/*
 * QEMU NE2000 emulation
 *
 * Copyright (c) 2003-2004 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <errno.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include "emu.h"
#include "dosemu_debug.h"
#include "ioselect.h"
#include "pic.h"
#include "port.h"
#include "libpacket.h"
#include "ne2000.h"

#define DEBUG_NE2000

#define MAX_ETH_FRAME_SIZE 1514

#define E8390_CMD	0x00  /* The command register (for all pages) */
/* Page 0 register offsets. */
#define EN0_CLDALO	0x01	/* Low byte of current local dma addr  RD */
#define EN0_STARTPG	0x01	/* Starting page of ring bfr WR */
#define EN0_CLDAHI	0x02	/* High byte of current local dma addr  RD */
#define EN0_STOPPG	0x02	/* Ending page +1 of ring bfr WR */
#define EN0_BOUNDARY	0x03	/* Boundary page of ring bfr RD WR */
#define EN0_TSR		0x04	/* Transmit status reg RD */
#define EN0_TPSR	0x04	/* Transmit starting page WR */
#define EN0_NCR		0x05	/* Number of collision reg RD */
#define EN0_TCNTLO	0x05	/* Low  byte of tx byte count WR */
#define EN0_FIFO	0x06	/* FIFO RD */
#define EN0_TCNTHI	0x06	/* High byte of tx byte count WR */
#define EN0_ISR		0x07	/* Interrupt status reg RD WR */
#define EN0_CRDALO	0x08	/* low byte of current remote dma address RD */
#define EN0_RSARLO	0x08	/* Remote start address reg 0 */
#define EN0_CRDAHI	0x09	/* high byte, current remote dma address RD */
#define EN0_RSARHI	0x09	/* Remote start address reg 1 */
#define EN0_RCNTLO	0x0a	/* Remote byte count reg WR */
#define EN0_RTL8029ID0	0x0a	/* Realtek ID byte #1 RD */
#define EN0_RCNTHI	0x0b	/* Remote byte count reg WR */
#define EN0_RTL8029ID1	0x0b	/* Realtek ID byte #2 RD */
#define EN0_RSR		0x0c	/* rx status reg RD */
#define EN0_RXCR	0x0c	/* RX configuration reg WR */
#define EN0_TXCR	0x0d	/* TX configuration reg WR */
#define EN0_COUNTER0	0x0d	/* Rcv alignment error counter RD */
#define EN0_DCFG	0x0e	/* Data configuration reg WR */
#define EN0_COUNTER1	0x0e	/* Rcv CRC error counter RD */
#define EN0_IMR		0x0f	/* Interrupt mask reg WR */
#define EN0_COUNTER2	0x0f	/* Rcv missed frame error counter RD */

#define EN1_PHYS        0x11
#define EN1_CURPAG      0x17
#define EN1_MULT        0x18

#define EN2_STARTPG	0x21	/* Starting page of ring bfr RD */
#define EN2_STOPPG	0x22	/* Ending page +1 of ring bfr RD */

#define EN3_CONFIG0	0x33
#define EN3_CONFIG1	0x34
#define EN3_CONFIG2	0x35
#define EN3_CONFIG3	0x36

/*  Register accessed at EN_CMD, the 8390 base addr.  */
#define E8390_STOP	0x01	/* Stop and reset the chip */
#define E8390_START	0x02	/* Start the chip, clear reset */
#define E8390_TRANS	0x04	/* Transmit a frame */
#define E8390_RREAD	0x08	/* Remote read */
#define E8390_RWRITE	0x10	/* Remote write  */
#define E8390_NODMA	0x20	/* Remote DMA */
#define E8390_PAGE0	0x00	/* Select page chip registers */
#define E8390_PAGE1	0x40	/* using the two high-order bits */
#define E8390_PAGE2	0x80	/* Page 3 is invalid. */

