE_RXON;
        else
                d->reg[0] |= LE_RXON;

        /*  Go to the start of the descriptor rings:  */
        d->rxp = d->txp = 0;

        /*  Set IDON and reset the INIT bit when we are done.  */
        d->reg[0] |= LE_IDON;
        d->reg[0] &= ~LE_INIT;

        /*  Free any old packets:  */
        if (d->tx_packet != NULL)
                free(d->tx_packet);
        d->tx_packet = NULL;
        d->tx_packet_len = 0;

        if (d->rx_packet != NULL)
                free(d->rx_packet);
        d->rx_packet = NULL;
        d->rx_packet_len = 0;
        d->rx_packet_offset = 0;
        d->rx_middle_bit = 0;
}


/*
 *  le_tx():
 *
 *  Check the transmitter descriptor ring for buffers that are owned by the
 *  Lance chip (that is, buffers that are to be transmitted).
 *
 *  This routine should only be called if TXON is enabled.
 */
static void le_tx(struct net *net, struct le_data *d)
{
        int start_txp = d->txp;
        uint16_t tx_descr[4];
        int stp, enp, cur_packet_offset;
        size_t i;
        uint32_t bufaddr, buflen;

        /*  TODO: This is just a guess:  */
        d->reg[0] &= ~LE_TDMD;

        do {
                /*  Load the 8 descriptor bytes:  */
                tx_descr[0] = le_read_16bit(d, d->tdra + d->txp*8 + 0);
                tx_descr[1] = le_read_16bit(d, d->tdra + d->txp*8 + 2);
                tx_descr[2] = le_read_16bit(d, d->tdra + d->txp*8 + 4);
                tx_descr[3] = le_read_16bit(d, d->tdra + d->txp*8 + 6);

                bufaddr = tx_descr[0] + ((tx_descr[1] & 0xff) << 16);
                stp = tx_descr[1] & LE_STP? 1 : 0;
                enp = tx_descr[1] & LE_ENP? 1 : 0;
                buflen = 4096 - (tx_descr[2] & 0xfff);

                /*
                 *  Check the OWN bit. If it is zero, then this buffer is
                 *  not ready to be transmitted yet.  Also check the '1111'
                 *  mark, and make sure that byte-count is reasonable.
                 */
                if (!(tx_descr[1] & LE_OWN))
                        return;
                if ((tx_descr[2] & 0xf000) != 0xf000)
                        return;
                if (buflen < 12 || buflen > 1900) {
                        fatal("[ le_tx(): buflen = %i ]\n", buflen);
                        return;
                }

                debug("[ le_tx(): descr %3i DUMP: 0x%04x 0x%04x 0x%04x 0x%04x "
                    "=> addr=0x%06x, len=%i bytes, STP=%i ENP=%i ]\n", d->txp,
                    tx_descr[0], tx_descr[1], tx_descr[2], tx_descr[3],
                    bufaddr, buflen, stp, enp);

                if (d->tx_packet == NULL && !stp) {
                        fatal("[ le_tx(): !stp but tx_packet == NULL ]\n");
                        return;
                }

                if (d->tx_packet != NULL && stp) {
                        fatal("[ le_tx(): stp but tx_packet != NULL ]\n");
                        free(d->tx_packet);
                        d->tx_packet = NULL;
                        d->tx_packet_len = 0;
                }

                /*  Where to write to in the tx_packet:  */
                cur_packet_offset = d->tx_packet_len;

                /*  Start of a new packet:  */
                if (stp) {
                        d->tx_packet_len = buflen;
                        d->tx_packet = malloc(buflen);
                        if (d->tx_packet == NULL) {
                                fprintf(stderr, "out of memory (1) in "
                                    "le_tx()\n");
                                exit(1);
                        }
                } else {
                        d->tx_packet_len += buflen;
                        d->tx_packet = realloc(d->tx_packet, d->tx_packet_len);
                        if (d->tx_packet == NULL) {
                                fprintf(stderr, "out of memory (2) in"
                                    " le_tx()\n");
                                exit(1);
                        }
                }

                /*  Copy data from SRAM into the tx packet:  */
                for (i=0; i<buflen; i++) {
                        unsigned char ch;
                        ch = d->sram[(bufaddr + i) & (SRAM_SIZE-1)];
                        d->tx_packet[cur_packet_offset + i] = ch;
                }

                /*
                 *  Is this the last buffer in a packet? Then transmit
                 *  it, cause an interrupt, and free the memory used by
                 *  the packet.
                 */
                if (enp) {
                        net_ethernet_tx(net, d, d->tx_packet, d->tx_packet_len);

