1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
|
/* $OpenBSD: alloc.c,v 1.12 2016/03/14 23:08:06 krw Exp $ */
/* $NetBSD: alloc.c,v 1.6 1997/02/04 18:36:33 thorpej 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. 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').
*
* NEEDS_HEAP_H needs to #include "heap.h" to declare things
* needed by HEAP_LIMIT and/or HEAP_START.
*
* NEEDS_HEAP_INIT needs to invoke heap_init() to initialize
* heap boundaries.
*
* DEBUG enable debugging sanity checks.
*/
#include <sys/param.h>
/*
* Each block actually has ALIGN(unsigned) + ALIGN(size) bytes allocated
* to it, as follows:
*
* 0 ... (sizeof(unsigned) - 1)
* allocated or unallocated: holds size of user-data part of block.
*
* sizeof(unsigned) ... (ALIGN(sizeof(unsigned)) - 1)
* allocated: unused
* unallocated: depends on packing of struct fl
*
* ALIGN(sizeof(unsigned)) ... (ALIGN(sizeof(unsigned)) + 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)) + ALIGN(data size) must
* be at least 'sizeof(struct fl)', so that blocks can be used as structures
* when on the free list.
*/
#include "stand.h"
struct fl {
unsigned size;
struct fl *next;
} *freelist = NULL;
#ifdef NEEDS_HEAP_H
#include "heap.h"
#endif
#ifndef NEEDS_HEAP_INIT
#ifdef HEAP_START
static char *top = (char *)HEAP_START;
#else
extern char end[];
static char *top = end;
#endif
#endif
void *
alloc(unsigned int size)
{
struct fl **f = &freelist, **bestf = NULL;
#ifndef ALLOC_FIRST_FIT
unsigned bestsize = 0xffffffff; /* greater than any real size */
#endif
char *help;
int failed;
#ifdef NEEDS_HEAP_INIT
heap_init();
#endif
#ifdef ALLOC_TRACE
printf("alloc(%u)", size);
#endif
#ifdef ALLOC_FIRST_FIT
while (*f != NULL && (*f)->size < size)
f = &((*f)->next);
bestf = f;
failed = (*bestf == NULL);
#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(unsigned)) + ALIGN(size);
#ifdef HEAP_LIMIT
if (top > (char *)HEAP_LIMIT)
panic("heap full (0x%lx+%u)", help, size);
#endif
*(unsigned *)help = ALIGN(size);
#ifdef ALLOC_TRACE
printf("=%p\n", help + ALIGN(sizeof(unsigned)));
#endif
return(help + ALIGN(sizeof(unsigned)));
}
/* we take the best fit */
f = bestf;
#ifndef ALLOC_FIRST_FIT
found:
#endif
/* remove from freelist */
help = (char *)*f;
*f = (*f)->next;
#ifdef ALLOC_TRACE
printf("=%p (origsize %u)\n", help + ALIGN(sizeof(unsigned)),
*(unsigned *)help);
#endif
return(help + ALIGN(sizeof(unsigned)));
}
void
free(void *ptr, unsigned int size)
{
struct fl *f;
if (ptr == NULL)
return;
f = (struct fl *)((char *)ptr - ALIGN(sizeof(unsigned)));
#ifdef ALLOC_TRACE
printf("free(%p, %u) (origsize %u)\n", ptr, size, f->size);
#endif
#ifdef DEBUG
if (size > f->size)
printf("free %u bytes @%p, should be <=%u\n",
size, ptr, f->size);
#ifdef HEAP_START
if (ptr < (void *)HEAP_START)
#else
if (ptr < (void *)end)
#endif
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;
}
|
