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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<mach.h>
+
+.help begmem, fixmem
+.nf ___________________________________________________________________________
+BEGMEM, FIXMEM -- Try to get/release physical memory for a process.  The
+actual amount of physical memory available (in chars) is returned.  On a
+machine with virtual memory, these routines adjust the working set size.
+
+On any machine, BEGMEM may be used to determine the amount of available
+physical memory, to tune algorithms for optimum performance.  BEGMEM returns
+as its function value the actual working set size of the process after
+the adjustment (or the current working set size if "best_size" is zero).
+On some systems this represents a soft limit on the actual amount of memory
+which can be used; it is a guarantee that at least that much space is
+available.  Some systems will allow the actual working set to dynamically
+exceed this value at runtime if the process pages heavily.  The hard limit
+on the working set of a process is given by the "max_size" parameter.
+
+Note that the working set must include space not only for a task specific
+data buffers, but also for all other process data buffers and for the text
+(instruction space) of the code being executed.  There is no easy way to
+determine this, hence the application is expected to estimate it.  A typical
+value for the base text+data size required to execute a program is 150Kb.
+.endhelp ______________________________________________________________________
+
+
+# BEGMEM -- Attempt to the adjust the amount of physical memory allocated
+# to a process.  Save the old memory size in OLD_SIZE, so that memory may
+# later be restored with FIXMEM.  The new working set size is returned as
+# the function value and the hard limit on the working set size is returned
+# in MAX_SIZE.  In general, the process can be expected to page, possibly
+# heavily, or swap out if the working set size is exceeded.  All sizes are
+# returned in SPP chars.  If BEST_SIZE is zero the working set size is not
+# changed, i.e., the current working set parameters are returned.
+
+int procedure begmem (best_size, old_size, max_size)
+
+int	best_size		# desired working set size
+int	old_size		# former working set size
+int	max_size		# max physical memory available to this process
+
+int	new_size
+
+begin
+	call zawset (best_size * SZB_CHAR, new_size, old_size, max_size)
+	new_size = new_size / SZB_CHAR
+	old_size = old_size / SZB_CHAR
+	max_size = max_size / SZB_CHAR
+
+	return (new_size)
+end
+
+
+# FIXMEM -- Restore the original working set size.
+
+procedure fixmem (old_size)
+
+int	old_size
+int	j1, j2, j3
+
+begin
+	call zawset (old_size * SZB_CHAR, j1, j2, j3)
+end