sbni.c

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/* sbni.c:  Granch SBNI12 leased line adapters driver for linux
 *
 *  Written 2001 by Denis I.Timofeev ([email protected])
 *
 *  Previous versions were written by Yaroslav Polyakov,
 *  Alexey Zverev and Max Khon.
 *
 *  Driver supports SBNI12-02,-04,-05,-10,-11 cards, single and
 *  double-channel, PCI and ISA modifications.
 *  More info and useful utilities to work with SBNI12 cards you can find
 *  at http://www.granch.com (English) or http://www.granch.ru (Russian)
 *
 *  This software may be used and distributed according to the terms
 *  of the GNU General Public License.
 *
 *
 *  5.0.1   Jun 22 2001
 *    - Fixed bug in probe
 *  5.0.0   Jun 06 2001
 *    - Driver was completely redesigned by Denis I.Timofeev,
 *    - now PCI/Dual, ISA/Dual (with single interrupt line) models are
 *    - supported
 *  3.3.0   Thu Feb 24 21:30:28 NOVT 2000 
 *        - PCI cards support
 *  3.2.0   Mon Dec 13 22:26:53 NOVT 1999
 *    - Completely rebuilt all the packet storage system
 *    -    to work in Ethernet-like style.
 *  3.1.1   just fixed some bugs (5 aug 1999)
 *  3.1.0   added balancing feature (26 apr 1999)
 *  3.0.1   just fixed some bugs (14 apr 1999).
 *  3.0.0   Initial Revision, Yaroslav Polyakov (24 Feb 1999)
 *        - added pre-calculation for CRC, fixed bug with "len-2" frames, 
 *        - removed outbound fragmentation (MTU=1000), written CRC-calculation 
 *        - on asm, added work with hard_headers and now we have our own cache 
 *        - for them, optionally supported word-interchange on some chipsets,
 * 
 *  Known problem: this driver wasn't tested on multiprocessor machine.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/fcntl.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/pci.h>
#include <linux/skbuff.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/delay.h>

#include <net/net_namespace.h>
#include <net/arp.h>

#include <asm/io.h>
#include <asm/types.h>
#include <asm/byteorder.h>
#include <asm/irq.h>
#include <asm/uaccess.h>

#include "sbni.h"

/* device private data */

struct net_local {
    struct timer_list   watchdog;

    spinlock_t  lock;
    struct sk_buff  *rx_buf_p;      /* receive buffer ptr */
    struct sk_buff  *tx_buf_p;      /* transmit buffer ptr */
    
    unsigned int    framelen;       /* current frame length */
    unsigned int    maxframe;       /* maximum valid frame length */
    unsigned int    state;
    unsigned int    inppos, outpos;     /* positions in rx/tx buffers */

    /* transmitting frame number - from frames qty to 1 */
    unsigned int    tx_frameno;

    /* expected number of next receiving frame */
    unsigned int    wait_frameno;

    /* count of failed attempts to frame send - 32 attempts do before
       error - while receiver tunes on opposite side of wire */
    unsigned int    trans_errors;

    /* idle time; send pong when limit exceeded */
    unsigned int    timer_ticks;

    /* fields used for receive level autoselection */
    int delta_rxl;
    unsigned int    cur_rxl_index, timeout_rxl;
    unsigned long   cur_rxl_rcvd, prev_rxl_rcvd;

    struct sbni_csr1    csr1;       /* current value of CSR1 */
    struct sbni_in_stats    in_stats;   /* internal statistics */ 

    struct net_device       *second;    /* for ISA/dual cards */

#ifdef CONFIG_SBNI_MULTILINE
    struct net_device       *master;
    struct net_device       *link;
#endif
};


static int  sbni_card_probe( unsigned long );
static int  sbni_pci_probe( struct net_device  * );
static struct net_device  *sbni_probe1(struct net_device *, unsigned long, int);
static int  sbni_open( struct net_device * );
static int  sbni_close( struct net_device * );
static netdev_tx_t sbni_start_xmit(struct sk_buff *,
                     struct net_device * );
static int  sbni_ioctl( struct net_device *, struct ifreq *, int );
static void  set_multicast_list( struct net_device * );

static irqreturn_t sbni_interrupt( int, void * );
static void  handle_channel( struct net_device * );
static int   recv_frame( struct net_device * );
static void  send_frame( struct net_device * );
static int   upload_data( struct net_device *,
              unsigned, unsigned, unsigned, u32 );
static void  download_data( struct net_device *, u32 * );
static void  sbni_watchdog( unsigned long );
static void  interpret_ack( struct net_device *, unsigned );
static int   append_frame_to_pkt( struct net_device *, unsigned, u32 );
static void  indicate_pkt( struct net_device * );
static void  card_start( struct net_device * );
static void  prepare_to_send( struct sk_buff *, struct net_device * );
static void  drop_xmit_queue( struct net_device * );
static void  send_frame_header( struct net_device *, u32 * );
static int   skip_tail( unsigned int, unsigned int, u32 );
static int   check_fhdr( u32, u32 *, u32 *, u32 *, u32 *, u32 * );
static void  change_level( struct net_device * );
static void  timeout_change_level( struct net_device * );
static u32   calc_crc32( u32, u8 *, u32 );
static struct sk_buff *  get_rx_buf( struct net_device * );
static int  sbni_init( struct net_device * );

#ifdef CONFIG_SBNI_MULTILINE
static int  enslave( struct net_device *, struct net_device * );
static int  emancipate( struct net_device * );
#endif

#ifdef __i386__
#define ASM_CRC 1
#endif

static const char  version[] =
    "Granch SBNI12 driver ver 5.0.1  Jun 22 2001  Denis I.Timofeev.\n";

static bool skip_pci_probe  __initdata = false;
static int  scandone    __initdata = 0;
static int  num     __initdata = 0;

static unsigned char  rxl_tab[];
static u32  crc32tab[];

/* A list of all installed devices, for removing the driver module. */
static struct net_device  *sbni_cards[ SBNI_MAX_NUM_CARDS ];

/* Lists of device's parameters */
static u32  io[   SBNI_MAX_NUM_CARDS ] __initdata =
    { [0 ... SBNI_MAX_NUM_CARDS-1] = -1 };
static u32  irq[  SBNI_MAX_NUM_CARDS ] __initdata;
static u32  baud[ SBNI_MAX_NUM_CARDS ] __initdata;
static u32  rxl[  SBNI_MAX_NUM_CARDS ] __initdata =
    { [0 ... SBNI_MAX_NUM_CARDS-1] = -1 };
static u32  mac[  SBNI_MAX_NUM_CARDS ] __initdata;

#ifndef MODULE
typedef u32  iarr[];
static iarr __initdata *dest[5] = { &io, &irq, &baud, &rxl, &mac };
#endif

/* A zero-terminated list of I/O addresses to be probed on ISA bus */
static unsigned int  netcard_portlist[ ] __initdata = { 
    0x210, 0x214, 0x220, 0x224, 0x230, 0x234, 0x240, 0x244, 0x250, 0x254,
    0x260, 0x264, 0x270, 0x274, 0x280, 0x284, 0x290, 0x294, 0x2a0, 0x2a4,
    0x2b0, 0x2b4, 0x2c0, 0x2c4, 0x2d0, 0x2d4, 0x2e0, 0x2e4, 0x2f0, 0x2f4,
    0 };

#define NET_LOCAL_LOCK(dev) (((struct net_local *)netdev_priv(dev))->lock)

