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/*

 * QEMU NS SONIC DP8393x netcard

 *

 * Copyright (c) 2008-2009 Herve Poussineau

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License as

 * published by the Free Software Foundation; either version 2 of

 * the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License along

 * with this program; if not, write to the Free Software Foundation, Inc.,

 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 */

#include "hw.h"

#include "qemu-timer.h"

#include "net.h"

#include "mips.h"

//#define DEBUG_SONIC

/* Calculate CRCs properly on Rx packets */

#define SONIC_CALCULATE_RXCRC

#if defined(SONIC_CALCULATE_RXCRC)

/* For crc32 */

#include <zlib.h>

#endif

#ifdef DEBUG_SONIC

#define DPRINTF(fmt, ...) \

do { printf("sonic: " fmt , ##  __VA_ARGS__); } while (0)

static const char* reg_names[] = {

    "CR", "DCR", "RCR", "TCR", "IMR", "ISR", "UTDA", "CTDA",

    "TPS", "TFC", "TSA0", "TSA1", "TFS", "URDA", "CRDA", "CRBA0",

    "CRBA1", "RBWC0", "RBWC1", "EOBC", "URRA", "RSA", "REA", "RRP",

    "RWP", "TRBA0", "TRBA1", "0x1b", "0x1c", "0x1d", "0x1e", "LLFA",

    "TTDA", "CEP", "CAP2", "CAP1", "CAP0", "CE", "CDP", "CDC",

    "SR", "WT0", "WT1", "RSC", "CRCT", "FAET", "MPT", "MDT",

    "0x30", "0x31", "0x32", "0x33", "0x34", "0x35", "0x36", "0x37",

    "0x38", "0x39", "0x3a", "0x3b", "0x3c", "0x3d", "0x3e", "DCR2" };

#else

#define DPRINTF(fmt, ...) do {} while (0)

#endif

#define SONIC_ERROR(fmt, ...) \

do { printf("sonic ERROR: %s: " fmt, __func__ , ## __VA_ARGS__); } while (0)