/* Bits in EN0_ISR - Interrupt status register */
#define ENISR_RX	0x01	/* Receiver, no error */
#define ENISR_TX	0x02	/* Transmitter, no error */
#define ENISR_RX_ERR	0x04	/* Receiver, with error */
#define ENISR_TX_ERR	0x08	/* Transmitter, with error */
#define ENISR_OVER	0x10	/* Receiver overwrote the ring */
#define ENISR_COUNTERS	0x20	/* Counters need emptying */
#define ENISR_RDC	0x40	/* remote dma complete */
#define ENISR_RESET	0x80	/* Reset completed */
#define ENISR_ALL	0x3f	/* Interrupts we will enable */

/* Bits in received packet status byte and EN0_RSR*/
#define ENRSR_RXOK	0x01	/* Received a good packet */
#define ENRSR_CRC	0x02	/* CRC error */
#define ENRSR_FAE	0x04	/* frame alignment error */
#define ENRSR_FO	0x08	/* FIFO overrun */
#define ENRSR_MPA	0x10	/* missed pkt */
#define ENRSR_PHY	0x20	/* physical/multicast address */
#define ENRSR_DIS	0x40	/* receiver disable. set in monitor mode */
#define ENRSR_DEF	0x80	/* deferring */

/* Transmitted packet status, EN0_TSR. */
#define ENTSR_PTX 0x01	/* Packet transmitted without error */
#define ENTSR_ND  0x02	/* The transmit wasn't deferred. */
#define ENTSR_COL 0x04	/* The transmit collided at least once. */
#define ENTSR_ABT 0x08  /* The transmit collided 16 times, and was deferred. */
#define ENTSR_CRS 0x10	/* The carrier sense was lost. */
#define ENTSR_FU  0x20  /* A "FIFO underrun" occurred during transmit. */
#define ENTSR_CDH 0x40	/* The collision detect "heartbeat" signal was lost. */
#define ENTSR_OWC 0x80  /* There was an out-of-window collision. */

#define NE2000_IRQ          10
#define NE2000_IOBASE       0x310

#define NE2000_PMEM_SIZE    (32 * 1024)
#define NE2000_PMEM_START   (16 * 1024)
#define NE2000_PMEM_END     (NE2000_PMEM_SIZE+NE2000_PMEM_START)
#define NE2000_MEM_SIZE     NE2000_PMEM_END

#define le16_to_cpu(x) x
#define le32_to_cpupu(x) *x
#define cpu_to_le16(x) x
#define cpu_to_le32wu(p,v) *p = v;

#define NE2000_EADDR0 0x00            /* hard coded address */
#define NE2000_EADDR1 0x00            /* this will need to be configurable */
#define NE2000_EADDR2 0x01
#define NE2000_EADDR3 0x61
#define NE2000_EADDR4 0x60
#define NE2000_EADDR5 0x59

typedef struct NE2000State {
    uint8_t cmd;
    uint32_t start;
    uint32_t stop;
    uint8_t boundary;
    uint8_t tsr;
    uint8_t tpsr;
    uint16_t tcnt;
    uint16_t rcnt;
    uint32_t rsar;
    uint8_t rsr;
    uint8_t rxcr;
    uint8_t isr;
    uint8_t dcfg;
    uint8_t imr;
    uint8_t phys[6]; /* mac address */
    uint8_t curpag;
    uint8_t mult[8]; /* multicast mask array */
    uint8_t mem[NE2000_MEM_SIZE];
    int fdnet;
    unsigned long irq;
} NE2000State;

// Just one instance
static NE2000State ne2000state;

// For io_device
Bit16u ne2000_io_read16(ioport_t port, void *arg);
void ne2000_io_write16(ioport_t port, Bit16u value, void *arg);
Bit8u ne2000_io_read8(ioport_t port, void *arg);
void ne2000_io_write8(ioport_t port, Bit8u value, void *arg);
static void ne2000_irq_activate(int);

static void ne2000_receive_req_async(int fd, void *arg);
static size_t ne2000_receive(NE2000State *s, const uint8_t *buf, size_t size_);
static int ne2000_buffer_full(NE2000State *s);