/*
 * Look for SBNI card which addr stored in dev->base_addr, if nonzero.
 * Otherwise, look through PCI bus. If none PCI-card was found, scan ISA.
 */

static inline int __init
sbni_isa_probe( struct net_device  *dev )
{
    if( dev->base_addr > 0x1ff &&
        request_region( dev->base_addr, SBNI_IO_EXTENT, dev->name ) &&
        sbni_probe1( dev, dev->base_addr, dev->irq ) )

        return  0;
    else {
        pr_err("base address 0x%lx is busy, or adapter is malfunctional!\n",
               dev->base_addr);
        return  -ENODEV;
    }
}

static const struct net_device_ops sbni_netdev_ops = {
    .ndo_open       = sbni_open,
    .ndo_stop       = sbni_close,
    .ndo_start_xmit     = sbni_start_xmit,
    .ndo_set_rx_mode    = set_multicast_list,
    .ndo_do_ioctl       = sbni_ioctl,
    .ndo_change_mtu     = eth_change_mtu,
    .ndo_set_mac_address    = eth_mac_addr,
    .ndo_validate_addr  = eth_validate_addr,
};

static void __init sbni_devsetup(struct net_device *dev)
{
    ether_setup( dev );
    dev->netdev_ops = &sbni_netdev_ops;
}

int __init sbni_probe(int unit)
{
    struct net_device *dev;
    int err;

    dev = alloc_netdev(sizeof(struct net_local), "sbni", sbni_devsetup);
    if (!dev)
        return -ENOMEM;

    dev->netdev_ops = &sbni_netdev_ops;

    sprintf(dev->name, "sbni%d", unit);
    netdev_boot_setup_check(dev);

    err = sbni_init(dev);
    if (err) {
        free_netdev(dev);
        return err;
    }

    err = register_netdev(dev);
    if (err) {
        release_region( dev->base_addr, SBNI_IO_EXTENT );
        free_netdev(dev);
        return err;
    }
    pr_info_once("%s", version);
    return 0;
}

static int __init sbni_init(struct net_device *dev)
{
    int  i;
    if( dev->base_addr )
        return  sbni_isa_probe( dev );
    /* otherwise we have to perform search our adapter */

    if( io[ num ] != -1 )
        dev->base_addr  = io[ num ],
        dev->irq    = irq[ num ];
    else if( scandone  ||  io[ 0 ] != -1 )
        return  -ENODEV;

    /* if io[ num ] contains non-zero address, then that is on ISA bus */
    if( dev->base_addr )
        return  sbni_isa_probe( dev );

    /* ...otherwise - scan PCI first */
    if( !skip_pci_probe  &&  !sbni_pci_probe( dev ) )
        return  0;

    if( io[ num ] == -1 ) {
        /* Auto-scan will be stopped when first ISA card were found */
        scandone = 1;
        if( num > 0 )
            return  -ENODEV;
    }

    for( i = 0;  netcard_portlist[ i ];  ++i ) {
        int  ioaddr = netcard_portlist[ i ];
        if( request_region( ioaddr, SBNI_IO_EXTENT, dev->name ) &&
            sbni_probe1( dev, ioaddr, 0 ))
            return 0;
    }

    return  -ENODEV;
}


static int __init
sbni_pci_probe( struct net_device  *dev )
{
    struct pci_dev  *pdev = NULL;

    while( (pdev = pci_get_class( PCI_CLASS_NETWORK_OTHER << 8, pdev ))
           != NULL ) {
        int  pci_irq_line;
        unsigned long  pci_ioaddr;

        if( pdev->vendor != SBNI_PCI_VENDOR &&
            pdev->device != SBNI_PCI_DEVICE )
            continue;

        pci_ioaddr = pci_resource_start( pdev, 0 );
        pci_irq_line = pdev->irq;

        /* Avoid already found cards from previous calls */
        if( !request_region( pci_ioaddr, SBNI_IO_EXTENT, dev->name ) ) {
            if (pdev->subsystem_device != 2)
                continue;

            /* Dual adapter is present */
            if (!request_region(pci_ioaddr += 4, SBNI_IO_EXTENT,
                            dev->name ) )
                continue;
        }

        if (pci_irq_line <= 0 || pci_irq_line >= nr_irqs)
            pr_warn(
"WARNING: The PCI BIOS assigned this PCI card to IRQ %d, which is unlikely to work!.\n"
"You should use the PCI BIOS setup to assign a valid IRQ line.\n",
                pci_irq_line );

        /* avoiding re-enable dual adapters */
        if( (pci_ioaddr & 7) == 0  &&  pci_enable_device( pdev ) ) {
            release_region( pci_ioaddr, SBNI_IO_EXTENT );
            pci_dev_put( pdev );
            return  -EIO;
        }
        if( sbni_probe1( dev, pci_ioaddr, pci_irq_line ) ) {
            SET_NETDEV_DEV(dev, &pdev->dev);
            /* not the best thing to do, but this is all messed up 
               for hotplug systems anyway... */
            pci_dev_put( pdev );
            return  0;
        }
    }
    return  -ENODEV;
}


static struct net_device * __init
sbni_probe1( struct net_device  *dev,  unsigned long  ioaddr,  int  irq )
{
    struct net_local  *nl;

    if( sbni_card_probe( ioaddr ) ) {
        release_region( ioaddr, SBNI_IO_EXTENT );
        return NULL;
    }

    outb( 0, ioaddr + CSR0 );

    if( irq < 2 ) {
        unsigned long irq_mask;

        irq_mask = probe_irq_on();
        outb( EN_INT | TR_REQ, ioaddr + CSR0 );
        outb( PR_RES, ioaddr + CSR1 );
        mdelay(50);
        irq = probe_irq_off(irq_mask);
        outb( 0, ioaddr + CSR0 );

        if( !irq ) {
            pr_err("%s: can't detect device irq!\n", dev->name);
            release_region( ioaddr, SBNI_IO_EXTENT );
            return NULL;
        }
    } else if( irq == 2 )
        irq = 9;

    dev->irq = irq;
    dev->base_addr = ioaddr;

    /* Fill in sbni-specific dev fields. */
    nl = netdev_priv(dev);
    if( !nl ) {
        pr_err("%s: unable to get memory!\n", dev->name);
        release_region( ioaddr, SBNI_IO_EXTENT );
        return NULL;
    }

    memset( nl, 0, sizeof(struct net_local) );
    spin_lock_init( &nl->lock );

    /* store MAC address (generate if that isn't known) */
    *(__be16 *)dev->dev_addr = htons( 0x00ff );
    *(__be32 *)(dev->dev_addr + 2) = htonl( 0x01000000 |
        ((mac[num] ?
        mac[num] :
        (u32)((long)netdev_priv(dev))) & 0x00ffffff));

    /* store link settings (speed, receive level ) */
    nl->maxframe  = DEFAULT_FRAME_LEN;
    nl->csr1.rate = baud[ num ];

    if( (nl->cur_rxl_index = rxl[ num ]) == -1 )
        /* autotune rxl */
        nl->cur_rxl_index = DEF_RXL,
        nl->delta_rxl = DEF_RXL_DELTA;
    else
        nl->delta_rxl = 0;
    nl->csr1.rxl  = rxl_tab[ nl->cur_rxl_index ];
    if( inb( ioaddr + CSR0 ) & 0x01 )
        nl->state |= FL_SLOW_MODE;

    pr_notice("%s: ioaddr %#lx, irq %d, MAC: 00:ff:01:%02x:%02x:%02x\n",
          dev->name, dev->base_addr, dev->irq,
          ((u8 *)dev->dev_addr)[3],
          ((u8 *)dev->dev_addr)[4],
          ((u8 *)dev->dev_addr)[5]);

    pr_notice("%s: speed %d",
          dev->name,
          ((nl->state & FL_SLOW_MODE) ? 500000 : 2000000)
          / (1 << nl->csr1.rate));

    if( nl->delta_rxl == 0 )
        pr_cont(", receive level 0x%x (fixed)\n", nl->cur_rxl_index);
    else
        pr_cont(", receive level (auto)\n");

