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#include "scheduler.h"
#include "api/error.h"
#include "hal/smp.h"
#include "sys/objdir.h"
#include "proc/init.h"
#include "proc/process.h"
//TODO: Better scheduling algorithm than round robin.
static struct pcb_header *s_running_list;
static struct pcb_header *s_ready_queue;
static struct pcb_header *s_mail_queue;
static uintmax_t s_this_tick;
static inline void
s_scheduler_swap_pcb(processor_t *proc, pcb_t *current_pcb, pcb_t *target_pcb)
{
jove_owned_obj_t *target_rootdir = obj_take(pcb_getrootdir(target_pcb));
jove_owned_obj_t *target_pcb_obj = pcb_getself(target_rootdir);
obj_release(target_rootdir);
processor_setpcb(proc, target_pcb_obj);
_scheduler_switch_pcb_arch(target_pcb);
scheduler_switch(pcb_getksp_ref(current_pcb), pcb_getksp(target_pcb));
}
int scheduler_yield(pid_t target_pid)
{
processor_t *proc = processor_current();
pcb_t *current_pcb = obj_deref(processor_getpcb(proc));
pcb_t *target_pcb = (pcb_t*)((struct pcb_header*)current_pcb)->sched_next;
if(target_pid != 0) {
pcb_t *target_pcb = pcb_frompid(target_pid);
}
if(target_pcb == 0) {
return -EBADPROC;
}
scheduler_savestate();
s_scheduler_swap_pcb(proc, current_pcb, target_pcb);
scheduler_restorestate();
return 0;
}
void
s_enqueue_pcb(struct pcb_header *pcb, struct pcb_header *list)
{
if(pcb->sched_prev) pcb->sched_prev->sched_next = pcb->sched_next;
if(pcb->sched_prev) pcb->sched_next->sched_prev = pcb->sched_prev;
list->sched_prev = pcb;
pcb->sched_next = list;
pcb->sched_prev = NULL;
}
void
scheduler_block_for_mail(struct pcb_header *pcb, uintmax_t timeout, pid_t yield_target)
{
pcb->state = PCB_STATE_BLOCKED_MAIL;
s_enqueue_pcb(pcb, s_mail_queue);
s_mail_queue = pcb;
pcb->block_until = s_this_tick + timeout;
scheduler_yield(yield_target);
}
void
s_schedule_ready_queue(void)
{
for(struct pcb_header *pcb = s_ready_queue; pcb; pcb = s_ready_queue) {
s_ready_queue = pcb->sched_next;
//Add this process to the ready list after the last ready process.
pcb->state = PCB_STATE_READY;
s_enqueue_pcb(pcb, s_running_list);
s_running_list = pcb;
}
}
void
s_schedule_mail_queue(void)
{
struct pcb_header *pcb = s_mail_queue;
while(pcb) {
struct pcb_header *next_pcb = pcb->sched_next;
if(pcb->send.obj) {
struct pcb_header *send_target = (struct pcb_header*)pcb_frompid(pcb->send.pid);
if(send_target->recv.pid == 0 || send_target->recv.pid == pcb->pid) {
objdir_swapobj(send_target->recv.obj, pcb->send.obj);
send_target->recv.pid = pcb->pid;
s_enqueue_pcb(pcb, s_running_list);
s_running_list = pcb;
goto loop_end;
}
}
if(pcb->recv.obj) {
s_enqueue_pcb(pcb, s_running_list);
s_running_list = pcb;
goto loop_end;
}
if(s_this_tick >= pcb->block_until) {
s_enqueue_pcb(pcb, s_running_list);
s_running_list = pcb;
}
loop_end:
pcb = next_pcb;
}
}
void
scheduler_tick()
{
size_t last_tick = s_this_tick++;
s_schedule_ready_queue();
s_schedule_mail_queue();
processor_t *proc = processor_current();
struct pcb_header *current_pcb = obj_deref(processor_getpcb(proc));
struct pcb_header *next_pcb = s_running_list;
struct pcb_header *tail = next_pcb;
while(tail->sched_next) {
tail = tail->sched_next;
if(tail == next_pcb) break;
}
tail->sched_next = next_pcb;
next_pcb->sched_prev = tail;
s_running_list = next_pcb->sched_next;
s_scheduler_swap_pcb(proc, (pcb_t*)current_pcb, (pcb_t*)next_pcb);
}
void scheduler_init(jove_owned_obj_t *pcb_obj, void *process_main)
{
struct pcb_header *pcb_header = obj_deref(pcb_obj);
pcb_header->state = PCB_STATE_RUNNING;
processor_t *proc = processor_current();
processor_setpcb(proc, pcb_obj);
s_running_list = pcb_header;
__asm__("movq %0, %%rsp; \
xorq %%rbp, %%rbp; \
jmp %1"::
"m"(pcb_header->ksp), "r"(process_main));
}
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