#ifdef DEBUG_NE2000
static void N_printhdr(uint8_t *buf);
#endif

static void init_cbk(int fd, int mode)
{
    ne2000state.fdnet = fd;
}

void ne2000_init(void)
{
    NE2000State *s = &ne2000state;
    emu_iodev_t io_device = {};

    s->fdnet = -1;

    if (!config.ne2k)
        return;

    N_printf("NE2000: ne2000_init()\n");

    if (OpenNetworkLink(init_cbk) < 0) {
        N_printf("NE2000: failed to open network device\n");
        return;
    }

    // Setup the IO device within Dosemu

    /* NE2000 Emulation */
    io_device.read_portb = ne2000_io_read8;
    io_device.write_portb = ne2000_io_write8;
    io_device.read_portw = ne2000_io_read16;
    io_device.write_portw = ne2000_io_write16;
    io_device.read_portd = NULL;
    io_device.write_portd = NULL;
    io_device.handler_name = "NE2000 Emulation";
    io_device.start_addr = /* config.ne2000_base */ NE2000_IOBASE;
    io_device.end_addr = /* config.ne2000_base */ NE2000_IOBASE + 0x1f;
    if (port_register_handler(io_device, 0) != 0) {
        N_printf("NE2000: Error registering NE2000 port handler\n");
        ne2000_done();
        return;
    }

    /* init control defaults */
    s->irq = NE2000_IRQ;

    N_printf("NE2000: Initialisation - Base 0x%03x, IRQ %d\n", NE2000_IOBASE, NE2000_IRQ);
}

static void _ne2000_reset(NE2000State *s)
{
    int i;

    if (s->fdnet < 0) { // Not initialised
	return;
    }

    N_printf("NE2000: ne2000_reset()\n");

    s->isr = ENISR_RESET;
    s->cmd = E8390_STOP;
    s->mem[0] = NE2000_EADDR0;
    s->mem[1] = NE2000_EADDR1;
    s->mem[2] = NE2000_EADDR2;
    s->mem[3] = NE2000_EADDR3;
    s->mem[4] = NE2000_EADDR4;
    s->mem[5] = NE2000_EADDR5;

    // try to get the MAC address from the device and just copy the card id
    GetDeviceHardwareAddress(s->mem);
    N_printf("NE2000: HWADDR %02x:%02x:%02x:%02x:%02x:%02x\n",
             s->mem[0], s->mem[1], s->mem[2], s->mem[3], s->mem[4], s->mem[5]);

    s->mem[14] = 0x57;
    s->mem[15] = 0x57;

    /* duplicate prom data */
    for(i = 15;i >= 0; i--) {
        s->mem[2 * i] = s->mem[i];
        s->mem[2 * i + 1] = s->mem[i];
    }
}

void ne2000_reset(void)
{
    _ne2000_reset(&ne2000state);
}

void ne2000_done(void)
{
    NE2000State *s = &ne2000state;

    if (s->fdnet < 0) { // Not initialised
	return;
    }

    N_printf("NE2000: ne2000_done()\n");

    if (!(s->cmd & E8390_STOP))
        remove_from_io_select(s->fdnet);
    CloseNetworkLink(s->fdnet);
    s->fdnet = -1;
}

static void ne2000_ether_send(NE2000State *s, uint8_t *buf, int len)
{
    int slen;

#ifdef DEBUG_NE2000
    N_printf("NE2000: ne2000_ether_send(%p, %d)\n", buf, len);
    N_printhdr(buf);
#endif
    slen = write(s->fdnet, buf, len);
    if (slen < 0)
        N_printf("NE2000: write() call failed: %s\n", strerror(errno));
    else if (slen < len)
        N_printf("NE2000: write() call underrun: %d/%d\n", slen, len);
}

static int ne2000_ether_recv(NE2000State *s, uint8_t *buf, int bufsiz)
{
    int ret;

    ret = read(s->fdnet, buf, bufsiz);
    ioselect_complete(s->fdnet);
    if (ret < 0) {
        N_printf("NE2000: ne2000_ether_recv() read failed\n");
        return -1;
    }