#define SONIC_CR     0x00

#define SONIC_DCR    0x01

#define SONIC_RCR    0x02

#define SONIC_TCR    0x03

#define SONIC_IMR    0x04

#define SONIC_ISR    0x05

#define SONIC_UTDA   0x06

#define SONIC_CTDA   0x07

#define SONIC_TPS    0x08

#define SONIC_TFC    0x09

#define SONIC_TSA0   0x0a

#define SONIC_TSA1   0x0b

#define SONIC_TFS    0x0c

#define SONIC_URDA   0x0d

#define SONIC_CRDA   0x0e

#define SONIC_CRBA0  0x0f

#define SONIC_CRBA1  0x10

#define SONIC_RBWC0  0x11

#define SONIC_RBWC1  0x12

#define SONIC_EOBC   0x13

#define SONIC_URRA   0x14

#define SONIC_RSA    0x15

#define SONIC_REA    0x16

#define SONIC_RRP    0x17

#define SONIC_RWP    0x18

#define SONIC_TRBA0  0x19

#define SONIC_TRBA1  0x1a

#define SONIC_LLFA   0x1f

#define SONIC_TTDA   0x20

#define SONIC_CEP    0x21

#define SONIC_CAP2   0x22

#define SONIC_CAP1   0x23

#define SONIC_CAP0   0x24

#define SONIC_CE     0x25

#define SONIC_CDP    0x26

#define SONIC_CDC    0x27

#define SONIC_SR     0x28

#define SONIC_WT0    0x29

#define SONIC_WT1    0x2a

#define SONIC_RSC    0x2b

#define SONIC_CRCT   0x2c

#define SONIC_FAET   0x2d

#define SONIC_MPT    0x2e

#define SONIC_MDT    0x2f

#define SONIC_DCR2   0x3f

#define SONIC_CR_HTX     0x0001

#define SONIC_CR_TXP     0x0002

#define SONIC_CR_RXDIS   0x0004

#define SONIC_CR_RXEN    0x0008

#define SONIC_CR_STP     0x0010

#define SONIC_CR_ST      0x0020

#define SONIC_CR_RST     0x0080

#define SONIC_CR_RRRA    0x0100

#define SONIC_CR_LCAM    0x0200

#define SONIC_CR_MASK    0x03bf

#define SONIC_DCR_DW     0x0020

#define SONIC_DCR_LBR    0x2000

#define SONIC_DCR_EXBUS  0x8000

#define SONIC_RCR_PRX    0x0001

#define SONIC_RCR_LBK    0x0002

#define SONIC_RCR_FAER   0x0004

#define SONIC_RCR_CRCR   0x0008

#define SONIC_RCR_CRS    0x0020

#define SONIC_RCR_LPKT   0x0040

#define SONIC_RCR_BC     0x0080

#define SONIC_RCR_MC     0x0100

#define SONIC_RCR_LB0    0x0200

#define SONIC_RCR_LB1    0x0400

#define SONIC_RCR_AMC    0x0800

#define SONIC_RCR_PRO    0x1000

#define SONIC_RCR_BRD    0x2000

#define SONIC_RCR_RNT    0x4000

#define SONIC_TCR_PTX    0x0001

#define SONIC_TCR_BCM    0x0002

#define SONIC_TCR_FU     0x0004

#define SONIC_TCR_EXC    0x0040

#define SONIC_TCR_CRSL   0x0080

#define SONIC_TCR_NCRS   0x0100

#define SONIC_TCR_EXD    0x0400

#define SONIC_TCR_CRCI   0x2000

#define SONIC_TCR_PINT   0x8000

#define SONIC_ISR_RBE    0x0020

#define SONIC_ISR_RDE    0x0040

#define SONIC_ISR_TC     0x0080

#define SONIC_ISR_TXDN   0x0200

#define SONIC_ISR_PKTRX  0x0400

#define SONIC_ISR_PINT   0x0800

#define SONIC_ISR_LCD    0x1000

typedef struct dp8393xState {

    /* Hardware */

    int it_shift;

    qemu_irq irq;

#ifdef DEBUG_SONIC

    int irq_level;

#endif

    QEMUTimer *watchdog;

    int64_t wt_last_update;

    VLANClientState *vc;

    int mmio_index;

    /* Registers */

    uint8_t cam[16][6];

    uint16_t regs[0x40];

    /* Temporaries */

    uint8_t tx_buffer[0x10000];

    int loopback_packet;

    /* Memory access */

    void (*memory_rw)(void *opaque, target_phys_addr_t addr, uint8_t *buf, int len, int is_write);

    void* mem_opaque;

} dp8393xState;

static void dp8393x_update_irq(dp8393xState *s)

{

    int level = (s->regs[SONIC_IMR] & s->regs[SONIC_ISR]) ? 1 : 0;

#ifdef DEBUG_SONIC

    if (level != s->irq_level) {

        s->irq_level = level;

        if (level) {

            DPRINTF("raise irq, isr is 0x%04x\n", s->regs[SONIC_ISR]);

        } else {

            DPRINTF("lower irq\n");

        }

    }

#endif

    qemu_set_irq(s->irq, level);

}

static void do_load_cam(dp8393xState *s)

{

    uint16_t data[8];

    int width, size;

    uint16_t index = 0;

    width = (s->regs[SONIC_DCR] & SONIC_DCR_DW) ? 2 : 1;

    size = sizeof(uint16_t) * 4 * width;

    while (s->regs[SONIC_CDC] & 0x1f) {

        /* Fill current entry */

        s->memory_rw(s->mem_opaque,

            (s->regs[SONIC_URRA] << 16) | s->regs[SONIC_CDP],

            (uint8_t *)data, size, 0);

        s->cam[index][0] = data[1 * width] & 0xff;

        s->cam[index][1] = data[1 * width] >> 8;

        s->cam[index][2] = data[2 * width] & 0xff;

        s->cam[index][3] = data[2 * width] >> 8;

        s->cam[index][4] = data[3 * width] & 0xff;

        s->cam[index][5] = data[3 * width] >> 8;

        DPRINTF("load cam[%d] with %02x%02x%02x%02x%02x%02x\n", index,

            s->cam[index][0], s->cam[index][1], s->cam[index][2],

            s->cam[index][3], s->cam[index][4], s->cam[index][5]);

