Floppy disk emulation (Jocelyn Mayer)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@545 c046a42c-6fe2-441c-8c8c-71466251a162

hw/fdc.c

+/*
+ * QEMU Floppy disk emulator
+ * 
+ * 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.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "cpu.h"
+#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_NONE  = 0x04, /* 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 struct fdrive_t {
+    BlockDriverState *bs;
+    /* Drive status */
+    fdrive_type_t drive;
+    uint8_t motor;            /* on/off                 */
+    uint8_t perpendicular;    /* 2.88 MB access mode    */
+    uint8_t rv;               /* Revalidated            */
+    /* Position */
+    uint8_t head;
+    uint8_t track;
+    uint8_t sect;
+    /* Last operation status */
+    uint8_t dir;              /* Direction              */
+    uint8_t rw;               /* Read/write             */
+    /* Media */
+    fdisk_type_t disk;        /* Disk type              */
+    uint8_t last_sect;        /* Nb sector per track    */
+    uint8_t max_track;        /* Nb of tracks           */
+    uint8_t ro;               /* Is read-only           */
+} fdrive_t;
+
+static void fd_init (fdrive_t *drv)
+{
+    /* Drive */
+    drv->bs = NULL;
+//    drv->drive = FDRIVE_DRV_288;
+    drv->drive = FDRIVE_DRV_144;
+    drv->motor = 0;
+    drv->perpendicular = 0;
+    drv->rv = 0;
+    /* Disk */
+    drv->disk = FDRIVE_DISK_NONE;
+    drv->last_sect = 1;
+    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;
+
+    if (track > drv->max_track) {
+        FLOPPY_ERROR("try to read %d %02x %02x (max=%d %02x %02x)\n",
+                     head, track, sect, 1, drv->max_track, drv->last_sect);
+        return 2;
+    }
+    if (sect > drv->last_sect) {
+        FLOPPY_ERROR("try to read %d %02x %02x (max=%d %02x %02x)\n",
+                     head, track, sect, 1, drv->max_track, drv->last_sect);
+        return 3;
+    }
+    sector = _fd_sector(head, track, sect, drv->last_sect);
+    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;
+        drv->track = track;
+        drv->sect = sect;
+        return 1;
+    }
+
+    return 0;
+}
+
+/* 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;
+}
+
+/* Revalidate a disk drive after a disk change */
+static void fd_revalidate (fdrive_t *drv, int ro)
+{
+    int64_t nb_sectors;
+
+    FLOPPY_DPRINTF("revalidate\n");
+    drv->rv = 0;
+    if (drv->bs != NULL) {
+        bdrv_get_geometry(drv->bs, &nb_sectors);
+#if 1
+        if (nb_sectors > 2880) 
+#endif
+        {
+            /* Pretend we have a 2.88 MB disk */
+            drv->disk = FDRIVE_DISK_288;
+            drv->last_sect = 36;
+            drv->max_track = 80;
+#if 1
+        } else if (nb_sectors > 1440) {
+            /* Pretend we have a 1.44 MB disk */
+            drv->disk = FDRIVE_DISK_144;
+            drv->last_sect = 18;
+            drv->max_track = 80;
+        } else {
+            /* Pretend we have a 720 kB disk */
+            drv->disk = FDRIVE_DISK_720;
+            drv->last_sect = 9;
+            drv->max_track = 80;
+#endif
+        }
+    } else {
+        drv->disk = FDRIVE_DISK_NONE;
+        drv->last_sect = 1; /* Avoid eventual divide by 0 bugs */
+    }
+    drv->ro = ro;
+    drv->rv = 1;
+}
+
+/* Motor control */
