path: root/kernel/sched/sched.c

#include "sched/sched.h"
#include "sched/idle.h"
#include "mcu/sched/context.h"

struct tcb_t* volatile current = 0;
DECLARE_TASK(idle, IDLE_STACK_SIZE, idle_entry);

struct list_head ready = LIST_HEAD_INIT(ready);
char* volatile kstack;

static void init_idle() {
  idle.sp = init_stack(idle.mem_low, idle.mem_high, idle.entry, 0);
  INIT_LIST_HEAD(&idle.q);
}

void sched_init() {
  init_kstack((char **) &kstack);
  init_idle();
  schedule();
  sei();
  RESTORE_CONTEXT();
  RETURN();
}

void schedule() {
  if(!list_empty(&ready)) {
    current = list_entry(ready.next, struct tcb_t, q);
    list_move_tail(&current->q, &ready);
  } else {
    current = &idle;
  }
}

void spawn(struct tcb_t* const tcb, char args) {
  tcb->sp = init_stack(tcb->mem_low, tcb->mem_high, tcb->entry, args);
  INIT_LIST_HEAD(&tcb->q);
  list_add_tail(&tcb->q, &ready);
}

void yield(void) {
  SAVE_CONTEXT();
  schedule();
  RESTORE_CONTEXT();
  asm volatile ( "ret" );
}

void freeze() {
  SAVE_CONTEXT();
  list_del_init(&current->q);
  schedule();
  RESTORE_CONTEXT();
  asm volatile ( "ret" );
}