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/* Project:     OSLib
 * Description: The OS Construction Kit
 * Date:                1.6.2000
 * Idea by:             Luca Abeni & Gerardo Lamastra
 *
 * OSLib is an SO project aimed at developing a common, easy-to-use
 * low-level infrastructure for developing OS kernels and Embedded
 * Applications; it partially derives from the HARTIK project but it
 * currently is independently developed.
 *
 * OSLib is distributed under GPL License, and some of its code has
 * been derived from the Linux kernel source; also some important
 * ideas come from studying the DJGPP go32 extender.
 *
 * We acknowledge the Linux Community, Free Software Foundation,
 * D.J. Delorie and all the other developers who believe in the
 * freedom of software and ideas.
 *
 * For legalese, check out the included GPL license.
 */

/*      Time Event routines     */

#include <ll/i386/stdlib.h>
#include <ll/i386/mem.h>
#include <ll/i386/error.h>
#include <ll/i386/hw-arch.h>
#include <ll/i386/pit.h>
#include <ll/sys/ll/ll-data.h>
#include <ll/sys/ll/ll-instr.h>
#include <ll/sys/ll/time.h>
#include <ll/sys/ll/event.h>

FILE(Event);

extern LL_ARCH ll_arch;

BYTE frc;

/* Timer 0 usec base tick */
DWORD ticksize;

/* Timer 0 loaded time constant (= ticksize * 1.197) */
WORD pit_time_const;
DWORD timermode;

static DWORD nts;               /* System tick in nanoSeconds... */
struct timespec actTime;        /* Time (in nanosecs)... */
extern int activeInt;

WORD lastTime;
struct pitspec globalCounter;

struct event eventlist[MAX_EVENT];

struct event *freeevents;
struct event *firstevent;

extern void *last_handler;
extern void (*evt_prol) (void);
extern void (*evt_epil) (void);

void event_setlasthandler(void *p)                                              {                                                                                       last_handler = p;                                                       }                                                                              

void event_setprologue(void *p)
{
    evt_prol = p;
}

void event_setepilogue(void *p)
{
    evt_epil = p;
}

/* Switched to timespec */
int periodic_event_post(struct timespec time, void (*handler) (void *p),
                        void *par)
{
    struct event *p;
    struct event *p1, *t;

    if (!freeevents) {
        return -1;
    }

    /* Extract from the ``free events'' queue */
    p = freeevents;
    freeevents = p->next;

    /* Fill the event fields */
    p->handler = handler;
    TIMESPEC_ASSIGN(&(p->time), &time);
    p->par = par;

    /* ...And insert it in the event queue!!! */

    t = NULL;
    /* walk through list, finding spot, adjusting ticks parameter */
    for (p1 = firstevent; p1; p1 = t->next) {
/*
                SUBTIMESPEC(&time, &(p1->time), &tmp);
                if ((tmp.tv_sec > 0) && (tmp.tv_nsec > 0)) {
*/
        if (TIMESPEC_A_GT_B(&time, &p1->time))
            t = p1;
        else
            break;
    }

    /* adjust next entry */
    if (t) {
        t->next = p;
    } else {
        firstevent = p;
    }
    p->next = p1;

    return p->index;
}

int periodic_event_delete(int index)
{
    struct event *p1, *t;

    t = NULL;
    /* walk through list, finding spot, adjusting ticks parameter */
    for (p1 = firstevent; (p1) && (index != p1->index); p1 = t->next) {
        t = p1;
    }

    if (p1 == NULL) {
        return -1;
    }

    if (t == NULL) {
        firstevent = p1->next;
    } else {
        t->next = p1->next;
    }
    p1->next = freeevents;
    freeevents = p1;

    return 1;
}

void periodic_wake_up(void)
{                               /* CHANGE the NAME, please... */
    struct event *p, *pp;
    WORD tmp;

    tmp = pit_read(frc);
    ADDPITSPEC((WORD) (lastTime - tmp), &globalCounter);
    lastTime = tmp;

    activeInt++;
    if (activeInt == 1 && evt_prol != NULL) {
        evt_prol();
    }

    ADDNANO2TIMESPEC(nts, &actTime);

    for (p = firstevent; p != NULL; p = pp) {
/*
                SUBTIMESPEC(&(p->time), &actTime, &tmp);
                if ((tmp.tv_sec > 0) && (tmp.tv_nsec > 0)) {
                        break;
                } */
        if ((p->time.tv_sec > actTime.tv_sec) ||
            ((p->time.tv_sec == actTime.tv_sec)
             && (p->time.tv_nsec > actTime.tv_nsec))) {
            break;
        }
        pp = p->next;
        p->next = freeevents;
        freeevents = p;
        firstevent = pp;
        p->handler(p->par);
    }

    if (activeInt == 1 && evt_epil != NULL) {
        evt_epil();
    }
    activeInt--;
}

void event_init(struct ll_initparms *l)
{
    extern void ll_timer(void);
    int i;
    BYTE mask;
    TIME t;

    IDT_place(0x40, ll_timer);

    if (l->mode != LL_PERIODIC) {
        message("One-shot timer selected...\n");
        t = 0;
        /* Mode: Binary/Mode 4/16 bit Time_const/Counter 0 */
        pit_init(0, TMR_MD4, 0xFFFF);   /* Timer 0, Mode 4, constant 0xFFFF */
    } else {
        message("Periodic timer selected...\n");
        t = l->tick;
        /* Translate the tick value in usec into a suitable time constant   */
        /* for 8254 timer chip; the chip is driven with a 1.19718 MHz       */
        /* frequency; then the effective frequency is given by the base     */
        /* frequency divided for the time constant; the tick is the inverse */
        /* of this effective frequency (in usec!)                           */
        /* Time-Constant = f_base (MHz) * tick (usec)                       */
        /* If T-C == 0 -> T-C = 65536 (Max available)                       */
        ticksize = t;
        t = t * 1197;
        t = t / 1000;
        /* Only for security! This should cause timer overrun */
        /* While 0 would set maximum period on timer          */
        if (t == 0)
            t = 1;
        pit_time_const = (WORD) (t & 0xFFFF);
        /* Mode: Binary/Mode 2/16 bit Time_const/Counter 0 */
        pit_init(0, TMR_MD2, t);        /* Timer 0, Mode 2, Time constant t */


    }
    timermode = l->mode;

    if (ll_arch.x86.cpu > 4) {
        /* Timer1: mode 0, time const 0... */
        pit_init(1, TMR_MD0, 0);
        frc = 1;
    } else {
        frc = 2;
        pit_init(2, TMR_MD0, 0);
        outp(0x61, 3);
    }

    mask = ll_in(0x21);
    mask &= 0xFE;               /* 0xFE = ~0x01 */
    ll_out(0x21, mask);


    /* Init the event list... */
    for (i = 0; i < MAX_EVENT; i++) {
        if (i < MAX_EVENT - 1) {
            eventlist[i].next = &(eventlist[i + 1]);
        }
        eventlist[i].index = i;
    }
    eventlist[MAX_EVENT - 1].next = NULL;
    freeevents = &(eventlist[0]);

    evt_prol = NULL;
    evt_epil = NULL;

    /* Initialization of the time variables for periodic mode */
    nts = ticksize * 1000;
    NULL_TIMESPEC(&actTime);

    /* Initialization of the general time variables */
    NULLPITSPEC(&globalCounter);
    lastTime = 0;

    if (timermode == LL_PERIODIC) {
        event_post = periodic_event_post;
        event_delete = periodic_event_delete;
    } else {
        event_post = oneshot_event_post;
        event_delete = oneshot_event_delete;
    }
}