+static void fd_start (fdrive_t *drv)
+{
+    drv->motor = 1;
+}
+
+static void fd_stop (fdrive_t *drv)
+{
+    drv->motor = 0;
+}
+
+/* Re-initialise a drives (motor off, repositioned) */
+static void fd_reset (fdrive_t *drv)
+{
+    fd_stop(drv);
+    fd_recalibrate(drv);
+}
+
+/********************************************************/
+/* Intel 82078 floppy disk controler emulation          */
+
+static void fdctrl_reset (int do_irq);
+static void fdctrl_reset_fifo (void);
+static int fdctrl_transfer_handler (uint32_t addr, int size, int *irq);
+static int fdctrl_misc_handler (int duknwo);
+static void fdctrl_raise_irq (uint8_t status);
+
+static uint32_t fdctrl_read_statusB (CPUState *env, uint32_t reg);
+static uint32_t fdctrl_read_dor (CPUState *env, uint32_t reg);
+static void fdctrl_write_dor (CPUState *env, uint32_t reg, uint32_t value);
+static uint32_t fdctrl_read_tape (CPUState *env, uint32_t reg);
+static void fdctrl_write_tape (CPUState *env, uint32_t reg, uint32_t value);
+static uint32_t fdctrl_read_main_status (CPUState *env, uint32_t reg);
+static void fdctrl_write_rate (CPUState *env, uint32_t reg, uint32_t value);
+static uint32_t fdctrl_read_data (CPUState *env, uint32_t reg);
+static void fdctrl_write_data (CPUState *env, uint32_t reg, uint32_t value);
+static uint32_t fdctrl_read_dir (CPUState *env, uint32_t reg);
+
+enum {
+    FD_CTRL_ACTIVE = 0x01,
+    FD_CTRL_RESET  = 0x02,
+    FD_CTRL_SLEEP  = 0x04,
+    FD_CTRL_BUSY   = 0x08,
+    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,
+};
+
+#define FD_STATE(state) ((state) & FD_STATE_STATE)
+#define FD_MULTI_TRACK(state) ((state) & FD_STATE_MULTI)
+#define FD_DID_SEEK(state) ((state) & FD_STATE_SEEK)
+
+typedef struct fdctrl_t {
+    /* Controler's identification */
+    uint8_t version;
+    /* HW */
+    int irq_lvl;
+    int dma_chann;
+    /* Controler state */
+    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;
+    /* 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];
+} fdctrl_t;
+
+static fdctrl_t fdctrl;
+
+void fdctrl_init (int irq_lvl, int dma_chann, int mem_mapped, uint32_t base,
+                  char boot_device)
+{
+//    int io_mem;
+    int i;
+
+    FLOPPY_DPRINTF("init controler\n");
+    memset(&fdctrl, 0, sizeof(fdctrl));
+    fdctrl.version = 0x90; /* Intel 82078 controler */
+    fdctrl.irq_lvl = irq_lvl;
+    fdctrl.dma_chann = dma_chann;
+    fdctrl.config = 0x40; /* Implicit seek, polling & FIFO enabled */
+    if (fdctrl.dma_chann != -1) {
+        fdctrl.dma_en = 1;
+        DMA_register_channel(dma_chann, &fdctrl_transfer_handler,
+                             &fdctrl_misc_handler);
+    } else {
+        fdctrl.dma_en = 0;
+    }
+    for (i = 0; i < MAX_FD; i++)
+        fd_init(&fdctrl.drives[i]);
+    fdctrl_reset(0);
+    fdctrl.state = FD_CTRL_ACTIVE;
+    if (mem_mapped) {
+        FLOPPY_ERROR("memory mapped floppy not supported by now !\n");
+#if 0
+        io_mem = cpu_register_io_memory(0, fdctrl_mem_read, fdctrl_mem_write);
+        cpu_register_physical_memory(base, 0x08, io_mem);
+#endif
+    } else {
+        register_ioport_read(base + 0x01, 1, fdctrl_read_statusB, 1);
+        register_ioport_read(base + 0x02, 1, fdctrl_read_dor, 1);
+        register_ioport_write(base + 0x02, 1, fdctrl_write_dor, 1);
+        register_ioport_read(base + 0x03, 1, fdctrl_read_tape, 1);
