source: vis_dev/glu-2.3/src/mem/mem.3 @ 104

.\" Storage management library man page
.TH MEM 3 "16 November 1993"
.SH NAME
mem \- a memory management package
.SH SYNOPSIS
.B #include <memuser.h>
.SH DESCRIPTION
The
.B libmem
library provides a set of routines for allocating storage.  Programs
designed to be used with the library should use the
.B -lmem
options to
.B cc
when linking.
.SH "LIST OF FUNCTIONS"
.nf
.ta 3in
\fIName\fP      \fIFunction\fP
mem_get_block   Allocate a block of memory
mem_free_block  Free a block of memory
mem_resize_block        Resize a block of memory
mem_copy        Copy a block of memory
mem_zero        Initialize a block of memory to all zeros
mem_allocation  Get total memory allocation
mem_new_rec_mgr Create a record manager
mem_free_rec_mgr        Destroy a record manager
mem_new_rec     Get a record from a record manager
mem_free_rec    Return a record to a record manager
.fi
.SH "OVERVIEW"
The library includes routines for handling blocks of memory and for
dealing with fixed size records.  The block manipulation routines use
a binary buddy scheme, so fragmentation generally is not a problem.
The record manager routines are designed for handling many small,
fixed size records.  There is essentially no storage overhead when
using these routines, and allocation and deallocation are particularly
fast.
.SH "DETAILED DESCRIPTION"
.B pointer
.br
.B mem_get_block(size)
.br
.B long size;
.in +4
Allocate a block of storage
.B size
bytes long.  The type
.B pointer
is defined to be either a character pointer or a void pointer,
depending on whether the C compiler is ANSI-standard.
.LP
.B void
.br
.B mem_free_block(p)
.br
.B pointer p;
.in +4
Free the block of storage pointed to by \fBp\fR.
.LP
.B pointer
.br
.B mem_resize_block(p, size)
.br
.B pointer p;
.br
.B long size;
.in +4
Try to resize the block of memory pointed to by
.B p
to be
.B size
bytes long.  If this is not possible, a new block is allocated and the
contents of the old block are copied.  A pointer to the expanded block
is returned.
.LP
.B void
.br
.B mem_copy(p, q, size)
.br
.B pointer p;
.br
.B pointer q;
.br
.B long size;
.in +4
Copy
.B size
bytes from the location given by
.B q
to the location give by \fBp\fR.
.LP
.LP
.B void
.br
.B mem_zero(p, size)
.br
.B pointer p;
.br
.B long size;
.in +4
Fill
.B size
bytes at the location given by
.B p
with zero.
.LP
.B long
.br
.B mem_allocation()
.in +4
Returns the total memory allocation in bytes.
.LP
.B rec_mgr
.br
.B mem_new_rec_mgr(size)
.br
.B int size;
.in +4
Returns a new record manager for handling record of
.B size
bytes.  The size is limited to approximately 4K, but is really
intended to be smaller.
.LP
.B void
.br
.B mem_free_rec_mgr(m)
.br
.B rec_mgr m;
.in +4
Free the record manager given by
.B m
and all of its associated storage.
.LP
.B pointer
.br
.B mem_new_rec(m)
.br
.B rec_mgr m;
.in +4
Return a pointer to a new record.
.LP
.B void
.br
.B mem_free_rec(m, p)
.br
.B rec_mgr m;
.br
.B pointer p;
.in +4
Return the record pointed to by
.B p
to the record manager \fBm\fR.
.SH "PORTABILITY NOTES"
The library is fairly UNIX specific; it calls
.B sbrk
directly.  If you don't have something similar, you may have to
rewrite parts of it.  The storage management routines need to be able
to move and clear blocks of memory whose size is given by a long.  You
may have to fiddle with these, especially if you have a machine where
int and long are different.  If you encounter portability problems,
let me know; maybe the next release will be able to accommodate your
machine.  For non-UNIX people, or if you are using malloc elsewhere
and it is unhappy about other routines calling sbrk, you can try
defining the symbol USE_MALLOC_FREE in memint.h.  It turns calls to
the memory management library routines into calls to malloc, free, and
cousins.  This has not been tested extensively.
.SH BUGS
It's a feature.
.SH AUTHOR
David E. Long
.br
long@research.att.com