        /* Move to next entry */

        s->regs[SONIC_CDC]--;

        s->regs[SONIC_CDP] += size;

        index++;

    }

    /* Read CAM enable */

    s->memory_rw(s->mem_opaque,

        (s->regs[SONIC_URRA] << 16) | s->regs[SONIC_CDP],

        (uint8_t *)data, size, 0);

    s->regs[SONIC_CE] = data[0 * width];

    DPRINTF("load cam done. cam enable mask 0x%04x\n", s->regs[SONIC_CE]);

    /* Done */

    s->regs[SONIC_CR] &= ~SONIC_CR_LCAM;

    s->regs[SONIC_ISR] |= SONIC_ISR_LCD;

    dp8393x_update_irq(s);

}

static void do_read_rra(dp8393xState *s)

{

    uint16_t data[8];

    int width, size;

    /* Read memory */

    width = (s->regs[SONIC_DCR] & SONIC_DCR_DW) ? 2 : 1;

    size = sizeof(uint16_t) * 4 * width;

    s->memory_rw(s->mem_opaque,

        (s->regs[SONIC_URRA] << 16) | s->regs[SONIC_RRP],

        (uint8_t *)data, size, 0);

    /* Update SONIC registers */

    s->regs[SONIC_CRBA0] = data[0 * width];

    s->regs[SONIC_CRBA1] = data[1 * width];

    s->regs[SONIC_RBWC0] = data[2 * width];

    s->regs[SONIC_RBWC1] = data[3 * width];

    DPRINTF("CRBA0/1: 0x%04x/0x%04x, RBWC0/1: 0x%04x/0x%04x\n",

        s->regs[SONIC_CRBA0], s->regs[SONIC_CRBA1],

        s->regs[SONIC_RBWC0], s->regs[SONIC_RBWC1]);

    /* Go to next entry */

    s->regs[SONIC_RRP] += size;

    /* Handle wrap */

    if (s->regs[SONIC_RRP] == s->regs[SONIC_REA]) {

        s->regs[SONIC_RRP] = s->regs[SONIC_RSA];

    }

    /* Check resource exhaustion */

    if (s->regs[SONIC_RRP] == s->regs[SONIC_RWP])

    {

        s->regs[SONIC_ISR] |= SONIC_ISR_RBE;

        dp8393x_update_irq(s);

    }

    /* Done */

    s->regs[SONIC_CR] &= ~SONIC_CR_RRRA;

}

static void do_software_reset(dp8393xState *s)

{

    qemu_del_timer(s->watchdog);

    s->regs[SONIC_CR] &= ~(SONIC_CR_LCAM | SONIC_CR_RRRA | SONIC_CR_TXP | SONIC_CR_HTX);

    s->regs[SONIC_CR] |= SONIC_CR_RST | SONIC_CR_RXDIS;

}

static void set_next_tick(dp8393xState *s)

{

    uint32_t ticks;

    int64_t delay;

    if (s->regs[SONIC_CR] & SONIC_CR_STP) {

        qemu_del_timer(s->watchdog);

        return;

    }

    ticks = s->regs[SONIC_WT1] << 16 | s->regs[SONIC_WT0];

    s->wt_last_update = qemu_get_clock(vm_clock);

    delay = ticks_per_sec * ticks / 5000000;

    qemu_mod_timer(s->watchdog, s->wt_last_update + delay);

}

static void update_wt_regs(dp8393xState *s)

{

    int64_t elapsed;

    uint32_t val;

    if (s->regs[SONIC_CR] & SONIC_CR_STP) {

        qemu_del_timer(s->watchdog);

        return;

    }

    elapsed = s->wt_last_update - qemu_get_clock(vm_clock);

    val = s->regs[SONIC_WT1] << 16 | s->regs[SONIC_WT0];

    val -= elapsed / 5000000;

    s->regs[SONIC_WT1] = (val >> 16) & 0xffff;

    s->regs[SONIC_WT0] = (val >> 0)  & 0xffff;

    set_next_tick(s);

}

static void do_start_timer(dp8393xState *s)

