nt-lite/code/kernel/ke_event.c

// ke_event.c - synchronisation events
#include "ke_event.h"
#include "ke_thread.h"
#include "ke_sched.h"
#include "ob_object.h"

static void EventDestroy(OBJECT* obj) { (void)obj; }

KSTATUS KeEventCreate(EVENT_TYPE type, uint32_t initialState, EVENT **out) {
    if (!out) return STATUS_INVALID_PARAMETER;
    EVENT* e = (EVENT *)ObAllocateObject(ObjectTypeEvent, sizeof(EVENT));
    if (!e)  return STATUS_NO_MEMORY;
    e->Header.Destroy = EventDestroy;
    e->Lock     = (SPINLOCK)SPINLOCK_INIT;
    e->Type     = type;
    e->Signaled = initialState ? 1 : 0;
    LIST_INIT(&e->WaitList);
    *out = e;
    return STATUS_SUCCESS;
}

void KeSignalEvent(EVENT* event) {
    if (!event) return;
    KeAcquireSpinlock(&event->Lock);

    if (event->Type == EventManualReset) {
        // Wake all waiters.
        event->Signaled = 1;
        while (!LIST_IS_EMPTY(&event->WaitList)) {
            LIST_ENTRY* node = ListPopHead(&event->WaitList);
            THREAD* t = CONTAINING_RECORD(node, THREAD, SchedulerLink);
            KeReleaseSpinlock(&event->Lock);
            KeUnblockThread(t);
            KeAcquireSpinlock(&event->Lock);
        }
    } else {
        // Auto-reset: wake one waiter or set the flag for the next waiter.
        if (!LIST_IS_EMPTY(&event->WaitList)) {
            LIST_ENTRY* node = ListPopHead(&event->WaitList);
            THREAD* t = CONTAINING_RECORD(node, THREAD, SchedulerLink);
            KeReleaseSpinlock(&event->Lock);
            KeUnblockThread(t);
            return;
        }
        event->Signaled = 1;
    }
    KeReleaseSpinlock(&event->Lock);
}

void KeClearEvent(EVENT* event) {
    if (!event) return;
    KeAcquireSpinlock(&event->Lock);
    event->Signaled = 0;
    KeReleaseSpinlock(&event->Lock);
}

KSTATUS KeWaitForEvent(EVENT* event) {
    if (!event) return STATUS_INVALID_PARAMETER;
    THREAD* self = KeCurrentThread();

    for (;;) {
        KeAcquireSpinlock(&event->Lock);
        if (event->Signaled) {
            if (event->Type == EventAutoReset) event->Signaled = 0;
            KeReleaseSpinlock(&event->Lock);
            return STATUS_SUCCESS;
        }
        ListInsertTail(&event->WaitList, &self->SchedulerLink);
        KeReleaseSpinlock(&event->Lock);
        KeBlockThread(self, &event->Header);
    }
}