    N_printf("NE2000: ne2000_ether_recv() read %d bytes\n", ret);
    N_printhdr(buf);
    return ret;
}

static void ne2000_receive_req_async(int fd, void *arg)
{
    NE2000State *s = &ne2000state;
    uint8_t mybuf[MAX_ETH_FRAME_SIZE];
    int ret;

    if (ne2000_buffer_full(s)) {
        N_printf("NE2000: ne2000_receive_req_async() called but buffer full\n");
        return;
    }

    N_printf("NE2000: ne2000_receive_req_async() called\n");

    ret = ne2000_ether_recv(s, mybuf, sizeof mybuf);
    if (ret < 0)
        return;

    ne2000_receive(s, mybuf, ret);
}

static void ne2000_update_irq(NE2000State *s)
{
    int isr;
    isr = (s->isr & s->imr) & 0x7f;
#if defined(DEBUG_NE2000)
    N_printf("NE2000: Set IRQ to %d (%02x %02x)\n", isr ? 1 : 0, s->isr, s->imr);
#endif
    ne2000_irq_activate(isr != 0);
}

static int ne2000_buffer_full(NE2000State *s)
{
    int avail, index, boundary;

    N_printf("NE2000: ne2000_buffer_full()\n");

    index = s->curpag << 8;
    boundary = s->boundary << 8;
    if (index < boundary)
        avail = boundary - index;
    else
        avail = (s->stop - s->start) - (index - boundary);
    if (avail < (MAX_ETH_FRAME_SIZE + 4))
        return 1;
    return 0;
}

#define MIN_BUF_SIZE 60

static size_t ne2000_receive(NE2000State *s, const uint8_t *buf, size_t size_)
{
    size_t size = size_;
    uint8_t *p;
    unsigned int total_len, next, avail, len, index;
    uint8_t buf1[MIN_BUF_SIZE];
    static const uint8_t broadcast_macaddr[6] =
        { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

    N_printf("NE2000: ne2000_receive()\n");

#if defined(DEBUG_NE2000)
    N_printf("NE2000: received len=%zd\n", size);
#endif

    if (s->cmd & E8390_STOP || ne2000_buffer_full(s))
        return -1;

    /* XXX: check this */
    if (s->rxcr & 0x10) {
        /* promiscuous: receive all */
    } else {
        if (!memcmp(buf,  broadcast_macaddr, 6)) {
            /* broadcast address */
            if (!(s->rxcr & 0x04))
                return size;
        } else if (buf[0] & 0x01) {
            /* multicast */
            if (!(s->rxcr & 0x08))
                return size;
#if 0
            mcast_idx = compute_mcast_idx(buf);
            if (!(s->mult[mcast_idx >> 3] & (1 << (mcast_idx & 7))))
                return size;
#else
            return size;
#endif
        } else if (s->mem[0] == buf[0] &&
                   s->mem[2] == buf[1] &&
                   s->mem[4] == buf[2] &&
                   s->mem[6] == buf[3] &&
                   s->mem[8] == buf[4] &&
                   s->mem[10] == buf[5]) {
            /* match */
        } else {
            return size;
        }
    }


    /* if too small buffer, then expand it */
    if (size < MIN_BUF_SIZE) {
        memcpy(buf1, buf, size);
        memset(buf1 + size, 0, MIN_BUF_SIZE - size);
        buf = buf1;
        size = MIN_BUF_SIZE;
    }

    index = s->curpag << 8;
    /* 4 bytes for header */
    total_len = size + 4;
    /* address for next packet (4 bytes for CRC) */
    next = index + ((total_len + 4 + 255) & ~0xff);
    if (next >= s->stop)
        next -= (s->stop - s->start);
    /* prepare packet header */
    p = s->mem + index;
    s->rsr = ENRSR_RXOK; /* receive status */
    /* XXX: check this */
    if (buf[0] & 0x01)
        s->rsr |= ENRSR_PHY;
    p[0] = s->rsr;
    p[1] = next >> 8;
    p[2] = total_len;
    p[3] = total_len >> 8;
    index += 4;

