1 /* $NetBSD: alloc.c,v 1.24 2010/12/25 01:08:44 jakllsch 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@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 int) + ALIGN(size) bytes allocated 123 * to it, as follows: 124 * 125 * 0 ... (sizeof(unsigned int) - 1) 126 * allocated or unallocated: holds size of user-data part of block. 127 * 128 * sizeof(unsigned int) ... (ALIGN(sizeof(unsigned int)) - 1) 129 * allocated: unused 130 * unallocated: depends on packing of struct fl 131 * 132 * ALIGN(sizeof(unsigned int)) ... 133 * (ALIGN(sizeof(unsigned int)) + ALIGN(data size) - 1) 134 * allocated: user data 135 * unallocated: depends on packing of struct fl 136 * 137 * 'next' is only used when the block is unallocated (i.e. on the free list). 138 * However, note that ALIGN(sizeof(unsigned int)) + ALIGN(data size) must 139 * be at least 'sizeof(struct fl)', so that blocks can be used as structures 140 * when on the free list. 141 */ 142 struct fl { 143 unsigned int size; 144 struct fl *next; 145 } *freelist; 146 147 #ifdef HEAP_VARIABLE 148 static char *top, *heapstart, *heaplimit; 149 void 150 setheap(void *start, void *limit) 151 { 152 heapstart = top = start; 153 heaplimit = limit; 154 } 155 #define HEAP_START heapstart 156 #define HEAP_LIMIT heaplimit 157 #else /* !HEAP_VARIABLE */ 158 #ifndef HEAP_START 159 extern char end[]; 160 #define HEAP_START end 161 #endif 162 static char *top = (char *)HEAP_START; 163 #endif /* HEAP_VARIABLE */ 164 165 void * 166 alloc(size_t size) 167 { 168 struct fl **f = &freelist, **bestf = NULL; 169 #ifndef ALLOC_FIRST_FIT 170 unsigned int bestsize = 0xffffffff; /* greater than any real size */ 171 #endif 172 char *help; 173 int failed; 174 175 #ifdef ALLOC_TRACE 176 printf("alloc(%zu)", size); 177 #endif 178 179 #ifdef ALLOC_FIRST_FIT 180 while (*f != (struct fl *)0 && (size_t)(*f)->size < size) 181 f = &((*f)->next); 182 bestf = f; 183 failed = (*bestf == (struct fl *)0); 184 #else 185 /* scan freelist */ 186 while (*f) { 187 if ((size_t)(*f)->size >= size) { 188 if ((size_t)(*f)->size == size) /* exact match */ 189 goto found; 190 191 if ((*f)->size < bestsize) { 192 /* keep best fit */ 193 bestf = f; 194 bestsize = (*f)->size; 195 } 196 } 197 f = &((*f)->next); 198 } 199 200 /* no match in freelist if bestsize unchanged */ 201 failed = (bestsize == 0xffffffff); 202 #endif 203 204 if (failed) { /* nothing found */ 205 /* 206 * allocate from heap, keep chunk len in 207 * first word 208 */ 209 help = top; 210 211 /* make _sure_ the region can hold a struct fl. */ 212 if (size < ALIGN(sizeof (struct fl *))) 213 size = ALIGN(sizeof (struct fl *)); 214 top += ALIGN(sizeof(unsigned int)) + ALIGN(size); 215 #ifdef HEAP_LIMIT 216 if (top > (char *)HEAP_LIMIT) 217 panic("heap full (%p+%zu)", help, size); 218 #endif 219 *(unsigned int *)(void *)help = (unsigned int)ALIGN(size); 220 #ifdef ALLOC_TRACE 221 printf("=%lx\n", (u_long)help + ALIGN(sizeof(unsigned int))); 222 #endif 223 return help + ALIGN(sizeof(unsigned int)); 224 } 225 226 /* we take the best fit */ 227 f = bestf; 228 229 #ifndef ALLOC_FIRST_FIT 230 found: 231 #endif 232 /* remove from freelist */ 233 help = (char *)(void *)*f; 234 *f = (*f)->next; 235 #ifdef ALLOC_TRACE 236 printf("=%lx (origsize %u)\n", 237 (u_long)help + ALIGN(sizeof(unsigned int)), *(unsigned int *)help); 238 #endif 239 return help + ALIGN(sizeof(unsigned int)); 240 } 241 242 void 243 /*ARGSUSED*/ 244 dealloc(void *ptr, size_t size) 245 { 246 struct fl *f = 247 (struct fl *)(void *)((char *)(void *)ptr - 248 ALIGN(sizeof(unsigned int))); 249 #ifdef ALLOC_TRACE 250 printf("dealloc(%lx, %zu) (origsize %u)\n", (u_long)ptr, size, f->size); 251 #endif 252 #ifdef DEBUG 253 if (size > (size_t)f->size) { 254 printf("dealloc %u bytes @%lx, should be <=%u\n", 255 size, (u_long)ptr, f->size); 256 } 257 258 if (ptr < (void *)HEAP_START) 259 printf("dealloc: %lx before start of heap.\n", (u_long)ptr); 260 261 #ifdef HEAP_LIMIT 262 if (ptr > (void *)HEAP_LIMIT) 263 printf("dealloc: %lx beyond end of heap.\n", (u_long)ptr); 264 #endif 265 #endif /* DEBUG */ 266 /* put into freelist */ 267 f->next = freelist; 268 freelist = f; 269 } 270