#pragma once
// ke_sched.h - Multi-Level Feedback Queue scheduler
// Three run queues (Low / Normal / High). IRQ 0 drives KeSchedulerTick.
#include <ke_thread.h>

#define SCHED_TICK_MS                  10u
#define SCHED_HIGH_QUANTUM_TICKS        2u
#define SCHED_NORMAL_QUANTUM_TICKS      4u
#define SCHED_LOW_QUANTUM_TICKS         8u
#define SCHED_DEMOTE_AFTER_BURST_TICKS 16u
#define SCHED_AGING_INTERVAL_TICKS    100u

typedef struct KE_SCHED_STATS {
    uint64_t Ticks;
    uint64_t ContextSwitches;
    uint64_t KeepCurrentDecisions;
    uint64_t IdleSelections;
    uint64_t Demotions;
    uint64_t AgingPromotions;
    uint64_t QuantumExpirations;
    uint64_t PriorityPreemptions;
    uint64_t VoluntaryBlocks;
    uint64_t CpuBurstDemotions;
} KE_SCHED_STATS;

// Called once by KernelMain before any threads are created.
void    KeInitializeScheduler(void);

// Add / remove a thread from the run queues.
void    KeReadyThread(THREAD* thread);
void    KeUnreadyThread(THREAD* thread);

// Called from the timer ISR every SCHED_TICK_MS.  This performs timer
// accounting and requests a reschedule only when the current thread has
// exhausted its scheduler budget, or when idle work becomes available.  The
// actual context switch happens from
// KiExitInterrupt after the IRQ handler has returned and EOI has been sent.
void    KeSchedulerTick(void);

// Internal scheduler hooks used by the interrupt-exit path.  KiRequestReschedule
// is cheap and can be called from interrupt context.  KiScheduleFromInterrupt
// consumes the pending request and performs the context switch, if needed.
void    KiRequestReschedule(void);
int     KiIsReschedulePending(void);
void    KiScheduleFromInterrupt(void);
void    KiSchedulerNoteVoluntaryBlock(THREAD* thread);

// Voluntarily yield the CPU. Picks the next runnable thread immediately.
__declspec(dllexport) void KeYield(void);

void KeGetSchedulerStats(KE_SCHED_STATS* out);

// Returns the thread currently running on this CPU (reads GS:[0]).
THREAD* KeGetCurrentThread(void);

// Set the current-thread GS slot. Called once per CPU at boot.
void    KeSetCurrentThread(THREAD* thread);