    /* write packet data */
    while (size > 0) {
        if (index <= s->stop)
            avail = s->stop - index;
        else
            avail = 0;
        len = size;
        if (len > avail)
            len = avail;
        memcpy(s->mem + index, buf, len);
        buf += len;
        index += len;
        if (index == s->stop)
            index = s->start;
        size -= len;
    }
    s->curpag = next >> 8;

    /* now we can signal we have received something */
    s->isr |= ENISR_RX;
    ne2000_update_irq(s);

    return size_;
}

static void ne2000_ioport_write(NE2000State *s, uint32_t addr, uint32_t val)
{
    int offset, page, index;
    int old_full = ne2000_buffer_full(s);

    N_printf("NE2000: ne2000_ioport_write()\n");

    addr &= 0xf;
#ifdef DEBUG_NE2000
    N_printf("NE2000: write addr=0x%x val=0x%02x\n", addr, val);
#endif
    if (addr == E8390_CMD) {
        uint32_t old_cmd = s->cmd;
        /* control register */
        s->cmd = val;
        if (!(val & E8390_STOP)) { /* START bit makes no sense on RTL8029... */
            if (old_cmd & E8390_STOP) {
                N_printf("NE2000: enable receiver\n");
                add_to_io_select(s->fdnet, ne2000_receive_req_async, NULL);
            }
            s->isr &= ~ENISR_RESET;
            /* test specific case: zero length transfer */
            if ((val & (E8390_RREAD | E8390_RWRITE)) &&
                s->rcnt == 0) {
                s->isr |= ENISR_RDC;
                ne2000_update_irq(s);
            }
            if (val & E8390_TRANS) {
                index = (s->tpsr << 8);
                /* XXX: next 2 lines are a hack to make netware 3.11 work */
                if (index >= NE2000_PMEM_END)
                    index -= NE2000_PMEM_SIZE;
                /* fail safe: check range on the transmitted length  */
                if (index + s->tcnt <= NE2000_PMEM_END) {
                    ne2000_ether_send(s, s->mem + index, s->tcnt);
                }
                /* signal end of transfer */
                s->tsr = ENTSR_PTX;
                s->isr |= ENISR_TX;
                s->cmd &= ~E8390_TRANS;
                ne2000_update_irq(s);
            }
        } else {
            if (!(old_cmd & E8390_STOP)) {
                N_printf("NE2000: disable receiver\n");
                remove_from_io_select(s->fdnet);
            }
        }
    } else {
        page = s->cmd >> 6;
        offset = addr | (page << 4);
        switch(offset) {
        case EN0_STARTPG:
            s->start = val << 8;
            break;
        case EN0_STOPPG:
            s->stop = val << 8;
            break;
        case EN0_BOUNDARY:
            s->boundary = val;
            break;
        case EN0_IMR:
            s->imr = val;
            ne2000_update_irq(s);
            break;
        case EN0_TPSR:
            s->tpsr = val;
            break;
        case EN0_TCNTLO:
            s->tcnt = (s->tcnt & 0xff00) | val;
            break;
        case EN0_TCNTHI:
            s->tcnt = (s->tcnt & 0x00ff) | (val << 8);
            break;
        case EN0_RSARLO:
            s->rsar = (s->rsar & 0xff00) | val;
            break;
        case EN0_RSARHI:
            s->rsar = (s->rsar & 0x00ff) | (val << 8);
            break;
        case EN0_RCNTLO:
            s->rcnt = (s->rcnt & 0xff00) | val;
            break;
        case EN0_RCNTHI:
            s->rcnt = (s->rcnt & 0x00ff) | (val << 8);
            break;
        case EN0_RXCR:
            s->rxcr = val;
            break;
        case EN0_DCFG:
            s->dcfg = val;
            break;
        case EN0_ISR:
            s->isr &= ~(val & 0x7f);
            ne2000_update_irq(s);
            break;
        case EN1_PHYS ... EN1_PHYS + 5:
            s->phys[offset - EN1_PHYS] = val;
            break;
        case EN1_CURPAG:
            s->curpag = val;
            break;
        case EN1_MULT ... EN1_MULT + 7:
            s->mult[offset - EN1_MULT] = val;
            break;
        }
    }

