lib/physmem.c

   1 /* Calculate the size of physical memory.
   2    Copyright 2000 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by Paul Eggert.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include "physmem.h"
  25
  26 #if HAVE_UNISTD_H
  27 # include <unistd.h>
  28 #endif
  29
  30 /* Return the total amount of physical memory.  */
  31 double
  32 physmem_total (void)
  33 {
  34 #if defined _SC_PHYS_PAGES && defined _SC_PAGESIZE
  35   double pages = sysconf (_SC_PHYS_PAGES);
  36   double pagesize = sysconf (_SC_PAGESIZE);
  37   if (0 <= pages && 0 <= pagesize)
  38     return pages * pagesize;
  39 #endif
  40
  41   /* Guess 64 MB.  It's probably an older host, so guess small.  */
  42   return 64 * 1024 * 1024;
  43 }
  44
  45 /* Return the amount of physical memory available.  */
  46 double
  47 physmem_available (void)
  48 {
  49 #if defined _SC_AVPHYS_PAGES && defined _SC_PAGESIZE
  50   double pages = sysconf (_SC_AVPHYS_PAGES);
  51   double pagesize = sysconf (_SC_PAGESIZE);
  52   if (0 <= pages && 0 <= pagesize)
  53     return pages * pagesize;
  54 #endif
  55
  56   /* Guess 25% of physical memory.  */
  57   return physmem_total () / 4;
  58 }