+        register_ioport_write(base + 0x03, 1, fdctrl_write_tape, 1);
+        register_ioport_read(base + 0x04, 1, fdctrl_read_main_status, 1);
+        register_ioport_write(base + 0x04, 1, fdctrl_write_rate, 1);
+        register_ioport_read(base + 0x05, 1, fdctrl_read_data, 1);
+        register_ioport_write(base + 0x05, 1, fdctrl_write_data, 1);
+        register_ioport_read(base + 0x07, 1, fdctrl_read_dir, 1);
+    }
+    if (boot_device == 'b')
+        fdctrl.bootsel = 1;
+    else
+        fdctrl.bootsel = 0;
+#if defined (TARGET_I386)
+    cmos_register_fd(fdctrl.drives[0].drive, fdctrl.drives[1].drive);
+#endif
+}
+
+int fdctrl_disk_change (int idx, const unsigned char *filename, int ro)
+{
+    fdrive_t *drv;
+    
+    if (idx < 0 || idx > 1)
+        return -1;
+    FLOPPY_DPRINTF("disk %d change: %s (%s)\n", idx, filename,
+                   ro == 0 ? "rw" : "ro");
+    drv = &fdctrl.drives[idx];
+    if (fd_table[idx] != NULL) {
+        bdrv_close(fd_table[idx]);
+        fd_table[idx] = NULL;
+    }
+    fd_table[idx] = bdrv_open(filename, ro);
+    drv->bs = fd_table[idx];
+    if (fd_table[idx] == NULL)
+        return -1;
+    fd_revalidate(drv, ro);
+#if 0
+    fd_recalibrate(drv);
+    fdctrl_reset_fifo();
+    fdctrl_raise_irq(0x20);
+#endif
+
+    return 0;
+}
+
+/* Change IRQ state */
+static void fdctrl_reset_irq (void)
+{
+    if (fdctrl.state & FD_CTRL_INTR) {
+        pic_set_irq(fdctrl.irq_lvl, 0);
+        fdctrl.state &= ~(FD_CTRL_INTR | FD_CTRL_SLEEP | FD_CTRL_BUSY);
+    }
+}
+
+static void fdctrl_raise_irq (uint8_t status)
+{
+    if (~(fdctrl.state & FD_CTRL_INTR)) {
+        pic_set_irq(fdctrl.irq_lvl, 1);
+        fdctrl.state |= FD_CTRL_INTR;
+    }
+    FLOPPY_DPRINTF("Set interrupt status to 0x%02x\n", status);
+    fdctrl.int_status = status;
+}
+
+/* Reset controler */
+static void fdctrl_reset (int do_irq)
+{
+    int i;
+
+    FLOPPY_DPRINTF("reset controler\n");
+    fdctrl_reset_irq();
+    /* Initialise controler */
+    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();
+    if (do_irq)
+        fdctrl_raise_irq(0x20);
+}
+
+/* Status B register : 0x01 (read-only) */
+static uint32_t fdctrl_read_statusB (CPUState *env, uint32_t reg)
+{
+    fdctrl_reset_irq();
+    FLOPPY_DPRINTF("status register: 0x00\n");
+
+    return 0;
+}
+
+/* Digital output register : 0x02 */
+static uint32_t fdctrl_read_dor (CPUState *env, uint32_t reg)
+{
+    fdrive_t *cur_drv, *drv0, *drv1;
+    uint32_t retval = 0;
+
+    drv0 = &fdctrl.drives[fdctrl.bootsel];
+    drv1 = &fdctrl.drives[1 - fdctrl.bootsel];
+    cur_drv = fdctrl.cur_drv == 0 ? drv0 : drv1;
+    /* Drive motors state indicators */
+    retval |= drv1->motor << 5;
+    retval |= drv0->motor << 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 (CPUState *env, uint32_t reg, uint32_t value)
+{
+    fdrive_t *drv0, *drv1;
+    
+    fdctrl_reset_irq();
+    drv0 = &fdctrl.drives[fdctrl.bootsel];
+    drv1 = &fdctrl.drives[1 - fdctrl.bootsel];
+    /* Reset mode */
+    if (fdctrl.state & FD_CTRL_RESET) {
+        if (!(value & 0x04)) {
+            FLOPPY_DPRINTF("Floppy controler 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);
+    else
+        fd_stop(drv1);
+    if (value & 0x10)
+        fd_start(drv0);
+    else
+        fd_stop(drv0);