                        free(d->tx_packet);
                        d->tx_packet = NULL;
                        d->tx_packet_len = 0;

                        d->reg[0] |= LE_TINT;
                }

                /*  Clear the OWN bit:  */
                tx_descr[1] &= ~LE_OWN;

                /*  Write back the descriptor to SRAM:  */
                le_write_16bit(d, d->tdra + d->txp*8 + 2, tx_descr[1]);
                le_write_16bit(d, d->tdra + d->txp*8 + 4, tx_descr[2]);
                le_write_16bit(d, d->tdra + d->txp*8 + 6, tx_descr[3]);

                /*  Go to the next descriptor:  */
                d->txp ++;
                if (d->txp >= d->tlen)
                        d->txp = 0;
        } while (d->txp != start_txp);

        /*  We are here if all descriptors were taken care of.  */
        fatal("[ le_tx(): all TX descriptors used up? ]\n");
}


/*
 *  le_rx():
 *
 *  This routine should only be called if RXON is enabled.
 */
static void le_rx(struct net *net, struct le_data *d)
{
        int start_rxp = d->rxp;
        size_t i;
        uint16_t rx_descr[4];
        uint32_t bufaddr, buflen;

        do {
                if (d->rx_packet == NULL)
                        return;

                /*  Load the 8 descriptor bytes:  */
                rx_descr[0] = le_read_16bit(d, d->rdra + d->rxp*8 + 0);
                rx_descr[1] = le_read_16bit(d, d->rdra + d->rxp*8 + 2);
                rx_descr[2] = le_read_16bit(d, d->rdra + d->rxp*8 + 4);
                rx_descr[3] = le_read_16bit(d, d->rdra + d->rxp*8 + 6);

                bufaddr = rx_descr[0] + ((rx_descr[1] & 0xff) << 16);
                buflen = 4096 - (rx_descr[2] & 0xfff);

                /*
                 *  Check the OWN bit. If it is zero, then this buffer is
                 *  not ready to receive data yet.  Also check the '1111'
                 *  mark, and make sure that byte-count is reasonable.
                 */
                if (!(rx_descr[1] & LE_OWN))
                        return;
                if ((rx_descr[2] & 0xf000) != 0xf000)
                        return;
                if (buflen < 12 || buflen > 1900) {
                        fatal("[ le_rx(): buflen = %i ]\n", buflen);
                        return;
                }

                debug("[ le_rx(): descr %3i DUMP: 0x%04x 0x%04x 0x%04x 0x%04x "
                    "=> addr=0x%06x, len=%i bytes ]\n", d->rxp,
                    rx_descr[0], rx_descr[1], rx_descr[2], rx_descr[3],
                    bufaddr, buflen);

                /*  Copy data from the packet into SRAM:  */
                for (i=0; i<buflen; i++) {
                        if (d->rx_packet_offset+(ssize_t)i >= d->rx_packet_len)
                                break;
                        d->sram[(bufaddr + i) & (SRAM_SIZE-1)] =
                            d->rx_packet[d->rx_packet_offset + i];
                }

                /*  Here, i is the number of bytes copied.  */
                d->rx_packet_offset += i;

                /*  Set the ENP bit if this was the end of a packet:  */
                if (d->rx_packet_offset >= d->rx_packet_len) {
                        rx_descr[1] |= LE_ENP;

                        /*
                         *  NOTE:  The Lance documentation that I have read
                         *  says _NOTHING_ about the length being 4 more than
                         *  the length of the data.  You can guess how
                         *  surprised I was when I saw the following in
                         *  NetBSD (dev/ic/am7990.c):
                         *
                         *      lance_read(sc, LE_RBUFADDR(sc, bix),
                         *              (int)rmd.rmd3 - 4);
                         */
                        rx_descr[3] &= ~0xfff;
                        rx_descr[3] |= d->rx_packet_len + 4;

                        free(d->rx_packet);
                        d->rx_packet = NULL;
                        d->rx_packet_len = 0;
                        d->rx_packet_offset = 0;
                        d->rx_middle_bit = 0;

                        d->reg[0] |= LE_RINT;
                }

                /*  Set the STP bit if this was the start of a packet:  */
                if (!d->rx_middle_bit) {
                        rx_descr[1] |= LE_STP;

                        /*  Are we continuing on this packet?  */
                        if (d->rx_packet != NULL)
                                d->rx_middle_bit = 1;
                }

                /*  Clear the OWN bit:  */
                rx_descr[1] &= ~LE_OWN;

