// Shahir Ahmed and Boosung Kim
#include "../h/scheduler.h"

extern pcb_t* readyQueue; // tail pointer to the queue of ready pcbs
extern pcb_t* currentProcess; // pointer to the current executing process
extern int processCount; // number of started but not terminated processes
extern int softBlockCount; // number of soft blocked processes
cpu_t startTime;

void Scheduler() {
    currentProcess = removeProcQ(&readyQueue); 
    if (currentProcess != NULL) {
        // current process exists
        STCK(startTime);
        setTIMER(5000);
        LDST(&(currentProcess->p_s));
    } else {
        // ready queue is empty
        if (processCount == 0) {
            // halt and only respond to reset signal
            HALT();
        } else if (softBlockCount > 0 && processCount > 0) {
            // idle waiting for device interrupt to occur
            setSTATUS(0xff01); // 0000 0 0000 0 000000 11111111 00 000001
            WAIT();
        } else if (softBlockCount == 0 && processCount > 0) {
            // deadlock
            PANIC();
        }
    }
}