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  last update: Mon Aug 15 08:55:52 2005  Doug Lea  (dl at gee)

  This header is for ANSI C/C++ only.  You can set any of

  the following #defines before including:

  * If USE_DL_PREFIX is defined, it is assumed that malloc.c

    was also compiled with this option, so all routines

    have names starting with "dl".

  * If HAVE_USR_INCLUDE_MALLOC_H is defined, it is assumed that this

    file will be #included AFTER <malloc.h>. This is needed only if

    your system defines a struct mallinfo that is incompatible with the

    standard one declared here.  Otherwise, you can include this file

    INSTEAD of your system system <malloc.h>.  At least on ANSI, all

    declarations should be compatible with system versions

  * If MSPACES is defined, declarations for mspace versions are included.

*/

#ifndef MALLOC_280_H

#define MALLOC_280_H

#ifdef __cplusplus

extern "C" {

#endif

#include <stddef.h>   /* for size_t */

#if !ONLY_MSPACES

#ifndef USE_DL_PREFIX

#define dlcalloc               calloc

#define dlfree                 free

#define dlmalloc               malloc

#define dlmemalign             memalign

#define dlrealloc              realloc

#define dlvalloc               valloc

#define dlpvalloc              pvalloc

#define dlmallinfo             mallinfo

#define dlmallopt              mallopt

#define dlmalloc_trim          malloc_trim

#define dlmalloc_stats         malloc_stats

#define dlmalloc_usable_size   malloc_usable_size

#define dlmalloc_footprint     malloc_footprint

#define dlmalloc_max_footprint malloc_max_footprint

#define dlindependent_calloc   independent_calloc

#define dlindependent_comalloc independent_comalloc

#endif /* USE_DL_PREFIX */

/*

  malloc(size_t n)

  Returns a pointer to a newly allocated chunk of at least n bytes, or

  null if no space is available, in which case errno is set to ENOMEM

  on ANSI C systems.

  If n is zero, malloc returns a minimum-sized chunk. (The minimum

  size is 16 bytes on most 32bit systems, and 32 bytes on 64bit

  systems.)  Note that size_t is an unsigned type, so calls with

  arguments that would be negative if signed are interpreted as

  requests for huge amounts of space, which will often fail. The

  maximum supported value of n differs across systems, but is in all

  cases less than the maximum representable value of a size_t.

*/

void* dlmalloc(size_t);

/*

  free(void* p)

  Releases the chunk of memory pointed to by p, that had been previously

  allocated using malloc or a related routine such as realloc.

  It has no effect if p is null. If p was not malloced or already

  freed, free(p) will by default cuase the current program to abort.

*/

void  dlfree(void*);

/*

  calloc(size_t n_elements, size_t element_size);

  Returns a pointer to n_elements * element_size bytes, with all locations

  set to zero.

*/

void* dlcalloc(size_t, size_t);

/*

  realloc(void* p, size_t n)

  Returns a pointer to a chunk of size n that contains the same data

  as does chunk p up to the minimum of (n, p's size) bytes, or null

  if no space is available.

  The returned pointer may or may not be the same as p. The algorithm

  prefers extending p in most cases when possible, otherwise it

  employs the equivalent of a malloc-copy-free sequence.

  If p is null, realloc is equivalent to malloc.

  If space is not available, realloc returns null, errno is set (if on

  ANSI) and p is NOT freed.

  if n is for fewer bytes than already held by p, the newly unused

  space is lopped off and freed if possible.  realloc with a size

  argument of zero (re)allocates a minimum-sized chunk.

  The old unix realloc convention of allowing the last-free'd chunk

  to be used as an argument to realloc is not supported.

*/

void* dlrealloc(void*, size_t);

/*

  memalign(size_t alignment, size_t n);

  Returns a pointer to a newly allocated chunk of n bytes, aligned

  in accord with the alignment argument.

  The alignment argument should be a power of two. If the argument is

  not a power of two, the nearest greater power is used.

  8-byte alignment is guaranteed by normal malloc calls, so don't

  bother calling memalign with an argument of 8 or less.

  Overreliance on memalign is a sure way to fragment space.

*/

void* dlmemalign(size_t, size_t);

/*

  valloc(size_t n);

  Equivalent to memalign(pagesize, n), where pagesize is the page

  size of the system. If the pagesize is unknown, 4096 is used.

