#ifndef __TRIGGER_H_
#define __TRIGGER_H_ 1
#include "util/debug.h"
#include "asm/bug.h"
/*
* Use trigger to model operations which need to be executed when
* an event (a signal, for example) is observed.
*
* States and transits:
*
*
* OFF--(on)--> READY --(hit)--> HIT
* ^ |
* | (ready)
* | |
* \_____________/
*
* is_hit and is_ready are two key functions to query the state of
* a trigger. is_hit means the event already happen; is_ready means the
* trigger is waiting for the event.
*/
struct trigger {
volatile enum {
TRIGGER_ERROR = -2,
TRIGGER_OFF = -1,
TRIGGER_READY = 0,
TRIGGER_HIT = 1,
} state;
const char *name;
};
#define TRIGGER_WARN_ONCE(t, exp) \
WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \
t->name, t->state, __func__)
static inline bool trigger_is_available(struct trigger *t)
{
return t->state >= 0;
}
static inline bool trigger_is_error(struct trigger *t)
{
return t->state <= TRIGGER_ERROR;
}
static inline void trigger_on(struct trigger *t)
{
TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
t->state = TRIGGER_READY;
}
static inline void trigger_ready(struct trigger *t)
{
if (!trigger_is_available(t))
return;
t->state = TRIGGER_READY;
}
static inline void trigger_hit(struct trigger *t)
{
if (!trigger_is_available(t))
return;
TRIGGER_WARN_ONCE(t, TRIGGER_READY);
t->state = TRIGGER_HIT;
}
static inline void trigger_off(struct trigger *t)
{
if (!trigger_is_available(t))
return;
t->state = TRIGGER_OFF;
}
static inline void trigger_error(struct trigger *t)
{
t->state = TRIGGER_ERROR;
}
static inline bool trigger_is_ready(struct trigger *t)
{
return t->state == TRIGGER_READY;
}
static inline bool trigger_is_hit(struct trigger *t)
{
return t->state == TRIGGER_HIT;
}
#define DEFINE_TRIGGER(n) \
struct trigger n = {.state = TRIGGER_OFF, .name = #n}
#endif
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