/*
 * drive.c - Hardware-level disk drive emulation.
 *
 * Written by
 *  Andreas Boose <viceteam@t-online.de>
 *
 * Based on old code by
 *  Daniel Sladic <sladic@eecg.toronto.edu>
 *  Ettore Perazzoli <ettore@comm2000.it>
 *  Andre Fachat <fachat@physik.tu-chemnitz.de>
 *  Teemu Rantanen <tvr@cs.hut.fi>
 *
 * This file is part of VICE, the Versatile Commodore Emulator.
 * See README for copyright notice.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 *  02111-1307  USA.
 *
 */

/* TODO:
        - more accurate emulation of disk rotation.
        - different speeds within one track.
        - check for byte ready *within* `BVC', `BVS' and `PHP'.
        - serial bus handling might be faster.  */

#include "vice.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <assert.h>

#include "attach.h"
#include "diskconstants.h"
#include "diskimage.h"
#include "drive-check.h"
#include "drive-overflow.h"
#include "drive.h"
#include "drivecpu.h"
#include "drivecpu65c02.h"
#include "driveimage.h"
#include "drivesync.h"
#include "driverom.h"
#include "drivetypes.h"
#include "gcr.h"
#include "iecbus.h"
#include "iecdrive.h"
#include "lib.h"
#include "log.h"
#include "machine-drive.h"
#include "machine.h"
#include "maincpu.h"
#include "resources.h"
#include "rotation.h"
#include "types.h"
#include "uiapi.h"
#include "ds1216e.h"
#include "drive-sound.h"
#include "p64.h"
#include "monitor.h"

static int drive_init_was_called = 0;

drive_context_t *drive_context[DRIVE_NUM];

/* Generic drive logging goes here.  */
static log_t drive_log = LOG_ERR;

/* If nonzero, at least one vaild drive ROM has already been loaded.  */
int rom_loaded = 0;

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

static int drive_led_color[DRIVE_NUM];

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

void drive_set_disk_memory(uint8_t *id, unsigned int track, unsigned int sector,
                           struct drive_context_s *drv)
{
    drive_t *drive;

    drive = drv->drive;

    if (drive->type == DRIVE_TYPE_1540
        || drive->type == DRIVE_TYPE_1541
        || drive->type == DRIVE_TYPE_1541II
        || drive->type == DRIVE_TYPE_1570
        || drive->type == DRIVE_TYPE_1571
        || drive->type == DRIVE_TYPE_1571CR) {
        drv->drive->drive_ram[0x12] = id[0];
        drv->drive->drive_ram[0x13] = id[1];
        drv->drive->drive_ram[0x16] = id[0];
        drv->drive->drive_ram[0x17] = id[1];
        drv->drive->drive_ram[0x18] = track;
        drv->drive->drive_ram[0x19] = sector;
        drv->drive->drive_ram[0x22] = track;
    }
}

void drive_set_last_read(unsigned int track, unsigned int sector, uint8_t *buffer,
                         struct drive_context_s *drv)
{
    drive_t *drive;
    int side = 0;

    drive = drv->drive;

    drive_gcr_data_writeback(drive);

    if (drive->type == DRIVE_TYPE_1570
        || drive->type == DRIVE_TYPE_1571
        || drive->type == DRIVE_TYPE_1571CR) {
        if (track > (DRIVE_HALFTRACKS_1571 / 2)) {
            track -= (DRIVE_HALFTRACKS_1571 / 2);
            side = 1;
        }
    }
    drive_set_half_track(track * 2, side, drive);

    if (drive->type == DRIVE_TYPE_1540
        || drive->type == DRIVE_TYPE_1541
        || drive->type == DRIVE_TYPE_1541II
        || drive->type == DRIVE_TYPE_1570
        || drive->type == DRIVE_TYPE_1571
        || drive->type == DRIVE_TYPE_1571CR) {
        memcpy(&(drv->drive->drive_ram[0x0400]), buffer, 256);
    }
}

