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#ifndef DEVICES_INTQ_H
#define DEVICES_INTQ_H
#include "threads/interrupt.h"
#include "threads/synch.h"
/* An "interrupt queue", a circular buffer shared between
kernel threads and external interrupt handlers.
Interrupt queue functions can be called from kernel threads or
from external interrupt handlers. Except for intq_init(),
interrupts must be off in either case.
The interrupt queue has the structure of a "monitor". Locks
and condition variables from threads/synch.h cannot be used in
this case, as they normally would, because they can only
protect kernel threads from one another, not from interrupt
handlers. */
/* Queue buffer size, in bytes. */
#define INTQ_BUFSIZE 64
/* A circular queue of bytes. */
struct intq
{
/* Waiting threads. */
struct lock lock; /* Only one thread may wait at once. */
struct thread *not_full; /* Thread waiting for not-full condition. */
struct thread *not_empty; /* Thread waiting for not-empty condition. */
/* Queue. */
uint8_t buf[INTQ_BUFSIZE]; /* Buffer. */
int head; /* New data is written here. */
int tail; /* Old data is read here. */
};
void intq_init (struct intq *);
bool intq_empty (const struct intq *);
bool intq_full (const struct intq *);
uint8_t intq_getc (struct intq *);
void intq_putc (struct intq *, uint8_t);
#endif /* devices/intq.h */
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