*/

void* dlvalloc(size_t);

/*

  mallopt(int parameter_number, int parameter_value)

  Sets tunable parameters The format is to provide a

  (parameter-number, parameter-value) pair.  mallopt then sets the

  corresponding parameter to the argument value if it can (i.e., so

  long as the value is meaningful), and returns 1 if successful else

  0.  SVID/XPG/ANSI defines four standard param numbers for mallopt,

  normally defined in malloc.h.  None of these are use in this malloc,

  so setting them has no effect. But this malloc also supports other

  options in mallopt:

  Symbol            param #  default    allowed param values

  M_TRIM_THRESHOLD     -1   2*1024*1024   any   (-1U disables trimming)

  M_GRANULARITY        -2     page size   any power of 2 >= page size

  M_MMAP_THRESHOLD     -3      256*1024   any   (or 0 if no MMAP support)

*/

int dlmallopt(int, int);

#define M_TRIM_THRESHOLD     (-1)

#define M_GRANULARITY        (-2)

#define M_MMAP_THRESHOLD     (-3)

/*

  malloc_footprint();

  Returns the number of bytes obtained from the system.  The total

  number of bytes allocated by malloc, realloc etc., is less than this

  value. Unlike mallinfo, this function returns only a precomputed

  result, so can be called frequently to monitor memory consumption.

  Even if locks are otherwise defined, this function does not use them,

  so results might not be up to date.

*/

size_t dlmalloc_footprint(void);

size_t dlmalloc_max_footprint(void);

#if !NO_MALLINFO

/*

  mallinfo()

  Returns (by copy) a struct containing various summary statistics:

  arena:     current total non-mmapped bytes allocated from system

  ordblks:   the number of free chunks

  smblks:    always zero.

  hblks:     current number of mmapped regions

  hblkhd:    total bytes held in mmapped regions

  usmblks:   the maximum total allocated space. This will be greater

                than current total if trimming has occurred.

  fsmblks:   always zero

  uordblks:  current total allocated space (normal or mmapped)

  fordblks:  total free space

  keepcost:  the maximum number of bytes that could ideally be released

               back to system via malloc_trim. ("ideally" means that

               it ignores page restrictions etc.)

  Because these fields are ints, but internal bookkeeping may

  be kept as longs, the reported values may wrap around zero and

  thus be inaccurate.

*/

#ifndef HAVE_USR_INCLUDE_MALLOC_H

#ifndef _MALLOC_H

#ifndef MALLINFO_FIELD_TYPE

#define MALLINFO_FIELD_TYPE size_t

#endif /* MALLINFO_FIELD_TYPE */

struct mallinfo {

  MALLINFO_FIELD_TYPE arena;    /* non-mmapped space allocated from system */

  MALLINFO_FIELD_TYPE ordblks;  /* number of free chunks */

  MALLINFO_FIELD_TYPE smblks;   /* always 0 */

  MALLINFO_FIELD_TYPE hblks;    /* always 0 */

  MALLINFO_FIELD_TYPE hblkhd;   /* space in mmapped regions */

  MALLINFO_FIELD_TYPE usmblks;  /* maximum total allocated space */

  MALLINFO_FIELD_TYPE fsmblks;  /* always 0 */

  MALLINFO_FIELD_TYPE uordblks; /* total allocated space */

  MALLINFO_FIELD_TYPE fordblks; /* total free space */

  MALLINFO_FIELD_TYPE keepcost; /* releasable (via malloc_trim) space */

};

#endif  /* _MALLOC_H */

#endif  /* HAVE_USR_INCLUDE_MALLOC_H */

struct mallinfo dlmallinfo(void);

#endif  /* NO_MALLINFO */

/*

  independent_calloc(size_t n_elements, size_t element_size, void* chunks[]);

  independent_calloc is similar to calloc, but instead of returning a

  single cleared space, it returns an array of pointers to n_elements

  independent elements that can hold contents of size elem_size, each

  of which starts out cleared, and can be independently freed,

  realloc'ed etc. The elements are guaranteed to be adjacently

  allocated (this is not guaranteed to occur with multiple callocs or

  mallocs), which may also improve cache locality in some

  applications.

  The "chunks" argument is optional (i.e., may be null, which is

  probably the most typical usage). If it is null, the returned array

  is itself dynamically allocated and should also be freed when it is

  no longer needed. Otherwise, the chunks array must be of at least

  n_elements in length. It is filled in with the pointers to the

  chunks.

  In either case, independent_calloc returns this pointer array, or

  null if the allocation failed.  If n_elements is zero and "chunks"

  is null, it returns a chunk representing an array with zero elements

  (which should be freed if not wanted).