#ifdef CONFIG_SBNI_MULTILINE
    nl->master = dev;
    nl->link   = NULL;
#endif
   
    sbni_cards[ num++ ] = dev;
    return  dev;
}

/* -------------------------------------------------------------------------- */

#ifdef CONFIG_SBNI_MULTILINE

static netdev_tx_t
sbni_start_xmit( struct sk_buff  *skb,  struct net_device  *dev )
{
    struct net_device  *p;

    netif_stop_queue( dev );

    /* Looking for idle device in the list */
    for( p = dev;  p; ) {
        struct net_local  *nl = netdev_priv(p);
        spin_lock( &nl->lock );
        if( nl->tx_buf_p  ||  (nl->state & FL_LINE_DOWN) ) {
            p = nl->link;
            spin_unlock( &nl->lock );
        } else {
            /* Idle dev is found */
            prepare_to_send( skb, p );
            spin_unlock( &nl->lock );
            netif_start_queue( dev );
            return NETDEV_TX_OK;
        }
    }

    return NETDEV_TX_BUSY;
}

#else   /* CONFIG_SBNI_MULTILINE */

static netdev_tx_t
sbni_start_xmit( struct sk_buff  *skb,  struct net_device  *dev )
{
    struct net_local  *nl  = netdev_priv(dev);

    netif_stop_queue( dev );
    spin_lock( &nl->lock );

    prepare_to_send( skb, dev );

    spin_unlock( &nl->lock );
    return NETDEV_TX_OK;
}

#endif  /* CONFIG_SBNI_MULTILINE */

/* -------------------------------------------------------------------------- */

/* interrupt handler */

/*
 *  SBNI12D-10, -11/ISA boards within "common interrupt" mode could not
 * be looked as two independent single-channel devices. Every channel seems
 * as Ethernet interface but interrupt handler must be common. Really, first
 * channel ("master") driver only registers the handler. In its struct net_local
 * it has got pointer to "slave" channel's struct net_local and handles that's
 * interrupts too.
 *  dev of successfully attached ISA SBNI boards is linked to list.
 * While next board driver is initialized, it scans this list. If one
 * has found dev with same irq and ioaddr different by 4 then it assumes
 * this board to be "master".
 */ 

static irqreturn_t
sbni_interrupt( int  irq,  void  *dev_id )
{
    struct net_device     *dev = dev_id;
    struct net_local  *nl  = netdev_priv(dev);
    int repeat;

    spin_lock( &nl->lock );
    if( nl->second )
        spin_lock(&NET_LOCAL_LOCK(nl->second));

    do {
        repeat = 0;
        if( inb( dev->base_addr + CSR0 ) & (RC_RDY | TR_RDY) )
            handle_channel( dev ),
            repeat = 1;
        if( nl->second  &&  /* second channel present */
            (inb( nl->second->base_addr+CSR0 ) & (RC_RDY | TR_RDY)) )
            handle_channel( nl->second ),
            repeat = 1;
    } while( repeat );

    if( nl->second )
        spin_unlock(&NET_LOCAL_LOCK(nl->second));
    spin_unlock( &nl->lock );
    return IRQ_HANDLED;
}


static void
handle_channel( struct net_device  *dev )
{
    struct net_local    *nl    = netdev_priv(dev);
    unsigned long       ioaddr = dev->base_addr;

    int  req_ans;
    unsigned char  csr0;

#ifdef CONFIG_SBNI_MULTILINE
    /* Lock the master device because we going to change its local data */
    if( nl->state & FL_SLAVE )
        spin_lock(&NET_LOCAL_LOCK(nl->master));
#endif

    outb( (inb( ioaddr + CSR0 ) & ~EN_INT) | TR_REQ, ioaddr + CSR0 );

    nl->timer_ticks = CHANGE_LEVEL_START_TICKS;
    for(;;) {
        csr0 = inb( ioaddr + CSR0 );
        if( ( csr0 & (RC_RDY | TR_RDY) ) == 0 )
            break;

        req_ans = !(nl->state & FL_PREV_OK);

        if( csr0 & RC_RDY )
            req_ans = recv_frame( dev );

        /*
         * TR_RDY always equals 1 here because we have owned the marker,
         * and we set TR_REQ when disabled interrupts
         */
        csr0 = inb( ioaddr + CSR0 );
        if( !(csr0 & TR_RDY)  ||  (csr0 & RC_RDY) )
            netdev_err(dev, "internal error!\n");

        /* if state & FL_NEED_RESEND != 0 then tx_frameno != 0 */
        if( req_ans  ||  nl->tx_frameno != 0 )
            send_frame( dev );
        else
            /* send marker without any data */
            outb( inb( ioaddr + CSR0 ) & ~TR_REQ, ioaddr + CSR0 );
    }

    outb( inb( ioaddr + CSR0 ) | EN_INT, ioaddr + CSR0 );

#ifdef CONFIG_SBNI_MULTILINE
    if( nl->state & FL_SLAVE )
        spin_unlock(&NET_LOCAL_LOCK(nl->master));
#endif
}


/*
 * Routine returns 1 if it need to acknoweledge received frame.
 * Empty frame received without errors won't be acknoweledged.
 */

static int
recv_frame( struct net_device  *dev )
{
    struct net_local  *nl   = netdev_priv(dev);
    unsigned long  ioaddr   = dev->base_addr;

    u32  crc = CRC32_INITIAL;

    unsigned  framelen = 0, frameno, ack;
    unsigned  is_first, frame_ok = 0;

    if( check_fhdr( ioaddr, &framelen, &frameno, &ack, &is_first, &crc ) ) {
        frame_ok = framelen > 4
            ?  upload_data( dev, framelen, frameno, is_first, crc )
            :  skip_tail( ioaddr, framelen, crc );
        if( frame_ok )
            interpret_ack( dev, ack );
    }

    outb( inb( ioaddr + CSR0 ) ^ CT_ZER, ioaddr + CSR0 );
    if( frame_ok ) {
        nl->state |= FL_PREV_OK;
        if( framelen > 4 )
            nl->in_stats.all_rx_number++;
    } else
        nl->state &= ~FL_PREV_OK,
        change_level( dev ),
        nl->in_stats.all_rx_number++,
        nl->in_stats.bad_rx_number++;

    return  !frame_ok  ||  framelen > 4;
}


static void
send_frame( struct net_device  *dev )
{
    struct net_local  *nl    = netdev_priv(dev);

    u32  crc = CRC32_INITIAL;

    if( nl->state & FL_NEED_RESEND ) {

        /* if frame was sended but not ACK'ed - resend it */
        if( nl->trans_errors ) {
            --nl->trans_errors;
            if( nl->framelen != 0 )
                nl->in_stats.resend_tx_number++;
        } else {
            /* cannot xmit with many attempts */
#ifdef CONFIG_SBNI_MULTILINE
            if( (nl->state & FL_SLAVE)  ||  nl->link )
#endif
            nl->state |= FL_LINE_DOWN;
            drop_xmit_queue( dev );
            goto  do_send;
        }
    } else
        nl->trans_errors = TR_ERROR_COUNT;