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

/* Initialize the hardware-level drive emulation (should be called at least
   once before anything else).  Return 0 on success, -1 on error.  */
int drive_init(void)
{
    unsigned int dnr;
    drive_t *drive;

    if (rom_loaded) {
        return 0;
    }

    drive_init_was_called = 1;

    driverom_init();
    drive_image_init();

    drive_log = log_open("Drive");

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        char *logname;

        drive = drive_context[dnr]->drive;
        logname = lib_msprintf("Drive %i", dnr + 8);
        drive->log = log_open(logname);
        lib_free(logname);

        drive_clk[dnr] = 0L;
        drive->clk = &drive_clk[dnr];
        drive->mynumber = dnr;
    }

    if (driverom_load_images() < 0) {
        resources_set_int("Drive8Type", DRIVE_TYPE_NONE);
        resources_set_int("Drive9Type", DRIVE_TYPE_NONE);
        resources_set_int("Drive10Type", DRIVE_TYPE_NONE);
        resources_set_int("Drive11Type", DRIVE_TYPE_NONE);
        return -1;
    }

    log_message(drive_log, "Finished loading ROM images.");
    rom_loaded = 1;

    drive_overflow_init();

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive = drive_context[dnr]->drive;

        machine_drive_port_default(drive_context[dnr]);

        if (drive_check_type(drive->type, dnr) < 1) {
            resources_set_int_sprintf("Drive%iType", DRIVE_TYPE_NONE, dnr + 8);
        }

        machine_drive_rom_setup_image(dnr);
    }

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive = drive_context[dnr]->drive;
        drive->gcr = gcr_create_image();
        drive->p64 = lib_calloc(1, sizeof(TP64Image));
        P64ImageCreate(drive->p64);
        drive->byte_ready_level = 1;
        drive->byte_ready_edge = 1;
        drive->GCR_dirty_track = 0;
        drive->GCR_write_value = 0x55;
        drive->GCR_track_start_ptr = NULL;
        drive->GCR_current_track_size = 0;
        drive->attach_clk = (CLOCK)0;
        drive->detach_clk = (CLOCK)0;
        drive->attach_detach_clk = (CLOCK)0;
        drive->old_led_status = 0;
        drive->old_half_track = 0;
        drive->side = 0;
        drive->GCR_image_loaded = 0;
        drive->P64_image_loaded = 0;
        drive->P64_dirty = 0;
        drive->read_only = 0;
        drive->clock_frequency = 1;
        drive->led_last_change_clk = *(drive->clk);
        drive->led_last_uiupdate_clk = *(drive->clk);
        drive->led_active_ticks = 0;

        rotation_reset(drive);

        /* Position the R/W head on the directory track.  */
        drive_set_half_track(36, 0, drive);
        drive_set_active_led_color(drive->type, dnr);
    }

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive = drive_context[dnr]->drive;
        driverom_initialize_traps(drive);

        drivesync_clock_frequency(drive->type, drive);

        rotation_init((drive->clock_frequency == 2) ? 1 : 0, dnr);

        if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
            drivecpu65c02_init(drive_context[dnr], drive->type);
        } else {
            drivecpu_init(drive_context[dnr], drive->type);
        }

        /* Make sure the sync factor is acknowledged correctly.  */
        drivesync_factor(drive_context[dnr]);

        /* Make sure the traps are moved as needed.  */
        if (drive->enable) {
            drive_enable(drive_context[dnr]);
        }
    }

    return 0;
}

void drive_shutdown(void)
{
    unsigned int dnr;

    if (!drive_init_was_called) {
        /* happens at the -help command line command*/
        return;
    }

