2002-11-03 00:07:02 +00:00
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/*
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A version of malloc/free/realloc written by Doug Lea and released to the
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public domain. Send questions/comments/complaints/performance data
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to dl@cs.oswego.edu
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* VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)
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Note: There may be an updated version of this malloc obtainable at
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2003-06-27 21:31:46 +00:00
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ftp://g.oswego.edu/pub/misc/malloc.c
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Check before installing!
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2002-11-03 00:07:02 +00:00
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* Why use this malloc?
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This is not the fastest, most space-conserving, most portable, or
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most tunable malloc ever written. However it is among the fastest
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while also being among the most space-conserving, portable and tunable.
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Consistent balance across these factors results in a good general-purpose
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allocator. For a high-level description, see
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http://g.oswego.edu/dl/html/malloc.html
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* Synopsis of public routines
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(Much fuller descriptions are contained in the program documentation below.)
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malloc(size_t n);
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Return a pointer to a newly allocated chunk of at least n bytes, or null
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if no space is available.
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free(Void_t* p);
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Release the chunk of memory pointed to by p, or no effect if p is null.
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realloc(Void_t* p, size_t n);
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Return a pointer to a chunk of size n that contains the same data
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as does chunk p up to the minimum of (n, p's size) bytes, or null
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if no space is available. The returned pointer may or may not be
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the same as p. If p is null, equivalent to malloc. Unless the
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#define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
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size argument of zero (re)allocates a minimum-sized chunk.
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memalign(size_t alignment, size_t n);
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Return a pointer to a newly allocated chunk of n bytes, aligned
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in accord with the alignment argument, which must be a power of
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two.
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valloc(size_t n);
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Equivalent to memalign(pagesize, n), where pagesize is the page
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size of the system (or as near to this as can be figured out from
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all the includes/defines below.)
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pvalloc(size_t n);
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Equivalent to valloc(minimum-page-that-holds(n)), that is,
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round up n to nearest pagesize.
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calloc(size_t unit, size_t quantity);
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Returns a pointer to quantity * unit bytes, with all locations
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set to zero.
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cfree(Void_t* p);
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Equivalent to free(p).
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malloc_trim(size_t pad);
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Release all but pad bytes of freed top-most memory back
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to the system. Return 1 if successful, else 0.
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malloc_usable_size(Void_t* p);
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Report the number usable allocated bytes associated with allocated
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chunk p. This may or may not report more bytes than were requested,
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due to alignment and minimum size constraints.
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malloc_stats();
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Prints brief summary statistics on stderr.
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mallinfo()
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Returns (by copy) a struct containing various summary statistics.
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mallopt(int parameter_number, int parameter_value)
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Changes one of the tunable parameters described below. Returns
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1 if successful in changing the parameter, else 0.
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* Vital statistics:
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Alignment: 8-byte
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8 byte alignment is currently hardwired into the design. This
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seems to suffice for all current machines and C compilers.
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Assumed pointer representation: 4 or 8 bytes
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Code for 8-byte pointers is untested by me but has worked
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reliably by Wolfram Gloger, who contributed most of the
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changes supporting this.
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Assumed size_t representation: 4 or 8 bytes
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Note that size_t is allowed to be 4 bytes even if pointers are 8.
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Minimum overhead per allocated chunk: 4 or 8 bytes
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Each malloced chunk has a hidden overhead of 4 bytes holding size
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and status information.
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Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
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2003-06-27 21:31:46 +00:00
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8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
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2002-11-03 00:07:02 +00:00
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When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
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ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
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needed; 4 (8) for a trailing size field
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and 8 (16) bytes for free list pointers. Thus, the minimum
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allocatable size is 16/24/32 bytes.
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Even a request for zero bytes (i.e., malloc(0)) returns a
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pointer to something of the minimum allocatable size.
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Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
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2003-06-27 21:31:46 +00:00
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8-byte size_t: 2^63 - 16 bytes
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2002-11-03 00:07:02 +00:00
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It is assumed that (possibly signed) size_t bit values suffice to
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represent chunk sizes. `Possibly signed' is due to the fact
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that `size_t' may be defined on a system as either a signed or
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an unsigned type. To be conservative, values that would appear
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as negative numbers are avoided.
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Requests for sizes with a negative sign bit when the request
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size is treaded as a long will return null.