                /*  Write back the descriptor to SRAM:  */
                le_write_16bit(d, d->rdra + d->rxp*8 + 2, rx_descr[1]);
                le_write_16bit(d, d->rdra + d->rxp*8 + 4, rx_descr[2]);
                le_write_16bit(d, d->rdra + d->rxp*8 + 6, rx_descr[3]);

                /*  Go to the next descriptor:  */
                d->rxp ++;
                if (d->rxp >= d->rlen)
                        d->rxp = 0;
        } while (d->rxp != start_rxp);

        /*  We are here if all descriptors were taken care of.  */
        fatal("[ le_rx(): all RX descriptors used up? ]\n");
}


/*
 *  le_register_fix():
 */
static void le_register_fix(struct net *net, struct le_data *d)
{
        /*  Init with new Initialization block, if needed.  */
        if (d->reg[0] & LE_INIT)
                le_chip_init(d);

#ifdef LE_DEBUG
        {
                static int x = 1234;
                if (x != d->reg[0]) {
                        debug("[ le reg[0] = 0x%04x ]\n", d->reg[0]);
                        x = d->reg[0];
                }
        }
#endif

        /*
         *  If the receiver is on:
         *  If there is a current rx_packet, try to receive it into the
         *  Lance buffers.  Then try to receive any additional packets.
         */
        if (d->reg[0] & LE_RXON) {
                do {
                        if (d->rx_packet != NULL)
                                /*  Try to receive the packet:  */
                                le_rx(net, d);

                        if (d->rx_packet != NULL)
                                /*  If the packet wasn't fully received, 
                                    then abort for now.  */
                                break;

                        if (d->rx_packet == NULL &&
                            net_ethernet_rx_avail(net, d))
                                net_ethernet_rx(net, d,
                                    &d->rx_packet, &d->rx_packet_len);
                } while (d->rx_packet != NULL);
        }

        /*  If the transmitter is on, check for outgoing buffers:  */
        if (d->reg[0] & LE_TXON)
                le_tx(net, d);

        /*  SERR should be the OR of BABL, CERR, MISS, and MERR:  */
        d->reg[0] &= ~LE_SERR;
        if (d->reg[0] & (LE_BABL | LE_CERR | LE_MISS | LE_MERR))
                d->reg[0] |= LE_SERR;

        /*  INTR should be the OR of BABL, MISS, MERR, RINT, TINT, IDON:  */
        d->reg[0] &= ~LE_INTR;
        if (d->reg[0] & (LE_BABL | LE_MISS | LE_MERR | LE_RINT |
            LE_TINT | LE_IDON))
                d->reg[0] |= LE_INTR;

        /*  The MERR bit clears some bits:  */
        if (d->reg[0] & LE_MERR)
                d->reg[0] &= ~(LE_RXON | LE_TXON);

        /*  The STOP bit clears a lot of stuff:  */
#if 0
        /*  According to the LANCE manual: (doesn't work with Ultrix)  */
        if (d->reg[0] & LE_STOP)
                d->reg[0] &= ~(LE_SERR | LE_BABL | LE_CERR | LE_MISS | LE_MERR
                    | LE_RINT | LE_TINT | LE_IDON | LE_INTR | LE_INEA
                    | LE_RXON | LE_TXON | LE_TDMD);
#else
        /*  Works with Ultrix:  */
        if (d->reg[0] & LE_STOP)
                d->reg[0] &= ~(LE_IDON);
#endif
}


/*
 *  dev_le_tick():
 */
void dev_le_tick(struct cpu *cpu, void *extra)
{
        struct le_data *d = (struct le_data *) extra;

        le_register_fix(cpu->machine->emul->net, d);

        if (d->reg[0] & LE_INTR && d->reg[0] & LE_INEA)
                cpu_interrupt(cpu, d->irq_nr);
        else
                cpu_interrupt_ack(cpu, d->irq_nr);
}


/*
 *  le_register_write():
 *
 *  This function is called when the value 'x' is written to register 'r'.
 */
void le_register_write(struct le_data *d, int r, uint32_t x)
{
        switch (r) {
        case 0: /*  CSR0:  */
                /*  Some bits are write-one-to-clear:  */
                if (x & LE_BABL)
                        d->reg[r] &= ~LE_BABL;
                if (x & LE_CERR)
                        d->reg[r] &= ~LE_CERR;
                if (x & LE_MISS)
                        d->reg[r] &= ~LE_MISS;
                if (x & LE_MERR)
                        d->reg[r] &= ~LE_MERR;
                if (x & LE_RINT)
                        d->reg[r] &= ~LE_RINT;
                if (x & LE_TINT)
                        d->reg[r] &= ~LE_TINT;
                if (x & LE_IDON)
                        d->reg[r] &= ~LE_IDON;

