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yap-6.3/OPTYap/locks_x86.h

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/************************************************************************
** **
** The YapTab/YapOr/OPTYap systems **
** **
** YapTab extends the Yap Prolog engine to support sequential tabling **
** YapOr extends the Yap Prolog engine to support or-parallelism **
** OPTYap extends the Yap Prolog engine to support or-parallel tabling **
** **
** **
** YAP Prolog was developed at University of Porto, Portugal **
** **
************************************************************************/
/************************************************************************
** Atomic locks for X86 **
************************************************************************/
typedef struct {
volatile unsigned int lock;
} spinlock_t;
static inline int
spin_trylock(spinlock_t *lock)
{
char tmp = 1;
__asm__ __volatile__(
"xchgb %b0, %1"
: "=q"(tmp), "=m"(lock->lock)
: "0"(tmp) : "memory");
return tmp == 0;
}
static inline void
spin_unlock(spinlock_t *lock)
{
/* To unlock we move 0 to the lock.
* On i386 this needs to be a locked operation
* to avoid Pentium Pro errata 66 and 92.
*/
#if defined(__x86_64__)
__asm__ __volatile__("" : : : "memory");
*(unsigned char*)&lock->lock = 0;
#else
char tmp = 0;
__asm__ __volatile__(
"xchgb %b0, %1"
: "=q"(tmp), "=m"(lock->lock)
: "0"(tmp) : "memory");
#endif
}
#define INIT_LOCK(LOCK_VAR) ((LOCK_VAR) = 0)
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#define TRY_LOCK(LOCK_VAR) spin_trylock((spinlock_t *)(LOCK_VAR))
//#define DEBUG_LOCKS 1
#if DEBUG_LOCKS
extern int debug_locks;
#define LOCK(LOCK_VAR) do { \
if (debug_locks) fprintf(stderr,"[%d] %s:%d: LOCK(%p)\n", \
(int)pthread_self(), \
__BASE_FILE__, __LINE__,&(LOCK_VAR)); \
if (TRY_LOCK(&(LOCK_VAR))) break; \
while (IS_LOCKED(LOCK_VAR)) continue; \
} while (1)
#define IS_LOCKED(LOCK_VAR) ((LOCK_VAR) != 0)
#define IS_UNLOCKED(LOCK_VAR) ((LOCK_VAR) == 0)
#define UNLOCK(LOCK_VAR) if (debug_locks) fprintf(stderr,"[%d] %s:%d: UNLOCK(%p)\n", \
(int)pthread_self(), \
__BASE_FILE__, __LINE__,&(LOCK_VAR)); \
spin_unlock((spinlock_t *)&(LOCK_VAR))
#else
#define LOCK(LOCK_VAR) do { \
if (TRY_LOCK(&(LOCK_VAR))) break; \
while (IS_LOCKED(LOCK_VAR)) continue; \
} while (1)
#define IS_LOCKED(LOCK_VAR) ((LOCK_VAR) != 0)
#define IS_UNLOCKED(LOCK_VAR) ((LOCK_VAR) == 0)
#define UNLOCK(LOCK_VAR) spin_unlock((spinlock_t *)&(LOCK_VAR))
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#endif
/* the code that follows has been adapted from the Erlang sources */
typedef struct {
volatile int lock;
} rwlock_t;
#define RWLOCK_OFFSET (1<<24)
static inline void
init_rwlock(rwlock_t *lock)
{
lock->lock = 0;
}
static inline void
read_unlock(rwlock_t *lock)
{
__asm__ __volatile__(
"lock; decl %0"
: "=m"(lock->lock)
: "m"(lock->lock)
);
}
static inline int
read_trylock(rwlock_t *lock)
{
int tmp;
tmp = 1;
__asm__ __volatile__(
"lock; xaddl %0, %1"
: "=r"(tmp)
: "m"(lock->lock), "0"(tmp));
/* tmp is now the lock's previous value */
if (__builtin_expect(tmp >= 0, 1))
return 1;
read_unlock(lock);
return 0;
}
static inline int
read_is_locked(rwlock_t *lock)
{
return lock->lock < 0;
}
static inline void
read_lock(rwlock_t *lock)
{
for(;;) {
if (__builtin_expect(read_trylock(lock) != 0, 1))
break;
do {
__asm__ __volatile__("rep;nop" : "=m"(lock->lock) : : "memory");
} while (read_is_locked(lock));
}
}
static inline void
write_unlock(rwlock_t *lock)
{
__asm__ __volatile__(
"lock; addl %2,%0"
: "=m"(lock->lock)
: "m"(lock->lock), "i"(RWLOCK_OFFSET));
}
static inline int
write_trylock(rwlock_t *lock)
{
int tmp;
tmp = -RWLOCK_OFFSET;
__asm__ __volatile__(
"lock; xaddl %0, %1"
: "=r"(tmp)
: "m"(lock->lock), "0"(tmp));
/* tmp is now the lock's previous value */
if (__builtin_expect(tmp == 0, 1))
return 1;
write_unlock(lock);
return 0;
}
static inline int
write_is_locked(rwlock_t *lock)
{
return lock->lock != 0;
}
static inline void
write_lock(rwlock_t *lock)
{
for(;;) {
if (__builtin_expect(write_trylock(lock) != 0, 1))
break;
do {
__asm__ __volatile__("rep;nop" : "=m"(lock->lock) : : "memory");
} while (write_is_locked(lock));
}
}
#define INIT_RWLOCK(lock) init_rwlock(&(lock))
#define READ_LOCK(lock) read_lock(&(lock))
#define READ_UNLOCK(lock) read_unlock(&(lock))
#define WRITE_LOCK(lock) write_lock(&(lock))
#define WRITE_UNLOCK(lock) write_unlock(&(lock))
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#if THREADS
/* pthread mutex */
#if DEBUG_LOCKS
#define MUTEX_LOCK(LOCK_VAR) ((debug_locks ? fprintf(stderr,"[%d] %s:%d: MULOCK(%p)\n", (int)pthread_self(), \
__BASE_FILE__, __LINE__,(LOCK_VAR)) : 1), \
pthread_mutex_lock((LOCK_VAR)) )
#define MUTEX_TRYLOCK(LOCK_VAR) pthread_mutex_trylock(LOCK_VAR)
#define MUTEX_UNLOCK(LOCK_VAR) if ((debug_locks ? fprintf(stderr,"[%d] %s:%d: MUNLOCK(%p)\n", (int)pthread_self(), \
__BASE_FILE__, __LINE__,(LOCK_VAR)) : 1), \
pthread_mutex_unlock((LOCK_VAR)) )
#else
#define MUTEX_LOCK(LOCK_VAR) pthread_mutex_lock(LOCK_VAR)
#define MUTEX_TRYLOCK(LOCK_VAR) pthread_mutex_trylock(LOCK_VAR)
#define MUTEX_UNLOCK(LOCK_VAR) pthread_mutex_unlock(LOCK_VAR)
#endif
#else
#define MUTEX_LOCK(LOCK_VAR)
#define MUTEX_TRYLOCK(LOCK_VAR)
#define MUTEX_UNLOCK(LOCK_VAR)
#endif