Rev 378 | Go to most recent revision | Details | Last modification | View Log | RSS feed
Rev | Author | Line No. | Line |
---|---|---|---|
377 | jermar | 1 | /* |
2 | * Copyright (C) 2005 Jakub Jermar |
||
3 | * All rights reserved. |
||
4 | * |
||
5 | * Redistribution and use in source and binary forms, with or without |
||
6 | * modification, are permitted provided that the following conditions |
||
7 | * are met: |
||
8 | * |
||
9 | * - Redistributions of source code must retain the above copyright |
||
10 | * notice, this list of conditions and the following disclaimer. |
||
11 | * - Redistributions in binary form must reproduce the above copyright |
||
12 | * notice, this list of conditions and the following disclaimer in the |
||
13 | * documentation and/or other materials provided with the distribution. |
||
14 | * - The name of the author may not be used to endorse or promote products |
||
15 | * derived from this software without specific prior written permission. |
||
16 | * |
||
17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
||
18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
||
19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
||
20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
||
21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
||
22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
||
23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
||
24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
||
25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
||
26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
||
27 | */ |
||
28 | |||
29 | #include <mm/buddy.h> |
||
30 | #include <mm/frame.h> |
||
31 | #include <mm/heap.h> |
||
32 | #include <arch/types.h> |
||
33 | #include <typedefs.h> |
||
34 | #include <list.h> |
||
35 | #include <debug.h> |
||
36 | |||
37 | /** Create buddy system |
||
38 | * |
||
39 | * Allocate memory for and initialize new buddy system. |
||
40 | * |
||
41 | * @param max_order The biggest allocable size will be 2^max_order. |
||
42 | * @param op Operations for new buddy system. |
||
43 | * |
||
44 | * @return New buddy system. |
||
45 | */ |
||
46 | buddy_system_t *buddy_system_create(__u8 max_order, buddy_operations_t *op) |
||
47 | { |
||
48 | buddy_system_t *b; |
||
49 | int i; |
||
50 | |||
51 | ASSERT(op->find_buddy); |
||
52 | ASSERT(op->set_order); |
||
53 | ASSERT(op->get_order); |
||
54 | ASSERT(op->bisect); |
||
55 | ASSERT(op->coalesce); |
||
56 | |||
57 | /* |
||
58 | * Allocate memory for structure describing the whole buddy system. |
||
59 | */ |
||
60 | b = (buddy_system_t *) early_malloc(sizeof(buddy_system_t)); |
||
61 | |||
62 | if (b) { |
||
63 | /* |
||
64 | * Allocate memory for all orders this buddy system will work with. |
||
65 | */ |
||
66 | b->order = (link_t *) early_malloc(max_order * sizeof(link_t)); |
||
67 | if (!b->order) { |
||
68 | early_free(b); |
||
69 | return NULL; |
||
70 | } |
||
71 | |||
72 | for (i = 0; i < max_order; i++) |
||
73 | list_initialize(&b->order[i]); |
||
74 | |||
75 | b->max_order = max_order; |
||
76 | b->op = op; |
||
77 | } |
||
78 | |||
79 | return b; |
||
80 | } |
||
81 | |||
82 | /** Allocate block from buddy system. |
||
83 | * |
||
84 | * Allocate block from buddy system. |
||
85 | * |
||
86 | * @param b Buddy system pointer. |
||
87 | * @param i Returned block will be 2^i big. |
||
88 | * |
||
89 | * @return Block of data represented by link_t. |
||
90 | */ |
||
91 | link_t *buddy_system_alloc(buddy_system_t *b, __u8 i) |
||
92 | { |
||
93 | link_t *res, *hlp; |
||
94 | |||
95 | ASSERT(i < b->max_order); |
||
96 | |||
97 | /* |
||
98 | * If the list of order i is not empty, |
||
99 | * the request can be immediatelly satisfied. |
||
100 | */ |
||
101 | if (!list_empty(&b->order[i])) { |
||
102 | res = b->order[i].next; |
||
103 | list_remove(res); |
||
104 | return res; |
||
105 | } |
||
106 | |||
107 | /* |
||
108 | * If order i is already the maximal order, |
||
109 | * the request cannot be satisfied. |
||
110 | */ |
||
111 | if (i == b->max_order - 1) |
||
112 | return NULL; |
||
113 | |||
114 | /* |
||
115 | * Try to recursively satisfy the request from higher order lists. |
||
116 | */ |
||
117 | hlp = buddy_system_alloc(b, i + 1); |
||
118 | |||
119 | /* |
||
120 | * The request could not be satisfied |
||
121 | * from higher order lists. |
||
122 | */ |
||
123 | if (!hlp) |
||
124 | return NULL; |
||
125 | |||
126 | res = hlp; |
||
127 | |||
128 | /* |
||
129 | * Bisect the block and set order of both of its parts to i. |
||
130 | */ |
||
131 | hlp = b->op->bisect(res); |
||
132 | b->op->set_order(res, i); |
||
133 | b->op->set_order(hlp, i); |
||
134 | |||
135 | /* |
||
136 | * Return the other half to buddy system. |
||
137 | */ |
||
138 | buddy_system_free(b, hlp); |
||
139 | |||
140 | return res; |
||
141 | |||
142 | } |
||
143 | |||
144 | /** Return block to buddy system. |
||
145 | * |
||
146 | * Return block to buddy system. |
||
147 | * |
||
148 | * @param b Buddy system pointer. |
||
149 | * @param block Block to return. |
||
150 | */ |
||
151 | void buddy_system_free(buddy_system_t *b, link_t *block) |
||
152 | { |
||
153 | link_t *buddy, *hlp; |
||
154 | __u8 i; |
||
155 | |||
156 | /* |
||
157 | * Determine block's order. |
||
158 | */ |
||
159 | i = b->op->get_order(block); |
||
160 | |||
161 | ASSERT(i < b->max_order); |
||
162 | |||
163 | /* |
||
164 | * See if there is any buddy in the list of order i. |
||
165 | */ |
||
166 | buddy = b->op->find_buddy(block); |
||
167 | |||
168 | if (buddy && i != b->max_order - 1) { |
||
169 | /* |
||
170 | * Remove buddy from the list of order i. |
||
171 | */ |
||
172 | list_remove(buddy); |
||
173 | |||
174 | /* |
||
175 | * Coalesce block and buddy into one block. |
||
176 | */ |
||
177 | hlp = b->op->coalesce(block, buddy); |
||
178 | |||
179 | /* |
||
180 | * Set order of the coalesced block to i + 1. |
||
181 | */ |
||
182 | b->op->set_order(hlp, i + 1); |
||
183 | |||
184 | /* |
||
185 | * Recursively add the coalesced block to the list of order i + 1. |
||
186 | */ |
||
187 | buddy_system_free(b, hlp); |
||
188 | } |
||
189 | else { |
||
190 | /* |
||
191 | * Insert block into the list of order i. |
||
192 | */ |
||
193 | list_append(block, &b->order[i]); |
||
194 | } |
||
195 | |||
196 | } |