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Diffstat (limited to 'lib/libstand/alloc.c')
| -rw-r--r-- | lib/libstand/alloc.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/lib/libstand/alloc.c b/lib/libstand/alloc.c new file mode 100644 index 000000000000..7fc63c18c687 --- /dev/null +++ b/lib/libstand/alloc.c @@ -0,0 +1,244 @@ +/* $NetBSD: alloc.c,v 1.11 1997/09/17 16:24:00 drochner Exp $ */ + +/* + * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved. + * Copyright (c) 1996 + * Matthias Drochner. All rights reserved. + * 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. 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 Software.Distribution@CS.CMU.EDU + * 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: + * + * ALLOC_TRACE enable tracing of allocations/deallocations + + * ALLOC_FIRST_FIT use a first-fit allocation algorithm, rather than + * the default best-fit algorithm. + * + * 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" + +/* Default to variable heap operation */ +#define HEAP_VARIABLE +#define DEBUG + +/* + * Each block actually has ALIGN(size_t) + ALIGN(size) bytes allocated + * to it, as follows: + * + * 0 ... (sizeof(size_t) - 1) + * allocated or unallocated: holds size of user-data part of block. + * + * sizeof(size_t) ... (ALIGN(sizeof(size_t)) - 1) + * allocated: unused + * unallocated: depends on packing of struct fl + * + * ALIGN(sizeof(size_t)) ... (ALIGN(sizeof(size_t)) + 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(size_t)) + ALIGN(data size) must + * be at least 'sizeof(struct fl)', so that blocks can be used as structures + * when on the free list. + */ +struct fl { + size_t size; + struct fl *next; +} *freelist = (struct fl *)0; + +#ifdef HEAP_VARIABLE +static char *top, *heapstart, *heaplimit; +void setheap(start, limit) +void *start, *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 */ + +void * +malloc(size) + size_t size; +{ + register struct fl **f = &freelist, **bestf = NULL; + size_t bestsize = 0xffffffff; /* greater than any real size */ + char *help; + int failed; + +#ifdef ALLOC_TRACE + printf("alloc(%u)", size); +#endif + +#ifdef ALLOC_FIRST_FIT + while (*f != (struct fl *)0 && (*f)->size < size) + f = &((*f)->next); + bestf = f; + failed = (*bestf == (struct fl *)0); +#else + /* scan freelist */ + while (*f) { + if ((*f)->size >= size) { + if ((*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); +#endif + + 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(size_t)) + ALIGN(size); +#ifdef HEAP_LIMIT + if (top > (char*)HEAP_LIMIT) + panic("heap full (0x%lx+%u)", help, size); +#endif + *(size_t *)help = ALIGN(size); +#ifdef ALLOC_TRACE + printf("=%lx\n", (u_long)help + ALIGN(sizeof(size_t))); + getchar(); +#endif + return(help + ALIGN(sizeof(size_t))); + } + + /* we take the best fit */ + f = bestf; + +found: + /* remove from freelist */ + help = (char*)*f; + *f = (*f)->next; +#ifdef ALLOC_TRACE + printf("=%lx (origsize %u)\n", (u_long)help + ALIGN(sizeof(size_t)), + *(size_t *)help); + getchar(); +#endif + return(help + ALIGN(sizeof(size_t))); +} + +void +free(ptr) + void *ptr; +{ + register struct fl *f = + (struct fl *)((char*)ptr - ALIGN(sizeof(size_t))); +#ifdef ALLOC_TRACE + printf("free(%lx, %u) (origsize %u)\n", (u_long)ptr, size, f->size); + getchar(); +#endif +#ifdef DEBUG + if (ptr < (void *)HEAP_START) + printf("free: %lx before start of heap.\n", (u_long)ptr); + +#ifdef HEAP_LIMIT + if (ptr > (void *)HEAP_LIMIT) + printf("free: %lx beyond end of heap.\n", (u_long)ptr); +#endif +#endif /* DEBUG */ + /* put into freelist */ + f->next = freelist; + freelist = f; +} + +/* + * Emulate sbrk(0) behaviour + */ +char * +sbrk(int junk) +{ + return((char *)top); +} |