1 /*
2 * Implement primitive realloc(3) functionality.
3 *
4 * Author: Mark A. Greer <mgreer@mvista.com>
5 *
6 * 2006 (c) MontaVista, Software, Inc. This file is licensed under
7 * the terms of the GNU General Public License version 2. This program
8 * is licensed "as is" without any warranty of any kind, whether express
9 * or implied.
10 */
11
12 #include <stddef.h>
13 #include "types.h"
14 #include "page.h"
15 #include "string.h"
16 #include "ops.h"
17
18 #define ENTRY_BEEN_USED 0x01
19 #define ENTRY_IN_USE 0x02
20
21 static struct alloc_info {
22 unsigned long flags;
23 unsigned long base;
24 unsigned long size;
25 } *alloc_tbl;
26
27 static unsigned long tbl_entries;
28 static unsigned long alloc_min;
29 static unsigned long next_base;
30 static unsigned long space_left;
31
32 /*
33 * First time an entry is used, its base and size are set.
34 * An entry can be freed and re-malloc'd but its base & size don't change.
35 * Should be smart enough for needs of bootwrapper.
36 */
simple_malloc(unsigned long size)37 static void *simple_malloc(unsigned long size)
38 {
39 unsigned long i;
40 struct alloc_info *p = alloc_tbl;
41
42 if (size == 0)
43 goto err_out;
44
45 size = _ALIGN_UP(size, alloc_min);
46
47 for (i=0; i<tbl_entries; i++, p++)
48 if (!(p->flags & ENTRY_BEEN_USED)) { /* never been used */
49 if (size <= space_left) {
50 p->base = next_base;
51 p->size = size;
52 p->flags = ENTRY_BEEN_USED | ENTRY_IN_USE;
53 next_base += size;
54 space_left -= size;
55 return (void *)p->base;
56 }
57 goto err_out; /* not enough space left */
58 }
59 /* reuse an entry keeping same base & size */
60 else if (!(p->flags & ENTRY_IN_USE) && (size <= p->size)) {
61 p->flags |= ENTRY_IN_USE;
62 return (void *)p->base;
63 }
64 err_out:
65 return NULL;
66 }
67
simple_find_entry(void * ptr)68 static struct alloc_info *simple_find_entry(void *ptr)
69 {
70 unsigned long i;
71 struct alloc_info *p = alloc_tbl;
72
73 for (i=0; i<tbl_entries; i++,p++) {
74 if (!(p->flags & ENTRY_BEEN_USED))
75 break;
76 if ((p->flags & ENTRY_IN_USE) &&
77 (p->base == (unsigned long)ptr))
78 return p;
79 }
80 return NULL;
81 }
82
simple_free(void * ptr)83 static void simple_free(void *ptr)
84 {
85 struct alloc_info *p = simple_find_entry(ptr);
86
87 if (p != NULL)
88 p->flags &= ~ENTRY_IN_USE;
89 }
90
91 /*
92 * Change size of area pointed to by 'ptr' to 'size'.
93 * If 'ptr' is NULL, then its a malloc(). If 'size' is 0, then its a free().
94 * 'ptr' must be NULL or a pointer to a non-freed area previously returned by
95 * simple_realloc() or simple_malloc().
96 */
simple_realloc(void * ptr,unsigned long size)97 static void *simple_realloc(void *ptr, unsigned long size)
98 {
99 struct alloc_info *p;
100 void *new;
101
102 if (size == 0) {
103 simple_free(ptr);
104 return NULL;
105 }
106
107 if (ptr == NULL)
108 return simple_malloc(size);
109
110 p = simple_find_entry(ptr);
111 if (p == NULL) /* ptr not from simple_malloc/simple_realloc */
112 return NULL;
113 if (size <= p->size) /* fits in current block */
114 return ptr;
115
116 new = simple_malloc(size);
117 memcpy(new, ptr, p->size);
118 simple_free(ptr);
119 return new;
120 }
121
122 /*
123 * Returns addr of first byte after heap so caller can see if it took
124 * too much space. If so, change args & try again.
125 */
simple_alloc_init(char * base,unsigned long heap_size,unsigned long granularity,unsigned long max_allocs)126 void *simple_alloc_init(char *base, unsigned long heap_size,
127 unsigned long granularity, unsigned long max_allocs)
128 {
129 unsigned long heap_base, tbl_size;
130
131 heap_size = _ALIGN_UP(heap_size, granularity);
132 alloc_min = granularity;
133 tbl_entries = max_allocs;
134
135 tbl_size = tbl_entries * sizeof(struct alloc_info);
136
137 alloc_tbl = (struct alloc_info *)_ALIGN_UP((unsigned long)base, 8);
138 memset(alloc_tbl, 0, tbl_size);
139
140 heap_base = _ALIGN_UP((unsigned long)alloc_tbl + tbl_size, alloc_min);
141
142 next_base = heap_base;
143 space_left = heap_size;
144
145 platform_ops.malloc = simple_malloc;
146 platform_ops.free = simple_free;
147 platform_ops.realloc = simple_realloc;
148
149 return (void *)(heap_base + heap_size);
150 }
151