malloc(3f) [bsd man page]

MALLOC(3F)																MALLOC(3F)

NAME

       malloc, free, falloc - memory allocator

SYNOPSIS

       subroutine malloc (size, addr)
       integer size, addr

       subroutine free (addr)
       integer addr

       subroutine falloc (nelem, elsize, clean, basevec, addr, offset)
       integer nelem, elsize, clean, addr, offset

DESCRIPTION

       Malloc, falloc  and  free  provide  a general-purpose memory allocation package.  Malloc returns in addr the address of a block of at least
       size bytes beginning on an even-byte boundary.

       Falloc allocates space for an array of nelem elements of size elsize and returns the address of the block in addr.  It zeros the  block	if
       clean  is  1.  It returns in offset an index such that the storage may be addressed as basevec(offset+1) ... basevec(offset+nelem).  Falloc
       gets extra bytes so that after address arithmetic, all the objects so addressed are within the block.

       The argument to free is the address of a block previously allocated by malloc or falloc; this space is made available for  further  alloca-
       tion, but its contents are left undisturbed.  To free blocks allocated by falloc, use addr in calls to free, do not use basevec(offset+1).

       Needless to say, grave disorder will result if the space assigned by mallocorfalloc is overrun or if some random number is handed to free.

DIAGNOSTICS

       Malloc and falloc set addr to 0 if there is no available memory or if the arena has been detectably corrupted by storing outside the bounds
       of a block.

       The following example shows how to obtain memory and use it within a subprogram:

	     integer addr, work(1), offset
		...
	     call falloc ( n, 4, 0, work, addr, offset )
	     do 10 i = 1, n
	     work(offset+i) = ...
       10    continue

       The next example reads in dimension information, allocates space for two arrays and two vectors, and calls subroutine doit to do the compu-
       tations:

	     integer addr, dummy(1), offs
	     read *, k, l, m
	     indm1   = 1
	     indm2   = indm1 + k*l
	     indm3   = indm2 + l*m
	     indsym  = indm3 + k*m
	     lsym = n*(n+1)/2
	     indv  = indsym + lsym
	     indtot = indv + m
	     call falloc ( indtot, 4, 0, dummy, addr, offs )
	     call doit( dummy(indm1+offs), dummy(indm2+offs),
	    .		dummy(indm3+offs), dummy(indsym+offs),
	    .		dummy(indv +offs), m, n, lsym )
	     end
	     subroutine doit( arr1, arr2, arr3, vsym, vec, m, n, lsym )
	     real arr1(k,l), arr2(l,m), arr3(k,m), vsym(lsym), v2(m)
		...

FILES

       /usr/lib/libU77.a

SEE ALSO

       malloc(3)

4.3 Berkeley Distribution					   May 15, 1985 							MALLOC(3F)

MALLOC(3)						     Library Functions Manual							 MALLOC(3)

NAME

       malloc, free, realloc, calloc, alloca - memory allocator

SYNOPSIS

       #include <sys/types.h>
       #include <stdlib.h>
       #include <alloca.h>

       void *malloc(size_t size)
       void free(void *ptr)
       void *realloc(void *ptr, size_t size)
       void *calloc(size_t nelem, size_t elsize)
       void *alloca(size_t size)

DESCRIPTION

       Malloc  and free provide a general-purpose memory allocation package.  Malloc returns a pointer to a block of at least size bytes beginning
       on a word boundary.

       The argument to free is a pointer to a block previously allocated by malloc; this space is made available for further allocation,  but  its
       contents are left undisturbed.  A call with a null ptr is legal and does nothing.

       Needless to say, grave disorder will result if the space assigned by malloc is overrun or if some random number is handed to free.

       Malloc  maintains  multiple lists of free blocks according to size, allocating space from the appropriate list.	It calls sbrk (see brk(2))
       to get more memory from the system when there is no suitable space already free.

       Realloc changes the size of the block pointed to by ptr to size bytes and returns a pointer to the (possibly moved)  block.   The  contents
       will be unchanged up to the lesser of the new and old sizes.  A call with a null ptr is legal and has the same result as malloc(size).

       Calloc allocates space for an array of nelem elements of size elsize.  The space is initialized to zeros.

       Alloca allocates size bytes of space in the stack frame of the caller.  This temporary space is automatically freed on return.

       Each  of  the  allocation routines returns a pointer to space suitably aligned (after possible pointer coercion) for storage of any type of
       object.

SEE ALSO

       brk(2).

DIAGNOSTICS

       Malloc, realloc and calloc return a null pointer if there is no available memory or if the arena has been detectably corrupted  by  storing
       outside the bounds of a block.

NOTES

       Other  implementations of malloc, realloc or calloc may return a null pointer if the size of the requested block is zero.  This implementa-
       tion will always return a zero length block at a unique address, but you should keep in mind that a null return is possible if the  program
       is run to another system and that this should not be mistakenly seen as an error.

BUGS

       When realloc returns a null pointer, the block pointed to by ptr may be destroyed.

       Alloca is machine dependent; its use is discouraged.

4th Berkeley Distribution					   May 14, 1986 							 MALLOC(3)