fdc.c

/*
 * QEMU Floppy disk emulator (Intel 82078)
 * 
 * Copyright (c) 2003 Jocelyn Mayer
 * 
 * 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.
 */
/*
 * The controller is used in Sun4m systems in a slightly different
 * way. There are changes in DOR register and DMA is not available.
 */
#include "vl.h"

/********************************************************/
/* debug Floppy devices */
//#define DEBUG_FLOPPY

#ifdef DEBUG_FLOPPY
#define FLOPPY_DPRINTF(fmt, args...) \
do { printf("FLOPPY: " fmt , ##args); } while (0)
#else
#define FLOPPY_DPRINTF(fmt, args...)
#endif

#define FLOPPY_ERROR(fmt, args...) \
do { printf("FLOPPY ERROR: %s: " fmt, __func__ , ##args); } while (0)

/********************************************************/
/* Floppy drive emulation                               */

/* Will always be a fixed parameter for us */
#define FD_SECTOR_LEN 512
#define FD_SECTOR_SC  2   /* Sector size code */

/* Floppy disk drive emulation */
typedef enum fdisk_type_t {
    FDRIVE_DISK_288   = 0x01, /* 2.88 MB disk           */
    FDRIVE_DISK_144   = 0x02, /* 1.44 MB disk           */
    FDRIVE_DISK_720   = 0x03, /* 720 kB disk            */
    FDRIVE_DISK_USER  = 0x04, /* User defined geometry  */
    FDRIVE_DISK_NONE  = 0x05, /* No disk                */
} fdisk_type_t;

typedef enum fdrive_type_t {
    FDRIVE_DRV_144  = 0x00,   /* 1.44 MB 3"5 drive      */
    FDRIVE_DRV_288  = 0x01,   /* 2.88 MB 3"5 drive      */
    FDRIVE_DRV_120  = 0x02,   /* 1.2  MB 5"25 drive     */
    FDRIVE_DRV_NONE = 0x03,   /* No drive connected     */
} fdrive_type_t;

typedef enum fdrive_flags_t {
    FDRIVE_MOTOR_ON   = 0x01, /* motor on/off           */
} fdrive_flags_t;

typedef enum fdisk_flags_t {
    FDISK_DBL_SIDES  = 0x01,
} fdisk_flags_t;

typedef struct fdrive_t {
    BlockDriverState *bs;
    /* Drive status */
    fdrive_type_t drive;
    fdrive_flags_t drflags;
    uint8_t perpendicular;    /* 2.88 MB access mode    */
    /* Position */
    uint8_t head;
    uint8_t track;
    uint8_t sect;
    /* Last operation status */
    uint8_t dir;              /* Direction              */
    uint8_t rw;               /* Read/write             */
    /* Media */
    fdisk_flags_t flags;
    uint8_t last_sect;        /* Nb sector per track    */
    uint8_t max_track;        /* Nb of tracks           */
    uint16_t bps;             /* Bytes per sector       */
    uint8_t ro;               /* Is read-only           */
} fdrive_t;

static void fd_init (fdrive_t *drv, BlockDriverState *bs)
{
    /* Drive */
    drv->bs = bs;
    drv->drive = FDRIVE_DRV_NONE;
    drv->drflags = 0;
    drv->perpendicular = 0;
    /* Disk */
    drv->last_sect = 0;
    drv->max_track = 0;
}

static int _fd_sector (uint8_t head, uint8_t track,
                        uint8_t sect, uint8_t last_sect)
{
    return (((track * 2) + head) * last_sect) + sect - 1;
}

/* Returns current position, in sectors, for given drive */
static int fd_sector (fdrive_t *drv)
{
    return _fd_sector(drv->head, drv->track, drv->sect, drv->last_sect);
}

static int fd_seek (fdrive_t *drv, uint8_t head, uint8_t track, uint8_t sect,
                    int enable_seek)
{
    uint32_t sector;
    int ret;

    if (track > drv->max_track ||
	(head != 0 && (drv->flags & FDISK_DBL_SIDES) == 0)) {
        FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n",
                       head, track, sect, 1,
                       (drv->flags & FDISK_DBL_SIDES) == 0 ? 0 : 1,
                       drv->max_track, drv->last_sect);
        return 2;
    }
    if (sect > drv->last_sect) {
        FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n",
                       head, track, sect, 1,
                       (drv->flags & FDISK_DBL_SIDES) == 0 ? 0 : 1,
                       drv->max_track, drv->last_sect);
        return 3;
    }
    sector = _fd_sector(head, track, sect, drv->last_sect);
    ret = 0;
    if (sector != fd_sector(drv)) {
#if 0
        if (!enable_seek) {
            FLOPPY_ERROR("no implicit seek %d %02x %02x (max=%d %02x %02x)\n",
                         head, track, sect, 1, drv->max_track, drv->last_sect);
            return 4;
        }
#endif
        drv->head = head;
	if (drv->track != track)
	    ret = 1;
        drv->track = track;
        drv->sect = sect;
    }

    return ret;
}

/* Set drive back to track 0 */
static void fd_recalibrate (fdrive_t *drv)
{
    FLOPPY_DPRINTF("recalibrate\n");
    drv->head = 0;
    drv->track = 0;
    drv->sect = 1;
    drv->dir = 1;
    drv->rw = 0;
}

/* Recognize floppy formats */
typedef struct fd_format_t {
    fdrive_type_t drive;
    fdisk_type_t  disk;
    uint8_t last_sect;
    uint8_t max_track;
    uint8_t max_head;
    const unsigned char *str;
} fd_format_t;

static fd_format_t fd_formats[] = {
    /* First entry is default format */
    /* 1.44 MB 3"1/2 floppy disks */
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 18, 80, 1, "1.44 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 20, 80, 1,  "1.6 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 21, 80, 1, "1.68 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 21, 82, 1, "1.72 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 21, 83, 1, "1.74 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 22, 80, 1, "1.76 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 23, 80, 1, "1.84 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_144, 24, 80, 1, "1.92 MB 3\"1/2", },
    /* 2.88 MB 3"1/2 floppy disks */
    { FDRIVE_DRV_288, FDRIVE_DISK_288, 36, 80, 1, "2.88 MB 3\"1/2", },
    { FDRIVE_DRV_288, FDRIVE_DISK_288, 39, 80, 1, "3.12 MB 3\"1/2", },
    { FDRIVE_DRV_288, FDRIVE_DISK_288, 40, 80, 1,  "3.2 MB 3\"1/2", },
    { FDRIVE_DRV_288, FDRIVE_DISK_288, 44, 80, 1, "3.52 MB 3\"1/2", },
    { FDRIVE_DRV_288, FDRIVE_DISK_288, 48, 80, 1, "3.84 MB 3\"1/2", },
    /* 720 kB 3"1/2 floppy disks */
    { FDRIVE_DRV_144, FDRIVE_DISK_720,  9, 80, 1,  "720 kB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_720, 10, 80, 1,  "800 kB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_720, 10, 82, 1,  "820 kB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_720, 10, 83, 1,  "830 kB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_720, 13, 80, 1, "1.04 MB 3\"1/2", },
    { FDRIVE_DRV_144, FDRIVE_DISK_720, 14, 80, 1, "1.12 MB 3\"1/2", },
    /* 1.2 MB 5"1/4 floppy disks */
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 15, 80, 1,  "1.2 kB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 18, 80, 1, "1.44 MB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 18, 82, 1, "1.48 MB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 18, 83, 1, "1.49 MB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 20, 80, 1,  "1.6 MB 5\"1/4", },
    /* 720 kB 5"1/4 floppy disks */
    { FDRIVE_DRV_120, FDRIVE_DISK_288,  9, 80, 1,  "720 kB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 11, 80, 1,  "880 kB 5\"1/4", },
    /* 360 kB 5"1/4 floppy disks */
    { FDRIVE_DRV_120, FDRIVE_DISK_288,  9, 40, 1,  "360 kB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288,  9, 40, 0,  "180 kB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 10, 41, 1,  "410 kB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288, 10, 42, 1,  "420 kB 5\"1/4", },
    /* 320 kB 5"1/4 floppy disks */ 
    { FDRIVE_DRV_120, FDRIVE_DISK_288,  8, 40, 1,  "320 kB 5\"1/4", },
    { FDRIVE_DRV_120, FDRIVE_DISK_288,  8, 40, 0,  "160 kB 5\"1/4", },
    /* 360 kB must match 5"1/4 better than 3"1/2... */
    { FDRIVE_DRV_144, FDRIVE_DISK_720,  9, 80, 0,  "360 kB 3\"1/2", },
    /* end */
    { FDRIVE_DRV_NONE, FDRIVE_DISK_NONE, -1, -1, 0, NULL, },
};