  Each element must be individually freed when it is no longer

  needed. If you'd like to instead be able to free all at once, you

  should instead use regular calloc and assign pointers into this

  space to represent elements.  (In this case though, you cannot

  independently free elements.)

  independent_calloc simplifies and speeds up implementations of many

  kinds of pools.  It may also be useful when constructing large data

  structures that initially have a fixed number of fixed-sized nodes,

  but the number is not known at compile time, and some of the nodes

  may later need to be freed. For example:

  struct Node { int item; struct Node* next; };

  struct Node* build_list() {

    struct Node** pool;

    int n = read_number_of_nodes_needed();

    if (n <= 0) return 0;

    pool = (struct Node**)(independent_calloc(n, sizeof(struct Node), 0);

    if (pool == 0) die();

    // organize into a linked list...

    struct Node* first = pool[0];

    for (i = 0; i < n-1; ++i)

      pool[i]->next = pool[i+1];

    free(pool);     // Can now free the array (or not, if it is needed later)

    return first;

  }

*/

void** dlindependent_calloc(size_t, size_t, void**);

/*

  independent_comalloc(size_t n_elements, size_t sizes[], void* chunks[]);

  independent_comalloc allocates, all at once, a set of n_elements

  chunks with sizes indicated in the "sizes" array.    It returns

  an array of pointers to these elements, each of which can be

  independently freed, realloc'ed etc. The elements are guaranteed to

  be adjacently allocated (this is not guaranteed to occur with

  multiple callocs or mallocs), which may also improve cache locality

  in some applications.

  The "chunks" argument is optional (i.e., may be null). If it is null

  the returned array is itself dynamically allocated and should also

  be freed when it is no longer needed. Otherwise, the chunks array

  must be of at least n_elements in length. It is filled in with the

  pointers to the chunks.

  In either case, independent_comalloc returns this pointer array, or

  null if the allocation failed.  If n_elements is zero and chunks is

  null, it returns a chunk representing an array with zero elements

  (which should be freed if not wanted).

  Each element must be individually freed when it is no longer

  needed. If you'd like to instead be able to free all at once, you

  should instead use a single regular malloc, and assign pointers at

  particular offsets in the aggregate space. (In this case though, you

  cannot independently free elements.)

  independent_comallac differs from independent_calloc in that each

  element may have a different size, and also that it does not

  automatically clear elements.

  independent_comalloc can be used to speed up allocation in cases

  where several structs or objects must always be allocated at the

  same time.  For example:

  struct Head { ... }

  struct Foot { ... }

  void send_message(char* msg) {

    int msglen = strlen(msg);

    size_t sizes[3] = { sizeof(struct Head), msglen, sizeof(struct Foot) };

    void* chunks[3];

    if (independent_comalloc(3, sizes, chunks) == 0)

      die();

    struct Head* head = (struct Head*)(chunks[0]);

    char*        body = (char*)(chunks[1]);

    struct Foot* foot = (struct Foot*)(chunks[2]);

    // ...

  }

  In general though, independent_comalloc is worth using only for

  larger values of n_elements. For small values, you probably won't

  detect enough difference from series of malloc calls to bother.

  Overuse of independent_comalloc can increase overall memory usage,

  since it cannot reuse existing noncontiguous small chunks that

  might be available for some of the elements.

*/

void** dlindependent_comalloc(size_t, size_t*, void**);

/*

  pvalloc(size_t n);

  Equivalent to valloc(minimum-page-that-holds(n)), that is,

  round up n to nearest pagesize.

 */

void*  dlpvalloc(size_t);

/*

  malloc_trim(size_t pad);

  If possible, gives memory back to the system (via negative arguments

  to sbrk) if there is unused memory at the `high' end of the malloc

  pool or in unused MMAP segments. You can call this after freeing

  large blocks of memory to potentially reduce the system-level memory

  requirements of a program. However, it cannot guarantee to reduce

  memory. Under some allocation patterns, some large free blocks of

  memory will be locked between two used chunks, so they cannot be

  given back to the system.

  The `pad' argument to malloc_trim represents the amount of free

  trailing space to leave untrimmed. If this argument is zero, only

  the minimum amount of memory to maintain internal data structures

  will be left. Non-zero arguments can be supplied to maintain enough

  trailing space to service future expected allocations without having

  to re-obtain memory from the system.

  Malloc_trim returns 1 if it actually released any memory, else 0.

*/

int  dlmalloc_trim(size_t);

/*

  malloc_usable_size(void* p);

  Returns the number of bytes you can actually use in

  an allocated chunk, which may be more than you requested (although

  often not) due to alignment and minimum size constraints.