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Maximum overhead wastage per allocated chunk: normally 15 bytes
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Alignnment demands, plus the minimum allocatable size restriction
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make the normal worst-case wastage 15 bytes (i.e., up to 15
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more bytes will be allocated than were requested in malloc), with
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two exceptions:
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2003-06-27 21:31:46 +00:00
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1. Because requests for zero bytes allocate non-zero space,
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the worst case wastage for a request of zero bytes is 24 bytes.
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2. For requests >= mmap_threshold that are serviced via
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mmap(), the worst case wastage is 8 bytes plus the remainder
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from a system page (the minimal mmap unit); typically 4096 bytes.
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2002-11-03 00:07:02 +00:00
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* Limitations
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Here are some features that are NOT currently supported
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* No user-definable hooks for callbacks and the like.
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* No automated mechanism for fully checking that all accesses
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to malloced memory stay within their bounds.
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* No support for compaction.
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* Synopsis of compile-time options:
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People have reported using previous versions of this malloc on all
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versions of Unix, sometimes by tweaking some of the defines
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below. It has been tested most extensively on Solaris and
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Linux. It is also reported to work on WIN32 platforms.
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People have also reported adapting this malloc for use in
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stand-alone embedded systems.
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The implementation is in straight, hand-tuned ANSI C. Among other
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consequences, it uses a lot of macros. Because of this, to be at
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all usable, this code should be compiled using an optimizing compiler
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(for example gcc -O2) that can simplify expressions and control
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paths.
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__STD_C (default: derived from C compiler defines)
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Nonzero if using ANSI-standard C compiler, a C++ compiler, or
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a C compiler sufficiently close to ANSI to get away with it.
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DEBUG (default: NOT defined)
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Define to enable debugging. Adds fairly extensive assertion-based
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checking to help track down memory errors, but noticeably slows down
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execution.
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REALLOC_ZERO_BYTES_FREES (default: NOT defined)
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Define this if you think that realloc(p, 0) should be equivalent
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to free(p). Otherwise, since malloc returns a unique pointer for
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malloc(0), so does realloc(p, 0).
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HAVE_MEMCPY (default: defined)
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Define if you are not otherwise using ANSI STD C, but still
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have memcpy and memset in your C library and want to use them.
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Otherwise, simple internal versions are supplied.
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USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
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Define as 1 if you want the C library versions of memset and
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memcpy called in realloc and calloc (otherwise macro versions are used).
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At least on some platforms, the simple macro versions usually
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outperform libc versions.
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HAVE_MMAP (default: defined as 1)
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Define to non-zero to optionally make malloc() use mmap() to
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allocate very large blocks.
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HAVE_MREMAP (default: defined as 0 unless Linux libc set)
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Define to non-zero to optionally make realloc() use mremap() to
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reallocate very large blocks.
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malloc_getpagesize (default: derived from system #includes)
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Either a constant or routine call returning the system page size.
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HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
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Optionally define if you are on a system with a /usr/include/malloc.h
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that declares struct mallinfo. It is not at all necessary to
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define this even if you do, but will ensure consistency.
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INTERNAL_SIZE_T (default: size_t)
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Define to a 32-bit type (probably `unsigned int') if you are on a
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64-bit machine, yet do not want or need to allow malloc requests of
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greater than 2^31 to be handled. This saves space, especially for
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very small chunks.
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INTERNAL_LINUX_C_LIB (default: NOT defined)
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Defined only when compiled as part of Linux libc.
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Also note that there is some odd internal name-mangling via defines
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(for example, internally, `malloc' is named `mALLOc') needed
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when compiling in this case. These look funny but don't otherwise
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affect anything.
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WIN32 (default: undefined)
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Define this on MS win (95, nt) platforms to compile in sbrk emulation.
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LACKS_UNISTD_H (default: undefined if not WIN32)
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Define this if your system does not have a <unistd.h>.
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LACKS_SYS_PARAM_H (default: undefined if not WIN32)
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Define this if your system does not have a <sys/param.h>.
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MORECORE (default: sbrk)
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The name of the routine to call to obtain more memory from the system.
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MORECORE_FAILURE (default: -1)
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The value returned upon failure of MORECORE.
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MORECORE_CLEARS (default 1)
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True (1) if the routine mapped to MORECORE zeroes out memory (which
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holds for sbrk).
