Archipelago » qemu

/* 

 * General purpose implementation of a simple periodic countdown timer.

 *

 * Copyright (c) 2007 CodeSourcery.

 *

 * This code is licenced under the GNU LGPL.

 */

#include "vl.h"

struct ptimer_state

{

    int enabled; /* 0 = disabled, 1 = periodic, 2 = oneshot.  */

    uint32_t limit;

    uint32_t delta;

    uint32_t period_frac;

    int64_t period;

    int64_t last_event;

    int64_t next_event;

    QEMUBH *bh;

    QEMUTimer *timer;

};

/* Use a bottom-half routine to avoid reentrancy issues.  */

static void ptimer_trigger(ptimer_state *s)

{

    if (s->bh) {

        qemu_bh_schedule(s->bh);

    }

}

static void ptimer_reload(ptimer_state *s)

{

    if (s->delta == 0) {

        ptimer_trigger(s);

        s->delta = s->limit;

    }

    if (s->delta == 0 || s->period == 0) {

        fprintf(stderr, "Timer with period zero, disabling\n");

        s->enabled = 0;

        return;

    }

    s->last_event = s->next_event;

    s->next_event = s->last_event + s->delta * s->period;

    if (s->period_frac) {

        s->next_event += ((int64_t)s->period_frac * s->delta) >> 32;

    }

    qemu_mod_timer(s->timer, s->next_event);

}

static void ptimer_tick(void *opaque)

{

    ptimer_state *s = (ptimer_state *)opaque;

    ptimer_trigger(s);

    s->delta = 0;

    if (s->enabled == 2) {

        s->enabled = 0;

    } else {

        ptimer_reload(s);

    }

}

uint32_t ptimer_get_count(ptimer_state *s)

{

    int64_t now;

    uint32_t counter;

    if (s->enabled) {

        now = qemu_get_clock(vm_clock);

        /* Figure out the current counter value.  */

        if (now - s->next_event > 0

            || s->period == 0) {

            /* Prevent timer underflowing if it should already have

               triggered.  */

            counter = 0;

        } else {

            int64_t rem;

            int64_t div;

            rem = s->next_event - now;

            div = s->period;

            counter = rem / div;

        }

    } else {

        counter = s->delta;

    }

    return counter;

}

void ptimer_set_count(ptimer_state *s, uint32_t count)

{

    s->delta = count;

    if (s->enabled) {

        s->next_event = qemu_get_clock(vm_clock);

        ptimer_reload(s);

    }

}

void ptimer_run(ptimer_state *s, int oneshot)

{

    if (s->period == 0) {

        fprintf(stderr, "Timer with period zero, disabling\n");

        return;

    }

    s->enabled = oneshot ? 2 : 1;

    s->next_event = qemu_get_clock(vm_clock);

    ptimer_reload(s);

}

/* Pause a timer.  Note that this may cause it to "loose" time, even if it

   is immediately restarted.  */

void ptimer_stop(ptimer_state *s)

{

    if (!s->enabled)

        return;

    s->delta = ptimer_get_count(s);

    qemu_del_timer(s->timer);

    s->enabled = 0;

}

/* Set counter increment interval in nanoseconds.  */

void ptimer_set_period(ptimer_state *s, int64_t period)

{

    if (s->enabled) {

        fprintf(stderr, "FIXME: ptimer_set_period with running timer");

    }

    s->period = period;

    s->period_frac = 0;

}

/* Set counter frequency in Hz.  */

void ptimer_set_freq(ptimer_state *s, uint32_t freq)

{

    if (s->enabled) {

        fprintf(stderr, "FIXME: ptimer_set_freq with running timer");

    }

    s->period = 1000000000ll / freq;

    s->period_frac = (1000000000ll << 32) / freq;

}

/* Set the initial countdown value.  If reload is nonzero then also set

   count = limit.  */

void ptimer_set_limit(ptimer_state *s, uint32_t limit, int reload)

{

    if (s->enabled) {

        fprintf(stderr, "FIXME: ptimer_set_limit with running timer");

    }

    s->limit = limit;

    if (reload)

        s->delta = limit;

}

ptimer_state *ptimer_init(QEMUBH *bh)

{

    ptimer_state *s;

    s = (ptimer_state *)qemu_mallocz(sizeof(ptimer_state));

    s->bh = bh;

    s->timer = qemu_new_timer(vm_clock, ptimer_tick, s);

    return s;

}