  You can use this many bytes without worrying about

  overwriting other allocated objects. This is not a particularly great

  programming practice. malloc_usable_size can be more useful in

  debugging and assertions, for example:

  p = malloc(n);

  assert(malloc_usable_size(p) >= 256);

*/

size_t dlmalloc_usable_size(void*);

/*

  malloc_stats();

  Prints on stderr the amount of space obtained from the system (both

  via sbrk and mmap), the maximum amount (which may be more than

  current if malloc_trim and/or munmap got called), and the current

  number of bytes allocated via malloc (or realloc, etc) but not yet

  freed. Note that this is the number of bytes allocated, not the

  number requested. It will be larger than the number requested

  because of alignment and bookkeeping overhead. Because it includes

  alignment wastage as being in use, this figure may be greater than

  zero even when no user-level chunks are allocated.

  The reported current and maximum system memory can be inaccurate if

  a program makes other calls to system memory allocation functions

  (normally sbrk) outside of malloc.

  malloc_stats prints only the most commonly interesting statistics.

  More information can be obtained by calling mallinfo.

*/

void  dlmalloc_stats(void);

#endif /* !ONLY_MSPACES */

#if MSPACES

/*

  mspace is an opaque type representing an independent

  region of space that supports mspace_malloc, etc.

*/

typedef void* mspace;

/*

  create_mspace creates and returns a new independent space with the

  given initial capacity, or, if 0, the default granularity size.  It

  returns null if there is no system memory available to create the

  space.  If argument locked is non-zero, the space uses a separate

  lock to control access. The capacity of the space will grow

  dynamically as needed to service mspace_malloc requests.  You can

  control the sizes of incremental increases of this space by

  compiling with a different DEFAULT_GRANULARITY or dynamically

  setting with mallopt(M_GRANULARITY, value).

*/

mspace create_mspace(size_t capacity, int locked);

/*

  destroy_mspace destroys the given space, and attempts to return all

  of its memory back to the system, returning the total number of

  bytes freed. After destruction, the results of access to all memory

  used by the space become undefined.

*/

size_t destroy_mspace(mspace msp);

/*

  create_mspace_with_base uses the memory supplied as the initial base

  of a new mspace. Part (less than 128*sizeof(size_t) bytes) of this

  space is used for bookkeeping, so the capacity must be at least this

  large. (Otherwise 0 is returned.) When this initial space is

  exhausted, additional memory will be obtained from the system.

  Destroying this space will deallocate all additionally allocated

  space (if possible) but not the initial base.

*/

mspace create_mspace_with_base(void* base, size_t capacity, int locked);

/*

  mspace_malloc behaves as malloc, but operates within

  the given space.

*/

void* mspace_malloc(mspace msp, size_t bytes);

/*

  mspace_free behaves as free, but operates within

  the given space.

  If compiled with FOOTERS==1, mspace_free is not actually needed.

  free may be called instead of mspace_free because freed chunks from

  any space are handled by their originating spaces.

*/

void mspace_free(mspace msp, void* mem);

/*

  mspace_realloc behaves as realloc, but operates within

  the given space.

  If compiled with FOOTERS==1, mspace_realloc is not actually

  needed.  realloc may be called instead of mspace_realloc because

  realloced chunks from any space are handled by their originating

  spaces.

*/

void* mspace_realloc(mspace msp, void* mem, size_t newsize);

/*

  mspace_calloc behaves as calloc, but operates within

  the given space.

*/

void* mspace_calloc(mspace msp, size_t n_elements, size_t elem_size);

/*

  mspace_memalign behaves as memalign, but operates within

  the given space.

*/

void* mspace_memalign(mspace msp, size_t alignment, size_t bytes);

/*

  mspace_independent_calloc behaves as independent_calloc, but

  operates within the given space.

*/

void** mspace_independent_calloc(mspace msp, size_t n_elements,

                                 size_t elem_size, void* chunks[]);

/*

  mspace_independent_comalloc behaves as independent_comalloc, but

  operates within the given space.

*/

void** mspace_independent_comalloc(mspace msp, size_t n_elements,

                                   size_t sizes[], void* chunks[]);

/*

  mspace_footprint() returns the number of bytes obtained from the

  system for this space.

*/

size_t mspace_footprint(mspace msp);

#if !NO_MALLINFO

/*

  mspace_mallinfo behaves as mallinfo, but reports properties of

  the given space.

*/

struct mallinfo mspace_mallinfo(mspace msp);

#endif /* NO_MALLINFO */

/*

  mspace_malloc_stats behaves as malloc_stats, but reports

  properties of the given space.

*/

void mspace_malloc_stats(mspace msp);

/*

  mspace_trim behaves as malloc_trim, but

  operates within the given space.

*/

int mspace_trim(mspace msp, size_t pad);

/*

  An alias for mallopt.

*/

int mspace_mallopt(int, int);

#endif  /* MSPACES */

#ifdef __cplusplus

};  /* end of extern "C" */

#endif /* MALLOC_280_H */