    send_frame_header( dev, &crc );
    nl->state |= FL_NEED_RESEND;
    /*
     * FL_NEED_RESEND will be cleared after ACK, but if empty
     * frame sended then in prepare_to_send next frame
     */


    if( nl->framelen ) {
        download_data( dev, &crc );
        nl->in_stats.all_tx_number++;
        nl->state |= FL_WAIT_ACK;
    }

    outsb( dev->base_addr + DAT, (u8 *)&crc, sizeof crc );

do_send:
    outb( inb( dev->base_addr + CSR0 ) & ~TR_REQ, dev->base_addr + CSR0 );

    if( nl->tx_frameno )
        /* next frame exists - we request card to send it */
        outb( inb( dev->base_addr + CSR0 ) | TR_REQ,
              dev->base_addr + CSR0 );
}


/*
 * Write the frame data into adapter's buffer memory, and calculate CRC.
 * Do padding if necessary.
 */

static void
download_data( struct net_device  *dev,  u32  *crc_p )
{
    struct net_local  *nl    = netdev_priv(dev);
    struct sk_buff    *skb   = nl->tx_buf_p;

    unsigned  len = min_t(unsigned int, skb->len - nl->outpos, nl->framelen);

    outsb( dev->base_addr + DAT, skb->data + nl->outpos, len );
    *crc_p = calc_crc32( *crc_p, skb->data + nl->outpos, len );

    /* if packet too short we should write some more bytes to pad */
    for( len = nl->framelen - len;  len--; )
        outb( 0, dev->base_addr + DAT ),
        *crc_p = CRC32( 0, *crc_p );
}


static int
upload_data( struct net_device  *dev,  unsigned  framelen,  unsigned  frameno,
         unsigned  is_first,  u32  crc )
{
    struct net_local  *nl = netdev_priv(dev);

    int  frame_ok;

    if( is_first )
        nl->wait_frameno = frameno,
        nl->inppos = 0;

    if( nl->wait_frameno == frameno ) {

        if( nl->inppos + framelen  <=  ETHER_MAX_LEN )
            frame_ok = append_frame_to_pkt( dev, framelen, crc );

        /*
         * if CRC is right but framelen incorrect then transmitter
         * error was occurred... drop entire packet
         */
        else if( (frame_ok = skip_tail( dev->base_addr, framelen, crc ))
             != 0 )
            nl->wait_frameno = 0,
            nl->inppos = 0,
#ifdef CONFIG_SBNI_MULTILINE
            nl->master->stats.rx_errors++,
            nl->master->stats.rx_missed_errors++;
#else
                dev->stats.rx_errors++,
            dev->stats.rx_missed_errors++;
#endif
            /* now skip all frames until is_first != 0 */
    } else
        frame_ok = skip_tail( dev->base_addr, framelen, crc );

    if( is_first  &&  !frame_ok )
        /*
         * Frame has been broken, but we had already stored
         * is_first... Drop entire packet.
         */
        nl->wait_frameno = 0,
#ifdef CONFIG_SBNI_MULTILINE
        nl->master->stats.rx_errors++,
        nl->master->stats.rx_crc_errors++;
#else
        dev->stats.rx_errors++,
        dev->stats.rx_crc_errors++;
#endif

    return  frame_ok;
}


static inline void
send_complete( struct net_device *dev )
{
    struct net_local  *nl = netdev_priv(dev);

#ifdef CONFIG_SBNI_MULTILINE
    nl->master->stats.tx_packets++;
    nl->master->stats.tx_bytes += nl->tx_buf_p->len;
#else
    dev->stats.tx_packets++;
    dev->stats.tx_bytes += nl->tx_buf_p->len;
#endif
    dev_kfree_skb_irq( nl->tx_buf_p );

    nl->tx_buf_p = NULL;

    nl->outpos = 0;
    nl->state &= ~(FL_WAIT_ACK | FL_NEED_RESEND);
    nl->framelen   = 0;
}


static void
interpret_ack( struct net_device  *dev,  unsigned  ack )
{
    struct net_local  *nl = netdev_priv(dev);

    if( ack == FRAME_SENT_OK ) {
        nl->state &= ~FL_NEED_RESEND;

        if( nl->state & FL_WAIT_ACK ) {
            nl->outpos += nl->framelen;

            if( --nl->tx_frameno )
                nl->framelen = min_t(unsigned int,
                           nl->maxframe,
                           nl->tx_buf_p->len - nl->outpos);
            else
                send_complete( dev ),
#ifdef CONFIG_SBNI_MULTILINE
                netif_wake_queue( nl->master );
#else
                netif_wake_queue( dev );
#endif
        }
    }

    nl->state &= ~FL_WAIT_ACK;
}


/*
 * Glue received frame with previous fragments of packet.
 * Indicate packet when last frame would be accepted.
 */

static int
append_frame_to_pkt( struct net_device  *dev,  unsigned  framelen,  u32  crc )
{
    struct net_local  *nl = netdev_priv(dev);

    u8  *p;

    if( nl->inppos + framelen  >  ETHER_MAX_LEN )
        return  0;

    if( !nl->rx_buf_p  &&  !(nl->rx_buf_p = get_rx_buf( dev )) )
        return  0;

    p = nl->rx_buf_p->data + nl->inppos;
    insb( dev->base_addr + DAT, p, framelen );
    if( calc_crc32( crc, p, framelen ) != CRC32_REMAINDER )
        return  0;

    nl->inppos += framelen - 4;
    if( --nl->wait_frameno == 0 )       /* last frame received */
        indicate_pkt( dev );

    return  1;
}


/*
 * Prepare to start output on adapter.
 * Transmitter will be actually activated when marker is accepted.
 */

static void
prepare_to_send( struct sk_buff  *skb,  struct net_device  *dev )
{
    struct net_local  *nl = netdev_priv(dev);

    unsigned int  len;

    /* nl->tx_buf_p == NULL here! */
    if( nl->tx_buf_p )
        netdev_err(dev, "memory leak!\n");

    nl->outpos = 0;
    nl->state &= ~(FL_WAIT_ACK | FL_NEED_RESEND);

    len = skb->len;
    if( len < SBNI_MIN_LEN )
        len = SBNI_MIN_LEN;

    nl->tx_buf_p    = skb;
    nl->tx_frameno  = DIV_ROUND_UP(len, nl->maxframe);
    nl->framelen    = len < nl->maxframe  ?  len  :  nl->maxframe;

    outb( inb( dev->base_addr + CSR0 ) | TR_REQ,  dev->base_addr + CSR0 );
#ifdef CONFIG_SBNI_MULTILINE
    nl->master->trans_start = jiffies;
#else
    dev->trans_start = jiffies;
#endif
}


static void
drop_xmit_queue( struct net_device  *dev )
{
    struct net_local  *nl = netdev_priv(dev);

    if( nl->tx_buf_p )
        dev_kfree_skb_any( nl->tx_buf_p ),
        nl->tx_buf_p = NULL,
#ifdef CONFIG_SBNI_MULTILINE
        nl->master->stats.tx_errors++,
        nl->master->stats.tx_carrier_errors++;
#else
        dev->stats.tx_errors++,
        dev->stats.tx_carrier_errors++;
#endif

