remote_rom: use UDP and implement go-back-N ARQ

include/remote_rom/util.h

@@ -0,0 +1,49 @@
+/*
+ * \brief  Utility functions used by ROM forwarder and receiver.
+ * \author Johannes Schlatow
+ * \date   2018-11-14
+ */
+
+/*
+ * Copyright (C) 2018 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef __INCLUDE__REMOTE_ROM__UTIL_H_
+#define __INCLUDE__REMOTE_ROM__UTIL_H_
+
+#include <base/fixed_stdint.h>
+
+namespace Remote_rom {
+	using Genode::uint32_t;
+	using Genode::int32_t;
+	using Genode::uint8_t;
+	using Genode::size_t;
+
+	uint32_t cksum(void const * const buf, size_t size);
+}
+/**
+ * Calculating checksum compatible to POSIX cksum
+ *
+ * \param buf   pointer to buffer containing data
+ * \param size  length of buffer in bytes
+ *
+ * \return CRC32 checksum of data
+ */
+Genode::uint32_t Remote_rom::cksum(void const * const buf, size_t size)
+{
+	uint8_t const *p = static_cast<uint8_t const*>(buf);
+	uint32_t crc = ~0U;
+
+	while (size--) {
+		crc ^= *p++;
+		for (uint32_t j = 0; j < 8; j++)
+			crc = (-int32_t(crc & 1) & 0xedb88320) ^ (crc >> 1);
+	}
+
+	return crc ^ ~0U;
+}
+
+#endif