dos/malloc.h

   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 (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;