Implement a fixed queue.
Change-Id: Ifad7605d0b6e1a57f4767f9de1bed7e99284ded7
diff --git a/osi/src/semaphore.c b/osi/src/semaphore.c
new file mode 100644
index 0000000..a46c435
--- /dev/null
+++ b/osi/src/semaphore.c
@@ -0,0 +1,53 @@
+#define LOG_TAG "osi_semaphore"
+
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/eventfd.h>
+#include <utils/Log.h>
+
+#include "semaphore.h"
+
+#if !defined(EFD_SEMAPHORE)
+# define EFD_SEMAPHORE (1 << 0)
+#endif
+
+struct semaphore_t {
+ int fd;
+};
+
+semaphore_t *semaphore_new(unsigned int value) {
+ semaphore_t *ret = malloc(sizeof(semaphore_t));
+ if (ret) {
+ ret->fd = eventfd(value, EFD_SEMAPHORE);
+ if (ret->fd == -1) {
+ ALOGE("%s unable to allocate semaphore: %s", __func__, strerror(errno));
+ free(ret);
+ ret = NULL;
+ }
+ }
+ return ret;
+}
+
+void semaphore_free(semaphore_t *semaphore) {
+ if (semaphore->fd != -1)
+ close(semaphore->fd);
+ free(semaphore);
+}
+
+void semaphore_wait(semaphore_t *semaphore) {
+ assert(semaphore != NULL);
+ assert(semaphore->fd != -1);
+
+ uint64_t value;
+ if (eventfd_read(semaphore->fd, &value) == -1)
+ ALOGE("%s unable to wait on semaphore: %s", __func__, strerror(errno));
+}
+
+void semaphore_post(semaphore_t *semaphore) {
+ assert(semaphore != NULL);
+ assert(semaphore->fd != -1);
+
+ if (eventfd_write(semaphore->fd, 1ULL) == -1)
+ ALOGE("%s unable to post to semaphore: %s", __func__, strerror(errno));
+}