    nl->tx_frameno  = 0;
    nl->framelen    = 0;
    nl->outpos  = 0;
    nl->state &= ~(FL_WAIT_ACK | FL_NEED_RESEND);
#ifdef CONFIG_SBNI_MULTILINE
    netif_start_queue( nl->master );
    nl->master->trans_start = jiffies;
#else
    netif_start_queue( dev );
    dev->trans_start = jiffies;
#endif
}


static void
send_frame_header( struct net_device  *dev,  u32  *crc_p )
{
    struct net_local  *nl  = netdev_priv(dev);

    u32  crc = *crc_p;
    u32  len_field = nl->framelen + 6;  /* CRC + frameno + reserved */
    u8   value;

    if( nl->state & FL_NEED_RESEND )
        len_field |= FRAME_RETRY;   /* non-first attempt... */

    if( nl->outpos == 0 )
        len_field |= FRAME_FIRST;

    len_field |= (nl->state & FL_PREV_OK) ? FRAME_SENT_OK : FRAME_SENT_BAD;
    outb( SBNI_SIG, dev->base_addr + DAT );

    value = (u8) len_field;
    outb( value, dev->base_addr + DAT );
    crc = CRC32( value, crc );
    value = (u8) (len_field >> 8);
    outb( value, dev->base_addr + DAT );
    crc = CRC32( value, crc );

    outb( nl->tx_frameno, dev->base_addr + DAT );
    crc = CRC32( nl->tx_frameno, crc );
    outb( 0, dev->base_addr + DAT );
    crc = CRC32( 0, crc );
    *crc_p = crc;
}


/*
 * if frame tail not needed (incorrect number or received twice),
 * it won't store, but CRC will be calculated
 */

static int
skip_tail( unsigned int  ioaddr,  unsigned int  tail_len,  u32 crc )
{
    while( tail_len-- )
        crc = CRC32( inb( ioaddr + DAT ), crc );

    return  crc == CRC32_REMAINDER;
}


/*
 * Preliminary checks if frame header is correct, calculates its CRC
 * and split it to simple fields
 */

static int
check_fhdr( u32  ioaddr,  u32  *framelen,  u32  *frameno,  u32  *ack,
        u32  *is_first,  u32  *crc_p )
{
    u32  crc = *crc_p;
    u8   value;

    if( inb( ioaddr + DAT ) != SBNI_SIG )
        return  0;

    value = inb( ioaddr + DAT );
    *framelen = (u32)value;
    crc = CRC32( value, crc );
    value = inb( ioaddr + DAT );
    *framelen |= ((u32)value) << 8;
    crc = CRC32( value, crc );

    *ack = *framelen & FRAME_ACK_MASK;
    *is_first = (*framelen & FRAME_FIRST) != 0;

    if( (*framelen &= FRAME_LEN_MASK) < 6 ||
        *framelen > SBNI_MAX_FRAME - 3 )
        return  0;

    value = inb( ioaddr + DAT );
    *frameno = (u32)value;
    crc = CRC32( value, crc );

    crc = CRC32( inb( ioaddr + DAT ), crc );    /* reserved byte */
    *framelen -= 2;

    *crc_p = crc;
    return  1;
}


static struct sk_buff *
get_rx_buf( struct net_device  *dev )
{
    /* +2 is to compensate for the alignment fixup below */
    struct sk_buff  *skb = dev_alloc_skb( ETHER_MAX_LEN + 2 );
    if( !skb )
        return  NULL;

    skb_reserve( skb, 2 );      /* Align IP on longword boundaries */
    return  skb;
}


static void
indicate_pkt( struct net_device  *dev )
{
    struct net_local  *nl  = netdev_priv(dev);
    struct sk_buff    *skb = nl->rx_buf_p;

    skb_put( skb, nl->inppos );

#ifdef CONFIG_SBNI_MULTILINE
    skb->protocol = eth_type_trans( skb, nl->master );
    netif_rx( skb );
    ++nl->master->stats.rx_packets;
    nl->master->stats.rx_bytes += nl->inppos;
#else
    skb->protocol = eth_type_trans( skb, dev );
    netif_rx( skb );
    ++dev->stats.rx_packets;
    dev->stats.rx_bytes += nl->inppos;
#endif
    nl->rx_buf_p = NULL;    /* protocol driver will clear this sk_buff */
}


/* -------------------------------------------------------------------------- */

/*
 * Routine checks periodically wire activity and regenerates marker if
 * connect was inactive for a long time.
 */

static void
sbni_watchdog( unsigned long  arg )
{
    struct net_device  *dev = (struct net_device *) arg;
    struct net_local   *nl  = netdev_priv(dev);
    struct timer_list  *w   = &nl->watchdog; 
    unsigned long      flags;
    unsigned char      csr0;

    spin_lock_irqsave( &nl->lock, flags );

    csr0 = inb( dev->base_addr + CSR0 );
    if( csr0 & RC_CHK ) {

        if( nl->timer_ticks ) {
            if( csr0 & (RC_RDY | BU_EMP) )
                /* receiving not active */
                nl->timer_ticks--;
        } else {
            nl->in_stats.timeout_number++;
            if( nl->delta_rxl )
                timeout_change_level( dev );

            outb( *(u_char *)&nl->csr1 | PR_RES,
                  dev->base_addr + CSR1 );
            csr0 = inb( dev->base_addr + CSR0 );
        }
    } else
        nl->state &= ~FL_LINE_DOWN;

    outb( csr0 | RC_CHK, dev->base_addr + CSR0 ); 

    init_timer( w );
    w->expires  = jiffies + SBNI_TIMEOUT;
    w->data     = arg;
    w->function = sbni_watchdog;
    add_timer( w );

    spin_unlock_irqrestore( &nl->lock, flags );
}


static unsigned char  rxl_tab[] = {
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x08,
    0x0a, 0x0c, 0x0f, 0x16, 0x18, 0x1a, 0x1c, 0x1f
};

#define SIZE_OF_TIMEOUT_RXL_TAB 4
static unsigned char  timeout_rxl_tab[] = {
    0x03, 0x05, 0x08, 0x0b
};

/* -------------------------------------------------------------------------- */

static void
card_start( struct net_device  *dev )
{
    struct net_local  *nl = netdev_priv(dev);

    nl->timer_ticks = CHANGE_LEVEL_START_TICKS;
    nl->state &= ~(FL_WAIT_ACK | FL_NEED_RESEND);
    nl->state |= FL_PREV_OK;

    nl->inppos = nl->outpos = 0;
    nl->wait_frameno = 0;
    nl->tx_frameno   = 0;
    nl->framelen     = 0;

    outb( *(u_char *)&nl->csr1 | PR_RES, dev->base_addr + CSR1 );
    outb( EN_INT, dev->base_addr + CSR0 );
}