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        if (drive_context[dnr]->drive->type == DRIVE_TYPE_2000 || drive_context[dnr]->drive->type == DRIVE_TYPE_4000) {
            drivecpu65c02_shutdown(drive_context[dnr]);
        } else {
            drivecpu_shutdown(drive_context[dnr]);
        }
        if (drive_context[dnr]->drive->gcr) {
            gcr_destroy_image(drive_context[dnr]->drive->gcr);
        }
        if (drive_context[dnr]->drive->p64) {
            P64ImageDestroy(drive_context[dnr]->drive->p64);
            lib_free(drive_context[dnr]->drive->p64);
        }
        if (drive_context[dnr]->drive->ds1216) {
            ds1216e_destroy(drive_context[dnr]->drive->ds1216, drive_context[dnr]->drive->rtc_save);
        }
    }

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        lib_free(drive_context[dnr]->drive);
        lib_free(drive_context[dnr]);
    }
}

void drive_set_active_led_color(unsigned int type, unsigned int dnr)
{
    switch (type) {
        case DRIVE_TYPE_1540:   /* green power, red drive, horizontal, round */
        case DRIVE_TYPE_1541:   /* green power, red drive, horizontal, round */
        case DRIVE_TYPE_1551:   /* green power, red drive, horizontal, round */
        case DRIVE_TYPE_1570:   /* green power, red drive, horizontal, round */
        case DRIVE_TYPE_2031:   /* green power, red drive, horizontal, round */
        case DRIVE_TYPE_1001:   /* green power, red drive, horizontal, round */
            drive_led_color[dnr] = DRIVE_LED1_RED;
            break;
        case DRIVE_TYPE_1571:   /* red power, green drive, horizontal, line */
        case DRIVE_TYPE_1571CR: /* red power, green drive, horizontal, line */
        case DRIVE_TYPE_1541II: /* red power, green drive, vertical, line (some models only) */
        case DRIVE_TYPE_1581:   /* red power, green drive, vertical, line */
            drive_led_color[dnr] = DRIVE_LED1_GREEN;
            break;
        case DRIVE_TYPE_2000:   /* red power, green activity, red error, horizontal, line */
        case DRIVE_TYPE_4000:   /* red power, green activity, red error, horizontal, line */
            drive_led_color[dnr] = DRIVE_LED1_GREEN | DRIVE_LED2_RED;
            break;
        case DRIVE_TYPE_2040:   /* red drive1, red power, red drive2, horizontal, round */
        case DRIVE_TYPE_3040:   /* red drive1, red power, red drive2, horizontal, round */
        case DRIVE_TYPE_4040:   /* red drive1, red power, red drive2, horizontal, round */
        case DRIVE_TYPE_8050:   /* red drive1, green power, red drive2, horizontal, round */
            drive_led_color[dnr] = DRIVE_LED1_RED | DRIVE_LED2_RED;
            break;
        case DRIVE_TYPE_8250:   /* red green, green power,green, horizontal, round */
            drive_led_color[dnr] = DRIVE_LED1_GREEN | DRIVE_LED2_GREEN; /* only the LP version is RED */
            break;
        default:
            drive_led_color[dnr] = DRIVE_LED1_RED;
            break;
    }
}

int drive_set_disk_drive_type(unsigned int type, struct drive_context_s *drv)
{
    unsigned int dnr;
    drive_t *drive;
    drive_t *drive1;

    dnr = drv->mynumber;

    if (machine_drive_rom_check_loaded(type) < 0) {
        return -1;
    }

    drive = drv->drive;
    rotation_rotate_disk(drive);

    drivesync_clock_frequency(type, drive);

    rotation_init(0, dnr);
    drive->type = type;
    if (type == DRIVE_TYPE_2000 || type == DRIVE_TYPE_4000) {
        drivecpu65c02_setup_context(drv, 0);
    } else {
        drivecpu_setup_context(drv, 0);
    }
    drive->side = 0;
    machine_drive_rom_setup_image(dnr);
    drivesync_factor(drv);
    drive_set_active_led_color(type, dnr);