/* Revalidate a disk drive after a disk change */
static void fd_revalidate (fdrive_t *drv)
{
    fd_format_t *parse;
    int64_t nb_sectors, size;
    int i, first_match, match;
    int nb_heads, max_track, last_sect, ro;

    FLOPPY_DPRINTF("revalidate\n");
    if (drv->bs != NULL && bdrv_is_inserted(drv->bs)) {
	ro = bdrv_is_read_only(drv->bs);
	bdrv_get_geometry_hint(drv->bs, &nb_heads, &max_track, &last_sect);
	if (nb_heads != 0 && max_track != 0 && last_sect != 0) {
	    FLOPPY_DPRINTF("User defined disk (%d %d %d)",
                           nb_heads - 1, max_track, last_sect);
	} else {
	    bdrv_get_geometry(drv->bs, &nb_sectors);
	    match = -1;
	    first_match = -1;
	    for (i = 0;; i++) {
		parse = &fd_formats[i];
		if (parse->drive == FDRIVE_DRV_NONE)
		    break;
		if (drv->drive == parse->drive ||
		    drv->drive == FDRIVE_DRV_NONE) {
		    size = (parse->max_head + 1) * parse->max_track *
			parse->last_sect;
		    if (nb_sectors == size) {
			match = i;
			break;
		    }
		    if (first_match == -1)
			first_match = i;
		}
	    }
	    if (match == -1) {
		if (first_match == -1)
		    match = 1;
		else
		    match = first_match;
		parse = &fd_formats[match];
	    }
	    nb_heads = parse->max_head + 1;
	    max_track = parse->max_track;
	    last_sect = parse->last_sect;
	    drv->drive = parse->drive;
	    FLOPPY_DPRINTF("%s floppy disk (%d h %d t %d s) %s\n", parse->str,
                           nb_heads, max_track, last_sect, ro ? "ro" : "rw");
	}
	    if (nb_heads == 1) {
		drv->flags &= ~FDISK_DBL_SIDES;
	    } else {
		drv->flags |= FDISK_DBL_SIDES;
	    }
	    drv->max_track = max_track;
	    drv->last_sect = last_sect;
	drv->ro = ro;
    } else {
	FLOPPY_DPRINTF("No disk in drive\n");
        drv->last_sect = 0;
	drv->max_track = 0;
	drv->flags &= ~FDISK_DBL_SIDES;
    }
}

/* Motor control */
static void fd_start (fdrive_t *drv)
{
    drv->drflags |= FDRIVE_MOTOR_ON;
}

static void fd_stop (fdrive_t *drv)
{
    drv->drflags &= ~FDRIVE_MOTOR_ON;
}

/* Re-initialise a drives (motor off, repositioned) */
static void fd_reset (fdrive_t *drv)
{
    fd_stop(drv);
    fd_recalibrate(drv);
}

/********************************************************/
/* Intel 82078 floppy disk controller emulation          */

static void fdctrl_reset (fdctrl_t *fdctrl, int do_irq);
static void fdctrl_reset_fifo (fdctrl_t *fdctrl);
static int fdctrl_transfer_handler (void *opaque, int nchan,
                                    int dma_pos, int dma_len);
static void fdctrl_raise_irq (fdctrl_t *fdctrl, uint8_t status);
static void fdctrl_result_timer(void *opaque);

static uint32_t fdctrl_read_statusB (fdctrl_t *fdctrl);
static uint32_t fdctrl_read_dor (fdctrl_t *fdctrl);
static void fdctrl_write_dor (fdctrl_t *fdctrl, uint32_t value);
static uint32_t fdctrl_read_tape (fdctrl_t *fdctrl);
static void fdctrl_write_tape (fdctrl_t *fdctrl, uint32_t value);
static uint32_t fdctrl_read_main_status (fdctrl_t *fdctrl);
static void fdctrl_write_rate (fdctrl_t *fdctrl, uint32_t value);
static uint32_t fdctrl_read_data (fdctrl_t *fdctrl);
static void fdctrl_write_data (fdctrl_t *fdctrl, uint32_t value);
static uint32_t fdctrl_read_dir (fdctrl_t *fdctrl);

enum {
    FD_CTRL_ACTIVE = 0x01, /* XXX: suppress that */
    FD_CTRL_RESET  = 0x02,
    FD_CTRL_SLEEP  = 0x04, /* XXX: suppress that */
    FD_CTRL_BUSY   = 0x08, /* dma transfer in progress */
    FD_CTRL_INTR   = 0x10,
};

enum {
    FD_DIR_WRITE   = 0,
    FD_DIR_READ    = 1,
    FD_DIR_SCANE   = 2,
    FD_DIR_SCANL   = 3,
    FD_DIR_SCANH   = 4,
};

enum {
    FD_STATE_CMD    = 0x00,
    FD_STATE_STATUS = 0x01,
    FD_STATE_DATA   = 0x02,
    FD_STATE_STATE  = 0x03,
    FD_STATE_MULTI  = 0x10,
    FD_STATE_SEEK   = 0x20,
    FD_STATE_FORMAT = 0x40,
};

#define FD_STATE(state) ((state) & FD_STATE_STATE)
#define FD_SET_STATE(state, new_state) \
do { (state) = ((state) & ~FD_STATE_STATE) | (new_state); } while (0)
#define FD_MULTI_TRACK(state) ((state) & FD_STATE_MULTI)
#define FD_DID_SEEK(state) ((state) & FD_STATE_SEEK)
#define FD_FORMAT_CMD(state) ((state) & FD_STATE_FORMAT)

struct fdctrl_t {
    fdctrl_t *fdctrl;
    /* Controller's identification */
    uint8_t version;
    /* HW */
    qemu_irq irq;
    int dma_chann;
    uint32_t io_base;
    /* Controller state */
    QEMUTimer *result_timer;
    uint8_t state;
    uint8_t dma_en;
    uint8_t cur_drv;
    uint8_t bootsel;
    /* Command FIFO */
    uint8_t fifo[FD_SECTOR_LEN];
    uint32_t data_pos;
    uint32_t data_len;
    uint8_t data_state;
    uint8_t data_dir;
    uint8_t int_status;
    uint8_t eot; /* last wanted sector */
    /* States kept only to be returned back */
    /* Timers state */
    uint8_t timer0;
    uint8_t timer1;
    /* precompensation */
    uint8_t precomp_trk;
    uint8_t config;
    uint8_t lock;
    /* Power down config (also with status regB access mode */
    uint8_t pwrd;
    /* Floppy drives */
    fdrive_t drives[2];
};

static uint32_t fdctrl_read (void *opaque, uint32_t reg)
{
    fdctrl_t *fdctrl = opaque;
    uint32_t retval;

    switch (reg & 0x07) {
#ifdef TARGET_SPARC
    case 0x00:
	// Identify to Linux as S82078B
	retval = fdctrl_read_statusB(fdctrl);
	break;
#endif
    case 0x01:
	retval = fdctrl_read_statusB(fdctrl);
	break;
    case 0x02:
	retval = fdctrl_read_dor(fdctrl);
	break;
    case 0x03:
        retval = fdctrl_read_tape(fdctrl);
	break;
    case 0x04:
        retval = fdctrl_read_main_status(fdctrl);
	break;
    case 0x05:
        retval = fdctrl_read_data(fdctrl);
	break;
    case 0x07:
        retval = fdctrl_read_dir(fdctrl);
	break;
    default:
	retval = (uint32_t)(-1);
	break;
    }
    FLOPPY_DPRINTF("read reg%d: 0x%02x\n", reg & 7, retval);

    return retval;
}

static void fdctrl_write (void *opaque, uint32_t reg, uint32_t value)
{
    fdctrl_t *fdctrl = opaque;

    FLOPPY_DPRINTF("write reg%d: 0x%02x\n", reg & 7, value);

    switch (reg & 0x07) {
    case 0x02:
	fdctrl_write_dor(fdctrl, value);
	break;
    case 0x03:
        fdctrl_write_tape(fdctrl, value);
	break;
    case 0x04:
        fdctrl_write_rate(fdctrl, value);
	break;
    case 0x05:
        fdctrl_write_data(fdctrl, value);
	break;
    default:
	break;
    }
}

static uint32_t fdctrl_read_mem (void *opaque, target_phys_addr_t reg)
{
    return fdctrl_read(opaque, reg);
}

static void fdctrl_write_mem (void *opaque, 
                              target_phys_addr_t reg, uint32_t value)
{
    fdctrl_write(opaque, reg, value);
}

static CPUReadMemoryFunc *fdctrl_mem_read[3] = {
    fdctrl_read_mem,
    fdctrl_read_mem,
    fdctrl_read_mem,
};

static CPUWriteMemoryFunc *fdctrl_mem_write[3] = {
    fdctrl_write_mem,
    fdctrl_write_mem,
    fdctrl_write_mem,
};

fdctrl_t *fdctrl_init (qemu_irq irq, int dma_chann, int mem_mapped, 
                       uint32_t io_base,
                       BlockDriverState **fds)
{
    fdctrl_t *fdctrl;
    int io_mem;
    int i;