{

    s->regs[SONIC_CR] &= ~SONIC_CR_STP;

    set_next_tick(s);

}

static void do_stop_timer(dp8393xState *s)

{

    s->regs[SONIC_CR] &= ~SONIC_CR_ST;

    update_wt_regs(s);

}

static void do_receiver_enable(dp8393xState *s)

{

    s->regs[SONIC_CR] &= ~SONIC_CR_RXDIS;

}

static void do_receiver_disable(dp8393xState *s)

{

    s->regs[SONIC_CR] &= ~SONIC_CR_RXEN;

}

static void do_transmit_packets(dp8393xState *s)

{

    uint16_t data[12];

    int width, size;

    int tx_len, len;

    uint16_t i;

    width = (s->regs[SONIC_DCR] & SONIC_DCR_DW) ? 2 : 1;

    while (1) {

        /* Read memory */

        DPRINTF("Transmit packet at %08x\n",

                (s->regs[SONIC_UTDA] << 16) | s->regs[SONIC_CTDA]);

        size = sizeof(uint16_t) * 6 * width;

        s->regs[SONIC_TTDA] = s->regs[SONIC_CTDA];

        s->memory_rw(s->mem_opaque,

            ((s->regs[SONIC_UTDA] << 16) | s->regs[SONIC_TTDA]) + sizeof(uint16_t) * width,

            (uint8_t *)data, size, 0);

        tx_len = 0;

        /* Update registers */

        s->regs[SONIC_TCR] = data[0 * width] & 0xf000;

        s->regs[SONIC_TPS] = data[1 * width];

        s->regs[SONIC_TFC] = data[2 * width];

        s->regs[SONIC_TSA0] = data[3 * width];

        s->regs[SONIC_TSA1] = data[4 * width];

        s->regs[SONIC_TFS] = data[5 * width];

        /* Handle programmable interrupt */

        if (s->regs[SONIC_TCR] & SONIC_TCR_PINT) {

            s->regs[SONIC_ISR] |= SONIC_ISR_PINT;

        } else {

            s->regs[SONIC_ISR] &= ~SONIC_ISR_PINT;

        }

        for (i = 0; i < s->regs[SONIC_TFC]; ) {

            /* Append fragment */

            len = s->regs[SONIC_TFS];

            if (tx_len + len > sizeof(s->tx_buffer)) {

                len = sizeof(s->tx_buffer) - tx_len;

            }

            s->memory_rw(s->mem_opaque,

                (s->regs[SONIC_TSA1] << 16) | s->regs[SONIC_TSA0],

                &s->tx_buffer[tx_len], len, 0);

            tx_len += len;

            i++;

            if (i != s->regs[SONIC_TFC]) {

                /* Read next fragment details */

                size = sizeof(uint16_t) * 3 * width;

                s->memory_rw(s->mem_opaque,

                    ((s->regs[SONIC_UTDA] << 16) | s->regs[SONIC_TTDA]) + sizeof(uint16_t) * (4 + 3 * i) * width,

                    (uint8_t *)data, size, 0);

                s->regs[SONIC_TSA0] = data[0 * width];

                s->regs[SONIC_TSA1] = data[1 * width];

                s->regs[SONIC_TFS] = data[2 * width];

            }

        }

        /* Handle Ethernet checksum */

        if (!(s->regs[SONIC_TCR] & SONIC_TCR_CRCI)) {

            /* Don't append FCS there, to look like slirp packets

             * which don't have one */

        } else {

            /* Remove existing FCS */

            tx_len -= 4;

        }

        if (s->regs[SONIC_RCR] & (SONIC_RCR_LB1 | SONIC_RCR_LB0)) {

            /* Loopback */

            s->regs[SONIC_TCR] |= SONIC_TCR_CRSL;

            if (s->vc->fd_can_read(s)) {

                s->loopback_packet = 1;

                s->vc->receive(s, s->tx_buffer, tx_len);

            }

        } else {

            /* Transmit packet */

            qemu_send_packet(s->vc, s->tx_buffer, tx_len);

        }

        s->regs[SONIC_TCR] |= SONIC_TCR_PTX;

