u-boot/include/malloc.h

14   This is not the fastest, most space-conserving, most portable, or
15   most tunable malloc ever written. However it is among the fastest
16   while also being among the most space-conserving, portable and tunable.
17   Consistent balance across these factors results in a good general-purpose
18   allocator. For a high-level description, see
36      size argument of zero (re)allocates a minimum-sized chunk.
46      Equivalent to valloc(minimum-page-that-holds(n)), that is,
54      Release all but pad bytes of freed top-most memory back
65      Changes one of the tunable parameters described below. Returns
70   Alignment:                            8-byte
75        Code for 8-byte pointers is untested by me but has worked
86   Minimum allocated size: 4-byte ptrs:  16 bytes    (including 4 overhead)
87 			  8-byte ptrs:  24/32 bytes (including, 4/8 overhead)
98   Maximum allocated size: 4-byte size_t: 2^31 -  8 bytes
99 			  8-byte size_t: 2^63 - 16 bytes
112        make the normal worst-case wastage 15 bytes (i.e., up to 15
115 	 1. Because requests for zero bytes allocate non-zero space,
125     * No user-definable hooks for callbacks and the like.
130 * Synopsis of compile-time options:
137     stand-alone embedded systems.
139     The implementation is in straight, hand-tuned ANSI C.  Among other
142     (for example gcc -O2) that can simplify expressions and control
146      Nonzero if using ANSI-standard C compiler, a C++ compiler, or
149      Define to enable debugging. Adds fairly extensive assertion-based
166      Define to non-zero to optionally make malloc() use mmap() to
169      Define to non-zero to optionally make realloc() use mremap() to
178      Define to a 32-bit type (probably `unsigned int') if you are on a
179      64-bit machine, yet do not want or need to allow malloc requests of
184      Also note that there is some odd internal name-mangling via defines
196   MORECORE_FAILURE          (default: -1)
205      Default values of tunable parameters (described in detail below)
254 #if 0	/* not for U-Boot */
260   Compile-time options
272     If you compile with -DDEBUG, a number of assertion checks are
278     attempt to check every non-mmapped allocated and free chunk in the
289   INTERNAL_SIZE_T is the word-size used for internal bookkeeping
290   of chunk sizes. On a 64-bit machine, you can reduce malloc
314   mmap-based options are not currently supported in WIN32.
379 /* The following macros are only invoked with (2n+1)-multiples of
426   if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
435     case 1:           *mzp++ = 0; if(mcn <= 0) break; mcn--; }                \
444   if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
453     case 1:           *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; }       \
471 #undef	HAVE_MMAP	/* Not available for U-Boot */
474   Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
488 #undef	HAVE_MREMAP	/* Not available for U-Boot */
504   manages memory from the system in page-size units.
510 #define	LACKS_UNISTD_H	/* Shortcut for U-Boot */
575   (by-copy) by mallinfo().  The SVID/XPG malloinfo struct contains a
598   int ordblks;  /* number of non-inuse chunks */
599   int smblks;   /* unused -- always zero */
602   int usmblks;  /* unused -- always zero */
603   int fsmblks;  /* unused -- always zero */
605   int fordblks; /* total non-inuse space */
606   int keepcost; /* top-most, releasable (via malloc_trim) space */
620 #define M_TRIM_THRESHOLD    -1
621 #define M_TOP_PAD           -2
622 #define M_MMAP_THRESHOLD    -3
623 #define M_MMAP_MAX          -4
631     M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
634       Automatic trimming is mainly useful in long-lived programs.
645       system-level demands of a long-lived program down to a bare
648       mmap threshold of 192K led to near-minimal long term resource
651       If you are using this malloc in a long-lived program, it should
660       chunks at all.  And in well-behaved long-lived programs,
665       protection against the system-level effects of carrying around
674       disable trimming completely, you can set to (unsigned long)(-1);
700       that nearly every malloc request during program start-up (or
704       Automatic rounding-up to page-size units is normally sufficient
721       be allocated using already-existing space will be serviced via mmap.
732       helps keep the system level memory demands of a long-lived
773 	    better off using normal sbrk-based allocation routines that
779       the default value is 0, and attempts to set it to non-zero values
841 #define MORECORE_FAILURE -1
910 /* Set up pre-relocation malloc() ready for use */