    /* flush if buffer was full */
    if (old_full && !ne2000_buffer_full(s))
        ioselect_complete(s->fdnet);
}

static uint32_t ne2000_ioport_read(NE2000State *s, uint32_t addr)
{
    int offset, page, ret;

    N_printf("NE2000: ne2000_ioport_read()\n");

    addr &= 0xf;
    if (addr == E8390_CMD) {
        ret = s->cmd;
    } else {
        page = s->cmd >> 6;
        offset = addr | (page << 4);
        switch(offset) {
        case EN0_TSR:
            ret = s->tsr;
            break;
        case EN0_BOUNDARY:
            ret = s->boundary;
            break;
        case EN0_ISR:
            ret = s->isr;
            break;
	case EN0_RSARLO:
	    ret = s->rsar & 0x00ff;
	    break;
	case EN0_RSARHI:
	    ret = s->rsar >> 8;
	    break;
        case EN1_PHYS ... EN1_PHYS + 5:
            ret = s->phys[offset - EN1_PHYS];
            break;
        case EN1_CURPAG:
            ret = s->curpag;
            break;
        case EN1_MULT ... EN1_MULT + 7:
            ret = s->mult[offset - EN1_MULT];
            break;
        case EN0_RSR:
            ret = s->rsr;
            break;
        case EN2_STARTPG:
            ret = s->start >> 8;
            break;
        case EN2_STOPPG:
            ret = s->stop >> 8;
            break;
	case EN0_RTL8029ID0:
	    ret = 0x50;
	    break;
	case EN0_RTL8029ID1:
	    ret = 0x43;
	    break;
	case EN3_CONFIG0:
	    ret = 0;		/* 10baseT media */
	    break;
	case EN3_CONFIG2:
	    ret = 0x40;		/* 10baseT active */
	    break;
	case EN3_CONFIG3:
	    ret = 0x40;		/* Full duplex */
	    break;
        default:
            ret = 0x00;
            break;
        }
    }
#ifdef DEBUG_NE2000
    N_printf("NE2000: read addr=0x%x val=%02x\n", addr, ret);
#endif
    return ret;
}

static inline void ne2000_mem_writeb(NE2000State *s, uint32_t addr,
                                     uint32_t val)
{
    N_printf("NE2000: ne2000_mem_writeb()\n");

    if (addr < 32 ||
        (addr >= NE2000_PMEM_START && addr < NE2000_MEM_SIZE)) {
        s->mem[addr] = val;
    }
}

static inline void ne2000_mem_writew(NE2000State *s, uint32_t addr,
                                     uint32_t val)
{
    N_printf("NE2000: ne2000_mem_writew()\n");

    addr &= ~1; /* XXX: check exact behaviour if not even */
    if (addr < 32 ||
        (addr >= NE2000_PMEM_START && addr < NE2000_MEM_SIZE)) {
        *(uint16_t *)(s->mem + addr) = cpu_to_le16(val);
    }
}

static inline void ne2000_mem_writel(NE2000State *s, uint32_t addr,
                                     uint32_t val)
{
    N_printf("NE2000: ne2000_mem_writel()\n");

    addr &= ~1; /* XXX: check exact behaviour if not even */
    if (addr < 32 ||
        (addr >= NE2000_PMEM_START && addr < NE2000_MEM_SIZE)) {
        cpu_to_le32wu((uint32_t *)(s->mem + addr), val);
    }
}

static inline uint32_t ne2000_mem_readb(NE2000State *s, uint32_t addr)
{
    N_printf("NE2000: ne2000_mem_readb()\n");

    if (addr < 32 ||
        (addr >= NE2000_PMEM_START && addr < NE2000_MEM_SIZE)) {
        return s->mem[addr];
    } else {
        return 0xff;
    }
}