/* -------------------------------------------------------------------------- */

/* Receive level auto-selection */

static void
change_level( struct net_device  *dev )
{
    struct net_local  *nl = netdev_priv(dev);

    if( nl->delta_rxl == 0 )    /* do not auto-negotiate RxL */
        return;

    if( nl->cur_rxl_index == 0 )
        nl->delta_rxl = 1;
    else if( nl->cur_rxl_index == 15 )
        nl->delta_rxl = -1;
    else if( nl->cur_rxl_rcvd < nl->prev_rxl_rcvd )
        nl->delta_rxl = -nl->delta_rxl;

    nl->csr1.rxl = rxl_tab[ nl->cur_rxl_index += nl->delta_rxl ];
    inb( dev->base_addr + CSR0 );   /* needs for PCI cards */
    outb( *(u8 *)&nl->csr1, dev->base_addr + CSR1 );

    nl->prev_rxl_rcvd = nl->cur_rxl_rcvd;
    nl->cur_rxl_rcvd  = 0;
}


static void
timeout_change_level( struct net_device  *dev )
{
    struct net_local  *nl = netdev_priv(dev);

    nl->cur_rxl_index = timeout_rxl_tab[ nl->timeout_rxl ];
    if( ++nl->timeout_rxl >= 4 )
        nl->timeout_rxl = 0;

    nl->csr1.rxl = rxl_tab[ nl->cur_rxl_index ];
    inb( dev->base_addr + CSR0 );
    outb( *(unsigned char *)&nl->csr1, dev->base_addr + CSR1 );

    nl->prev_rxl_rcvd = nl->cur_rxl_rcvd;
    nl->cur_rxl_rcvd  = 0;
}

/* -------------------------------------------------------------------------- */

/*
 *  Open/initialize the board. 
 */

static int
sbni_open( struct net_device  *dev )
{
    struct net_local    *nl = netdev_priv(dev);
    struct timer_list   *w  = &nl->watchdog;

    /*
     * For double ISA adapters within "common irq" mode, we have to
     * determine whether primary or secondary channel is initialized,
     * and set the irq handler only in first case.
     */
    if( dev->base_addr < 0x400 ) {      /* ISA only */
        struct net_device  **p = sbni_cards;
        for( ;  *p  &&  p < sbni_cards + SBNI_MAX_NUM_CARDS;  ++p )
            if( (*p)->irq == dev->irq &&
                ((*p)->base_addr == dev->base_addr + 4 ||
                 (*p)->base_addr == dev->base_addr - 4) &&
                (*p)->flags & IFF_UP ) {

                ((struct net_local *) (netdev_priv(*p)))
                    ->second = dev;
                netdev_notice(dev, "using shared irq with %s\n",
                          (*p)->name);
                nl->state |= FL_SECONDARY;
                goto  handler_attached;
            }
    }

    if( request_irq(dev->irq, sbni_interrupt, IRQF_SHARED, dev->name, dev) ) {
        netdev_err(dev, "unable to get IRQ %d\n", dev->irq);
        return  -EAGAIN;
    }

handler_attached:

    spin_lock( &nl->lock );
    memset( &dev->stats, 0, sizeof(struct net_device_stats) );
    memset( &nl->in_stats, 0, sizeof(struct sbni_in_stats) );

    card_start( dev );

    netif_start_queue( dev );

    /* set timer watchdog */
    init_timer( w );
    w->expires  = jiffies + SBNI_TIMEOUT;
    w->data     = (unsigned long) dev;
    w->function = sbni_watchdog;
    add_timer( w );
   
    spin_unlock( &nl->lock );
    return 0;
}


static int
sbni_close( struct net_device  *dev )
{
    struct net_local  *nl = netdev_priv(dev);

    if( nl->second  &&  nl->second->flags & IFF_UP ) {
        netdev_notice(dev, "Secondary channel (%s) is active!\n",
                  nl->second->name);
        return  -EBUSY;
    }

#ifdef CONFIG_SBNI_MULTILINE
    if( nl->state & FL_SLAVE )
        emancipate( dev );
    else
        while( nl->link )   /* it's master device! */
            emancipate( nl->link );
#endif

    spin_lock( &nl->lock );

    nl->second = NULL;
    drop_xmit_queue( dev ); 
    netif_stop_queue( dev );
   
    del_timer( &nl->watchdog );

    outb( 0, dev->base_addr + CSR0 );

    if( !(nl->state & FL_SECONDARY) )
        free_irq( dev->irq, dev );
    nl->state &= FL_SECONDARY;

    spin_unlock( &nl->lock );
    return 0;
}


/*
    Valid combinations in CSR0 (for probing):

    VALID_DECODER   0000,0011,1011,1010

                        ; 0   ; -
                TR_REQ  ; 1   ; +
            TR_RDY          ; 2   ; -
            TR_RDY  TR_REQ  ; 3   ; +
        BU_EMP              ; 4   ; +
        BU_EMP          TR_REQ  ; 5   ; +
        BU_EMP  TR_RDY          ; 6   ; -
        BU_EMP  TR_RDY  TR_REQ  ; 7   ; +
    RC_RDY                  ; 8   ; +
    RC_RDY          TR_REQ  ; 9   ; +
    RC_RDY      TR_RDY      ; 10  ; -
    RC_RDY      TR_RDY  TR_REQ  ; 11  ; -
    RC_RDY  BU_EMP          ; 12  ; -
    RC_RDY  BU_EMP      TR_REQ  ; 13  ; -
    RC_RDY  BU_EMP  TR_RDY      ; 14  ; -
    RC_RDY  BU_EMP  TR_RDY  TR_REQ  ; 15  ; -
*/

#define VALID_DECODER (2 + 8 + 0x10 + 0x20 + 0x80 + 0x100 + 0x200)


static int
sbni_card_probe( unsigned long  ioaddr )
{
    unsigned char  csr0;

    csr0 = inb( ioaddr + CSR0 );
    if( csr0 != 0xff  &&  csr0 != 0x00 ) {
        csr0 &= ~EN_INT;
        if( csr0 & BU_EMP )
            csr0 |= EN_INT;
      
        if( VALID_DECODER & (1 << (csr0 >> 4)) )
            return  0;
    }
   
    return  -ENODEV;
}

/* -------------------------------------------------------------------------- */

static int
sbni_ioctl( struct net_device  *dev,  struct ifreq  *ifr,  int  cmd )
{
    struct net_local  *nl = netdev_priv(dev);
    struct sbni_flags  flags;
    int  error = 0;

#ifdef CONFIG_SBNI_MULTILINE
    struct net_device  *slave_dev;
    char  slave_name[ 8 ];
#endif
  
    switch( cmd ) {
    case  SIOCDEVGETINSTATS :
        if (copy_to_user( ifr->ifr_data, &nl->in_stats,
                    sizeof(struct sbni_in_stats) ))
            error = -EFAULT;
        break;

    case  SIOCDEVRESINSTATS :
        if (!capable(CAP_NET_ADMIN))
            return  -EPERM;
        memset( &nl->in_stats, 0, sizeof(struct sbni_in_stats) );
        break;

    case  SIOCDEVGHWSTATE :
        flags.mac_addr  = *(u32 *)(dev->dev_addr + 3);
        flags.rate  = nl->csr1.rate;
        flags.slow_mode = (nl->state & FL_SLOW_MODE) != 0;
        flags.rxl   = nl->cur_rxl_index;
        flags.fixed_rxl = nl->delta_rxl == 0;

        if (copy_to_user( ifr->ifr_data, &flags, sizeof flags ))
            error = -EFAULT;
        break;

    case  SIOCDEVSHWSTATE :
        if (!capable(CAP_NET_ADMIN))
            return  -EPERM;

        spin_lock( &nl->lock );
        flags = *(struct sbni_flags*) &ifr->ifr_ifru;
        if( flags.fixed_rxl )
            nl->delta_rxl = 0,
            nl->cur_rxl_index = flags.rxl;
        else
            nl->delta_rxl = DEF_RXL_DELTA,
            nl->cur_rxl_index = DEF_RXL;

        nl->csr1.rxl = rxl_tab[ nl->cur_rxl_index ];
        nl->csr1.rate = flags.rate;
        outb( *(u8 *)&nl->csr1 | PR_RES, dev->base_addr + CSR1 );
        spin_unlock( &nl->lock );
        break;

