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44ef8912d6
Add a allocator using bit maps to maintain used/unused caps. It supports the allocation of 2^n aligned caps solely and freeing of caps. Fixes #247
68 lines
1.3 KiB
C++
68 lines
1.3 KiB
C++
/*
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* \brief Allocator using bitmaps to maintain cap space
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* \author Alexander Boettcher
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* \date 2012-06-14
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*/
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/*
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* Copyright (C) 2012 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 _INCLUDE__BASE__BIT_ALLOCATOR_H_
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#define _INCLUDE__BASE__BIT_ALLOCATOR_H_
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#include <base/bit_array.h>
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namespace Genode {
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template<addr_t WORDS>
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class Bit_allocator
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{
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protected:
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Bit_array<WORDS> _array;
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void _reserve(addr_t bit_start, size_t const num_cap)
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{
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if (!num_cap) return;
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_array.set(bit_start, num_cap);
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}
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public:
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addr_t alloc(size_t const num_log2)
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{
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addr_t const step = 1UL << num_log2;
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addr_t i = 0;
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try {
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/*
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* Throws exception if array is
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* accessed outside bounds
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*/
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while (true) {
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if (_array.get(i, step)) {
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i += step;
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continue;
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}
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_array.set(i, step);
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return i;
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}
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} catch (Bit_array_invalid_index_access) {}
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throw Bit_array_out_of_indexes();
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}
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void free(addr_t const bit_start,
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size_t const num_log2)
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{
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_array.clear(bit_start, 1UL << num_log2);
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}
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};
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}
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#endif /* _INCLUDE__BASE__BIT_ALLOCATOR_H_ */
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