dlmalloc.h

void* malloc(size_t);
void free(void*);
void* calloc(size_t, size_t);
void* realloc(void*, size_t);
void brk_snapshot(void*);


struct malloc_chunk {
  size_t               prev_foot;  /* Size of previous chunk (if free).  */
  size_t               head;       /* Size and inuse bits. */
  struct malloc_chunk* fd;         /* double links -- used only if free. */
  struct malloc_chunk* bk;
};

typedef struct malloc_chunk  mchunk;
typedef struct malloc_chunk* mchunkptr;
typedef struct malloc_chunk* sbinptr;  /* The type of bins of chunks */
typedef unsigned int bindex_t;         /* Described below */
typedef unsigned int binmap_t;         /* Described below */
typedef unsigned int flag_t;           /* The type of various bit flag sets */

struct malloc_tree_chunk {
  /* The first four fields must be compatible with malloc_chunk */
  size_t                    prev_foot;
  size_t                    head;
  struct malloc_tree_chunk* fd;
  struct malloc_tree_chunk* bk;

  struct malloc_tree_chunk* child[2];
  struct malloc_tree_chunk* parent;
  bindex_t                  index;
};

typedef struct malloc_tree_chunk  tchunk;
typedef struct malloc_tree_chunk* tchunkptr;
typedef struct malloc_tree_chunk* tbinptr; /* The type of bins of trees */

struct malloc_segment {
  char*        base;             /* base address */
  size_t       size;             /* allocated size */
  struct malloc_segment* next;   /* ptr to next segment */
  flag_t       sflags;           /* mmap and extern flag */
};

typedef struct malloc_segment  msegment;
typedef struct malloc_segment* msegmentptr;

#define NSMALLBINS        (32U)
#define NTREEBINS         (32U)
#define SMALLBIN_SHIFT    (3U)
#define SMALLBIN_WIDTH    (SIZE_T_ONE << SMALLBIN_SHIFT)
#define TREEBIN_SHIFT     (8U)
#define MIN_LARGE_SIZE    (SIZE_T_ONE << TREEBIN_SHIFT)
#define MAX_SMALL_SIZE    (MIN_LARGE_SIZE - SIZE_T_ONE)
#define MAX_SMALL_REQUEST (MAX_SMALL_SIZE - CHUNK_ALIGN_MASK - CHUNK_OVERHEAD)

struct malloc_state {
  binmap_t   smallmap;
  binmap_t   treemap;
  size_t     dvsize;
  size_t     topsize;
  char*      least_addr;
  mchunkptr  dv;
  mchunkptr  top;
  size_t     trim_check;
  size_t     release_checks;
  size_t     magic;
  mchunkptr  smallbins[(NSMALLBINS+1)*2];
  tbinptr    treebins[NTREEBINS];
  size_t     footprint;
  size_t     max_footprint;
  size_t     footprint_limit; /* zero means no limit */
  flag_t     mflags;
#if USE_LOCKS
  MLOCK_T    mutex;     /* locate lock among fields that rarely change */
#endif /* USE_LOCKS */
  msegment   seg;
  void*      extp;      /* Unused but available for extensions */
  size_t     exts;
};