1 /*
2  * malloc.h
3  *
4  * Internals for the memory allocator
5  */
6 
7 #include <stdint.h>
8 #include <stddef.h>
9 
10 /*
11  * This is the minimum chunk size we will ask the kernel for; this should
12  * be a multiple of the page size on all architectures.
13  */
14 #define MALLOC_CHUNK_SIZE	65536
15 #define MALLOC_CHUNK_MASK       (MALLOC_CHUNK_SIZE-1)
16 
17 /*
18  * This structure should be a power of two.  This becomes the
19  * alignment unit.
20  */
21 struct free_arena_header;
22 
23 struct arena_header {
24     size_t type;
25     size_t size;		/* Also gives the location of the next entry */
26     struct free_arena_header *next, *prev;
27 };
28 
29 #ifdef DEBUG_MALLOC
30 #define ARENA_TYPE_USED 0x64e69c70
31 #define ARENA_TYPE_FREE 0x012d610a
32 #define ARENA_TYPE_HEAD 0x971676b5
33 #define ARENA_TYPE_DEAD 0xeeeeeeee
34 #else
35 #define ARENA_TYPE_USED 0
36 #define ARENA_TYPE_FREE 1
37 #define ARENA_TYPE_HEAD 2
38 #endif
39 
40 #define ARENA_SIZE_MASK (~(uintptr_t)(sizeof(struct arena_header)-1))
41 
42 #define ARENA_ALIGN_UP(p)	((char *)(((uintptr_t)(p) + ~ARENA_SIZE_MASK) & ARENA_SIZE_MASK))
43 #define ARENA_ALIGN_DOWN(p)	((char *)((uintptr_t)(p) & ARENA_SIZE_MASK))
44 
45 /*
46  * This structure should be no more than twice the size of the
47  * previous structure.
48  */
49 struct free_arena_header {
50     struct arena_header a;
51     struct free_arena_header *next_free, *prev_free;
52 };
53 
54 extern struct free_arena_header __malloc_head;
55 void __inject_free_block(struct free_arena_header *ah);
56