67 lines
1.4 KiB
C
67 lines
1.4 KiB
C
#include <stdlib.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <syscall.h>
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#include <syscall_nums.h>
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#include <signal.h>
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#include <pthread.h>
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#include <errno.h>
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#include <sys/wait.h>
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extern int __libc_is_multicore;
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static inline void _yield(void) {
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if (!__libc_is_multicore) syscall_yield();
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}
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#define ACQUIRE_LOCK() do { while (__sync_lock_test_and_set(&lock->atomic_lock, 0x01)) { _yield(); } } while (0)
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#define RELEASE_LOCK() do { __sync_lock_release(&lock->atomic_lock); } while (0)
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int pthread_rwlock_init(pthread_rwlock_t * lock, void * args) {
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lock->readers = 0;
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lock->atomic_lock = 0;
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if (args != NULL) {
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fprintf(stderr, "pthread: pthread_rwlock_init arg unsupported\n");
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return 1;
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}
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return 0;
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}
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int pthread_rwlock_wrlock(pthread_rwlock_t * lock) {
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ACQUIRE_LOCK();
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while (1) {
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if (lock->readers == 0) {
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lock->readers = -1;
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lock->writerPid = syscall_getpid();
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RELEASE_LOCK();
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return 0;
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}
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_yield();
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}
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}
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int pthread_rwlock_rdlock(pthread_rwlock_t * lock) {
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ACQUIRE_LOCK();
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while (1) {
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if (lock->readers >= 0) {
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lock->readers++;
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RELEASE_LOCK();
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return 0;
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}
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_yield();
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}
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}
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int pthread_rwlock_unlock(pthread_rwlock_t * lock) {
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ACQUIRE_LOCK();
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if (lock->readers > 0) lock->readers--;
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else if (lock->readers < 0) lock->readers = 0;
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else fprintf(stderr, "pthread: bad lock state detected\n");
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RELEASE_LOCK();
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return 0;
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}
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int pthread_rwlock_destroy(pthread_rwlock_t * lock) {
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return 0;
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}
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