#include <stddef.h>
#include <stdint.h>
#include <stdatomic.h>
#include <exec/list.h>
#include <exec/task.h>
#include <exec/sync.h>

void NewSemaphore(struct Semaphore *semaphore, int count, uint8_t type) {
    semaphore->count = count;
    semaphore->type = type;
}

void NewMutex(struct Semaphore *semaphore, uint8_t type) {
    NewSemaphore(semaphore, 1, type);
}

void Acquire(struct Semaphore *semaphore) {
    int expected;
    int semtype = (semaphore->type & 3);
    
    //if (!(semaphore->type & SF_NOTRECURSIVE) && semaphore->owner == ThisTask()) return;

    if (semtype == SF_CLI) {
        InterruptsSaveAndDisable();
    } else {
        for (;;) {
            expected = atomic_load_explicit(&semaphore->count, memory_order_relaxed);
            while (expected <= 0) {
                if (semtype == SF_BLOCK) {
                    Block(ThisTask(), &semaphore->count, expected);
                } else if ((semaphore->type & 3) == SF_NONE) {
                    return;
                }
                expected = atomic_load_explicit(&semaphore->count,
                    memory_order_relaxed);
            }
            if (atomic_compare_exchange_weak_explicit(
                    &semaphore->count, &expected, expected - 1,
                    memory_order_acquire, memory_order_relaxed)) {
                //if (!(semaphore->type & SF_NOTRECURSIVE)) semaphore->owner = ThisTask();
                return;
            }
        }
    }
}

void Release(struct Semaphore *semaphore) {
    if (semaphore->type == SF_CLI) {
        InterruptsRestore();
    } else {
        atomic_fetch_add_explicit(&semaphore->count, 1, memory_order_release);
    }
}