#ifdef CONFIG_SBNI_MULTILINE

    case  SIOCDEVENSLAVE :
        if (!capable(CAP_NET_ADMIN))
            return  -EPERM;

        if (copy_from_user( slave_name, ifr->ifr_data, sizeof slave_name ))
            return -EFAULT;
        slave_dev = dev_get_by_name(&init_net, slave_name );
        if( !slave_dev  ||  !(slave_dev->flags & IFF_UP) ) {
            netdev_err(dev, "trying to enslave non-active device %s\n",
                   slave_name);
            return  -EPERM;
        }

        return  enslave( dev, slave_dev );

    case  SIOCDEVEMANSIPATE :
        if (!capable(CAP_NET_ADMIN))
            return  -EPERM;

        return  emancipate( dev );

#endif  /* CONFIG_SBNI_MULTILINE */

    default :
        return  -EOPNOTSUPP;
    }

    return  error;
}


#ifdef CONFIG_SBNI_MULTILINE

static int
enslave( struct net_device  *dev,  struct net_device  *slave_dev )
{
    struct net_local  *nl  = netdev_priv(dev);
    struct net_local  *snl = netdev_priv(slave_dev);

    if( nl->state & FL_SLAVE )  /* This isn't master or free device */
        return  -EBUSY;

    if( snl->state & FL_SLAVE ) /* That was already enslaved */
        return  -EBUSY;

    spin_lock( &nl->lock );
    spin_lock( &snl->lock );

    /* append to list */
    snl->link = nl->link;
    nl->link  = slave_dev;
    snl->master = dev;
    snl->state |= FL_SLAVE;

    /* Summary statistics of MultiLine operation will be stored
       in master's counters */
    memset( &slave_dev->stats, 0, sizeof(struct net_device_stats) );
    netif_stop_queue( slave_dev );
    netif_wake_queue( dev );    /* Now we are able to transmit */

    spin_unlock( &snl->lock );
    spin_unlock( &nl->lock );
    netdev_notice(dev, "slave device (%s) attached\n", slave_dev->name);
    return  0;
}


static int
emancipate( struct net_device  *dev )
{
    struct net_local   *snl = netdev_priv(dev);
    struct net_device  *p   = snl->master;
    struct net_local   *nl  = netdev_priv(p);

    if( !(snl->state & FL_SLAVE) )
        return  -EINVAL;

    spin_lock( &nl->lock );
    spin_lock( &snl->lock );
    drop_xmit_queue( dev );

    /* exclude from list */
    for(;;) {   /* must be in list */
        struct net_local  *t = netdev_priv(p);
        if( t->link == dev ) {
            t->link = snl->link;
            break;
        }
        p = t->link;
    }

    snl->link = NULL;
    snl->master = dev;
    snl->state &= ~FL_SLAVE;

    netif_start_queue( dev );

    spin_unlock( &snl->lock );
    spin_unlock( &nl->lock );

    dev_put( dev );
    return  0;
}

#endif

static void
set_multicast_list( struct net_device  *dev )
{
    return;     /* sbni always operate in promiscuos mode */
}


#ifdef MODULE
module_param_array(io, int, NULL, 0);
module_param_array(irq, int, NULL, 0);
module_param_array(baud, int, NULL, 0);
module_param_array(rxl, int, NULL, 0);
module_param_array(mac, int, NULL, 0);
module_param(skip_pci_probe, bool, 0);

MODULE_LICENSE("GPL");


int __init init_module( void )
{
    struct net_device  *dev;
    int err;

    while( num < SBNI_MAX_NUM_CARDS ) {
        dev = alloc_netdev(sizeof(struct net_local), 
                   "sbni%d", sbni_devsetup);
        if( !dev)
            break;

        sprintf( dev->name, "sbni%d", num );

        err = sbni_init(dev);
        if (err) {
            free_netdev(dev);
            break;
        }

        if( register_netdev( dev ) ) {
            release_region( dev->base_addr, SBNI_IO_EXTENT );
            free_netdev( dev );
            break;
        }
    }

    return  *sbni_cards  ?  0  :  -ENODEV;
}

void
cleanup_module(void)
{
    int i;

    for (i = 0;  i < SBNI_MAX_NUM_CARDS;  ++i) {
        struct net_device *dev = sbni_cards[i];
        if (dev != NULL) {
            unregister_netdev(dev);
            release_region(dev->base_addr, SBNI_IO_EXTENT);
            free_netdev(dev);
        }
    }
}

#else   /* MODULE */

static int __init
sbni_setup( char  *p )
{
    int  n, parm;

    if( *p++ != '(' )
        goto  bad_param;

    for( n = 0, parm = 0;  *p  &&  n < 8; ) {
        (*dest[ parm ])[ n ] = simple_strtol( p, &p, 0 );
        if( !*p  ||  *p == ')' )
            return 1;
        if( *p == ';' )
            ++p, ++n, parm = 0;
        else if( *p++ != ',' )
            break;
        else
            if( ++parm >= 5 )
                break;
    }
bad_param:
    pr_err("Error in sbni kernel parameter!\n");
    return 0;
}

__setup( "sbni=", sbni_setup );

#endif  /* MODULE */

/* -------------------------------------------------------------------------- */

#ifdef ASM_CRC

static u32
calc_crc32( u32  crc,  u8  *p,  u32  len )
{
    register u32  _crc;
    _crc = crc;
    
    __asm__ __volatile__ (
        "xorl   %%ebx, %%ebx\n"
        "movl   %2, %%esi\n" 
        "movl   %3, %%ecx\n" 
        "movl   $crc32tab, %%edi\n"
        "shrl   $2, %%ecx\n"
        "jz 1f\n"

        ".align 4\n"
    "0:\n"
        "movb   %%al, %%bl\n"
        "movl   (%%esi), %%edx\n"
        "shrl   $8, %%eax\n"
        "xorb   %%dl, %%bl\n"
        "shrl   $8, %%edx\n"
        "xorl   (%%edi,%%ebx,4), %%eax\n"

        "movb   %%al, %%bl\n"
        "shrl   $8, %%eax\n"
        "xorb   %%dl, %%bl\n"
        "shrl   $8, %%edx\n"
        "xorl   (%%edi,%%ebx,4), %%eax\n"

        "movb   %%al, %%bl\n"
        "shrl   $8, %%eax\n"
        "xorb   %%dl, %%bl\n"
        "movb   %%dh, %%dl\n" 
        "xorl   (%%edi,%%ebx,4), %%eax\n"

        "movb   %%al, %%bl\n"
        "shrl   $8, %%eax\n"
        "xorb   %%dl, %%bl\n"
        "addl   $4, %%esi\n"
        "xorl   (%%edi,%%ebx,4), %%eax\n"

        "decl   %%ecx\n"
        "jnz    0b\n"

    "1:\n"
        "movl   %3, %%ecx\n"
        "andl   $3, %%ecx\n"
        "jz 2f\n"

        "movb   %%al, %%bl\n"
        "shrl   $8, %%eax\n"
        "xorb   (%%esi), %%bl\n"
        "xorl   (%%edi,%%ebx,4), %%eax\n"

