alloc.c revision 1.22
1 /* $NetBSD: alloc.c,v 1.22 2007/11/24 13:20:53 isaki Exp $ */ 2 3 /* 4 * Copyright (c) 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * The Mach Operating System project at Carnegie-Mellon University. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)alloc.c 8.1 (Berkeley) 6/11/93 35 * 36 * 37 * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved. 38 * Copyright (c) 1996 39 * Matthias Drochner. All rights reserved. 40 * 41 * This code is derived from software contributed to Berkeley by 42 * The Mach Operating System project at Carnegie-Mellon University. 43 * 44 * Redistribution and use in source and binary forms, with or without 45 * modification, are permitted provided that the following conditions 46 * are met: 47 * 1. Redistributions of source code must retain the above copyright 48 * notice, this list of conditions and the following disclaimer. 49 * 2. Redistributions in binary form must reproduce the above copyright 50 * notice, this list of conditions and the following disclaimer in the 51 * documentation and/or other materials provided with the distribution. 52 * 3. All advertising materials mentioning features or use of this software 53 * must display the following acknowledgement: 54 * This product includes software developed by the University of 55 * California, Berkeley and its contributors. 56 * 4. Neither the name of the University nor the names of its contributors 57 * may be used to endorse or promote products derived from this software 58 * without specific prior written permission. 59 * 60 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 61 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 62 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 63 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 64 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 65 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 66 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 67 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 68 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 69 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 70 * SUCH DAMAGE. 71 * 72 * @(#)alloc.c 8.1 (Berkeley) 6/11/93 73 * 74 * 75 * Copyright (c) 1989, 1990, 1991 Carnegie Mellon University 76 * All Rights Reserved. 77 * 78 * Author: Alessandro Forin 79 * 80 * Permission to use, copy, modify and distribute this software and its 81 * documentation is hereby granted, provided that both the copyright 82 * notice and this permission notice appear in all copies of the 83 * software, derivative works or modified versions, and any portions 84 * thereof, and that both notices appear in supporting documentation. 85 * 86 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 87 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 88 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 89 * 90 * Carnegie Mellon requests users of this software to return to 91 * 92 * Software Distribution Coordinator or Software.Distribution (at) CS.CMU.EDU 93 * School of Computer Science 94 * Carnegie Mellon University 95 * Pittsburgh PA 15213-3890 96 * 97 * any improvements or extensions that they make and grant Carnegie the 98 * rights to redistribute these changes. 99 */ 100 101 /* 102 * Dynamic memory allocator. 103 * 104 * Compile options: 105 * 106 * ALLOC_TRACE enable tracing of allocations/deallocations 107 108 * ALLOC_FIRST_FIT use a first-fit allocation algorithm, rather than 109 * the default best-fit algorithm. 110 * 111 * HEAP_LIMIT heap limit address (defaults to "no limit"). 112 * 113 * HEAP_START start address of heap (defaults to '&end'). 114 * 115 * DEBUG enable debugging sanity checks. 116 */ 117 118 #include <sys/param.h> 119 #include "stand.h" 120 121 /* 122 * Each block actually has ALIGN(unsigned) + ALIGN(size) bytes allocated 123 * to it, as follows: 124 * 125 * 0 ... (sizeof(unsigned) - 1) 126 * allocated or unallocated: holds size of user-data part of block. 