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researchv10 Dan Cross

.ds ZZ DEVELOPMENT PACKAGE
.TH ALLOC 3R "630 MTG"
.XE "alloc()"
.XE "lalloc()"
.XE "allocown()"
.XE "free()"
.SH NAME
alloc, lalloc, free, allocown \- memory allocation
.SH SYNOPSIS
.B #include <dmd.h>
.br
.B char \(**alloc (nbytes)
.PP
.B char \(**lalloc (lnbytes)
.PP
.B void free (s)
.PP
.B void allocown (s, p)
.sp
.B unsigned nbytes;
.br
.B unsigned long lnbytes;
.br
.B Proc \(**p
.br
.B char \(**s;
.SH DESCRIPTION
The
.I alloc
function
is equivalent to the standard C function
.IR  malloc (3C).
It either returns a pointer to a block of
\f2nbytes\f1,
contiguous bytes of storage
or a 0 (\s-1NULL\s+1) if there is no available memory.
The storage is aligned on 4-byte boundaries.
Unlike
.IR malloc ,
\f2alloc\f1,
clears the storage to zeros.
.PP
The
.I lalloc
function is identical to
.I alloc
except it takes an unsigned long as an argument.
.PP
The
.I free
function
frees storage allocated by
.IR alloc .
The space is made available for further allocation.
.PP
The
.I allocown
function
changes the ownership of memory allocated by
.IR alloc.
The argument
.I s
is a value previously returned from
.IR alloc .
The argument
.I p
is the process taking over ownership of the memory.
If
.I p
is zero, the memory belongs to no one, and only an explicit call to
.I free
will free it.
.PP
The terminal
automatically frees all memory allocated by a process
when the process terminates or when
the window it is running in is deleted.
If the ownership of allocated memory is changed, it will
only be freed when the new owner is deleted or when
.I free
is called.
However, it is recommended that a process free its allocated
memory when the storage is no longer needed so that other
processes
will be able to use it.
.SH EXAMPLE
The following example shows the use of
.I alloc
and
.I free
in dynamically allocating memory for a \fIPoint\fR.
.PP
.RS 3
.ft CM
.nf
#include <dmd.h>

main()
{
    Point *p;
    char *alloc();
    void free();

    p = (Point *)alloc (sizeof(Point));

    .
    .
    .

    free (p);
}
.fi
.ft R
.RE
.SH SEE ALSO
balloc(3R), gcalloc(3R), structures(3R).
.br
malloc(3C) in the \f2UNIX System V Programmer's Reference Manual\f1.


.SH WARNINGS
The
.I alloc
function accepts an integer as argument; therefore, it can only allocate a
contiguous block of memory of 64K bytes or less.

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