#include <kern/env.h>
#include <kern/pmap.h>
#include <kern/picirq.h>
#include <kern/printf.h>

#include "bochs.h"



// The real clock interrupt handler,
// implementing round-robin scheduling
void
sched_yield(void)
{  int i,j;
 
 if (curenv !=  NULL)
   i = curenv-envs;
 else
   i = 0;

 if (i == 0) {
   i++;  //  0 is the one we never want unless no choice.
 }

 //  Never even look at envs[0] here...
 for (j=i+1; j != i; j=((j%(NENV-1)) + 1))
   if (envs[j].env_status == ENV_RUNNABLE) {
     envs[j].env_runs += 1;
     env_run(&envs[j]);
     return;  //  errr
   }

 //  Stay in the same proc if none else was found
 if (envs[j].env_status == ENV_RUNNABLE) {
   env_run(&envs[j]); // stay in same environment
 } else if (envs[0].env_status == ENV_RUNNABLE) {
   //  Otherwise, switch back to idle process
   envs[0].env_runs += 1;
   env_run(&envs[0]); // switch to the idle process
 } else {
   //  Gah, idle process is busy!!
   panic("No environments left to run");
 }
}