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74 lines
3.4 KiB
C
74 lines
3.4 KiB
C
#ifndef COSMOPOLITAN_LIBC_INTRIN_SPINLOCK_H_
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#define COSMOPOLITAN_LIBC_INTRIN_SPINLOCK_H_
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/*───────────────────────────────────────────────────────────────────────────│─╗
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│ cosmopolitan § spinlocks ─╬─│┼
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╚────────────────────────────────────────────────────────────────────────────│─╝
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fast tiny inline synchronization routines */
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#ifdef TINY
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#define _spinlock(lock) _spinlock_tiny(lock)
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#else
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#define _spinlock(lock) _spinlock_cooperative(lock)
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#endif
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#define _spunlock(lock) __atomic_store_n(lock, 0, __ATOMIC_RELAXED)
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#define _seizelock(lock, value) \
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({ \
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autotype(lock) __lock = (lock); \
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typeof(*__lock) __x = (value); \
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__atomic_store(__lock, &__x, __ATOMIC_RELEASE); \
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})
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#define _spinlock_tiny(lock) \
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({ \
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while (_trylock(lock)) { \
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__builtin_ia32_pause(); \
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} \
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0; \
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})
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#define _spinlock_cooperative(lock) \
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({ \
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char __x; \
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unsigned __tries = 0; \
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char *__lock = (lock); \
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for (;;) { \
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__atomic_load(__lock, &__x, __ATOMIC_RELAXED); \
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if (!__x && !_trylock(__lock)) { \
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break; \
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} else if (++__tries & 7) { \
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__builtin_ia32_pause(); \
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} else { \
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_spinlock_yield(); \
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} \
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} \
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0; \
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})
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#define _spinlock_cooperative_(lock) \
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({ \
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char __x; \
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volatile int __i; \
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unsigned __tries = 0; \
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char *__lock = (lock); \
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for (;;) { \
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__atomic_load(__lock, &__x, __ATOMIC_RELAXED); \
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if (!__x && !_trylock(__lock)) { \
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break; \
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} else if (__tries < 7) { \
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for (__i = 0; __i != 1 << __tries; __i++) { \
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} \
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__tries++; \
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} else { \
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_spinlock_yield(); \
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} \
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} \
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0; \
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})
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#define _trylock(lock) __atomic_test_and_set(lock, __ATOMIC_SEQ_CST)
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void _spinlock_yield(void);
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#endif /* COSMOPOLITAN_LIBC_INTRIN_SPINLOCK_H_ */
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