/*
* This module derived from code donated to the FreeBSD Project by
* Matthew Dillon <dillon@backplane.com>
*
* Copyright (c) 1998 The FreeBSD Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
__FBSDID("$FreeBSD$");
/*
* LIB/MEMORY/ZALLOC.C - self contained low-overhead memory pool/allocation
* subsystem
*
* This subsystem implements memory pools and memory allocation
* routines.
*
* Pools are managed via a linked list of 'free' areas. Allocating
* memory creates holes in the freelist, freeing memory fills them.
* Since the freelist consists only of free memory areas, it is possible
* to allocate the entire pool without incuring any structural overhead.
*
* The system works best when allocating similarly-sized chunks of
* memory. Care must be taken to avoid fragmentation when
* allocating/deallocating dissimilar chunks.
*
* When a memory pool is first allocated, the entire pool is marked as
* allocated. This is done mainly because we do not want to modify any
* portion of a pool's data area until we are given permission. The
* caller must explicitly deallocate portions of the pool to make them
* available.
*
* z[n]xalloc() works like z[n]alloc() but the allocation is made from
* within the specified address range. If the segment could not be
* allocated, NULL is returned. WARNING! The address range will be
* aligned to an 8 or 16 byte boundry depending on the cpu so if you
* give an unaligned address range, unexpected results may occur.
*
* If a standard allocation fails, the reclaim function will be called
* to recover some space. This usually causes other portions of the
* same pool to be released. Memory allocations at this low level
* should not block but you can do that too in your reclaim function
* if you want. Reclaim does not function when z[n]xalloc() is used,
* only for z[n]alloc().
*
* Allocation and frees of 0 bytes are valid operations.
*/
#include "zalloc_defs.h"
/*
* Objects in the pool must be aligned to at least the size of struct MemNode.
* They must also be aligned to MALLOCALIGN, which should normally be larger
* than the struct, so assert that to be so at compile time.
*/
/*
* znalloc() - allocate memory (without zeroing) from pool. Call reclaim
* and retry if appropriate, return NULL if unable to allocate
* memory.
*/
void *
{
/*
* align according to pool object size (can be 0). This is
* inclusive of the MEMNODE_SIZE_MASK minimum alignment.
*
*/
if (bytes == 0)
return((void *)-1);
/*
* locate freelist entry big enough to hold the object. If all objects
* are the same size, this is a constant-time function.
*/
continue;
/*
* Cut a chunk of memory out of the beginning of this
* block and fixup the link appropriately.
*/
{
} else {
}
return(ptr);
}
}
}
/*
* Memory pool is full, return NULL.
*/
return(NULL);
}
/*
* zfree() - free previously allocated memory
*/
void
{
/*
* align according to pool object size (can be 0). This is
* inclusive of the MEMNODE_SIZE_MASK minimum alignment.
*/
if (bytes == 0)
return;
/*
* panic if illegal pointer
*/
/*
* free the segment
*/
{
/*
* If area between last node and current node
* - check range
* - check merge with next area
* - check merge with previous area
*/
/*
* range check
*/
}
/*
* merge against next area or create independant area
*/
} else {
}
/*
* merge against previous area (if there is a previous
* area).
*/
}
}
return;
/* NOT REACHED */
}
}
}
/*
* We are beyond the last MemNode, append new MemNode. Merge against
* previous area if possible.
*/
) {
} else {
}
}
}
/*
* zextendPool() - extend memory pool to cover additional space.
*
* Note: the added memory starts out as allocated, you
* must free it to make it available to the memory subsystem.
*
* Note: mp_Size may not reflect (mp_End - mp_Base) range
* due to other parts of the system doing their own sbrk()
* calls.
*/
void
{
} else {
}
}
}
}
#ifdef ZALLOCDEBUG
void
{
int abytes = 0;
int hbytes = 0;
int fcount = 0;
}
while (mn) {
++fcount;
}
}
printf(" %d bytes allocated\n%d fragments (%d bytes fragmented)\n",
);
}
#endif