/*
 * (C) 2022, Cornell University
 * All rights reserved.
 */

/* Author: Yunhao Zhang
 * Description: process util functions
 */

#include "egos.h"
#include "grass.h"
#include <string.h>

static int proc_nprocs;
extern int proc_curr_idx;
extern struct process proc_set[MAX_NPROCESS];

void intr_entry(int id);

void proc_init() {
    earth->intr_register(intr_entry);

    proc_nprocs = 0;
    memset(proc_set, 0, sizeof(struct process) * MAX_NPROCESS);

    /* the first process is now running */
    proc_alloc();
    proc_curr_idx = 0;
    proc_set_running(PID(proc_curr_idx));
}

int proc_alloc() {
    proc_nprocs++;
    for (int i = 0; i < MAX_NPROCESS; i++) {
        if (proc_set[i].pid == 0) {
            proc_set[i].pid = proc_nprocs;
            proc_set[i].status = PROC_UNUSED;
            return proc_nprocs;
        }
    }
    FATAL("Reach the limit of %d processes", MAX_NPROCESS);
    return -1;
}

void proc_free(int pid) {
    FATAL("proc_free not implemented");
}

static void proc_set_status(int pid, int status) {
    for (int i = 0; i < MAX_NPROCESS; i++) {
        if (proc_set[i].pid == pid) {
            proc_set[i].status = status;
            return;
        }
    }
}

void proc_set_ready(int pid) {
    proc_set_status(pid, PROC_READY);
}

void proc_set_running(int pid) {
    proc_set_status(pid, PROC_RUNNING);
}

void proc_set_runnable(int pid) {
    proc_set_status(pid, PROC_RUNNABLE);
}