85 lines
3.1 KiB
C
85 lines
3.1 KiB
C
/*
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* Copyright (c) 2014, Steffen Vogel, RWTH Aachen University
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* @author Steffen Vogel <steffen.vogel@rwth-aachen.de>
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*/
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#ifndef __MALLOC_H__
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#define __MALLOC_H__
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#include <eduos/stddef.h>
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#include <eduos/stdlib.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/// Binary exponent of maximal size for kmalloc()
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#define BUDDY_MAX 32 // 4 GB
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/// Binary exponent of minimal buddy size
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#define BUDDY_MIN 3 // 8 Byte >= sizeof(buddy_t)
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/// Binary exponent of the size which we allocate with buddy_fill()
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#define BUDDY_ALLOC 16 // 64 KByte = 16 * PAGE_SIZE
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#define BUDDY_LISTS (BUDDY_MAX-BUDDY_MIN+1)
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#define BUDDY_MAGIC 0xBABE
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union buddy;
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/** @brief Buddy
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*
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* Every free memory block is stored in a linked list according to its size.
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* We can use this free memory to store store this buddy_t union which represents
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* this block (the buddy_t union is alligned to the front).
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* Therefore the address of the buddy_t union is equal with the address
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* of the underlying free memory block.
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*
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* Every allocated memory block is prefixed with its binary size exponent and
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* a known magic number. This prefix is hidden by the user because its located
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* before the actual memory address returned by kmalloc()
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*/
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typedef union buddy {
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/// Pointer to the next buddy in the linked list.
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union buddy* next;
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struct {
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/// The binary exponent of the block size
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uint8_t exponent;
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/// Must be equal to BUDDY_MAGIC for a valid memory block
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uint16_t magic;
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} prefix;
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} buddy_t;
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/** @brief Dump free buddies */
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void buddy_dump(void);
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#ifdef __cplusplus
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}
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#endif
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#endif
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