/* $NetBSD: alloc.c,v 1.28 2019/03/31 20:08:45 christos Exp $ */
/*
* Copyright (c) 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* 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
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)alloc.c 8.1 (Berkeley) 6/11/93
*
*
* Copyright (c) 1997 Christopher G. Demetriou. All rights reserved.
* Copyright (c) 1996
* Matthias Drochner. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* 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
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)alloc.c 8.1 (Berkeley) 6/11/93
*
*
* Copyright (c) 1989, 1990, 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Author: Alessandro Forin
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or
[email protected]
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* Dynamic memory allocator.
*
* Compile options:
*
* HEAP_LIMIT heap limit address (defaults to "no limit").
*
* HEAP_START start address of heap (defaults to '&end').
*
* DEBUG enable debugging sanity checks.
*/
#include <sys/param.h>
#include "stand.h"
/*
* Each block actually has ALIGN(unsigned int) + ALIGN(size) bytes allocated
* to it, as follows:
*
* 0 ... (sizeof(unsigned int) - 1)
* allocated or unallocated: holds size of user-data part of block.
*
* sizeof(unsigned int) ... (ALIGN(sizeof(unsigned int)) - 1)
* allocated: unused
* unallocated: depends on packing of struct fl
*
* ALIGN(sizeof(unsigned int)) ...
* (ALIGN(sizeof(unsigned int)) + ALIGN(data size) - 1)
* allocated: user data
* unallocated: depends on packing of struct fl
*
* 'next' is only used when the block is unallocated (i.e. on the free list).
* However, note that ALIGN(sizeof(unsigned int)) + ALIGN(data size) must
* be at least 'sizeof(struct fl)', so that blocks can be used as structures
* when on the free list.
*
* When HEAP_LIMIT is defined and the heap limit is reached, alloc() panics.
* Otherwise, it never fails.
*/
struct fl {
unsigned int size;
struct fl *next;
} *freelist;
#ifdef HEAP_VARIABLE
static char *top, *heapstart, *heaplimit;
void
setheap(void *start, void *limit)
{
heapstart = top = start;
heaplimit = limit;
}
#define HEAP_START heapstart
#define HEAP_LIMIT heaplimit
#else /* !HEAP_VARIABLE */
#ifndef HEAP_START
extern char end[];
#define HEAP_START end
#endif
static char *top = (char *)HEAP_START;
#endif /* HEAP_VARIABLE */
__compactcall void *
alloc(size_t size)
{
struct fl **f = &freelist, **bestf = NULL;
unsigned int bestsize = 0xffffffff; /* greater than any real size */
char *help;
int failed;
/* scan freelist */
while (*f) {
if ((size_t)(*f)->size >= size) {
if ((size_t)(*f)->size == size) /* exact match */
goto found;
if ((*f)->size < bestsize) {
/* keep best fit */
bestf = f;
bestsize = (*f)->size;
}
}
f = &((*f)->next);
}
/* no match in freelist if bestsize unchanged */
failed = (bestsize == 0xffffffff);
if (failed) { /* nothing found */
/*
* allocate from heap, keep chunk len in
* first word
*/
help = top;
/* make _sure_ the region can hold a struct fl. */
if (size < ALIGN(sizeof (struct fl *)))
size = ALIGN(sizeof (struct fl *));
top += ALIGN(sizeof(unsigned int)) + ALIGN(size);
#ifdef HEAP_LIMIT
if (top > (char *)HEAP_LIMIT)
panic("heap full (%p+%zu)", help, size);
#endif
*(unsigned int *)(void *)help = (unsigned int)ALIGN(size);
return help + ALIGN(sizeof(unsigned int));
}
/* we take the best fit */
f = bestf;
found:
/* remove from freelist */
help = (char *)(void *)*f;
*f = (*f)->next;
return help + ALIGN(sizeof(unsigned int));
}
__compactcall void
/*ARGSUSED*/
dealloc(void *ptr, size_t size)
{
struct fl *f =
(struct fl *)(void *)((char *)(void *)ptr -
ALIGN(sizeof(unsigned int)));
#ifdef DEBUG
if (size > (size_t)f->size) {
printf("%s: %zu bytes @%p, should be <=%u\n", __func__,
size, ptr, f->size);
}
if (ptr < (void *)HEAP_START)
printf("%s: %p before start of heap.\n", __func__, ptr);
#ifdef HEAP_LIMIT
if (ptr > (void *)HEAP_LIMIT)
printf("%s: %p beyond end of heap.\n", __func__, ptr);
#endif
#endif /* DEBUG */
/* put into freelist */
f->next = freelist;
freelist = f;
}
