151 lines
4.2 KiB
C++
151 lines
4.2 KiB
C++
/*
|
|
* \brief Fast-bitmap allocator for packet streams
|
|
* \author Sebastian Sumpf
|
|
* \author Stefan Kalkowski
|
|
* \date 2012-07-30
|
|
*/
|
|
|
|
/*
|
|
* Copyright (C) 2012-2013 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__OS__PACKET_ALLOCATOR__
|
|
#define _INCLUDE__OS__PACKET_ALLOCATOR__
|
|
|
|
#include <base/allocator.h>
|
|
#include <util/bit_array.h>
|
|
|
|
namespace Genode { class Packet_allocator; }
|
|
|
|
|
|
/**
|
|
* This allocator is designed to be used as packet allocator for the
|
|
* packet stream interface. It uses a minimal block size, which is the
|
|
* granularity packets will be allocated with. As backend, it uses a
|
|
* simple bit array to manage free, and allocated blocks.
|
|
*/
|
|
class Genode::Packet_allocator : public Genode::Range_allocator
|
|
{
|
|
private:
|
|
|
|
Allocator *_md_alloc; /* meta-data allocator */
|
|
size_t _block_size; /* granularity of packet allocations */
|
|
void *_bits; /* memory chunk containing the bits */
|
|
Bit_array_base *_array; /* bit array managing available blocks */
|
|
addr_t _base; /* allocation base */
|
|
addr_t _next; /* next free bit index */
|
|
|
|
/*
|
|
* Returns the count of blocks fitting the given size
|
|
*
|
|
* The block count returned is aligned to the bit count
|
|
* of a machine word to fit the needs of the used bit array.
|
|
*/
|
|
inline size_t _block_cnt(size_t bytes)
|
|
{
|
|
bytes /= _block_size;
|
|
return bytes - (bytes % (sizeof(addr_t)*8));
|
|
}
|
|
|
|
public:
|
|
|
|
/**
|
|
* Constructor
|
|
*
|
|
* \param md_alloc Meta-data allocator
|
|
* \param block_size Granularity of packets in stream
|
|
*/
|
|
Packet_allocator(Allocator *md_alloc, size_t block_size)
|
|
: _md_alloc(md_alloc), _block_size(block_size), _bits(0),
|
|
_array(nullptr), _base(0) {}
|
|
|
|
|
|
/*******************************
|
|
** Range-allocator interface **
|
|
*******************************/
|
|
|
|
int add_range(addr_t base, size_t size) override
|
|
{
|
|
if (_base || _array) return -1;
|
|
|
|
_base = base;
|
|
_bits = _md_alloc->alloc(_block_cnt(size)/8);
|
|
_array = new (_md_alloc) Bit_array_base(_block_cnt(size),
|
|
(addr_t*)_bits,
|
|
true);
|
|
return 0;
|
|
}
|
|
|
|
int remove_range(addr_t base, size_t size) override
|
|
{
|
|
if (_base != base) return -1;
|
|
|
|
if (_array) destroy(_md_alloc, _array);
|
|
if (_bits) _md_alloc->free(_bits, _block_cnt(size)/8);
|
|
return 0;
|
|
}
|
|
|
|
Alloc_return alloc_aligned(size_t size, void **out_addr, int, addr_t,
|
|
addr_t) override
|
|
{
|
|
return alloc(size, out_addr) ? Alloc_return::OK
|
|
: Alloc_return::RANGE_CONFLICT;
|
|
}
|
|
|
|
bool alloc(size_t size, void **out_addr) override
|
|
{
|
|
addr_t const cnt = (size % _block_size) ? size / _block_size + 1
|
|
: size / _block_size;
|
|
addr_t max = ~0UL;
|
|
|
|
do {
|
|
try {
|
|
/* throws exception if array is accessed outside bounds */
|
|
for (addr_t i = _next & ~(cnt - 1); i < max; i += cnt) {
|
|
if (_array->get(i, cnt))
|
|
continue;
|
|
|
|
_array->set(i, cnt);
|
|
_next = i + cnt;
|
|
*out_addr = reinterpret_cast<void *>(i * _block_size
|
|
+ _base);
|
|
return true;
|
|
}
|
|
} catch (typename Bit_array_base::Invalid_index_access) { }
|
|
|
|
max = _next;
|
|
_next = 0;
|
|
|
|
} while (max != 0);
|
|
|
|
return false;
|
|
}
|
|
|
|
void free(void *addr, size_t size) override
|
|
{
|
|
addr_t i = (((addr_t)addr) - _base) / _block_size;
|
|
size_t cnt = (size % _block_size) ? size / _block_size + 1
|
|
: size / _block_size;
|
|
try { _array->clear(i, cnt); } catch(...) { }
|
|
_next = i;
|
|
}
|
|
|
|
|
|
/*************
|
|
** Dummies **
|
|
*************/
|
|
|
|
bool need_size_for_free() const override { return false; }
|
|
void free(void *addr) override { }
|
|
size_t overhead(size_t) const override { return 0;}
|
|
size_t avail() const override { return 0; }
|
|
bool valid_addr(addr_t) const override { return 0; }
|
|
Alloc_return alloc_addr(size_t, addr_t) override {
|
|
return Alloc_return(Alloc_return::OUT_OF_METADATA); }
|
|
};
|
|
|
|
#endif /* _INCLUDE__OS__PACKET_ALLOCATOR__ */
|