MACsec: Refactor API

include/icsneo/core/ringbuffer.h

@@ -0,0 +1,75 @@
+#ifndef _RINGBUFFER_H_
+#define _RINGBUFFER_H_
+
+#include <cstdint>
+#include <cstddef>
+#include <memory>
+#include <cstring>
+#include <mutex>
+#include <atomic>
+#include <vector>
+#if __cplusplus >= 202002L
+#include <bit>
+#endif
+namespace icsneo {
+
+class RingBuffer
+{
+private:
+	static constexpr size_t RoundUp(size_t size) {
+		if (size == 0) {
+			// Avoid underflow when decrementing later
+			return 1;
+		} else if (size >= SIZE_MAX) {
+			// overflow case - resolve to max size
+			return MaxSize;
+		}
+#if __cplusplus >= 202002L
+		// c++20 gives us countl_zero which should be more effecient on most platforms
+		auto lzero = std::countl_zero(size - 1);
+		auto shift = (sizeof(size_t) * 8) - lzero;
+		return 1ull << shift;
+#else
+		// Bit twiddling magic! See http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
+		--size;
+		size |= size >> 1;
+		size |= size >> 2;
+		size |= size >> 4;
+		for (size_t i = 1; i < sizeof(size_t); i <<= 1) {
+			size |= size >> (i << 3);
+		}
+		++size;
+		return size;
+#endif
+	}
+	//static_assert(std::atomic<size_t>::is_always_lock_free, "RingBuffer cursor types are not lock-free");
+	std::atomic<size_t> readCursor;
+	std::atomic<size_t> writeCursor;
+	// Use this to mask the cursor values to the buffer size. This is set to capacity - 1 where capacity is always an integral power of 2 (2, 4, 8, 16, etc)
+	size_t mask;
+	uint8_t* buf;
+
+public:
+	static constexpr auto MaxSize =  1ull << ((8 * sizeof(size_t)) - 1);
+	RingBuffer(size_t bufferSize);
+	~RingBuffer();
+	const uint8_t& operator[](size_t offset) const;
+	size_t size() const;
+	void pop_front();
+	void pop(size_t count);
+	const uint8_t& get(size_t offset) const;
+	bool write(const uint8_t* addr, size_t count);
+	bool write(const std::vector<uint8_t>& source);
+	bool read(uint8_t* dest, size_t startIndex, size_t length) const;
+	void clear();
+	constexpr size_t capacity() const {
+		return mask + 1;
+	}
+
+protected:
+	inline uint8_t* resolve(size_t cursor, size_t offset) const {
+		return &buf[(cursor + offset) & mask];
+	}
+};
+}
+#endif