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1 files changed, 78 insertions, 0 deletions

diff --git a/operating-system-experiment/Semaphore.cpp b/operating-system-experiment/Semaphore.cpp
new file mode 100644
index 0000000..e8221fd
--- /dev/null
+++ b/operating-system-experiment/Semaphore.cpp
@@ -0,0 +1,78 @@
+#include "Semaphore.h"
+
+#include <cassert>
+
+#ifndef CRU_WINDOWS
+#include <errno.h>
+#endif
+
+namespace cru {
+Semaphore::Semaphore(unsigned init_value) {
+#ifdef CRU_WINDOWS
+#else
+  semaphore_ = std::make_unique<sem_t>();
+  auto c = sem_init(semaphore_.get(), 0, init_value);
+  assert(c == 0);
+#endif
+}
+
+Semaphore::Semaphore(Semaphore &&other)
+#ifdef CRU_WINDOWS
+#else
+    : semaphore_(std::move(other.semaphore_))
+#endif
+{
+}
+
+Semaphore &Semaphore::operator=(Semaphore &&other) {
+  if (this != &other) {
+    Destroy();
+#ifdef CRU_WINDOWS
+#else
+    semaphore_ = std::move(other.semaphore_);
+#endif
+  }
+  return *this;
+}
+
+Semaphore::~Semaphore() { Destroy(); }
+
+void Semaphore::P() { Acquire(); }
+void Semaphore::V() { Release(); }
+
+void Semaphore::Acquire() {
+#ifdef CRU_WINDOWS
+#else
+  auto c = sem_wait(semaphore_.get());
+  assert(c == 0);
+#endif
+}
+
+bool Semaphore::TryAcquire() {
+#ifdef CRU_WINDOWS
+#else
+  auto c = sem_trywait(semaphore_.get());
+  assert((c == 0) || (c == -1 && errno == EAGAIN));
+  return c == 0 ? true : false;
+#endif
+}
+
+void Semaphore::Release() {
+#ifdef CRU_WINDOWS
+#else
+  auto c = sem_post(semaphore_.get());
+  assert(c == 0);
+#endif
+}
+
+void Semaphore::Destroy() {
+#ifdef CRU_WINDOWS
+#else
+  if (semaphore_ != nullptr) {
+    auto c = sem_destroy(semaphore_.get());
+    assert(c == 0);
+    semaphore_ = nullptr;
+  }
+#endif
+}
+} // namespace cru
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