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