        /* Write status */

        data[0 * width] = s->regs[SONIC_TCR] & 0x0fff; /* status */

        size = sizeof(uint16_t) * width;

        s->memory_rw(s->mem_opaque,

            (s->regs[SONIC_UTDA] << 16) | s->regs[SONIC_TTDA],

            (uint8_t *)data, size, 1);

        if (!(s->regs[SONIC_CR] & SONIC_CR_HTX)) {

            /* Read footer of packet */

            size = sizeof(uint16_t) * width;

            s->memory_rw(s->mem_opaque,

                ((s->regs[SONIC_UTDA] << 16) | s->regs[SONIC_TTDA]) + sizeof(uint16_t) * (4 + 3 * s->regs[SONIC_TFC]) * width,

                (uint8_t *)data, size, 0);

            s->regs[SONIC_CTDA] = data[0 * width] & ~0x1;

            if (data[0 * width] & 0x1) {

                /* EOL detected */

                break;

            }

        }

    }

    /* Done */

    s->regs[SONIC_CR] &= ~SONIC_CR_TXP;

    s->regs[SONIC_ISR] |= SONIC_ISR_TXDN;

    dp8393x_update_irq(s);

}

static void do_halt_transmission(dp8393xState *s)

{

    /* Nothing to do */

}

static void do_command(dp8393xState *s, uint16_t command)

{

    if ((s->regs[SONIC_CR] & SONIC_CR_RST) && !(command & SONIC_CR_RST)) {

        s->regs[SONIC_CR] &= ~SONIC_CR_RST;

        return;

    }

    s->regs[SONIC_CR] |= (command & SONIC_CR_MASK);

    if (command & SONIC_CR_HTX)

        do_halt_transmission(s);

    if (command & SONIC_CR_TXP)

        do_transmit_packets(s);

    if (command & SONIC_CR_RXDIS)

        do_receiver_disable(s);

    if (command & SONIC_CR_RXEN)

        do_receiver_enable(s);

    if (command & SONIC_CR_STP)

        do_stop_timer(s);

    if (command & SONIC_CR_ST)

        do_start_timer(s);

    if (command & SONIC_CR_RST)

        do_software_reset(s);

    if (command & SONIC_CR_RRRA)

        do_read_rra(s);

    if (command & SONIC_CR_LCAM)

        do_load_cam(s);

}

static uint16_t read_register(dp8393xState *s, int reg)

{

    uint16_t val = 0;

    switch (reg) {

        /* Update data before reading it */

        case SONIC_WT0:

        case SONIC_WT1:

            update_wt_regs(s);

            val = s->regs[reg];

            break;

        /* Accept read to some registers only when in reset mode */

        case SONIC_CAP2:

        case SONIC_CAP1:

        case SONIC_CAP0:

            if (s->regs[SONIC_CR] & SONIC_CR_RST) {

                val = s->cam[s->regs[SONIC_CEP] & 0xf][2* (SONIC_CAP0 - reg) + 1] << 8;

                val |= s->cam[s->regs[SONIC_CEP] & 0xf][2* (SONIC_CAP0 - reg)];

            }

            break;

        /* All other registers have no special contrainst */

        default:

            val = s->regs[reg];

    }

    DPRINTF("read 0x%04x from reg %s\n", val, reg_names[reg]);

    return val;

}

static void write_register(dp8393xState *s, int reg, uint16_t val)

{

    DPRINTF("write 0x%04x to reg %s\n", val, reg_names[reg]);

    switch (reg) {

        /* Command register */

        case SONIC_CR:

            do_command(s, val);;

            break;

        /* Prevent write to read-only registers */

        case SONIC_CAP2:

        case SONIC_CAP1:

        case SONIC_CAP0:

        case SONIC_SR:

        case SONIC_MDT:

            DPRINTF("writing to reg %d invalid\n", reg);

            break;

        /* Accept write to some registers only when in reset mode */

        case SONIC_DCR:

            if (s->regs[SONIC_CR] & SONIC_CR_RST) {

                s->regs[reg] = val & 0xbfff;

            } else {

                DPRINTF("writing to DCR invalid\n");