static inline uint32_t ne2000_mem_readw(NE2000State *s, uint32_t addr)
{
    N_printf("NE2000: ne2000_mem_readw()\n");

    addr &= ~1; /* XXX: check exact behaviour if not even */
    if (addr < 32 ||
        (addr >= NE2000_PMEM_START && addr < NE2000_MEM_SIZE)) {
        return le16_to_cpu(*(uint16_t *)(s->mem + addr));
    } else {
        return 0xffff;
    }
}

static inline uint32_t ne2000_mem_readl(NE2000State *s, uint32_t addr)
{
    N_printf("NE2000: ne2000_mem_readl()\n");

    addr &= ~1; /* XXX: check exact behaviour if not even */
    if (addr < 32 ||
        (addr >= NE2000_PMEM_START && addr < NE2000_MEM_SIZE)) {
        return le32_to_cpupu((uint32_t *)(s->mem + addr));
    } else {
        return 0xffffffff;
    }
}

static inline void ne2000_dma_update(NE2000State *s, int len)
{
    N_printf("NE2000: ne2000_dma_update()\n");

    s->rsar += len;
    /* wrap */
    /* XXX: check what to do if rsar > stop */
    if (s->rsar == s->stop)
        s->rsar = s->start;

    if (s->rcnt <= len) {
        s->rcnt = 0;
        /* signal end of transfer */
        s->isr |= ENISR_RDC;
        ne2000_update_irq(s);
    } else {
        s->rcnt -= len;
    }
}

static void ne2000_asic_ioport_write(NE2000State *s, uint32_t addr, uint32_t val)
{
    N_printf("NE2000: ne2000_asic_ioport_write()\n");

#ifdef DEBUG_NE2000
    N_printf("NE2000: asic write val=0x%04x\n", val);
#endif
    if (s->rcnt == 0)
        return;
    if (s->dcfg & 0x01) {
        /* 16 bit access */
        ne2000_mem_writew(s, s->rsar, val);
        ne2000_dma_update(s, 2);
    } else {
        /* 8 bit access */
        ne2000_mem_writeb(s, s->rsar, val);
        ne2000_dma_update(s, 1);
    }
}

static uint32_t ne2000_asic_ioport_read(NE2000State *s, uint32_t addr)
{
    int ret;

    N_printf("NE2000: ne2000_asic_ioport_read()\n");

    if (s->dcfg & 0x01) {
        /* 16 bit access */
        ret = ne2000_mem_readw(s, s->rsar);
        ne2000_dma_update(s, 2);
    } else {
        /* 8 bit access */
        ret = ne2000_mem_readb(s, s->rsar);
        ne2000_dma_update(s, 1);
    }
#ifdef DEBUG_NE2000
    N_printf("NE2000: asic read val=0x%04x\n", ret);
#endif
    return ret;
}

static void ne2000_asic_ioport_writel(NE2000State *s, uint32_t addr, uint32_t val)
{
    N_printf("NE2000: ne2000_asic_ioport_writel()\n");

#ifdef DEBUG_NE2000
    N_printf("NE2000: asic writel val=0x%04x\n", val);
#endif
    if (s->rcnt == 0)
        return;
    /* 32 bit access */
    ne2000_mem_writel(s, s->rsar, val);
    ne2000_dma_update(s, 4);
}

static uint32_t ne2000_asic_ioport_readl(NE2000State *s, uint32_t addr)
{
    int ret;

    N_printf("NE2000: ne2000_asic_ioport_readl()\n");

    /* 32 bit access */
    ret = ne2000_mem_readl(s, s->rsar);
    ne2000_dma_update(s, 4);
#ifdef DEBUG_NE2000
    N_printf("NE2000: asic readl val=0x%04x\n", ret);
#endif
    return ret;
}

static void ne2000_reset_ioport_write(NE2000State *s, uint32_t addr, uint32_t val)
{
    /* nothing to do (end of reset pulse) */
    N_printf("NE2000: ne2000_reset_ioport_write()\n");
}

static uint32_t ne2000_reset_ioport_read(NE2000State *s, uint32_t addr)
{
    N_printf("NE2000: ne2000_reset_ioport_read()\n");