    FLOPPY_DPRINTF("init controller\n");
    fdctrl = qemu_mallocz(sizeof(fdctrl_t));
    if (!fdctrl)
        return NULL;
    fdctrl->result_timer = qemu_new_timer(vm_clock, 
                                          fdctrl_result_timer, fdctrl);

    fdctrl->version = 0x90; /* Intel 82078 controller */
    fdctrl->irq = irq;
    fdctrl->dma_chann = dma_chann;
    fdctrl->io_base = io_base;
    fdctrl->config = 0x60; /* Implicit seek, polling & FIFO enabled */
    if (fdctrl->dma_chann != -1) {
        fdctrl->dma_en = 1;
        DMA_register_channel(dma_chann, &fdctrl_transfer_handler, fdctrl);
    } else {
        fdctrl->dma_en = 0;
    }
    for (i = 0; i < 2; i++) {
        fd_init(&fdctrl->drives[i], fds[i]);
    }
    fdctrl_reset(fdctrl, 0);
    fdctrl->state = FD_CTRL_ACTIVE;
    if (mem_mapped) {
        io_mem = cpu_register_io_memory(0, fdctrl_mem_read, fdctrl_mem_write, fdctrl);
        cpu_register_physical_memory(io_base, 0x08, io_mem);
    } else {
        register_ioport_read(io_base + 0x01, 5, 1, &fdctrl_read, fdctrl);
        register_ioport_read(io_base + 0x07, 1, 1, &fdctrl_read, fdctrl);
        register_ioport_write(io_base + 0x01, 5, 1, &fdctrl_write, fdctrl);
        register_ioport_write(io_base + 0x07, 1, 1, &fdctrl_write, fdctrl);
    }
    for (i = 0; i < 2; i++) {
        fd_revalidate(&fdctrl->drives[i]);
    }

    return fdctrl;
}

/* XXX: may change if moved to bdrv */
int fdctrl_get_drive_type(fdctrl_t *fdctrl, int drive_num)
{
    return fdctrl->drives[drive_num].drive;
}

/* Change IRQ state */
static void fdctrl_reset_irq (fdctrl_t *fdctrl)
{
    FLOPPY_DPRINTF("Reset interrupt\n");
    qemu_set_irq(fdctrl->irq, 0);
    fdctrl->state &= ~FD_CTRL_INTR;
}

static void fdctrl_raise_irq (fdctrl_t *fdctrl, uint8_t status)
{
#ifdef TARGET_SPARC
    // Sparc mutation
    if (!fdctrl->dma_en) {
	fdctrl->state &= ~FD_CTRL_BUSY;
	fdctrl->int_status = status;
	return;
    }
#endif
    if (~(fdctrl->state & FD_CTRL_INTR)) {
        qemu_set_irq(fdctrl->irq, 1);
        fdctrl->state |= FD_CTRL_INTR;
    }
    FLOPPY_DPRINTF("Set interrupt status to 0x%02x\n", status);
    fdctrl->int_status = status;
}

/* Reset controller */
static void fdctrl_reset (fdctrl_t *fdctrl, int do_irq)
{
    int i;

    FLOPPY_DPRINTF("reset controller\n");
    fdctrl_reset_irq(fdctrl);
    /* Initialise controller */
    fdctrl->cur_drv = 0;
    /* FIFO state */
    fdctrl->data_pos = 0;
    fdctrl->data_len = 0;
    fdctrl->data_state = FD_STATE_CMD;
    fdctrl->data_dir = FD_DIR_WRITE;
    for (i = 0; i < MAX_FD; i++)
        fd_reset(&fdctrl->drives[i]);
    fdctrl_reset_fifo(fdctrl);
    if (do_irq)
        fdctrl_raise_irq(fdctrl, 0xc0);
}

static inline fdrive_t *drv0 (fdctrl_t *fdctrl)
{
    return &fdctrl->drives[fdctrl->bootsel];
}

static inline fdrive_t *drv1 (fdctrl_t *fdctrl)
{
    return &fdctrl->drives[1 - fdctrl->bootsel];
}

static fdrive_t *get_cur_drv (fdctrl_t *fdctrl)
{
    return fdctrl->cur_drv == 0 ? drv0(fdctrl) : drv1(fdctrl);
}

/* Status B register : 0x01 (read-only) */
static uint32_t fdctrl_read_statusB (fdctrl_t *fdctrl)
{
    FLOPPY_DPRINTF("status register: 0x00\n");
    return 0;
}

/* Digital output register : 0x02 */
static uint32_t fdctrl_read_dor (fdctrl_t *fdctrl)
{
    uint32_t retval = 0;

    /* Drive motors state indicators */
    if (drv0(fdctrl)->drflags & FDRIVE_MOTOR_ON)
	retval |= 1 << 5;
    if (drv1(fdctrl)->drflags & FDRIVE_MOTOR_ON)
	retval |= 1 << 4;
    /* DMA enable */
    retval |= fdctrl->dma_en << 3;
    /* Reset indicator */
    retval |= (fdctrl->state & FD_CTRL_RESET) == 0 ? 0x04 : 0;
    /* Selected drive */
    retval |= fdctrl->cur_drv;
    FLOPPY_DPRINTF("digital output register: 0x%02x\n", retval);

    return retval;
}

static void fdctrl_write_dor (fdctrl_t *fdctrl, uint32_t value)
{
    /* Reset mode */
    if (fdctrl->state & FD_CTRL_RESET) {
        if (!(value & 0x04)) {
            FLOPPY_DPRINTF("Floppy controller in RESET state !\n");
            return;
        }
    }
    FLOPPY_DPRINTF("digital output register set to 0x%02x\n", value);
    /* Drive motors state indicators */
    if (value & 0x20)
        fd_start(drv1(fdctrl));
    else
        fd_stop(drv1(fdctrl));
    if (value & 0x10)
        fd_start(drv0(fdctrl));
    else
        fd_stop(drv0(fdctrl));
    /* DMA enable */
#if 0
    if (fdctrl->dma_chann != -1)
        fdctrl->dma_en = 1 - ((value >> 3) & 1);
#endif
    /* Reset */
    if (!(value & 0x04)) {
        if (!(fdctrl->state & FD_CTRL_RESET)) {
            FLOPPY_DPRINTF("controller enter RESET state\n");
            fdctrl->state |= FD_CTRL_RESET;
        }
    } else {
        if (fdctrl->state & FD_CTRL_RESET) {
            FLOPPY_DPRINTF("controller out of RESET state\n");
            fdctrl_reset(fdctrl, 1);
            fdctrl->state &= ~(FD_CTRL_RESET | FD_CTRL_SLEEP);
        }
    }
    /* Selected drive */
    fdctrl->cur_drv = value & 1;
}

/* Tape drive register : 0x03 */
static uint32_t fdctrl_read_tape (fdctrl_t *fdctrl)
{
    uint32_t retval = 0;

    /* Disk boot selection indicator */
    retval |= fdctrl->bootsel << 2;
    /* Tape indicators: never allowed */
    FLOPPY_DPRINTF("tape drive register: 0x%02x\n", retval);

    return retval;
}

static void fdctrl_write_tape (fdctrl_t *fdctrl, uint32_t value)
{
    /* Reset mode */
    if (fdctrl->state & FD_CTRL_RESET) {
        FLOPPY_DPRINTF("Floppy controller in RESET state !\n");
        return;
    }
    FLOPPY_DPRINTF("tape drive register set to 0x%02x\n", value);
    /* Disk boot selection indicator */
    fdctrl->bootsel = (value >> 2) & 1;
    /* Tape indicators: never allow */
}

