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/*

 * libc/stdlib/malloc/malloc.h -- small malloc implementation

 *

 *  Copyright (C) 2002  NEC Corporation

 *  Copyright (C) 2002  Miles Bader <miles@gnu.org>

 *

 * This file is subject to the terms and conditions of the GNU Lesser

 * General Public License.  See the file COPYING.LIB in the main

 * directory of this archive for more details.

 *

 * Written by Miles Bader <miles@gnu.org>

 */

/* The alignment we guarantee for malloc return values.  */

#define MALLOC_ALIGNMENT        (sizeof (double))

/* The system pagesize we assume; we really ought to get it with

   getpagesize, but gee, how annoying.  */

#define MALLOC_PAGE_SIZE        4096

/* The minimum size of block we request from the the system to extend the

   heap for small allocations (we may request a bigger block if necessary to

   satisfy a particularly big request).  */

#define MALLOC_HEAP_EXTEND_SIZE MALLOC_PAGE_SIZE

/* When a heap free-area grows above this size, try to unmap it, releasing

   the memory back to the system.  */

#define MALLOC_UNMAP_THRESHOLD  (8*MALLOC_PAGE_SIZE)

/* When unmapping a free-area, retain this many bytes if it's the only one,

   to avoid completely emptying the heap.  This is only a heuristic -- the

   existance of another free area, even if it's smaller than

   MALLOC_MIN_SIZE, will cause us not to reserve anything.  */

#define MALLOC_MIN_SIZE         (2*MALLOC_PAGE_SIZE)

/* When realloc shrinks an allocation, it only does so if more than this

   many bytes will be freed; it must at at least HEAP_MIN_SIZE.  Larger

   values increase speed (by reducing heap fragmentation) at the expense of

   space.  */

#define MALLOC_REALLOC_MIN_FREE_SIZE  (HEAP_MIN_SIZE + 16)

/* For systems with an MMU, use sbrk to map/unmap memory for the malloc

   heap, instead of mmap/munmap.  This is a tradeoff -- sbrk is faster than

   mmap/munmap, and guarantees contiguous allocation, but is also less

   flexible, and causes the heap to only be shrinkable from the end.  */

#ifdef __UCLIBC_HAS_MMU__

# define MALLOC_USE_SBRK

#endif

/* The current implementation of munmap in uClinux doesn't work correctly:

   it requires that ever call to munmap exactly match a corresponding call

   to mmap (that is, it doesn't allow you to unmap only part of a

   previously allocated block, or to unmap two contiguous blocks with a

   single call to munmap).  This behavior is broken, and uClinux should be

   fixed; however, until it is, we add code to work around the problem in

   malloc.  */

#ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__

/* A structure recording a block of memory mmapped by malloc.  */

struct malloc_mmb

{

  void *mem;                    /* the mmapped block */

  size_t size;                  /* its size */

  struct malloc_mmb *next;

};

/* A list of all malloc_mmb structures describing blocsk that malloc has

   mmapped, ordered by the block address.  */

extern struct malloc_mmb *__malloc_mmapped_blocks;

/* A heap used for allocating malloc_mmb structures.  We could allocate

   them from the main heap, but that tends to cause heap fragmentation in

   annoying ways.  */

extern struct heap __malloc_mmb_heap;

/* Define MALLOC_MMB_DEBUGGING to cause malloc to emit debugging info about

   about mmap block allocation/freeing by the `uclinux broken munmap' code

   to stderr, when the variable __malloc_mmb_debug is set to true. */

#ifdef MALLOC_MMB_DEBUGGING

# include <stdio.h>

extern int __malloc_mmb_debug;

# define MALLOC_MMB_DEBUG(indent, fmt, args...)                               \

   (__malloc_mmb_debug ? __malloc_debug_printf (indent, fmt , ##args) : 0)

# define MALLOC_MMB_DEBUG_INDENT(indent)                                      \

   (__malloc_mmb_debug ? __malloc_debug_indent (indent) : 0)

# ifndef MALLOC_DEBUGGING

#  define MALLOC_DEBUGGING

# endif

#else /* !MALLOC_MMB_DEBUGGING */

# define MALLOC_MMB_DEBUG(fmt, args...) (void)0

# define MALLOC_MMB_DEBUG_INDENT(indent) (void)0

#endif /* MALLOC_MMB_DEBUGGING */

#endif /* __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */

/* The size of a malloc allocation is stored in a size_t word

   MALLOC_ALIGNMENT bytes prior to the start address of the allocation:

     +--------+---------+-------------------+

     | SIZE   |(unused) | allocation  ...   |

     +--------+---------+-------------------+

     ^ BASE             ^ ADDR

     ^ ADDR - MALLOC_ALIGN

*/

/* The amount of extra space used by the malloc header.  */

#define MALLOC_HEADER_SIZE      MALLOC_ALIGNMENT

/* Set up the malloc header, and return the user address of a malloc block. */

#define MALLOC_SETUP(base, size)  \

  (MALLOC_SET_SIZE (base, size), (void *)((char *)base + MALLOC_HEADER_SIZE))

