minix/include/minix/spin.h
2010-07-12 23:14:40 +00:00

38 lines
1,018 B
C

/* Prototypes for condition spinning helper functions (part of libsys). */
#ifndef _MINIX_SPIN_H
#define _MINIX_SPIN_H
/* Opaque spin state structure. */
typedef struct {
int s_state;
u32_t s_usecs;
u64_t s_base_tsc;
clock_t s_base_uptime;
int s_timeout;
} spin_t;
/* Functions. */
_PROTOTYPE( void spin_init, (spin_t *s, u32_t usecs) );
_PROTOTYPE( int spin_check, (spin_t *s) );
/* Macros. */
/* Execute a loop for at least 'u' microseconds, using spin object 's'.
* The body of the loop is guaranteed to be executed at least once.
*/
#define SPIN_FOR(s,u) \
for (spin_init((s), (u)); spin_check((s)); )
/* Return whether spin object 's' timed out after a loop. */
#define SPIN_TIMEOUT(s) ((s)->s_timeout)
/* Spin until the given condition becomes true, or 'u' microseconds expired.
* The condition is guaranteed to be checked at least once.
*/
#define SPIN_UNTIL(c,u) do { \
spin_t s; \
SPIN_FOR(&s,(u)) \
if (c) break; \
} while (0)
#endif /* _MINIX_SPIN_H */