/* Main status register : 0x04 (read) */
static uint32_t fdctrl_read_main_status (fdctrl_t *fdctrl)
{
    uint32_t retval = 0;

    fdctrl->state &= ~(FD_CTRL_SLEEP | FD_CTRL_RESET);
    if (!(fdctrl->state & FD_CTRL_BUSY)) {
        /* Data transfer allowed */
        retval |= 0x80;
        /* Data transfer direction indicator */
        if (fdctrl->data_dir == FD_DIR_READ)
            retval |= 0x40;
    }
    /* Should handle 0x20 for SPECIFY command */
    /* Command busy indicator */
    if (FD_STATE(fdctrl->data_state) == FD_STATE_DATA ||
        FD_STATE(fdctrl->data_state) == FD_STATE_STATUS)
        retval |= 0x10;
    FLOPPY_DPRINTF("main status register: 0x%02x\n", retval);

    return retval;
}

/* Data select rate register : 0x04 (write) */
static void fdctrl_write_rate (fdctrl_t *fdctrl, uint32_t value)
{
    /* Reset mode */
    if (fdctrl->state & FD_CTRL_RESET) {
            FLOPPY_DPRINTF("Floppy controller in RESET state !\n");
            return;
        }
    FLOPPY_DPRINTF("select rate register set to 0x%02x\n", value);
    /* Reset: autoclear */
    if (value & 0x80) {
        fdctrl->state |= FD_CTRL_RESET;
        fdctrl_reset(fdctrl, 1);
        fdctrl->state &= ~FD_CTRL_RESET;
    }
    if (value & 0x40) {
        fdctrl->state |= FD_CTRL_SLEEP;
        fdctrl_reset(fdctrl, 1);
    }
//        fdctrl.precomp = (value >> 2) & 0x07;
}

static int fdctrl_media_changed(fdrive_t *drv)
{
    int ret;
    if (!drv->bs) 
        return 0;
    ret = bdrv_media_changed(drv->bs);
    if (ret) {
        fd_revalidate(drv);
    }
    return ret;
}

/* Digital input register : 0x07 (read-only) */
static uint32_t fdctrl_read_dir (fdctrl_t *fdctrl)
{
    uint32_t retval = 0;

    if (fdctrl_media_changed(drv0(fdctrl)) ||
	fdctrl_media_changed(drv1(fdctrl)))
        retval |= 0x80;
    if (retval != 0)
        FLOPPY_DPRINTF("Floppy digital input register: 0x%02x\n", retval);

    return retval;
}

/* FIFO state control */
static void fdctrl_reset_fifo (fdctrl_t *fdctrl)
{
    fdctrl->data_dir = FD_DIR_WRITE;
    fdctrl->data_pos = 0;
    FD_SET_STATE(fdctrl->data_state, FD_STATE_CMD);
}

/* Set FIFO status for the host to read */
static void fdctrl_set_fifo (fdctrl_t *fdctrl, int fifo_len, int do_irq)
{
    fdctrl->data_dir = FD_DIR_READ;
    fdctrl->data_len = fifo_len;
    fdctrl->data_pos = 0;
    FD_SET_STATE(fdctrl->data_state, FD_STATE_STATUS);
    if (do_irq)
        fdctrl_raise_irq(fdctrl, 0x00);
}

/* Set an error: unimplemented/unknown command */
static void fdctrl_unimplemented (fdctrl_t *fdctrl)
{
#if 0
    fdrive_t *cur_drv;

    cur_drv = get_cur_drv(fdctrl);
    fdctrl->fifo[0] = 0x60 | (cur_drv->head << 2) | fdctrl->cur_drv;
    fdctrl->fifo[1] = 0x00;
    fdctrl->fifo[2] = 0x00;
    fdctrl_set_fifo(fdctrl, 3, 1);
#else
    //    fdctrl_reset_fifo(fdctrl);
    fdctrl->fifo[0] = 0x80;
    fdctrl_set_fifo(fdctrl, 1, 0);
#endif
}

/* Callback for transfer end (stop or abort) */
static void fdctrl_stop_transfer (fdctrl_t *fdctrl, uint8_t status0,
				  uint8_t status1, uint8_t status2)
{
    fdrive_t *cur_drv;

    cur_drv = get_cur_drv(fdctrl);
    FLOPPY_DPRINTF("transfer status: %02x %02x %02x (%02x)\n",
                   status0, status1, status2,
                   status0 | (cur_drv->head << 2) | fdctrl->cur_drv);
    fdctrl->fifo[0] = status0 | (cur_drv->head << 2) | fdctrl->cur_drv;
    fdctrl->fifo[1] = status1;
    fdctrl->fifo[2] = status2;
    fdctrl->fifo[3] = cur_drv->track;
    fdctrl->fifo[4] = cur_drv->head;
    fdctrl->fifo[5] = cur_drv->sect;
    fdctrl->fifo[6] = FD_SECTOR_SC;
    fdctrl->data_dir = FD_DIR_READ;
    if (fdctrl->state & FD_CTRL_BUSY) {
        DMA_release_DREQ(fdctrl->dma_chann);
        fdctrl->state &= ~FD_CTRL_BUSY;
    }
    fdctrl_set_fifo(fdctrl, 7, 1);
}

/* Prepare a data transfer (either DMA or FIFO) */
static void fdctrl_start_transfer (fdctrl_t *fdctrl, int direction)
{
    fdrive_t *cur_drv;
    uint8_t kh, kt, ks;
    int did_seek;

    fdctrl->cur_drv = fdctrl->fifo[1] & 1;
    cur_drv = get_cur_drv(fdctrl);
    kt = fdctrl->fifo[2];
    kh = fdctrl->fifo[3];
    ks = fdctrl->fifo[4];
    FLOPPY_DPRINTF("Start transfer at %d %d %02x %02x (%d)\n",
                   fdctrl->cur_drv, kh, kt, ks,
                   _fd_sector(kh, kt, ks, cur_drv->last_sect));
    did_seek = 0;
    switch (fd_seek(cur_drv, kh, kt, ks, fdctrl->config & 0x40)) {
    case 2:
        /* sect too big */
        fdctrl_stop_transfer(fdctrl, 0x40, 0x00, 0x00);
        fdctrl->fifo[3] = kt;
        fdctrl->fifo[4] = kh;
        fdctrl->fifo[5] = ks;
        return;
    case 3:
        /* track too big */
        fdctrl_stop_transfer(fdctrl, 0x40, 0x80, 0x00);
        fdctrl->fifo[3] = kt;
        fdctrl->fifo[4] = kh;
        fdctrl->fifo[5] = ks;
        return;
    case 4:
        /* No seek enabled */
        fdctrl_stop_transfer(fdctrl, 0x40, 0x00, 0x00);
        fdctrl->fifo[3] = kt;
        fdctrl->fifo[4] = kh;
        fdctrl->fifo[5] = ks;
        return;
    case 1:
        did_seek = 1;
        break;
    default:
        break;
    }
    /* Set the FIFO state */
    fdctrl->data_dir = direction;
    fdctrl->data_pos = 0;
    FD_SET_STATE(fdctrl->data_state, FD_STATE_DATA); /* FIFO ready for data */
    if (fdctrl->fifo[0] & 0x80)
        fdctrl->data_state |= FD_STATE_MULTI;
    else
        fdctrl->data_state &= ~FD_STATE_MULTI;
    if (did_seek)
        fdctrl->data_state |= FD_STATE_SEEK;
    else
        fdctrl->data_state &= ~FD_STATE_SEEK;
    if (fdctrl->fifo[5] == 00) {
        fdctrl->data_len = fdctrl->fifo[8];
    } else {
	int tmp;
        fdctrl->data_len = 128 << (fdctrl->fifo[5] > 7 ? 7 : fdctrl->fifo[5]);
        tmp = (cur_drv->last_sect - ks + 1);
        if (fdctrl->fifo[0] & 0x80)
            tmp += cur_drv->last_sect;
	fdctrl->data_len *= tmp;
    }
    fdctrl->eot = fdctrl->fifo[6];
    if (fdctrl->dma_en) {
        int dma_mode;
        /* DMA transfer are enabled. Check if DMA channel is well programmed */
        dma_mode = DMA_get_channel_mode(fdctrl->dma_chann);
        dma_mode = (dma_mode >> 2) & 3;
        FLOPPY_DPRINTF("dma_mode=%d direction=%d (%d - %d)\n",
		       dma_mode, direction,
                       (128 << fdctrl->fifo[5]) *
		       (cur_drv->last_sect - ks + 1), fdctrl->data_len);
        if (((direction == FD_DIR_SCANE || direction == FD_DIR_SCANL ||
              direction == FD_DIR_SCANH) && dma_mode == 0) ||
            (direction == FD_DIR_WRITE && dma_mode == 2) ||
            (direction == FD_DIR_READ && dma_mode == 1)) {
            /* No access is allowed until DMA transfer has completed */
            fdctrl->state |= FD_CTRL_BUSY;
            /* Now, we just have to wait for the DMA controller to
             * recall us...
             */
            DMA_hold_DREQ(fdctrl->dma_chann);
            DMA_schedule(fdctrl->dma_chann);
            return;
        } else {
	    FLOPPY_ERROR("dma_mode=%d direction=%d\n", dma_mode, direction);
        }
    }
    FLOPPY_DPRINTF("start non-DMA transfer\n");
    /* IO based transfer: calculate len */
    fdctrl_raise_irq(fdctrl, 0x00);

    return;
}

/* Prepare a transfer of deleted data */
static void fdctrl_start_transfer_del (fdctrl_t *fdctrl, int direction)
{
    /* We don't handle deleted data,
     * so we don't return *ANYTHING*
     */
    fdctrl_stop_transfer(fdctrl, 0x60, 0x00, 0x00);
}