                /*  Some bits are write-only settable, not clearable:  */
                if (x & LE_TDMD)
                        d->reg[r] |= LE_TDMD;
                if (x & LE_STRT) {
                        d->reg[r] |= LE_STRT;
                        d->reg[r] &= ~LE_STOP;
                }
                if (x & LE_INIT) {
                        if (!(d->reg[r] & LE_STOP))
                                fatal("[ le: attempt to INIT before"
                                    " STOPped! ]\n");
                        d->reg[r] |= LE_INIT;
                        d->reg[r] &= ~LE_STOP;
                }
                if (x & LE_STOP) {
                        d->reg[r] |= LE_STOP;
                        /*  STOP takes precedence over STRT and INIT:  */
                        d->reg[r] &= ~(LE_STRT | LE_INIT);
                }

                /*  Some bits get through, both settable and clearable:  */
                d->reg[r] &= ~LE_INEA;
                d->reg[r] |= (x & LE_INEA);
                break;

        default:
                /*  CSR1, CSR2, and CSR3:  */
                d->reg[r] = x;
        }
}


DEVICE_ACCESS(le_sram)
{
        size_t i;
        int retval;
        struct le_data *d = extra;

#ifdef LE_DEBUG
        if (writeflag == MEM_WRITE) {
                fatal("[ le_sram: write to addr 0x%06x: ", (int)relative_addr);
                for (i=0; i<len; i++)
                        fatal("%02x ", data[i]);
                fatal("]\n");
        }
#endif

        /*  Read/write of the SRAM:  */
        if (relative_addr < SRAM_SIZE && relative_addr + len <= SRAM_SIZE) {
                if (writeflag == MEM_READ) {
                        memcpy(data, d->sram + relative_addr, len);
                        if (!quiet_mode) {
                                debug("[ le: read from SRAM offset 0x%05x:",
                                    relative_addr);
                                for (i=0; i<len; i++)
                                        debug(" %02x", data[i]);
                                debug(" ]\n");
                        }
                        retval = 9;     /*  9 cycles  */
                } else {
                        memcpy(d->sram + relative_addr, data, len);
                        if (!quiet_mode) {
                                debug("[ le: write to SRAM offset 0x%05x:",
                                    relative_addr);
                                for (i=0; i<len; i++)
                                        debug(" %02x", data[i]);
                                debug(" ]\n");
                        }
                        retval = 6;     /*  6 cycles  */
                }
                return retval;
        }

        return 0;
}


DEVICE_ACCESS(le)
{
        uint64_t idata = 0, odata = 0;
        size_t i;
        int retval = 1;
        struct le_data *d = extra;

        if (writeflag == MEM_WRITE)
                idata = memory_readmax64(cpu, data, len);

#ifdef LE_DEBUG
        if (writeflag == MEM_WRITE) {
                fatal("[ le: write to addr 0x%06x: ", (int)relative_addr);
                for (i=0; i<len; i++)
                        fatal("%02x ", data[i]);
                fatal("]\n");
        }
#endif

        /*  Read from station's ROM (ethernet address):  */
        if (relative_addr >= 0xc0000 && relative_addr <= 0xfffff) {
                uint32_t a;
                int j = (relative_addr & 0xff) / 4;
                a = d->rom[j & (ROM_SIZE-1)];

                if (writeflag == MEM_READ) {
                        odata = (a << 24) + (a << 16) + (a << 8) + a;
                } else {
                        fatal("[ le: WRITE to ethernet addr (%08lx):",
                            (long)relative_addr);
                        for (i=0; i<len; i++)
                                fatal(" %02x", data[i]);
                        fatal(" ]\n");
                }

                retval = 13;    /*  13 cycles  */
                goto do_return;
        }


        switch (relative_addr) {

        /*  Register read/write:  */
        case 0:
                if (writeflag==MEM_READ) {
                        odata = d->reg[d->reg_select];
                        if (!quiet_mode)
                                debug("[ le: read from register 0x%02x: 0x"
                                    "%02x ]\n", d->reg_select, (int)odata);
                        /*
                         *  A read from csr1..3 should return "undefined"
                         *  result if the stop bit is set.  However, Ultrix
                         *  seems to do just that, so let's _not_ print
                         *  a warning here.
                         */
                } else {
                        if (!quiet_mode)
                                debug("[ le: write to register 0x%02x: 0x"
                                    "%02x ]\n", d->reg_select, (int)idata);
                        /*
                         *  A write to from csr1..3 when the stop bit is
                         *  set should be ignored. However, Ultrix writes
                         *  even if the stop bit is set, so let's _not_
                         *  print a warning about it.
                         */
                        le_register_write(d, d->reg_select, idata);
                }
                break;

