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

Syntax
       char *malloc(size)
       unsigned size;

       free(ptr)
       void *ptr;

       char *realloc(ptr, size)
       void *ptr;
       unsigned size;

       char *calloc(nelem, elsize)
       unsigned nelem, elsize;

       char *alloca(size)
       int size;

Description
       The  and  subroutines  provide a simple general-purpose memory allocation package.  The subroutine returns a pointer to a block of at least
       size bytes beginning on a word boundary.

       The argument to is a pointer to a block previously allocated by This space is made available for further allocation, but its  contents  are
       left undisturbed.

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

       The subroutine maintains multiple lists of free blocks according to size, allocating space from the appropriate list.  It calls to get more
       memory from the system when there is no suitable space already free.  For further information, see

       The subroutine changes the size of the block pointed to by ptr to size bytes and returns a pointer to the (possibly moved) block.  The con-
       tents will be unchanged up to the lesser of the new and old sizes.

       In  order  to  be compatible with older versions, also works if ptr points to a block freed since the last call of or Sequences of and were
       previously used to attempt storage compaction.  This procedure is no longer recommended.

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

       The subroutine allocates size bytes of space associated with the stack frame of the caller.  This temporary space is  available	for  reuse
       when  the  caller returns.  On MIPS machines, calling reclaims all available storage.  On VAX machines, the 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.

Restrictions
       When returns 0, the block pointed to by ptr may be destroyed.

       Currently,  the	allocator is unsuitable for direct use in a large virtual environment where many small blocks are kept, since it keeps all
       allocated and freed blocks on a circular list.  Just before more memory is allocated, all allocated and freed blocks are referenced.

       Because the subroutine is machine dependent, its use should be avoided.

Diagnostics
       The and subroutines return a null pointer (0) if there is no available memory or if the arena has been detectably corrupted by storing out-
       side the bounds of a block.

								       RISC								 malloc(3)