            }

            break;

        case SONIC_DCR2:

            if (s->regs[SONIC_CR] & SONIC_CR_RST) {

                s->regs[reg] = val & 0xf017;

            } else {

                DPRINTF("writing to DCR2 invalid\n");

            }

            break;

        /* 12 lower bytes are Read Only */

        case SONIC_TCR:

            s->regs[reg] = val & 0xf000;

            break;

        /* 9 lower bytes are Read Only */

        case SONIC_RCR:

            s->regs[reg] = val & 0xffe0;

            break;

        /* Ignore most significant bit */

        case SONIC_IMR:

            s->regs[reg] = val & 0x7fff;

            dp8393x_update_irq(s);

            break;

        /* Clear bits by writing 1 to them */

        case SONIC_ISR:

            val &= s->regs[reg];

            s->regs[reg] &= ~val;

            if (val & SONIC_ISR_RBE) {

                do_read_rra(s);

            }

            dp8393x_update_irq(s);

            break;

        /* Ignore least significant bit */

        case SONIC_RSA:

        case SONIC_REA:

        case SONIC_RRP:

        case SONIC_RWP:

            s->regs[reg] = val & 0xfffe;

            break;

        /* Invert written value for some registers */

        case SONIC_CRCT:

        case SONIC_FAET:

        case SONIC_MPT:

            s->regs[reg] = val ^ 0xffff;

            break;

        /* All other registers have no special contrainst */

        default:

            s->regs[reg] = val;

    }

    if (reg == SONIC_WT0 || reg == SONIC_WT1) {

        set_next_tick(s);

    }

}

static void dp8393x_watchdog(void *opaque)

{

    dp8393xState *s = opaque;

    if (s->regs[SONIC_CR] & SONIC_CR_STP) {

        return;

    }

    s->regs[SONIC_WT1] = 0xffff;

    s->regs[SONIC_WT0] = 0xffff;

    set_next_tick(s);

    /* Signal underflow */

    s->regs[SONIC_ISR] |= SONIC_ISR_TC;

    dp8393x_update_irq(s);

}

static uint32_t dp8393x_readw(void *opaque, target_phys_addr_t addr)

{

    dp8393xState *s = opaque;

    int reg;

    if ((addr & ((1 << s->it_shift) - 1)) != 0) {

        return 0;

    }

    reg = addr >> s->it_shift;

    return read_register(s, reg);

}

static uint32_t dp8393x_readb(void *opaque, target_phys_addr_t addr)

{

    uint16_t v = dp8393x_readw(opaque, addr & ~0x1);

    return (v >> (8 * (addr & 0x1))) & 0xff;

}

static uint32_t dp8393x_readl(void *opaque, target_phys_addr_t addr)

{

    uint32_t v;

    v = dp8393x_readw(opaque, addr);

    v |= dp8393x_readw(opaque, addr + 2) << 16;

    return v;

}

static void dp8393x_writew(void *opaque, target_phys_addr_t addr, uint32_t val)

{

    dp8393xState *s = opaque;

    int reg;

    if ((addr & ((1 << s->it_shift) - 1)) != 0) {

        return;

    }

    reg = addr >> s->it_shift;

    write_register(s, reg, (uint16_t)val);

}

static void dp8393x_writeb(void *opaque, target_phys_addr_t addr, uint32_t val)

{

    uint16_t old_val = dp8393x_readw(opaque, addr & ~0x1);

    switch (addr & 3) {

    case 0:

        val = val | (old_val & 0xff00);

        break;

    case 1:

        val = (val << 8) | (old_val & 0x00ff);

        break;

    }

    dp8393x_writew(opaque, addr & ~0x1, val);

}

static void dp8393x_writel(void *opaque, target_phys_addr_t addr, uint32_t val)

{

    dp8393x_writew(opaque, addr, val & 0xffff);

    dp8393x_writew(opaque, addr + 2, (val >> 16) & 0xffff);

}

static CPUReadMemoryFunc *dp8393x_read[3] = {

    dp8393x_readb,

    dp8393x_readw,

    dp8393x_readl,

};

static CPUWriteMemoryFunc *dp8393x_write[3] = {

    dp8393x_writeb,

    dp8393x_writew,

    dp8393x_writel,

};

static int nic_can_receive(void *opaque)

