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
|
/************************************************************
* mm_malloc.c
*
* Copyright (C) 2007 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 Gregory Nutt 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 COPYRIGHT HOLDERS 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
* COPYRIGHT OWNER 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.
*
************************************************************/
/************************************************************
* Included Files
************************************************************/
/* Special definitions when we operate in the normal vs. the
* host-pc test environement.
*/
#include <assert.h>
#include "mm_environment.h"
#include "mm_internal.h"
/************************************************************
* Definitions
************************************************************/
#ifndef NULL
# define NULL ((void*)0)
#endif
/************************************************************
* Type Definitions
************************************************************/
/************************************************************
* Private Data
************************************************************/
/************************************************************
* Public Data
************************************************************/
/************************************************************
* Private Functions
************************************************************/
/************************************************************
* Public Functions
************************************************************/
/************************************************************
* malloc
*
* Description:
* Find the smallest chunk that satisfies the request.
* Take the memory from that chunk, save the remaining,
* smaller chunk (if any).
*
* 8-byte alignment of the allocated data is assured.
*
************************************************************/
void *malloc(size_t size)
{
struct mm_freenode_s *node;
void *ret = NULL;
int ndx;
/* Handle bad sizes */
if (size <= 0)
{
return NULL;
}
/* Adjust the size to account for (1) the size of the allocated
* node and (2) to make sure that it is an even multiple of
* our granule size.
*/
size = MM_ALIGN_UP(size + SIZEOF_MM_ALLOCNODE);
/* We need to hold the MM semaphore while we muck with the
* nodelist.
*/
mm_takesemaphore();
/* Get the location in the node list to start the search.
* Special case really big alloctions
*/
if (size >= MM_MAX_CHUNK)
{
ndx = MM_NNODES-1;
}
else
{
/* Convert the request size into a nodelist index */
ndx = mm_size2ndx(size);
}
/* Search for a large enough chunk in the list of nodes.
* This list is ordered by size, but will have occasional
* zero sized nodes as we visit other g_nodelist[] entries.
*/
for (node = g_nodelist[ndx].flink;
node && node->size < size;
node = node->flink);
/* If we found a node with non-zero size, then this is one
* to use. Since the list is ordered, we know that is must be
* best fitting chunk available.
*/
if (node)
{
struct mm_freenode_s *remainder;
struct mm_freenode_s *next;
uint32 remaining;
/* Remove the node. There must be a predecessor, but there may
* not be a successor node.
*/
DEBUGASSERT(node->blink);
node->blink->flink = node->flink;
if (node->flink)
{
node->flink->blink = node->blink;
}
/* Check if we have to split the free node into one of the
* allocated size and another smaller freenode. In some
* cases, the remaining bytes can be smaller (they may be
* SIZEOF_MM_ALLOCNODE). In that case, we will just carry
* the few wasted bytes at the end of the allocation.
*/
remaining = node->size - size;
if (remaining >= SIZEOF_MM_FREENODE)
{
/* Get a pointer to the next node in physical memory */
next = (struct mm_freenode_s*)(((char*)node) + node->size);
/* Create the remainder node */
remainder = (struct mm_freenode_s*)(((char*)node) + size);
remainder->size = remaining;
remainder->preceding = size;
/* Adjust the size of the node under consideration */
node->size = size;
/* Adjust the 'preceding' size of the (old) next node,
* preserving the allocated flag.
*/
next->preceding = remaining | (next->preceding & MM_ALLOC_BIT);
/* Add the remainder back into the nodelist */
mm_addfreechunk(remainder);
}
/* Handle the case of an exact size match */
node->preceding |= MM_ALLOC_BIT;
ret = (void*)((char*)node + SIZEOF_MM_ALLOCNODE);
}
mm_givesemaphore();
return ret;
}
|
