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81 lines
1.5 KiB
C++
81 lines
1.5 KiB
C++
/*
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* \brief MAC-address allocator
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* \author Stefan Kalkowski
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* \date 2010-08-25
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*/
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/*
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* Copyright (C) 2010-2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _MAC_ALLOCATOR_H_
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#define _MAC_ALLOCATOR_H_
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/* Genode includes */
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#include <base/exception.h>
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#include <net/ethernet.h>
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namespace Net {
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/**
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* The MAC allocator is used to administer MAC addresses for
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* NIC session clients.
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*/
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class Mac_allocator
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{
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private:
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/* limit available MAC addresses to one byte range */
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enum { MSB_MAX = 0xFF };
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/* signals, whether most significant byte is in use */
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typedef struct
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{
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unsigned used : 1;
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} Msb;
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Msb _msbs[MSB_MAX]; /* bitfield of MSBs */
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public:
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class Alloc_failed : Genode::Exception {};
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/* reference MAC address */
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static Mac_address mac_addr_base;
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Mac_allocator() { Genode::memset(&_msbs, 0, sizeof(_msbs)); }
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/**
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* Allocates a new MAC address.
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*
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* \throws Alloc_failed if no more MAC addresses are available.
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* \return MAC address
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*/
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Mac_address alloc()
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{
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for (int i=0; i < MSB_MAX; i++) {
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if (!_msbs[i].used) {
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_msbs[i].used = 1;
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Mac_address mac = mac_addr_base;
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mac.addr[5] = i;
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return mac;
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}
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}
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throw Alloc_failed();
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}
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/**
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* Frees a formerly allocated MAC address.
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*/
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void free(Mac_address mac) {
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_msbs[(unsigned)mac.addr[5]].used = 0; }
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};
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}
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#endif /* _MAC_ALLOCATOR_H_ */
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