{

    dp8393xState *s = opaque;

    if (!(s->regs[SONIC_CR] & SONIC_CR_RXEN))

        return 0;

    if (s->regs[SONIC_ISR] & SONIC_ISR_RBE)

        return 0;

    return 1;

}

static int receive_filter(dp8393xState *s, const uint8_t * buf, int size)

{

    static const uint8_t bcast[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};

    int i;

    /* Check for runt packet (remember that checksum is not there) */

    if (size < 64 - 4) {

        return (s->regs[SONIC_RCR] & SONIC_RCR_RNT) ? 0 : -1;

    }

    /* Check promiscuous mode */

    if ((s->regs[SONIC_RCR] & SONIC_RCR_PRO) && (buf[0] & 1) == 0) {

        return 0;

    }

    /* Check multicast packets */

    if ((s->regs[SONIC_RCR] & SONIC_RCR_AMC) && (buf[0] & 1) == 1) {

        return SONIC_RCR_MC;

    }

    /* Check broadcast */

    if ((s->regs[SONIC_RCR] & SONIC_RCR_BRD) && !memcmp(buf, bcast, sizeof(bcast))) {

        return SONIC_RCR_BC;

    }

    /* Check CAM */

    for (i = 0; i < 16; i++) {

        if (s->regs[SONIC_CE] & (1 << i)) {

             /* Entry enabled */

             if (!memcmp(buf, s->cam[i], sizeof(s->cam[i]))) {

                 return 0;

             }

        }

    }

    return -1;

}

static void nic_receive(void *opaque, const uint8_t * buf, size_t size)

{

    uint16_t data[10];

    dp8393xState *s = opaque;

    int packet_type;

    uint32_t available, address;

    int width, rx_len = size;

    uint32_t checksum;

    width = (s->regs[SONIC_DCR] & SONIC_DCR_DW) ? 2 : 1;

    s->regs[SONIC_RCR] &= ~(SONIC_RCR_PRX | SONIC_RCR_LBK | SONIC_RCR_FAER |

        SONIC_RCR_CRCR | SONIC_RCR_LPKT | SONIC_RCR_BC | SONIC_RCR_MC);

    packet_type = receive_filter(s, buf, size);

    if (packet_type < 0) {

        DPRINTF("packet not for netcard\n");

        return;

    }

    /* XXX: Check byte ordering */

    /* Check for EOL */

    if (s->regs[SONIC_LLFA] & 0x1) {

        /* Are we still in resource exhaustion? */

        size = sizeof(uint16_t) * 1 * width;

        address = ((s->regs[SONIC_URDA] << 16) | s->regs[SONIC_CRDA]) + sizeof(uint16_t) * 5 * width;

        s->memory_rw(s->mem_opaque, address, (uint8_t*)data, size, 0);

        if (data[0 * width] & 0x1) {

            /* Still EOL ; stop reception */

            return;

        } else {

            s->regs[SONIC_CRDA] = s->regs[SONIC_LLFA];

        }

    }

    /* Save current position */

    s->regs[SONIC_TRBA1] = s->regs[SONIC_CRBA1];

    s->regs[SONIC_TRBA0] = s->regs[SONIC_CRBA0];

    /* Calculate the ethernet checksum */

#ifdef SONIC_CALCULATE_RXCRC

    checksum = cpu_to_le32(crc32(0, buf, rx_len));

#else

    checksum = 0;

#endif

    /* Put packet into RBA */

    DPRINTF("Receive packet at %08x\n", (s->regs[SONIC_CRBA1] << 16) | s->regs[SONIC_CRBA0]);

    address = (s->regs[SONIC_CRBA1] << 16) | s->regs[SONIC_CRBA0];

    s->memory_rw(s->mem_opaque, address, (uint8_t*)buf, rx_len, 1);

    address += rx_len;

    s->memory_rw(s->mem_opaque, address, (uint8_t*)&checksum, 4, 1);

    rx_len += 4;

    s->regs[SONIC_CRBA1] = address >> 16;

    s->regs[SONIC_CRBA0] = address & 0xffff;

    available = (s->regs[SONIC_RBWC1] << 16) | s->regs[SONIC_RBWC0];

    available -= rx_len / 2;

    s->regs[SONIC_RBWC1] = available >> 16;

    s->regs[SONIC_RBWC0] = available & 0xffff;

