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#ifndef SCHED_H
#define SCHED_H
#include "collection/list.h"
#include "mcu/sched/context.h"
/** Proposed default stack size, you may use this definition for declaring tasks. */
#define STACK_SIZE 256
/** Stack size to be allocated for the idle task. */
#define IDLE_STACK_SIZE 64
/**
* Task control block, contains runtime
* information about tasks.
*/
struct tcb_t {
/** Stack pointer of this task. (must be first in structure) */
char* volatile sp;
/** Lowest address of this task's memory (inclusive). */
char* mem_low;
/** Highest address of this task's memory (inclusive). */
char* mem_high;
/** Entry function of this task. */
void (*entry)(char);
/** Current wait queue that this task is in. */
struct list_head q;
long sleep_left;
};
/**
* Utility for declaring a task with statically allocated memory.
* Note: for a task to be scheduled, it must first be spawned (see spawn()).
*/
#define DECLARE_TASK(name, stack_size, entry_function) \
static char declared_stack_##name[stack_size]; \
static struct tcb_t name = { \
.sp = 0, \
.mem_low = declared_stack_##name, \
.mem_high = declared_stack_##name + stack_size - 1, \
.entry = entry_function, \
.q = {}, \
.sleep_left = 0 \
};
/**
* Points to currently executing task. If no scheduling has been enabled,
* this points to NULL
*/
extern struct tcb_t* volatile current;
/**
* Queue that contains all tasks that are ready to be run, awaiting their
* turn from the scheduler.
*/
extern struct list_head ready;
/**
* Stack pointer for operations performed out of task context, including any
* calls made after SAVE_CONTEXT().
*/
extern char* volatile kstack;
/**
* Makes the current task sleep on a specific queue.
* This moves the current task to the given queue's tail.
*/
static inline void sleep_on(struct list_head* queue) {
list_move_tail(¤t->q, queue);
}
/**
* Wakes all tasks waiting in the given queue.
* This moves all tasks contained in the queue to the ready queue.
*/
void wake_all(struct list_head* queue);
/**
* Initializes the scheduler by setting up kstack, initializing the idle task
* and selecting the first task to run.
*/
void sched_init();
/**
* Enters the scheduler, setting current to the next runnable task.
*/
void schedule();
/**
* Ticks the scheduler.
*/
void sched_tick();
/**
* Initializes a given task and adds it to the ready queue.
*/
void spawn(struct tcb_t* const tcb, char args);
/**
* Voluntarily yields control of the CPU to the scheduler.
*/
void yield() __attribute__ ( ( naked ) );
void sleep(long ms) __attribute__ ( ( naked) );
#define ENTER_CRITICAL() cli()
#define EXIT_CRITICAL() sei()
#endif
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