source:
EcnlProtoTool/trunk/musl-1.1.18/src/thread/sem_trywait.c
Last change on this file was 444, checked in by , 4 years ago | |
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File size: 254 bytes |
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1 | #include <semaphore.h> |
2 | #include "pthread_impl.h" |
3 | |
4 | int sem_trywait(sem_t *sem) |
5 | { |
6 | int val; |
7 | while ((val=sem->__val[0]) > 0) { |
8 | int new = val-1-(val==1 && sem->__val[1]); |
9 | if (a_cas(sem->__val, val, new)==val) return 0; |
10 | } |
11 | errno = EAGAIN; |
12 | return -1; |
13 | } |
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