        "decl   %%ecx\n"
        "jz 2f\n"

        "movb   %%al, %%bl\n"
        "shrl   $8, %%eax\n"
        "xorb   1(%%esi), %%bl\n"
        "xorl   (%%edi,%%ebx,4), %%eax\n"

        "decl   %%ecx\n"
        "jz 2f\n"

        "movb   %%al, %%bl\n"
        "shrl   $8, %%eax\n"
        "xorb   2(%%esi), %%bl\n"
        "xorl   (%%edi,%%ebx,4), %%eax\n"
    "2:\n"
        : "=a" (_crc)
        : "0" (_crc), "g" (p), "g" (len)
        : "bx", "cx", "dx", "si", "di"
    );

    return  _crc;
}

#else   /* ASM_CRC */

static u32
calc_crc32( u32  crc,  u8  *p,  u32  len )
{
    while( len-- )
        crc = CRC32( *p++, crc );

    return  crc;
}

#endif  /* ASM_CRC */


static u32  crc32tab[] __attribute__ ((aligned(8))) = {
    0xD202EF8D,  0xA505DF1B,  0x3C0C8EA1,  0x4B0BBE37,
    0xD56F2B94,  0xA2681B02,  0x3B614AB8,  0x4C667A2E,
    0xDCD967BF,  0xABDE5729,  0x32D70693,  0x45D03605,
    0xDBB4A3A6,  0xACB39330,  0x35BAC28A,  0x42BDF21C,
    0xCFB5FFE9,  0xB8B2CF7F,  0x21BB9EC5,  0x56BCAE53,
    0xC8D83BF0,  0xBFDF0B66,  0x26D65ADC,  0x51D16A4A,
    0xC16E77DB,  0xB669474D,  0x2F6016F7,  0x58672661,
    0xC603B3C2,  0xB1048354,  0x280DD2EE,  0x5F0AE278,
    0xE96CCF45,  0x9E6BFFD3,  0x0762AE69,  0x70659EFF,
    0xEE010B5C,  0x99063BCA,  0x000F6A70,  0x77085AE6,
    0xE7B74777,  0x90B077E1,  0x09B9265B,  0x7EBE16CD,
    0xE0DA836E,  0x97DDB3F8,  0x0ED4E242,  0x79D3D2D4,
    0xF4DBDF21,  0x83DCEFB7,  0x1AD5BE0D,  0x6DD28E9B,
    0xF3B61B38,  0x84B12BAE,  0x1DB87A14,  0x6ABF4A82,
    0xFA005713,  0x8D076785,  0x140E363F,  0x630906A9,
    0xFD6D930A,  0x8A6AA39C,  0x1363F226,  0x6464C2B0,
    0xA4DEAE1D,  0xD3D99E8B,  0x4AD0CF31,  0x3DD7FFA7,
    0xA3B36A04,  0xD4B45A92,  0x4DBD0B28,  0x3ABA3BBE,
    0xAA05262F,  0xDD0216B9,  0x440B4703,  0x330C7795,
    0xAD68E236,  0xDA6FD2A0,  0x4366831A,  0x3461B38C,
    0xB969BE79,  0xCE6E8EEF,  0x5767DF55,  0x2060EFC3,
    0xBE047A60,  0xC9034AF6,  0x500A1B4C,  0x270D2BDA,
    0xB7B2364B,  0xC0B506DD,  0x59BC5767,  0x2EBB67F1,
    0xB0DFF252,  0xC7D8C2C4,  0x5ED1937E,  0x29D6A3E8,
    0x9FB08ED5,  0xE8B7BE43,  0x71BEEFF9,  0x06B9DF6F,
    0x98DD4ACC,  0xEFDA7A5A,  0x76D32BE0,  0x01D41B76,
    0x916B06E7,  0xE66C3671,  0x7F6567CB,  0x0862575D,
    0x9606C2FE,  0xE101F268,  0x7808A3D2,  0x0F0F9344,
    0x82079EB1,  0xF500AE27,  0x6C09FF9D,  0x1B0ECF0B,
    0x856A5AA8,  0xF26D6A3E,  0x6B643B84,  0x1C630B12,
    0x8CDC1683,  0xFBDB2615,  0x62D277AF,  0x15D54739,
    0x8BB1D29A,  0xFCB6E20C,  0x65BFB3B6,  0x12B88320,
    0x3FBA6CAD,  0x48BD5C3B,  0xD1B40D81,  0xA6B33D17,
    0x38D7A8B4,  0x4FD09822,  0xD6D9C998,  0xA1DEF90E,
    0x3161E49F,  0x4666D409,  0xDF6F85B3,  0xA868B525,
    0x360C2086,  0x410B1010,  0xD80241AA,  0xAF05713C,
    0x220D7CC9,  0x550A4C5F,  0xCC031DE5,  0xBB042D73,
    0x2560B8D0,  0x52678846,  0xCB6ED9FC,  0xBC69E96A,
    0x2CD6F4FB,  0x5BD1C46D,  0xC2D895D7,  0xB5DFA541,
    0x2BBB30E2,  0x5CBC0074,  0xC5B551CE,  0xB2B26158,
    0x04D44C65,  0x73D37CF3,  0xEADA2D49,  0x9DDD1DDF,
    0x03B9887C,  0x74BEB8EA,  0xEDB7E950,  0x9AB0D9C6,
    0x0A0FC457,  0x7D08F4C1,  0xE401A57B,  0x930695ED,
    0x0D62004E,  0x7A6530D8,  0xE36C6162,  0x946B51F4,
    0x19635C01,  0x6E646C97,  0xF76D3D2D,  0x806A0DBB,
    0x1E0E9818,  0x6909A88E,  0xF000F934,  0x8707C9A2,
    0x17B8D433,  0x60BFE4A5,  0xF9B6B51F,  0x8EB18589,
    0x10D5102A,  0x67D220BC,  0xFEDB7106,  0x89DC4190,
    0x49662D3D,  0x3E611DAB,  0xA7684C11,  0xD06F7C87,
    0x4E0BE924,  0x390CD9B2,  0xA0058808,  0xD702B89E,
    0x47BDA50F,  0x30BA9599,  0xA9B3C423,  0xDEB4F4B5,
    0x40D06116,  0x37D75180,  0xAEDE003A,  0xD9D930AC,
    0x54D13D59,  0x23D60DCF,  0xBADF5C75,  0xCDD86CE3,
    0x53BCF940,  0x24BBC9D6,  0xBDB2986C,  0xCAB5A8FA,
    0x5A0AB56B,  0x2D0D85FD,  0xB404D447,  0xC303E4D1,
    0x5D677172,  0x2A6041E4,  0xB369105E,  0xC46E20C8,
    0x72080DF5,  0x050F3D63,  0x9C066CD9,  0xEB015C4F,
    0x7565C9EC,  0x0262F97A,  0x9B6BA8C0,  0xEC6C9856,
    0x7CD385C7,  0x0BD4B551,  0x92DDE4EB,  0xE5DAD47D,
    0x7BBE41DE,  0x0CB97148,  0x95B020F2,  0xE2B71064,
    0x6FBF1D91,  0x18B82D07,  0x81B17CBD,  0xF6B64C2B,
    0x68D2D988,  0x1FD5E91E,  0x86DCB8A4,  0xF1DB8832,
    0x616495A3,  0x1663A535,  0x8F6AF48F,  0xF86DC419,
    0x660951BA,  0x110E612C,  0x88073096,  0xFF000000
};