/* handlers for DMA transfers */
static int fdctrl_transfer_handler (void *opaque, int nchan,
                                    int dma_pos, int dma_len)
{
    fdctrl_t *fdctrl;
    fdrive_t *cur_drv;
    int len, start_pos, rel_pos;
    uint8_t status0 = 0x00, status1 = 0x00, status2 = 0x00;

    fdctrl = opaque;
    if (!(fdctrl->state & FD_CTRL_BUSY)) {
        FLOPPY_DPRINTF("Not in DMA transfer mode !\n");
        return 0;
    }
    cur_drv = get_cur_drv(fdctrl);
    if (fdctrl->data_dir == FD_DIR_SCANE || fdctrl->data_dir == FD_DIR_SCANL ||
        fdctrl->data_dir == FD_DIR_SCANH)
        status2 = 0x04;
    if (dma_len > fdctrl->data_len)
        dma_len = fdctrl->data_len;
    if (cur_drv->bs == NULL) {
	if (fdctrl->data_dir == FD_DIR_WRITE)
	    fdctrl_stop_transfer(fdctrl, 0x60, 0x00, 0x00);
	else
	    fdctrl_stop_transfer(fdctrl, 0x40, 0x00, 0x00);
	len = 0;
        goto transfer_error;
    }
    rel_pos = fdctrl->data_pos % FD_SECTOR_LEN;
    for (start_pos = fdctrl->data_pos; fdctrl->data_pos < dma_len;) {
        len = dma_len - fdctrl->data_pos;
        if (len + rel_pos > FD_SECTOR_LEN)
            len = FD_SECTOR_LEN - rel_pos;
        FLOPPY_DPRINTF("copy %d bytes (%d %d %d) %d pos %d %02x "
                       "(%d-0x%08x 0x%08x)\n", len, dma_len, fdctrl->data_pos,
                       fdctrl->data_len, fdctrl->cur_drv, cur_drv->head,
                       cur_drv->track, cur_drv->sect, fd_sector(cur_drv),
                       fd_sector(cur_drv) * 512);
        if (fdctrl->data_dir != FD_DIR_WRITE ||
	    len < FD_SECTOR_LEN || rel_pos != 0) {
            /* READ & SCAN commands and realign to a sector for WRITE */
            if (bdrv_read(cur_drv->bs, fd_sector(cur_drv),
			  fdctrl->fifo, 1) < 0) {
                FLOPPY_DPRINTF("Floppy: error getting sector %d\n",
                               fd_sector(cur_drv));
                /* Sure, image size is too small... */
                memset(fdctrl->fifo, 0, FD_SECTOR_LEN);
            }
        }
	switch (fdctrl->data_dir) {
	case FD_DIR_READ:
	    /* READ commands */
            DMA_write_memory (nchan, fdctrl->fifo + rel_pos,
                              fdctrl->data_pos, len);
/* 	    cpu_physical_memory_write(addr + fdctrl->data_pos, */
/* 				      fdctrl->fifo + rel_pos, len); */
	    break;
	case FD_DIR_WRITE:
            /* WRITE commands */
            DMA_read_memory (nchan, fdctrl->fifo + rel_pos,
                             fdctrl->data_pos, len);
/*             cpu_physical_memory_read(addr + fdctrl->data_pos, */
/* 				     fdctrl->fifo + rel_pos, len); */
            if (bdrv_write(cur_drv->bs, fd_sector(cur_drv),
			   fdctrl->fifo, 1) < 0) {
                FLOPPY_ERROR("writting sector %d\n", fd_sector(cur_drv));
                fdctrl_stop_transfer(fdctrl, 0x60, 0x00, 0x00);
                goto transfer_error;
            }
	    break;
	default:
	    /* SCAN commands */
            {
		uint8_t tmpbuf[FD_SECTOR_LEN];
                int ret;
                DMA_read_memory (nchan, tmpbuf, fdctrl->data_pos, len);
/*                 cpu_physical_memory_read(addr + fdctrl->data_pos, */
/*                                          tmpbuf, len); */
                ret = memcmp(tmpbuf, fdctrl->fifo + rel_pos, len);
                if (ret == 0) {
                    status2 = 0x08;
                    goto end_transfer;
                }
                if ((ret < 0 && fdctrl->data_dir == FD_DIR_SCANL) ||
                    (ret > 0 && fdctrl->data_dir == FD_DIR_SCANH)) {
                    status2 = 0x00;
                    goto end_transfer;
                }
            }
	    break;
        }
	fdctrl->data_pos += len;
	rel_pos = fdctrl->data_pos % FD_SECTOR_LEN;
        if (rel_pos == 0) {
            /* Seek to next sector */
	    FLOPPY_DPRINTF("seek to next sector (%d %02x %02x => %d) (%d)\n",
			   cur_drv->head, cur_drv->track, cur_drv->sect,
			   fd_sector(cur_drv),
			   fdctrl->data_pos - len);
            /* XXX: cur_drv->sect >= cur_drv->last_sect should be an
               error in fact */
            if (cur_drv->sect >= cur_drv->last_sect ||
                cur_drv->sect == fdctrl->eot) {
		cur_drv->sect = 1;
		if (FD_MULTI_TRACK(fdctrl->data_state)) {
		    if (cur_drv->head == 0 &&
			(cur_drv->flags & FDISK_DBL_SIDES) != 0) {	
                        cur_drv->head = 1;
                    } else {
                        cur_drv->head = 0;
			cur_drv->track++;
			if ((cur_drv->flags & FDISK_DBL_SIDES) == 0)
			    break;
                    }
                } else {
                    cur_drv->track++;
                    break;
                }
		FLOPPY_DPRINTF("seek to next track (%d %02x %02x => %d)\n",
			       cur_drv->head, cur_drv->track,
			       cur_drv->sect, fd_sector(cur_drv));
            } else {
                cur_drv->sect++;
            }
        }
    }
end_transfer:
    len = fdctrl->data_pos - start_pos;
    FLOPPY_DPRINTF("end transfer %d %d %d\n",
		   fdctrl->data_pos, len, fdctrl->data_len);
    if (fdctrl->data_dir == FD_DIR_SCANE ||
        fdctrl->data_dir == FD_DIR_SCANL ||
        fdctrl->data_dir == FD_DIR_SCANH)
        status2 = 0x08;
    if (FD_DID_SEEK(fdctrl->data_state))
        status0 |= 0x20;
    fdctrl->data_len -= len;
    //    if (fdctrl->data_len == 0)
    fdctrl_stop_transfer(fdctrl, status0, status1, status2);
transfer_error:

    return len;
}

/* Data register : 0x05 */
static uint32_t fdctrl_read_data (fdctrl_t *fdctrl)
{
    fdrive_t *cur_drv;
    uint32_t retval = 0;
    int pos, len;

    cur_drv = get_cur_drv(fdctrl);
    fdctrl->state &= ~FD_CTRL_SLEEP;
    if (FD_STATE(fdctrl->data_state) == FD_STATE_CMD) {
        FLOPPY_ERROR("can't read data in CMD state\n");
        return 0;
    }
    pos = fdctrl->data_pos;
    if (FD_STATE(fdctrl->data_state) == FD_STATE_DATA) {
        pos %= FD_SECTOR_LEN;
        if (pos == 0) {
            len = fdctrl->data_len - fdctrl->data_pos;
            if (len > FD_SECTOR_LEN)
                len = FD_SECTOR_LEN;
            bdrv_read(cur_drv->bs, fd_sector(cur_drv),
                      fdctrl->fifo, len);
        }
    }
    retval = fdctrl->fifo[pos];
    if (++fdctrl->data_pos == fdctrl->data_len) {
        fdctrl->data_pos = 0;
        /* Switch from transfer mode to status mode
         * then from status mode to command mode
         */
        if (FD_STATE(fdctrl->data_state) == FD_STATE_DATA) {
            fdctrl_stop_transfer(fdctrl, 0x20, 0x00, 0x00);
        } else {
            fdctrl_reset_fifo(fdctrl);
            fdctrl_reset_irq(fdctrl);
        }
    }
    FLOPPY_DPRINTF("data register: 0x%02x\n", retval);