127 * 128 * sizeof(unsigned) ... (ALIGN(sizeof(unsigned)) - 1) 129 * allocated: unused 130 * unallocated: depends on packing of struct fl 131 * 132 * ALIGN(sizeof(unsigned)) ... (ALIGN(sizeof(unsigned)) + ALIGN(data size) - 1) 133 * allocated: user data 134 * unallocated: depends on packing of struct fl 135 * 136 * 'next' is only used when the block is unallocated (i.e. on the free list). 137 * However, note that ALIGN(sizeof(unsigned)) + ALIGN(data size) must 138 * be at least 'sizeof(struct fl)', so that blocks can be used as structures 139 * when on the free list. 140 */ 141 struct fl { 142 unsigned size; 143 struct fl *next; 144 } *freelist; 145 146 #ifdef HEAP_VARIABLE 147 static char *top, *heapstart, *heaplimit; 148 void 149 setheap(void *start, void *limit) 150 { 151 heapstart = top = start; 152 heaplimit = limit; 153 } 154 #define HEAP_START heapstart 155 #define HEAP_LIMIT heaplimit 156 #else /* !HEAP_VARIABLE */ 157 #ifndef HEAP_START 158 extern char end[]; 159 #define HEAP_START end 160 #endif 161 static char *top = (char *)HEAP_START; 162 #endif /* HEAP_VARIABLE */ 163 164 void * 165 alloc(size_t size) 166 { 167 struct fl **f = &freelist, **bestf = NULL; 168 #ifndef ALLOC_FIRST_FIT 169 unsigned bestsize = 0xffffffff; /* greater than any real size */ 170 #endif 171 char *help; 172 int failed; 173 174 #ifdef ALLOC_TRACE 175 printf("alloc(%zu)", size); 176 #endif 177 178 #ifdef ALLOC_FIRST_FIT 179 while (*f != (struct fl *)0 && (size_t)(*f)->size < size) 180 f = &((*f)->next); 181 bestf = f; 182 failed = (*bestf == (struct fl *)0); 183 #else 184 /* scan freelist */ 185 while (*f) { 186 if ((size_t)(*f)->size >= size) { 187 if ((size_t)(*f)->size == size) /* exact match */ 188 goto found; 189 190 if ((*f)->size < bestsize) { 191 /* keep best fit */ 192 bestf = f; 193 bestsize = (*f)->size; 194 } 195 } 196 f = &((*f)->next); 197 } 198 199 /* no match in freelist if bestsize unchanged */ 200 failed = (bestsize == 0xffffffff); 201 #endif 202 203 if (failed) { /* nothing found */ 204 /* 205 * allocate from heap, keep chunk len in 206 * first word 207 */ 208 help = top; 209 210 /* make _sure_ the region can hold a struct fl. */ 211 if (size < ALIGN(sizeof (struct fl *))) 212 size = ALIGN(sizeof (struct fl *)); 213 top += ALIGN(sizeof(unsigned)) + ALIGN(size); 214 #ifdef HEAP_LIMIT 215 if (top > (char *)HEAP_LIMIT) 216 panic("heap full (0x%lx+%zu)", help, size); 217 #endif 218 *(unsigned *)(void *)help = (unsigned)ALIGN(size); 219 #ifdef ALLOC_TRACE 220 printf("=%lx\n", (u_long)help + ALIGN(sizeof(unsigned))); 221 #endif 222 return help + ALIGN(sizeof(unsigned)); 223 } 224 225 /* we take the best fit */ 226 f = bestf; 227 228 #ifndef ALLOC_FIRST_FIT 229 found: 230 #endif 231 /* remove from freelist */ 232 help = (char *)(void *)*f; 233 *f = (*f)->next; 234 #ifdef ALLOC_TRACE 235 printf("=%lx (origsize %u)\n", (u_long)help + ALIGN(sizeof(unsigned)), 236 *(unsigned *)help); 237 #endif 238 return help + ALIGN(sizeof(unsigned)); 239 } 240 241 void 242 /*ARGSUSED*/ 243 dealloc(void *ptr, size_t size) 244 { 245 struct fl *f = 246 (struct fl *)(void *)((char *)(void *)ptr - ALIGN(sizeof(unsigned))); 247 #ifdef ALLOC_TRACE 248 printf("dealloc(%lx, %zu) (origsize %u)\n", (u_long)ptr, size, f->size); 249 #endif 250 #ifdef DEBUG 251 if (size > (size_t)f->size) { 252 printf("dealloc %u bytes @%lx, should be <=%u\n", 253 size, (u_long)ptr, f->size); 254 } 255 256 if (ptr < (void *)HEAP_START) 257 printf("dealloc: %lx before start of heap.\n", (u_long)ptr); 258 259 #ifdef HEAP_LIMIT 260 if (ptr > (void *)HEAP_LIMIT) 261 printf("dealloc: %lx beyond end of heap.\n", (u_long)ptr); 262 #endif 263 #endif /* DEBUG */ 264 /* put into freelist */ 265 f->next = freelist; 266 freelist = f; 267 } 268
Indexes created Wed Sep 24 05:09:52 GMT 2025