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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 (__alignof__ (double))
/* The system pagesize... */
extern size_t __pagesize;
#define MALLOC_PAGE_SIZE __pagesize
/* 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 __ARCH_USE_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 __putc(int c, FILE *stream) attribute_hidden;
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;
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