        /*  Register select:  */
        case 4:
                if (writeflag==MEM_READ) {
                        odata = d->reg_select;
                        if (!quiet_mode)
                                debug("[ le: read from register select: "
                                    "0x%02x ]\n", (int)odata);
                } else {
                        if (!quiet_mode)
                                debug("[ le: write to register select: "
                                    "0x%02x ]\n", (int)idata);
                        d->reg_select = idata & (N_REGISTERS - 1);
                        if (idata >= N_REGISTERS)
                                fatal("[ le: WARNING! register select %i "
                                    "(max is %i) ]\n", idata, N_REGISTERS - 1);
                }
                break;

        default:
                if (writeflag==MEM_READ) {
                        fatal("[ le: read from UNIMPLEMENTED addr 0x%06x ]\n",
                            (int)relative_addr);
                } else {
                        fatal("[ le: write to UNIMPLEMENTED addr 0x%06x: "
                            "0x%08x ]\n", (int)relative_addr, (int)idata);
                }
        }

do_return:
        if (writeflag == MEM_READ) {
                memory_writemax64(cpu, data, len, odata);
#ifdef LE_DEBUG
                fatal("[ le: read from addr 0x%06x: 0x%08x ]\n",
                    relative_addr, odata);
#endif
        }

        dev_le_tick(cpu, extra);

        return retval;
}


/*
 *  dev_le_init():
 */
void dev_le_init(struct machine *machine, struct memory *mem, uint64_t baseaddr,
        uint64_t buf_start, uint64_t buf_end, int irq_nr, int len)
{
        char *name2;
        size_t nlen = 55;
        struct le_data *d = malloc(sizeof(struct le_data));

        if (d == NULL) {
                fprintf(stderr, "out of memory\n");
                exit(1);
        }

        memset(d, 0, sizeof(struct le_data));
        d->irq_nr    = irq_nr;

        d->sram = malloc(SRAM_SIZE);
        if (d->sram == NULL) {
                fprintf(stderr, "out of memory\n");
                exit(1);
        }
        memset(d->sram, 0, SRAM_SIZE);

        /*  TODO:  Are these actually used yet?  */
        d->len       = len;
        d->buf_start = buf_start;
        d->buf_end   = buf_end;

        /*  Initial register contents:  */
        d->reg[0] = LE_STOP;

        d->tx_packet = NULL;
        d->rx_packet = NULL;

        /*  ROM (including the MAC address):  */
        net_generate_unique_mac(machine, &d->rom[0]);

        /*  Copies of the MAC address and a test pattern:  */
        d->rom[10] = d->rom[21] = d->rom[5];
        d->rom[11] = d->rom[20] = d->rom[4];
        d->rom[12] = d->rom[19] = d->rom[3];
        d->rom[7] =  d->rom[8]  = d->rom[23] =
                     d->rom[13] = d->rom[18] = d->rom[2];
        d->rom[6] =  d->rom[9]  = d->rom[22] =
                     d->rom[14] = d->rom[17] = d->rom[1];
        d->rom[15] = d->rom[16] = d->rom[0];
        d->rom[24] = d->rom[28] = 0xff;
        d->rom[25] = d->rom[29] = 0x00;
        d->rom[26] = d->rom[30] = 0x55;
        d->rom[27] = d->rom[31] = 0xaa;

        memory_device_register(mem, "le_sram", baseaddr,
            SRAM_SIZE, dev_le_sram_access, (void *)d,
            DM_DYNTRANS_OK | DM_DYNTRANS_WRITE_OK
            | DM_READS_HAVE_NO_SIDE_EFFECTS, d->sram);

        name2 = malloc(nlen);
        if (name2 == NULL) {
                fprintf(stderr, "out of memory in dev_le_init()\n");
                exit(1);
        }
        snprintf(name2, nlen, "le [%02x:%02x:%02x:%02x:%02x:%02x]",
            d->rom[0], d->rom[1], d->rom[2], d->rom[3], d->rom[4], d->rom[5]);

        memory_device_register(mem, name2, baseaddr + 0x100000,
            len - 0x100000, dev_le_access, (void *)d, DM_DEFAULT, NULL);

        machine_add_tickfunction(machine, dev_le_tick, d, LE_TICK_SHIFT, 0.0);

        net_add_nic(machine->emul->net, d, &d->rom[0]);
}