    return retval;
}

static void fdctrl_format_sector (fdctrl_t *fdctrl)
{
    fdrive_t *cur_drv;
    uint8_t kh, kt, ks;
    int did_seek;

    fdctrl->cur_drv = fdctrl->fifo[1] & 1;
    cur_drv = get_cur_drv(fdctrl);
    kt = fdctrl->fifo[6];
    kh = fdctrl->fifo[7];
    ks = fdctrl->fifo[8];
    FLOPPY_DPRINTF("format sector at %d %d %02x %02x (%d)\n",
                   fdctrl->cur_drv, kh, kt, ks,
                   _fd_sector(kh, kt, ks, cur_drv->last_sect));
    did_seek = 0;
    switch (fd_seek(cur_drv, kh, kt, ks, fdctrl->config & 0x40)) {
    case 2:
        /* sect too big */
        fdctrl_stop_transfer(fdctrl, 0x40, 0x00, 0x00);
        fdctrl->fifo[3] = kt;
        fdctrl->fifo[4] = kh;
        fdctrl->fifo[5] = ks;
        return;
    case 3:
        /* track too big */
        fdctrl_stop_transfer(fdctrl, 0x40, 0x80, 0x00);
        fdctrl->fifo[3] = kt;
        fdctrl->fifo[4] = kh;
        fdctrl->fifo[5] = ks;
        return;
    case 4:
        /* No seek enabled */
        fdctrl_stop_transfer(fdctrl, 0x40, 0x00, 0x00);
        fdctrl->fifo[3] = kt;
        fdctrl->fifo[4] = kh;
        fdctrl->fifo[5] = ks;
        return;
    case 1:
        did_seek = 1;
        fdctrl->data_state |= FD_STATE_SEEK;
        break;
    default:
        break;
    }
    memset(fdctrl->fifo, 0, FD_SECTOR_LEN);
    if (cur_drv->bs == NULL ||
        bdrv_write(cur_drv->bs, fd_sector(cur_drv), fdctrl->fifo, 1) < 0) {
        FLOPPY_ERROR("formating sector %d\n", fd_sector(cur_drv));
        fdctrl_stop_transfer(fdctrl, 0x60, 0x00, 0x00);
    } else {
	if (cur_drv->sect == cur_drv->last_sect) {
	    fdctrl->data_state &= ~FD_STATE_FORMAT;
	    /* Last sector done */
	    if (FD_DID_SEEK(fdctrl->data_state))
		fdctrl_stop_transfer(fdctrl, 0x20, 0x00, 0x00);
	    else
		fdctrl_stop_transfer(fdctrl, 0x00, 0x00, 0x00);
	} else {
	    /* More to do */
	    fdctrl->data_pos = 0;
	    fdctrl->data_len = 4;
	}
    }
}

static void fdctrl_write_data (fdctrl_t *fdctrl, uint32_t value)
{
    fdrive_t *cur_drv;