    /* set up (relatively) easy detection of dual drives */
    drive1 = drive_context[mk_drive1(dnr)]->drive;
    drive->drive0 = NULL;
    drive1->drive1 = NULL;
    if (is_drive0(dnr) && drive_check_dual(type)) {
        drive->drive1 = drive1;
        drive1->drive0 = drive;
    } else {
        drive->drive1 = NULL;
        drive1->drive0 = NULL;
    }

    if (type == DRIVE_TYPE_2000 || type == DRIVE_TYPE_4000) {
        drivecpu65c02_init(drv, type);
    } else {
        drivecpu_init(drv, type);
    }

    return 0;
}

int drive_get_disk_drive_type(int dnr)
{
    if (dnr >= 0 && dnr < DRIVE_NUM) {
        return drive_context[dnr]->drive->type;
    }

    return DRIVE_TYPE_NONE;
}

void drive_enable_update_ui(drive_context_t *drv)
{
    int i;
    unsigned int enabled_drives = 0;

    for (i = 0; i < DRIVE_NUM; i++) {
        unsigned int the_drive;
        drive_t *drive = drive_context[i]->drive;

        the_drive = 1 << i;

        if (drive->enable || (drive->drive0 && drive->drive0->enable)) {
            enabled_drives |= the_drive;
            drive->old_led_status = -1;
            drive->old_half_track = -1;
            drive->old_side = -1;
        }
    }

    ui_enable_drive_status(enabled_drives,
                           drive_led_color);
}

/* Activate full drive emulation. */
int drive_enable(drive_context_t *drv)
{
    int drive_true_emulation = 0;
    unsigned int dnr;
    drive_t *drive;

    dnr = drv->mynumber;
    drive = drv->drive;

    /* This must come first, because this might be called before the drive
       initialization.  */
    if (!rom_loaded) {
        return -1;
    }

    resources_get_int("DriveTrueEmulation", &drive_true_emulation);

    /* Always disable kernal traps. */
    if (!drive_true_emulation) {
        return 0;
    }

    if (drive->type == DRIVE_TYPE_NONE) {
        return 0;
    }

    /* Recalculate drive geometry.  */
    if (drive->image != NULL) {
        drive_image_attach(drive->image, dnr + 8);
    }

    /* resync */
    drv->cpu->stop_clk = *(drv->clk_ptr);

    if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
        drivecpu65c02_wake_up(drv);
    } else {
        drivecpu_wake_up(drv);
    }

    /* Make sure the UI is updated.  */
    drive_enable_update_ui(drv);
    return 0;
}

/* Disable full drive emulation.  */
void drive_disable(drive_context_t *drv)
{
    int drive_true_emulation = 0;
    drive_t *drive;

    drive = drv->drive;

    /* This must come first, because this might be called before the true
       drive initialization.  */
    drive->enable = 0;

    resources_get_int("DriveTrueEmulation", &drive_true_emulation);

    if (rom_loaded) {
        if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
            drivecpu65c02_sleep(drv);
        } else {
            drivecpu_sleep(drv);
        }
        machine_drive_port_default(drv);

        drive_gcr_data_writeback(drive);
    }

    /* Make sure the UI is updated.  */
    drive_enable_update_ui(drv);
}

monitor_interface_t *drive_cpu_monitor_interface_get(unsigned int dnr)
{
    return drive_context[dnr]->cpu->monitor_interface;
}

void drive_cpu_early_init_all(void)
{
    unsigned int dnr;

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        machine_drive_init(drive_context[dnr]);
    }
}

void drive_cpu_prevent_clk_overflow_all(CLOCK sub)
{
    unsigned int dnr;