/* Set the size of a malloc allocation, given the base address.  */

#define MALLOC_SET_SIZE(base, size)     (*(size_t *)(base) = (size))

/* Return base-address of a malloc allocation, given the user address.  */

#define MALLOC_BASE(addr)       ((void *)((char *)addr - MALLOC_HEADER_SIZE))

/* Return the size of a malloc allocation, given the user address.  */

#define MALLOC_SIZE(addr)       (*(size_t *)MALLOC_BASE(addr))

/* Locking for multithreaded apps.  */

#ifdef __UCLIBC_HAS_THREADS__

# include <pthread.h>

# define MALLOC_USE_LOCKING

typedef pthread_mutex_t malloc_mutex_t;

# define MALLOC_MUTEX_INIT      PTHREAD_MUTEX_INITIALIZER

# ifdef MALLOC_USE_SBRK

/* This lock is used to serialize uses of the `sbrk' function (in both

   malloc and free, sbrk may be used several times in succession, and

   things will break if these multiple calls are interleaved with another

   thread's use of sbrk!).  */

extern malloc_mutex_t __malloc_sbrk_lock;

#  define __malloc_lock_sbrk()  __pthread_mutex_lock (&__malloc_sbrk_lock)

#  define __malloc_unlock_sbrk() __pthread_mutex_unlock (&__malloc_sbrk_lock)

# endif /* MALLOC_USE_SBRK */

#else /* !__UCLIBC_HAS_THREADS__ */

/* Without threads, mutex operations are a nop.  */

# define __malloc_lock_sbrk()   (void)0

# define __malloc_unlock_sbrk() (void)0

#endif /* __UCLIBC_HAS_THREADS__ */

/* branch-prediction macros; they may already be defined by libc.  */

#ifndef likely

#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)

#define likely(cond)    __builtin_expect(!!(int)(cond), 1)

#define unlikely(cond)  __builtin_expect((int)(cond), 0)

#else

#define likely(cond)    (cond)

#define unlikely(cond)  (cond)

#endif

#endif /* !likely */

/* Define MALLOC_DEBUGGING to cause malloc to emit debugging info to stderr

   when the variable __malloc_debug is set to true. */

#ifdef MALLOC_DEBUGGING

extern void __malloc_debug_init (void);

/* The number of spaces in a malloc debug indent level.  */

#define MALLOC_DEBUG_INDENT_SIZE 3

extern int __malloc_debug, __malloc_check;

# define MALLOC_DEBUG(indent, fmt, args...)                                   \

   (__malloc_debug ? __malloc_debug_printf (indent, fmt , ##args) : 0)

# define MALLOC_DEBUG_INDENT(indent)                                          \

   (__malloc_debug ? __malloc_debug_indent (indent) : 0)

extern int __malloc_debug_cur_indent;

/* Print FMT and args indented at the current debug print level, followed

   by a newline, and change the level by INDENT.  */

extern void __malloc_debug_printf (int indent, const char *fmt, ...);

/* Change the current debug print level by INDENT, and return the value.  */

#define __malloc_debug_indent(indent) (__malloc_debug_cur_indent += indent)

/* Set the current debug print level to LEVEL.  */

#define __malloc_debug_set_indent(level) (__malloc_debug_cur_indent = level)

#else /* !MALLOC_DEBUGGING */

# define MALLOC_DEBUG(fmt, args...) (void)0

# define MALLOC_DEBUG_INDENT(indent) (void)0

#endif /* MALLOC_DEBUGGING */

/* Return SZ rounded down to POWER_OF_2_SIZE (which must be power of 2).  */

#define MALLOC_ROUND_DOWN(sz, power_of_2_size)  \

  ((sz) & ~(power_of_2_size - 1))

/* Return SZ rounded to POWER_OF_2_SIZE (which must be power of 2).  */

#define MALLOC_ROUND_UP(sz, power_of_2_size)                            \

  MALLOC_ROUND_DOWN ((sz) + (power_of_2_size - 1), (power_of_2_size))

/* Return SZ rounded down to a multiple MALLOC_PAGE_SIZE.  */

#define MALLOC_ROUND_DOWN_TO_PAGE_SIZE(sz)  \

  MALLOC_ROUND_DOWN (sz, MALLOC_PAGE_SIZE)

/* Return SZ rounded up to a multiple MALLOC_PAGE_SIZE.  */

#define MALLOC_ROUND_UP_TO_PAGE_SIZE(sz)  \

  MALLOC_ROUND_UP (sz, MALLOC_PAGE_SIZE)

/* The malloc heap.  */

extern struct heap __malloc_heap;