    _ne2000_reset(s);
    return 0;
}

static uint64_t ne2000_read(NE2000State *s, uint32_t addr, unsigned size)
{
    N_printf("NE2000: ne2000_read()\n");

    if (addr < 0x10 && size == 1) {
        return ne2000_ioport_read(s, addr);
    } else if (addr == 0x10) {
        if (size <= 2) {
            return ne2000_asic_ioport_read(s, addr);
        } else {
            return ne2000_asic_ioport_readl(s, addr);
        }
    } else if (addr == 0x1f && size == 1) {
        return ne2000_reset_ioport_read(s, addr);
    }
    return ((uint64_t)1 << (size * 8)) - 1;
}

static void ne2000_write(NE2000State *s, uint32_t addr, uint64_t data, unsigned size)
{
    N_printf("NE2000: ne2000_write()\n");

    if (addr < 0x10 && size == 1) {
        ne2000_ioport_write(s, addr, data);
    } else if (addr == 0x10) {
        if (size <= 2) {
            ne2000_asic_ioport_write(s, addr, data);
        } else {
            ne2000_asic_ioport_writel(s, addr, data);
        }
    } else if (addr == 0x1f && size == 1) {
        ne2000_reset_ioport_write(s, addr, data);
    }
}

/* from Scott Pitcher's driver */

/* --------------------------------- */
/* 16 bit io functions - only on data port */

Bit16u ne2000_io_read16(ioport_t port, void *arg)
{
    NE2000State *s = &ne2000state;
    ioport_t addr = port - NE2000_IOBASE;

    N_printf("\nNE2000: ne2000_io_read16()\n");

    if (addr == 0x10)
        return ne2000_read(s, addr, 2);
    else
        return ne2000_read(s, addr, 1);
}

void ne2000_io_write16(ioport_t port, Bit16u value, void *arg)
{
    NE2000State *s = &ne2000state;
    ioport_t addr = port - NE2000_IOBASE;

    N_printf("\nNE2000: ne2000_io_write16()\n");

    if (addr == 0x10)
        ne2000_write(s, addr, value, 2);
    else
        ne2000_write(s, addr, (uint8_t)value, 1); /* default to 8 bit */
}

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

/* handle io reads from ne2000 */

Bit8u ne2000_io_read8(ioport_t port, void *arg)
{
    NE2000State *s = &ne2000state;
    ioport_t addr = port - NE2000_IOBASE;

    N_printf("\nNE2000: ne2000_io_read8() %d\n", addr);
    return ne2000_read(s, addr, 1);
}

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

/* handle io writes to ne2000 */

void ne2000_io_write8(ioport_t port, Bit8u value, void *arg)
{
    NE2000State *s = &ne2000state;
    ioport_t addr = port - NE2000_IOBASE;

    N_printf("\nNE2000: ne2000_io_write8() %d, 0x%02x\n", addr, value);
    ne2000_write(s, addr, value, 1);
}

/* activate our irq */
static void ne2000_irq_activate(int level)
{
    NE2000State *s = &ne2000state;

    N_printf("NE2000: ne2000_irq_activate(%d)\n", level);

    if (level)
        pic_request(s->irq);
    else
        pic_untrigger(s->irq);
}

/* debug print an ethernet header */
#ifdef DEBUG_NE2000
static void N_printhdr(uint8_t *buf)
{
    N_printf("NE2000: dest[%02x,%02x,%02x,%02x,%02x,%02x]\n"
             "         src[%02x,%02x,%02x,%02x,%02x,%02x]\n"
             "        prot[%02x,%02x]\n",
             buf[0], buf[1], buf[2], buf[3], buf[4], buf[5],
             buf[6], buf[7], buf[8], buf[9], buf[10], buf[11],
             buf[12], buf[13]);
}
#endif