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive_t *drive = drive_context[dnr]->drive;
        if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
            drivecpu65c02_prevent_clk_overflow(drive_context[dnr], sub);
        } else {
            drivecpu_prevent_clk_overflow(drive_context[dnr], sub);
        }
    }
}

void drive_cpu_trigger_reset(unsigned int dnr)
{
    drive_t *drive = drive_context[dnr]->drive;
    if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
        drivecpu65c02_trigger_reset(dnr);
    } else {
        drivecpu_trigger_reset(dnr);
    }
}

/* called by machine_specific_reset() */
void drive_reset(void)
{
    unsigned int dnr;
    drive_t *drive;

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive = drive_context[dnr]->drive;

        if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
            drivecpu65c02_reset(drive_context[dnr]);
        } else {
            drivecpu_reset(drive_context[dnr]);
        }

        drive->led_last_change_clk = *(drive->clk);
        drive->led_last_uiupdate_clk = *(drive->clk);
        drive->led_active_ticks = 0;
    }
}

/* Move the head to half track `num'.  */
void drive_set_half_track(int num, int side, drive_t *dptr)
{
    int tmp;
    if ((dptr->type == DRIVE_TYPE_1540
         || dptr->type == DRIVE_TYPE_1541
         || dptr->type == DRIVE_TYPE_1541II
         || dptr->type == DRIVE_TYPE_1551
         || dptr->type == DRIVE_TYPE_1570
         || dptr->type == DRIVE_TYPE_2031) && (num > DRIVE_HALFTRACKS_1541)) {
        num = DRIVE_HALFTRACKS_1541;
    }
    if ((dptr->type == DRIVE_TYPE_1571 || dptr->type == DRIVE_TYPE_1571CR)
        && (num > DRIVE_HALFTRACKS_1571)) {
        num = DRIVE_HALFTRACKS_1571;
    }
    if (num < 2) {
        num = 2;
    }

    if (dptr->current_half_track != num || dptr->side != side) {
        dptr->current_half_track = num;
        if (dptr->p64) {
            dptr->p64->PulseStreams[dptr->side][dptr->current_half_track].CurrentIndex = -1;
        }
    }
    dptr->side = side;

    /* FIXME: why would the offset be different for D71 and G71? */
    tmp = (dptr->image && dptr->image->type == DISK_IMAGE_TYPE_G71) ? DRIVE_HALFTRACKS_1571 : 70;

    dptr->GCR_track_start_ptr = dptr->gcr->tracks[dptr->current_half_track - 2 + (dptr->side * tmp)].data;

    if (dptr->GCR_current_track_size != 0) {
        dptr->GCR_head_offset = (dptr->GCR_head_offset
                                 * dptr->gcr->tracks[dptr->current_half_track - 2 + (dptr->side * tmp)].size)
                                / dptr->GCR_current_track_size;
    } else {
        dptr->GCR_head_offset = 0;
    }

    dptr->GCR_current_track_size =
        dptr->gcr->tracks[dptr->current_half_track - 2 + (dptr->side * tmp)].size;
}

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

/* Increment the head position by `step' half-tracks. Valid values
   for `step' are `+1', '+2' and `-1'.  */
void drive_move_head(int step, drive_t *drive)
{
    if ((step < -1) || (step > 1)) {
        log_warning(drive_log, "ambiguous step count (%d)", step);
    }
    drive_gcr_data_writeback(drive);
    drive_sound_head(drive->current_half_track, step, drive->mynumber);
    drive_set_half_track(drive->current_half_track + step, drive->side, drive);
}

void drive_gcr_data_writeback(drive_t *drive)
{
    int extend;
    unsigned int half_track, track;
    int tmp;

    if (drive->image == NULL) {
        return;
    }

    /* FIXME: why would the offset be different for D71 and G71? */
    tmp = (drive->image && drive->image->type == DISK_IMAGE_TYPE_G71) ? DRIVE_HALFTRACKS_1571 : 70;
    half_track = drive->current_half_track + (drive->side * tmp);
    track = drive->current_half_track / 2;