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DEFAULT_TRIM_THRESHOLD
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DEFAULT_TOP_PAD
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DEFAULT_MMAP_THRESHOLD
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DEFAULT_MMAP_MAX
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Default values of tunable parameters (described in detail below)
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controlling interaction with host system routines (sbrk, mmap, etc).
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These values may also be changed dynamically via mallopt(). The
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preset defaults are those that give best performance for typical
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programs/systems.
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USE_DL_PREFIX (default: undefined)
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Prefix all public routines with the string 'dl'. Useful to
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quickly avoid procedure declaration conflicts and linker symbol
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conflicts with existing memory allocation routines.
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*/
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2009-02-20 16:45:38 +00:00
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#ifndef __MALLOC_H
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#define __MALLOC_H
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2002-11-03 00:07:02 +00:00
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2009-12-10 12:09:02 +00:00
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#include <types.h>
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2002-11-03 00:07:02 +00:00
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/* Preliminaries */
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#ifndef __STD_C
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#ifdef __STDC__
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#define __STD_C 1
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#else
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#if __cplusplus
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#define __STD_C 1
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#else
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#define __STD_C 0
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#endif /*__cplusplus*/
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#endif /*__STDC__*/
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#endif /*__STD_C*/
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#if __STD_C
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#include <linux/stddef.h> /* for size_t */
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#else
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#include <sys/types.h>
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#endif /* __STD_C */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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Compile-time options
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*/
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#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
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#define cALLOc __libc_calloc
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#define fREe __libc_free
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#define mALLOc __libc_malloc
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#define mEMALIGn __libc_memalign
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#define rEALLOc __libc_realloc
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#define vALLOc __libc_valloc
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#define pvALLOc __libc_pvalloc
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#define mALLINFo __libc_mallinfo
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#define mALLOPt __libc_mallopt
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#pragma weak calloc = __libc_calloc
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#pragma weak free = __libc_free
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#pragma weak cfree = __libc_free
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#pragma weak malloc = __libc_malloc
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#pragma weak memalign = __libc_memalign
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#pragma weak realloc = __libc_realloc
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#pragma weak valloc = __libc_valloc
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#pragma weak pvalloc = __libc_pvalloc
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#pragma weak mallinfo = __libc_mallinfo
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#pragma weak mallopt = __libc_mallopt
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#else
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#ifdef USE_DL_PREFIX
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#define cALLOc dlcalloc
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#define fREe dlfree
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#define mALLOc dlmalloc
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#define mEMALIGn dlmemalign
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#define rEALLOc dlrealloc
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#define vALLOc dlvalloc
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#define pvALLOc dlpvalloc
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#define mALLINFo dlmallinfo
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#define mALLOPt dlmallopt
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#else /* USE_DL_PREFIX */
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#define cALLOc calloc
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#define fREe free
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#define mALLOc malloc
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#define mEMALIGn memalign
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#define rEALLOc realloc
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#define vALLOc valloc
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#define pvALLOc pvalloc
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#define mALLINFo mallinfo
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#define mALLOPt mallopt
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#endif /* USE_DL_PREFIX */
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#endif
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/* Public routines */
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#if __STD_C
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2009-12-10 12:09:02 +00:00
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void* mALLOc(size_t);
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void fREe(void*);
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void* rEALLOc(void*, size_t);
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void* mEMALIGn(size_t, size_t);
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void* vALLOc(size_t);
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void* pvALLOc(size_t);
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void* cALLOc(size_t, size_t);
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void cfree(void*);
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2002-11-03 00:07:02 +00:00
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int malloc_trim(size_t);
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2009-12-10 12:09:02 +00:00
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size_t malloc_usable_size(void*);
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2002-11-03 00:07:02 +00:00
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void malloc_stats(void);
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int mALLOPt(int, int);
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struct mallinfo mALLINFo(void);
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#else
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2009-12-10 12:09:02 +00:00
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void* mALLOc();
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2002-11-03 00:07:02 +00:00
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void fREe();
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2009-12-10 12:09:02 +00:00
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void* rEALLOc();
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void* mEMALIGn();
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void* vALLOc();
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void* pvALLOc();
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void* cALLOc();
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2002-11-03 00:07:02 +00:00
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void cfree();
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int malloc_trim();
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size_t malloc_usable_size();
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void malloc_stats();
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int mALLOPt();
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struct mallinfo mALLINFo();
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#endif
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#ifdef __cplusplus
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}; /* end of extern "C" */
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#endif
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2009-02-20 16:45:38 +00:00
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#endif
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