init

Telegram/lib_base/base/random.h

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+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#pragma once
+
+#include <cstddef>
+#include <type_traits>
+
+#include "base/bytes.h"
+
+namespace base {
+
+void RandomFill(bytes::span bytes);
+
+inline void RandomFill(void *data, std::size_t length) {
+	RandomFill({ static_cast<bytes::type*>(data), length });
+}
+
+template <
+	typename T,
+	typename = std::enable_if_t<std::is_trivially_copyable_v<T>>>
+[[nodiscard]] inline T RandomValue() {
+	auto result = T();
+	RandomFill({ reinterpret_cast<std::byte*>(&result), sizeof(T) });
+	return result;
+}
+
+[[nodiscard]] int RandomIndex(int count);
+
+template <typename T>
+class BufferedRandom final {
+public:
+	explicit BufferedRandom(int bufferSize) : _buffer(bufferSize) {
+		Expects(bufferSize > 0);
+	}
+
+	[[nodiscard]] T next() {
+		if (_index == _buffer.size()) {
+			_index = 0;
+		}
+		if (!_index) {
+			RandomFill(bytes::make_span(_buffer));
+		}
+		return _buffer[_index++];
+	}
+
+private:
+	std::vector<T> _buffer;
+	int _index = 0;
+
+};
+
+[[nodiscard]] int RandomIndex(int count, BufferedRandom<uint32> buffered);
+
+void RandomAddSeed(bytes::const_span bytes);
+
+} // namespace base