    if (drive->image->type == DISK_IMAGE_TYPE_P64) {
        return;
    }

    if (!(drive->GCR_dirty_track)) {
        return;
    }

    if ((drive->image->type == DISK_IMAGE_TYPE_G64)
        || (drive->image->type == DISK_IMAGE_TYPE_G71)) {
        disk_image_write_half_track(drive->image, half_track,
                                    &drive->gcr->tracks[half_track - 2]);
        drive->GCR_dirty_track = 0;
        return;
    }

    if (half_track > drive->image->max_half_tracks) {
        drive->GCR_dirty_track = 0;
        return;
    }
    if (track > drive->image->tracks) {
        switch (drive->extend_image_policy) {
            case DRIVE_EXTEND_NEVER:
                drive->ask_extend_disk_image = 1;
                drive->GCR_dirty_track = 0;
                return;
            case DRIVE_EXTEND_ASK:
                if (drive->ask_extend_disk_image == 1) {
                    extend = ui_extend_image_dialog();
                    if (extend == 0) {
                        drive->GCR_dirty_track = 0;
                        drive->ask_extend_disk_image = 0;
                        return;
                    }
                    drive->ask_extend_disk_image = 2;
                } else if (drive->ask_extend_disk_image == 0) {
                    drive->GCR_dirty_track = 0;
                    return;
                }
                break;
            case DRIVE_EXTEND_ACCESS:
                drive->ask_extend_disk_image = 1;
                break;
        }
    }

    disk_image_write_half_track(drive->image, half_track,
                                &drive->gcr->tracks[half_track - 2]);

    drive->GCR_dirty_track = 0;
}

void drive_gcr_data_writeback_all(void)
{
    drive_t *drive;
    unsigned int i;

    for (i = 0; i < DRIVE_NUM; i++) {
        drive = drive_context[i]->drive;
        drive_gcr_data_writeback(drive);
        if (drive->P64_image_loaded && drive->image && drive->image->p64) {
            if (drive->image->type == DISK_IMAGE_TYPE_P64) {
                if (drive->P64_dirty) {
                    drive->P64_dirty = 0;
                    disk_image_write_p64_image(drive->image);
                }
            }
        }
    }
}

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

static void drive_led_update(drive_t *drive, drive_t *drive0)
{
    int my_led_status = 0;
    CLOCK led_period;
    unsigned int led_pwm;

    /* Actually update the LED status only if the `trap idle'
       idling method is being used, as the LED status could be
       incorrect otherwise.  */

    if (drive0->idling_method != DRIVE_IDLE_SKIP_CYCLES) {
        my_led_status = drive->led_status;
    }

    /* Update remaining led clock ticks. */
    if (drive->led_status & 1) {
        drive->led_active_ticks += *(drive0->clk)
                                   - drive->led_last_change_clk;
    }
    drive->led_last_change_clk = *(drive0->clk);

    led_period = *(drive0->clk) - drive->led_last_uiupdate_clk;
    drive->led_last_uiupdate_clk = *(drive0->clk);

    if (led_period == 0) {
        return;
    }

    if (drive->led_active_ticks > led_period) {
        /* during startup it has been observer that led_pwm > 1000,
           which potentially breaks several UIs */
        /* this also happens when the drive is reset from UI
           and the LED was on */
        led_pwm = 1000;
    } else {
        led_pwm = drive->led_active_ticks * 1000 / led_period;
    }
    assert(led_pwm <= MAX_PWM);
    if (led_pwm > MAX_PWM) {
        led_pwm = MAX_PWM;
    }

    drive->led_active_ticks = 0;

    if (led_pwm != drive->led_last_pwm
        || my_led_status != drive->old_led_status) {
        ui_display_drive_led(drive->mynumber, led_pwm,
                             (my_led_status & 2) ? 1000 : 0);
        drive->led_last_pwm = led_pwm;
        drive->old_led_status = my_led_status;
    }
}

