From 6b9fdc6ad3ac84cf8b8543b6e46b0ca8c4d61860 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 31 Jul 2021 17:14:21 +0100
Subject: Build a basic hacky semaphore for compilers that don't support
 std::binary_semaphore yet

---
 test/semaphore.cpp | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 test/semaphore.cpp

(limited to 'test/semaphore.cpp')

diff --git a/test/semaphore.cpp b/test/semaphore.cpp
new file mode 100644
index 0000000..09124ee
--- /dev/null
+++ b/test/semaphore.cpp
@@ -0,0 +1,37 @@
+#include "semaphore.h"
+
+#ifndef __cpp_lib_semaphore
+#	include <thread>
+
+semaphore::semaphore(unsigned int v_) : v {v_} { }
+
+void
+semaphore::release(unsigned int n)
+{
+	std::lock_guard lk {m};
+	v += n;
+}
+
+void
+semaphore::acquire()
+{
+	while (!try_dec()) { }
+}
+
+bool
+semaphore::try_dec()
+{
+	std::lock_guard lk {m};
+	if (v) {
+		v--;
+		m.unlock();
+		return true;
+	}
+	else {
+		m.unlock();
+		std::this_thread::sleep_for(std::chrono::milliseconds(100));
+		return false;
+	}
+}
+
+#endif
-- 
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