    cur_drv = get_cur_drv(fdctrl);
    /* Reset mode */
    if (fdctrl->state & FD_CTRL_RESET) {
        FLOPPY_DPRINTF("Floppy controller in RESET state !\n");
        return;
    }
    fdctrl->state &= ~FD_CTRL_SLEEP;
    if (FD_STATE(fdctrl->data_state) == FD_STATE_STATUS) {
        FLOPPY_ERROR("can't write data in status mode\n");
        return;
    }
    /* Is it write command time ? */
    if (FD_STATE(fdctrl->data_state) == FD_STATE_DATA) {
        /* FIFO data write */
        fdctrl->fifo[fdctrl->data_pos++] = value;
        if (fdctrl->data_pos % FD_SECTOR_LEN == (FD_SECTOR_LEN - 1) ||
            fdctrl->data_pos == fdctrl->data_len) {
            bdrv_write(cur_drv->bs, fd_sector(cur_drv),
                       fdctrl->fifo, FD_SECTOR_LEN);
        }
        /* Switch from transfer mode to status mode
         * then from status mode to command mode
         */
        if (FD_STATE(fdctrl->data_state) == FD_STATE_DATA)
            fdctrl_stop_transfer(fdctrl, 0x20, 0x00, 0x00);
        return;
    }
    if (fdctrl->data_pos == 0) {
        /* Command */
        switch (value & 0x5F) {
        case 0x46:
            /* READ variants */
            FLOPPY_DPRINTF("READ command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        case 0x4C:
            /* READ_DELETED variants */
            FLOPPY_DPRINTF("READ_DELETED command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        case 0x50:
            /* SCAN_EQUAL variants */
            FLOPPY_DPRINTF("SCAN_EQUAL command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        case 0x56:
            /* VERIFY variants */
            FLOPPY_DPRINTF("VERIFY command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        case 0x59:
            /* SCAN_LOW_OR_EQUAL variants */
            FLOPPY_DPRINTF("SCAN_LOW_OR_EQUAL command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        case 0x5D:
            /* SCAN_HIGH_OR_EQUAL variants */
            FLOPPY_DPRINTF("SCAN_HIGH_OR_EQUAL command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        default:
            break;
        }
        switch (value & 0x7F) {
        case 0x45:
            /* WRITE variants */
            FLOPPY_DPRINTF("WRITE command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        case 0x49:
            /* WRITE_DELETED variants */
            FLOPPY_DPRINTF("WRITE_DELETED command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        default:
            break;
        }
        switch (value) {
        case 0x03:
            /* SPECIFY */
            FLOPPY_DPRINTF("SPECIFY command\n");
            /* 1 parameter cmd */
            fdctrl->data_len = 3;
            goto enqueue;
        case 0x04:
            /* SENSE_DRIVE_STATUS */
            FLOPPY_DPRINTF("SENSE_DRIVE_STATUS command\n");
            /* 1 parameter cmd */
            fdctrl->data_len = 2;
            goto enqueue;
        case 0x07:
            /* RECALIBRATE */
            FLOPPY_DPRINTF("RECALIBRATE command\n");
            /* 1 parameter cmd */
            fdctrl->data_len = 2;
            goto enqueue;
        case 0x08:
            /* SENSE_INTERRUPT_STATUS */
            FLOPPY_DPRINTF("SENSE_INTERRUPT_STATUS command (%02x)\n",
                           fdctrl->int_status);
            /* No parameters cmd: returns status if no interrupt */
#if 0
            fdctrl->fifo[0] =
                fdctrl->int_status | (cur_drv->head << 2) | fdctrl->cur_drv;
#else
            /* XXX: int_status handling is broken for read/write
               commands, so we do this hack. It should be suppressed
               ASAP */
            fdctrl->fifo[0] =
                0x20 | (cur_drv->head << 2) | fdctrl->cur_drv;
#endif
            fdctrl->fifo[1] = cur_drv->track;
            fdctrl_set_fifo(fdctrl, 2, 0);
	    fdctrl_reset_irq(fdctrl);
	    fdctrl->int_status = 0xC0;
            return;
        case 0x0E:
            /* DUMPREG */
            FLOPPY_DPRINTF("DUMPREG command\n");
            /* Drives position */
            fdctrl->fifo[0] = drv0(fdctrl)->track;
            fdctrl->fifo[1] = drv1(fdctrl)->track;
            fdctrl->fifo[2] = 0;
            fdctrl->fifo[3] = 0;
            /* timers */
            fdctrl->fifo[4] = fdctrl->timer0;
            fdctrl->fifo[5] = (fdctrl->timer1 << 1) | fdctrl->dma_en;
            fdctrl->fifo[6] = cur_drv->last_sect;
            fdctrl->fifo[7] = (fdctrl->lock << 7) |
                    (cur_drv->perpendicular << 2);
            fdctrl->fifo[8] = fdctrl->config;
            fdctrl->fifo[9] = fdctrl->precomp_trk;
            fdctrl_set_fifo(fdctrl, 10, 0);
            return;
        case 0x0F:
            /* SEEK */
            FLOPPY_DPRINTF("SEEK command\n");
            /* 2 parameters cmd */
            fdctrl->data_len = 3;
            goto enqueue;
        case 0x10:
            /* VERSION */
            FLOPPY_DPRINTF("VERSION command\n");
            /* No parameters cmd */
            /* Controller's version */
            fdctrl->fifo[0] = fdctrl->version;
            fdctrl_set_fifo(fdctrl, 1, 1);
            return;
        case 0x12:
            /* PERPENDICULAR_MODE */
            FLOPPY_DPRINTF("PERPENDICULAR_MODE command\n");
            /* 1 parameter cmd */
            fdctrl->data_len = 2;
            goto enqueue;
        case 0x13:
            /* CONFIGURE */
            FLOPPY_DPRINTF("CONFIGURE command\n");
            /* 3 parameters cmd */
            fdctrl->data_len = 4;
            goto enqueue;
        case 0x14:
            /* UNLOCK */
            FLOPPY_DPRINTF("UNLOCK command\n");
            /* No parameters cmd */
            fdctrl->lock = 0;
            fdctrl->fifo[0] = 0;
            fdctrl_set_fifo(fdctrl, 1, 0);
            return;
        case 0x17:
            /* POWERDOWN_MODE */
            FLOPPY_DPRINTF("POWERDOWN_MODE command\n");
            /* 2 parameters cmd */
            fdctrl->data_len = 3;
            goto enqueue;
        case 0x18:
            /* PART_ID */
            FLOPPY_DPRINTF("PART_ID command\n");
            /* No parameters cmd */
            fdctrl->fifo[0] = 0x41; /* Stepping 1 */
            fdctrl_set_fifo(fdctrl, 1, 0);
            return;
        case 0x2C:
            /* SAVE */
            FLOPPY_DPRINTF("SAVE command\n");
            /* No parameters cmd */
            fdctrl->fifo[0] = 0;
            fdctrl->fifo[1] = 0;
            /* Drives position */
            fdctrl->fifo[2] = drv0(fdctrl)->track;
            fdctrl->fifo[3] = drv1(fdctrl)->track;
            fdctrl->fifo[4] = 0;
            fdctrl->fifo[5] = 0;
            /* timers */
            fdctrl->fifo[6] = fdctrl->timer0;
            fdctrl->fifo[7] = fdctrl->timer1;
            fdctrl->fifo[8] = cur_drv->last_sect;
            fdctrl->fifo[9] = (fdctrl->lock << 7) |
                    (cur_drv->perpendicular << 2);
            fdctrl->fifo[10] = fdctrl->config;
            fdctrl->fifo[11] = fdctrl->precomp_trk;
            fdctrl->fifo[12] = fdctrl->pwrd;
            fdctrl->fifo[13] = 0;
            fdctrl->fifo[14] = 0;
            fdctrl_set_fifo(fdctrl, 15, 1);
            return;
        case 0x33:
            /* OPTION */
            FLOPPY_DPRINTF("OPTION command\n");
            /* 1 parameter cmd */
            fdctrl->data_len = 2;
            goto enqueue;
        case 0x42:
            /* READ_TRACK */
            FLOPPY_DPRINTF("READ_TRACK command\n");
            /* 8 parameters cmd */
            fdctrl->data_len = 9;
            goto enqueue;
        case 0x4A:
            /* READ_ID */
            FLOPPY_DPRINTF("READ_ID command\n");
            /* 1 parameter cmd */
            fdctrl->data_len = 2;
            goto enqueue;
        case 0x4C:
            /* RESTORE */
            FLOPPY_DPRINTF("RESTORE command\n");
            /* 17 parameters cmd */
            fdctrl->data_len = 18;
            goto enqueue;
        case 0x4D:
            /* FORMAT_TRACK */
            FLOPPY_DPRINTF("FORMAT_TRACK command\n");
            /* 5 parameters cmd */
            fdctrl->data_len = 6;
            goto enqueue;
        case 0x8E:
            /* DRIVE_SPECIFICATION_COMMAND */
            FLOPPY_DPRINTF("DRIVE_SPECIFICATION_COMMAND command\n");
            /* 5 parameters cmd */
            fdctrl->data_len = 6;
            goto enqueue;
        case 0x8F:
            /* RELATIVE_SEEK_OUT */
            FLOPPY_DPRINTF("RELATIVE_SEEK_OUT command\n");
            /* 2 parameters cmd */
            fdctrl->data_len = 3;
            goto enqueue;
        case 0x94:
            /* LOCK */
            FLOPPY_DPRINTF("LOCK command\n");
            /* No parameters cmd */
            fdctrl->lock = 1;
            fdctrl->fifo[0] = 0x10;
            fdctrl_set_fifo(fdctrl, 1, 1);
            return;
        case 0xCD:
            /* FORMAT_AND_WRITE */
            FLOPPY_DPRINTF("FORMAT_AND_WRITE command\n");
            /* 10 parameters cmd */
            fdctrl->data_len = 11;
            goto enqueue;
        case 0xCF:
            /* RELATIVE_SEEK_IN */
            FLOPPY_DPRINTF("RELATIVE_SEEK_IN command\n");
            /* 2 parameters cmd */
            fdctrl->data_len = 3;
            goto enqueue;
        default:
            /* Unknown command */
            FLOPPY_ERROR("unknown command: 0x%02x\n", value);
            fdctrl_unimplemented(fdctrl);
            return;
        }
    }
enqueue:
    FLOPPY_DPRINTF("%s: %02x\n", __func__, value);
    fdctrl->fifo[fdctrl->data_pos] = value;
    if (++fdctrl->data_pos == fdctrl->data_len) {
        /* We now have all parameters
         * and will be able to treat the command
         */
	if (fdctrl->data_state & FD_STATE_FORMAT) {
	    fdctrl_format_sector(fdctrl);
	    return;
	}