/* Update the status bar in the UI.  */
void drive_update_ui_status(void)
{
    int i;

    if (console_mode || (machine_class == VICE_MACHINE_VSID)) {
        return;
    }

    /* Update the LEDs and the track indicators.  */
    for (i = 0; i < DRIVE_NUM; i++) {
        drive_t *drive = drive_context[i]->drive;
        drive_t *drive0 = drive->drive0;
        int dual = drive0 && drive0->enable;

        if (drive->enable || dual) {
            if (!drive0) {
                drive0 = drive;
            }

            drive_led_update(drive, drive0);

            if (drive->current_half_track != drive->old_half_track
                || drive->side != drive->old_side) {
                drive->old_half_track = drive->current_half_track;
                drive->old_side = drive->side;
                dual = dual || drive->drive1;   /* also include drive 0 */
                ui_display_drive_track(i,
                                       dual ? 0 : 8,
                                       drive->current_half_track + (drive->side * DRIVE_HALFTRACKS_1571));
            }
        }
    }
}

int drive_num_leds(unsigned int dnr)
{
    drive_t *drive = drive_context[dnr]->drive;

    switch (drive->type) {
    case DRIVE_TYPE_2040:
    case DRIVE_TYPE_3040:
    case DRIVE_TYPE_4040:
    case DRIVE_TYPE_8050:
    case DRIVE_TYPE_8250:
    case DRIVE_TYPE_2000:
    case DRIVE_TYPE_4000:
        return 2;
    default:
        return 1;
    }
}

void drive_cpu_execute_one(drive_context_t *drv, CLOCK clk_value)
{
    drive_t *drive = drv->drive;

    if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
        drivecpu65c02_execute(drv, clk_value);
    } else {
        drivecpu_execute(drv, clk_value);
    }
}

void drive_cpu_execute_all(CLOCK clk_value)
{
    unsigned int dnr;
    drive_t *drive;

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive = drive_context[dnr]->drive;
        if (drive->enable) {
            drive_cpu_execute_one(drive_context[dnr], clk_value);
        }
    }
}

void drive_cpu_set_overflow(drive_context_t *drv)
{
    drive_t *drive = drv->drive;

    if (drive->type == DRIVE_TYPE_2000 || drive->type == DRIVE_TYPE_4000) {
        /* nothing */
    } else {
        drivecpu_set_overflow(drv);
    }
}

/* This is called at every vsync. */
void drive_vsync_hook(void)
{
    unsigned int dnr;

    drive_update_ui_status();

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive_t *drive = drive_context[dnr]->drive;
        if (drive->enable) {
            if (drive->idling_method != DRIVE_IDLE_SKIP_CYCLES) {
                drive_cpu_execute_one(drive_context[dnr], maincpu_clk);
            }
            if (drive->idling_method == DRIVE_IDLE_NO_IDLE) {
                /* if drive is never idle, also rotate the disk. this prevents
                 * huge peaks in cpu usage when the drive must catch up with
                 * a longer period of time.
                 */
                rotation_rotate_disk(drive);
            }
            /* printf("drive_vsync_hook drv %d @clk:%d\n", dnr, maincpu_clk); */
        }
    }
}

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

static void drive_setup_context_for_drive(drive_context_t *drv,
                                          unsigned int dnr)
{
    drv->mynumber = dnr;
    drv->drive = lib_calloc(1, sizeof(drive_t));
    drv->clk_ptr = &drive_clk[dnr];

    drivecpu_setup_context(drv, 1); /* no need for 65c02, only allocating common stuff */

    machine_drive_setup_context(drv);
}

void drive_setup_context(void)
{
    unsigned int dnr;

    for (dnr = 0; dnr < DRIVE_NUM; dnr++) {
        drive_context[dnr] = lib_calloc(1, sizeof(drive_context_t));
        drive_setup_context_for_drive(drive_context[dnr], dnr);
    }
}
