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28 /*=============================================================================
29 VideoCore OS Abstraction Layer - named semaphores
30 =============================================================================*/
32 #ifndef VCOS_NAMED_SEMAPHORE_H
33 #define VCOS_NAMED_SEMAPHORE_H
39 #include "interface/vcos/vcos_types.h"
45 * Create a named semaphore, or open an existing one by name.
50 * \brief Create a named semaphore.
52 * Semaphores are not re-entrant.
54 * @param sem Pointer to memory to be initialized
55 * @param name A name for this semaphore.
56 * @param count The initial count for the semaphore.
58 * @return VCOS_SUCCESS if the semaphore was created.
62 VCOS_STATUS_T vcos_named_semaphore_create(VCOS_NAMED_SEMAPHORE_T *sem, const char *name, VCOS_UNSIGNED count);
65 * \brief Wait on a named semaphore.
67 * There is no timeout option on a semaphore, as adding this will slow down
68 * implementations on some platforms. If you need that kind of behaviour, use
71 * This always returns VCOS_SUCCESS and so should really be a void function. However
72 * too many lines of code would need to be changed in non-trivial ways, so for now
75 * @param sem Semaphore to wait on
76 * @return VCOS_SUCCESS - semaphore was taken.
80 void vcos_named_semaphore_wait(VCOS_NAMED_SEMAPHORE_T *sem);
83 * \brief Try to wait for a semaphore.
85 * Try to obtain the semaphore. If it is already taken, return VCOS_TIMEOUT.
86 * @param sem Semaphore to wait on
87 * @return VCOS_SUCCESS - semaphore was taken.
88 * VCOS_EAGAIN - could not take semaphore
91 VCOS_STATUS_T vcos_named_semaphore_trywait(VCOS_NAMED_SEMAPHORE_T *sem);
94 * \brief Post a semaphore.
96 * @param sem Semaphore to wait on
99 void vcos_named_semaphore_post(VCOS_NAMED_SEMAPHORE_T *sem);
102 * \brief Delete a semaphore, releasing any resources consumed by it.
104 * @param sem Semaphore to wait on
106 void vcos_named_semaphore_delete(VCOS_NAMED_SEMAPHORE_T *sem);