    /* Update status */

    if (((s->regs[SONIC_RBWC1] << 16) | s->regs[SONIC_RBWC0]) < s->regs[SONIC_EOBC]) {

        s->regs[SONIC_RCR] |= SONIC_RCR_LPKT;

    }

    s->regs[SONIC_RCR] |= packet_type;

    s->regs[SONIC_RCR] |= SONIC_RCR_PRX;

    if (s->loopback_packet) {

        s->regs[SONIC_RCR] |= SONIC_RCR_LBK;

        s->loopback_packet = 0;

    }

    /* Write status to memory */

    DPRINTF("Write status at %08x\n", (s->regs[SONIC_URDA] << 16) | s->regs[SONIC_CRDA]);

    data[0 * width] = s->regs[SONIC_RCR]; /* status */

    data[1 * width] = rx_len; /* byte count */

    data[2 * width] = s->regs[SONIC_TRBA0]; /* pkt_ptr0 */

    data[3 * width] = s->regs[SONIC_TRBA1]; /* pkt_ptr1 */

    data[4 * width] = s->regs[SONIC_RSC]; /* seq_no */

    size = sizeof(uint16_t) * 5 * width;

    s->memory_rw(s->mem_opaque, (s->regs[SONIC_URDA] << 16) | s->regs[SONIC_CRDA], (uint8_t *)data, size, 1);

    /* Move to next descriptor */

    size = sizeof(uint16_t) * width;

    s->memory_rw(s->mem_opaque,

        ((s->regs[SONIC_URDA] << 16) | s->regs[SONIC_CRDA]) + sizeof(uint16_t) * 5 * width,

        (uint8_t *)data, size, 0);

    s->regs[SONIC_LLFA] = data[0 * width];

    if (s->regs[SONIC_LLFA] & 0x1) {

        /* EOL detected */

        s->regs[SONIC_ISR] |= SONIC_ISR_RDE;

    } else {

        data[0 * width] = 0; /* in_use */

        s->memory_rw(s->mem_opaque,

            ((s->regs[SONIC_URDA] << 16) | s->regs[SONIC_CRDA]) + sizeof(uint16_t) * 6 * width,

            (uint8_t *)data, size, 1);

        s->regs[SONIC_CRDA] = s->regs[SONIC_LLFA];

        s->regs[SONIC_ISR] |= SONIC_ISR_PKTRX;

        s->regs[SONIC_RSC] = (s->regs[SONIC_RSC] & 0xff00) | (((s->regs[SONIC_RSC] & 0x00ff) + 1) & 0x00ff);

        if (s->regs[SONIC_RCR] & SONIC_RCR_LPKT) {

            /* Read next RRA */

            do_read_rra(s);

        }

    }

    /* Done */

    dp8393x_update_irq(s);

}

static void nic_reset(void *opaque)

{

    dp8393xState *s = opaque;

    qemu_del_timer(s->watchdog);

    s->regs[SONIC_CR] = SONIC_CR_RST | SONIC_CR_STP | SONIC_CR_RXDIS;

    s->regs[SONIC_DCR] &= ~(SONIC_DCR_EXBUS | SONIC_DCR_LBR);

    s->regs[SONIC_RCR] &= ~(SONIC_RCR_LB0 | SONIC_RCR_LB1 | SONIC_RCR_BRD | SONIC_RCR_RNT);

    s->regs[SONIC_TCR] |= SONIC_TCR_NCRS | SONIC_TCR_PTX;

    s->regs[SONIC_TCR] &= ~SONIC_TCR_BCM;

    s->regs[SONIC_IMR] = 0;

    s->regs[SONIC_ISR] = 0;

    s->regs[SONIC_DCR2] = 0;

    s->regs[SONIC_EOBC] = 0x02F8;

    s->regs[SONIC_RSC] = 0;

    s->regs[SONIC_CE] = 0;