        switch (fdctrl->fifo[0] & 0x1F) {
        case 0x06:
        {
            /* READ variants */
            FLOPPY_DPRINTF("treat READ command\n");
            fdctrl_start_transfer(fdctrl, FD_DIR_READ);
            return;
        }
        case 0x0C:
            /* READ_DELETED variants */
//            FLOPPY_DPRINTF("treat READ_DELETED command\n");
            FLOPPY_ERROR("treat READ_DELETED command\n");
            fdctrl_start_transfer_del(fdctrl, FD_DIR_READ);
            return;
        case 0x16:
            /* VERIFY variants */
//            FLOPPY_DPRINTF("treat VERIFY command\n");
            FLOPPY_ERROR("treat VERIFY command\n");
            fdctrl_stop_transfer(fdctrl, 0x20, 0x00, 0x00);
            return;
        case 0x10:
            /* SCAN_EQUAL variants */
//            FLOPPY_DPRINTF("treat SCAN_EQUAL command\n");
            FLOPPY_ERROR("treat SCAN_EQUAL command\n");
            fdctrl_start_transfer(fdctrl, FD_DIR_SCANE);
            return;
        case 0x19:
            /* SCAN_LOW_OR_EQUAL variants */
//            FLOPPY_DPRINTF("treat SCAN_LOW_OR_EQUAL command\n");
            FLOPPY_ERROR("treat SCAN_LOW_OR_EQUAL command\n");
            fdctrl_start_transfer(fdctrl, FD_DIR_SCANL);
            return;
        case 0x1D:
            /* SCAN_HIGH_OR_EQUAL variants */
//            FLOPPY_DPRINTF("treat SCAN_HIGH_OR_EQUAL command\n");
            FLOPPY_ERROR("treat SCAN_HIGH_OR_EQUAL command\n");
            fdctrl_start_transfer(fdctrl, FD_DIR_SCANH);
            return;
        default:
            break;
        }
        switch (fdctrl->fifo[0] & 0x3F) {
        case 0x05:
            /* WRITE variants */
            FLOPPY_DPRINTF("treat WRITE command (%02x)\n", fdctrl->fifo[0]);
            fdctrl_start_transfer(fdctrl, FD_DIR_WRITE);
            return;
        case 0x09:
            /* WRITE_DELETED variants */
//            FLOPPY_DPRINTF("treat WRITE_DELETED command\n");
            FLOPPY_ERROR("treat WRITE_DELETED command\n");
            fdctrl_start_transfer_del(fdctrl, FD_DIR_WRITE);
            return;
        default:
            break;
        }
        switch (fdctrl->fifo[0]) {
        case 0x03:
            /* SPECIFY */
            FLOPPY_DPRINTF("treat SPECIFY command\n");
            fdctrl->timer0 = (fdctrl->fifo[1] >> 4) & 0xF;
            fdctrl->timer1 = fdctrl->fifo[2] >> 1;
	    fdctrl->dma_en = 1 - (fdctrl->fifo[2] & 1) ;
            /* No result back */
            fdctrl_reset_fifo(fdctrl);
            break;
        case 0x04:
            /* SENSE_DRIVE_STATUS */
            FLOPPY_DPRINTF("treat SENSE_DRIVE_STATUS command\n");
            fdctrl->cur_drv = fdctrl->fifo[1] & 1;
	    cur_drv = get_cur_drv(fdctrl);
            cur_drv->head = (fdctrl->fifo[1] >> 2) & 1;
            /* 1 Byte status back */
            fdctrl->fifo[0] = (cur_drv->ro << 6) |
                (cur_drv->track == 0 ? 0x10 : 0x00) |
                (cur_drv->head << 2) |
                fdctrl->cur_drv |
                0x28;
            fdctrl_set_fifo(fdctrl, 1, 0);
            break;
        case 0x07:
            /* RECALIBRATE */
            FLOPPY_DPRINTF("treat RECALIBRATE command\n");
            fdctrl->cur_drv = fdctrl->fifo[1] & 1;
	    cur_drv = get_cur_drv(fdctrl);
            fd_recalibrate(cur_drv);
	    fdctrl_reset_fifo(fdctrl);
            /* Raise Interrupt */
	    fdctrl_raise_irq(fdctrl, 0x20);
            break;
        case 0x0F:
            /* SEEK */
            FLOPPY_DPRINTF("treat SEEK command\n");
            fdctrl->cur_drv = fdctrl->fifo[1] & 1;
	    cur_drv = get_cur_drv(fdctrl);
	    fd_start(cur_drv);
            if (fdctrl->fifo[2] <= cur_drv->track)
                cur_drv->dir = 1;
            else
                cur_drv->dir = 0;
	    fdctrl_reset_fifo(fdctrl);
            if (fdctrl->fifo[2] > cur_drv->max_track) {
                fdctrl_raise_irq(fdctrl, 0x60);
            } else {
                cur_drv->track = fdctrl->fifo[2];
                /* Raise Interrupt */
                fdctrl_raise_irq(fdctrl, 0x20);
            }
            break;
        case 0x12:
            /* PERPENDICULAR_MODE */
            FLOPPY_DPRINTF("treat PERPENDICULAR_MODE command\n");
            if (fdctrl->fifo[1] & 0x80)
                cur_drv->perpendicular = fdctrl->fifo[1] & 0x7;
            /* No result back */
            fdctrl_reset_fifo(fdctrl);
            break;
        case 0x13:
            /* CONFIGURE */
            FLOPPY_DPRINTF("treat CONFIGURE command\n");
            fdctrl->config = fdctrl->fifo[2];
            fdctrl->precomp_trk =  fdctrl->fifo[3];
            /* No result back */
            fdctrl_reset_fifo(fdctrl);
            break;
        case 0x17:
            /* POWERDOWN_MODE */
            FLOPPY_DPRINTF("treat POWERDOWN_MODE command\n");
            fdctrl->pwrd = fdctrl->fifo[1];
            fdctrl->fifo[0] = fdctrl->fifo[1];
            fdctrl_set_fifo(fdctrl, 1, 1);
            break;
        case 0x33:
            /* OPTION */
            FLOPPY_DPRINTF("treat OPTION command\n");
            /* No result back */
            fdctrl_reset_fifo(fdctrl);
            break;
        case 0x42:
            /* READ_TRACK */
//            FLOPPY_DPRINTF("treat READ_TRACK command\n");
            FLOPPY_ERROR("treat READ_TRACK command\n");
            fdctrl_start_transfer(fdctrl, FD_DIR_READ);
            break;
        case 0x4A:
                /* READ_ID */
            FLOPPY_DPRINTF("treat READ_ID command\n");
            /* XXX: should set main status register to busy */
            cur_drv->head = (fdctrl->fifo[1] >> 2) & 1;
            qemu_mod_timer(fdctrl->result_timer, 
                           qemu_get_clock(vm_clock) + (ticks_per_sec / 50));
            break;
        case 0x4C:
            /* RESTORE */
            FLOPPY_DPRINTF("treat RESTORE command\n");
            /* Drives position */
            drv0(fdctrl)->track = fdctrl->fifo[3];
            drv1(fdctrl)->track = fdctrl->fifo[4];
            /* timers */
            fdctrl->timer0 = fdctrl->fifo[7];
            fdctrl->timer1 = fdctrl->fifo[8];
            cur_drv->last_sect = fdctrl->fifo[9];
            fdctrl->lock = fdctrl->fifo[10] >> 7;
            cur_drv->perpendicular = (fdctrl->fifo[10] >> 2) & 0xF;
            fdctrl->config = fdctrl->fifo[11];
            fdctrl->precomp_trk = fdctrl->fifo[12];
            fdctrl->pwrd = fdctrl->fifo[13];
            fdctrl_reset_fifo(fdctrl);
            break;
        case 0x4D:
            /* FORMAT_TRACK */
	    FLOPPY_DPRINTF("treat FORMAT_TRACK command\n");
	    fdctrl->cur_drv = fdctrl->fifo[1] & 1;
	    cur_drv = get_cur_drv(fdctrl);
	    fdctrl->data_state |= FD_STATE_FORMAT;
	    if (fdctrl->fifo[0] & 0x80)
		fdctrl->data_state |= FD_STATE_MULTI;
	    else
		fdctrl->data_state &= ~FD_STATE_MULTI;
	    fdctrl->data_state &= ~FD_STATE_SEEK;
	    cur_drv->bps =
		fdctrl->fifo[2] > 7 ? 16384 : 128 << fdctrl->fifo[2];
#if 0
	    cur_drv->last_sect =
		cur_drv->flags & FDISK_DBL_SIDES ? fdctrl->fifo[3] :
		fdctrl->fifo[3] / 2;
#else
	    cur_drv->last_sect = fdctrl->fifo[3];
#endif
	    /* TODO: implement format using DMA expected by the Bochs BIOS
	     * and Linux fdformat (read 3 bytes per sector via DMA and fill
	     * the sector with the specified fill byte
	     */
	    fdctrl->data_state &= ~FD_STATE_FORMAT;
	    fdctrl_stop_transfer(fdctrl, 0x00, 0x00, 0x00);
            break;
        case 0x8E:
            /* DRIVE_SPECIFICATION_COMMAND */
            FLOPPY_DPRINTF("treat DRIVE_SPECIFICATION_COMMAND command\n");
            if (fdctrl->fifo[fdctrl->data_pos - 1] & 0x80) {
                /* Command parameters done */
                if (fdctrl->fifo[fdctrl->data_pos - 1] & 0x40) {
                    fdctrl->fifo[0] = fdctrl->fifo[1];
                    fdctrl->fifo[2] = 0;
                    fdctrl->fifo[3] = 0;
                    fdctrl_set_fifo(fdctrl, 4, 1);
                } else {
                    fdctrl_reset_fifo(fdctrl);
                }
            } else if (fdctrl->data_len > 7) {
                /* ERROR */
                fdctrl->fifo[0] = 0x80 |
                    (cur_drv->head << 2) | fdctrl->cur_drv;
                fdctrl_set_fifo(fdctrl, 1, 1);
            }
            break;
        case 0x8F:
            /* RELATIVE_SEEK_OUT */
            FLOPPY_DPRINTF("treat RELATIVE_SEEK_OUT command\n");
            fdctrl->cur_drv = fdctrl->fifo[1] & 1;
	    cur_drv = get_cur_drv(fdctrl);
	    fd_start(cur_drv);
                cur_drv->dir = 0;
            if (fdctrl->fifo[2] + cur_drv->track >= cur_drv->max_track) {
		cur_drv->track = cur_drv->max_track - 1;
            } else {
                cur_drv->track += fdctrl->fifo[2];
            }
	    fdctrl_reset_fifo(fdctrl);
	    fdctrl_raise_irq(fdctrl, 0x20);
            break;
        case 0xCD:
            /* FORMAT_AND_WRITE */
//                FLOPPY_DPRINTF("treat FORMAT_AND_WRITE command\n");
            FLOPPY_ERROR("treat FORMAT_AND_WRITE command\n");
            fdctrl_unimplemented(fdctrl);
            break;
        case 0xCF:
                /* RELATIVE_SEEK_IN */
            FLOPPY_DPRINTF("treat RELATIVE_SEEK_IN command\n");
            fdctrl->cur_drv = fdctrl->fifo[1] & 1;
	    cur_drv = get_cur_drv(fdctrl);
	    fd_start(cur_drv);
                cur_drv->dir = 1;
            if (fdctrl->fifo[2] > cur_drv->track) {
		cur_drv->track = 0;
            } else {
                cur_drv->track -= fdctrl->fifo[2];
            }
	    fdctrl_reset_fifo(fdctrl);
	    /* Raise Interrupt */
	    fdctrl_raise_irq(fdctrl, 0x20);
            break;
        }
    }
}

static void fdctrl_result_timer(void *opaque)
{
    fdctrl_t *fdctrl = opaque;
    fdctrl_stop_transfer(fdctrl, 0x00, 0x00, 0x00);
}