+    /* 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("controler enter RESET state\n");
+            fdctrl.state |= FD_CTRL_RESET;
+            fdctrl_reset(1);
+        }
+    } else {
+        if (fdctrl.state & FD_CTRL_RESET) {
+            FLOPPY_DPRINTF("controler out of RESET state\n");
+            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 (CPUState *env, uint32_t reg)
+{
+    uint32_t retval = 0;
+
+    fdctrl_reset_irq();
+    /* 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 (CPUState *env, uint32_t reg, uint32_t value)
+{
+    fdctrl_reset_irq();
+    /* Reset mode */
+    if (fdctrl.state & FD_CTRL_RESET) {
+        FLOPPY_DPRINTF("Floppy controler 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 (CPUState *env, uint32_t reg)
+{
+    uint32_t retval = 0;
+
+    fdctrl_reset_irq();
+    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 (CPUState *env, uint32_t reg, uint32_t value)
+{
+    fdctrl_reset_irq();
+    /* Reset mode */
+    if (fdctrl.state & FD_CTRL_RESET) {
+        if (reg != 0x2 || !(value & 0x04)) {
+            FLOPPY_DPRINTF("Floppy controler 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(1);
+        fdctrl.state &= ~FD_CTRL_RESET;
+    }
+    if (value & 0x40) {
+        fdctrl.state |= FD_CTRL_SLEEP;
+        fdctrl_reset(1);
+    }
+//        fdctrl.precomp = (value >> 2) & 0x07;
+}
+
+/* Digital input register : 0x07 (read-only) */
+static uint32_t fdctrl_read_dir (CPUState *env, uint32_t reg)
+{
+    fdrive_t *drv0, *drv1;
+    uint32_t retval = 0;
+
+    fdctrl_reset_irq();
+    drv0 = &fdctrl.drives[fdctrl.bootsel];
+    drv1 = &fdctrl.drives[1 - fdctrl.bootsel];
+    if (drv0->rv || drv1->rv)
+        retval |= 0x80;
+    if (retval != 0)
+        FLOPPY_ERROR("Floppy digital input register: 0x%02x\n", retval);
+    drv0->rv = 0;
+    drv1->rv = 0;
+
+    return retval;
+}
+
+/* FIFO state control */
+static void fdctrl_reset_fifo (void)
+{
+    fdctrl.data_dir = FD_DIR_WRITE;
+    fdctrl.data_pos = 0;
+    fdctrl.data_state = FD_STATE_CMD;
+}
+
+/* Set FIFO status for the host to read */
+static void fdctrl_set_fifo (int fifo_len, int do_irq)
+{
+    fdctrl.data_dir = FD_DIR_READ;
+    fdctrl.data_len = fifo_len;
+    fdctrl.data_pos = 0;
+    fdctrl.data_state = FD_STATE_STATUS;
+    if (do_irq)
+        fdctrl_raise_irq(0x00);
+}
+
+/* Set an error: unimplemented/unknown command */
+static void fdctrl_unimplemented (void)
+{
+#if 0
+    fdrive_t *cur_drv, *drv0, *drv1;
+
+    drv0 = &fdctrl.drives[fdctrl.bootsel];
+    drv1 = &fdctrl.drives[1 - fdctrl.bootsel];
+    cur_drv = fdctrl.cur_drv == 0 ? drv0 : drv1;
+    fdctrl.fifo[0] = 0x60 | (cur_drv->head << 1) | fdctrl.cur_drv;
+    fdctrl.fifo[1] = 0x00;
+    fdctrl.fifo[2] = 0x00;
+    fdctrl_set_fifo(3, 1);
+#else
+    fdctrl_reset_fifo();
+#endif
+}
+
+/* Callback for transfer end (stop or abort) */
+static void fdctrl_stop_transfer (uint8_t status0, uint8_t status1,
+                                  uint8_t status2)
+{
+    fdrive_t *cur_drv, *drv0, *drv1;
+
+    drv0 = &fdctrl.drives[fdctrl.bootsel];
+    drv1 = &fdctrl.drives[1 - fdctrl.bootsel];
+    cur_drv = fdctrl.cur_drv == 0 ? drv0 : drv1;
+    FLOPPY_DPRINTF("transfer status: %02x %02x %02x (%02x)\n",
+                   status0, status1, status2,
+                   status0 | (cur_drv->head << 1) |