libiberty/getpagesize.c

   1 /* Emulation of getpagesize() for systems that need it. */
   2
   3 /*
   4
   5 NAME
   6
   7         getpagesize -- return the number of bytes in page of memory
   8
   9 SYNOPSIS
  10
  11         int getpagesize (void)
  12
  13 DESCRIPTION
  14
  15         Returns the number of bytes in a page of memory.  This is the
  16         granularity of many of the system memory management routines.
  17         No guarantee is made as to whether or not it is the same as the
  18         basic memory management hardware page size.
  19
  20 BUGS
  21
  22         Is intended as a reasonable replacement for systems where this
  23         is not provided as a system call.  The value of 4096 may or may
  24         not be correct for the systems where it is returned as the default
  25         value.
  26
  27 */
  28
  29 #ifndef VMS
  30
  31 #include "config.h"
  32
  33 #include <sys/types.h>
  34 #ifdef HAVE_SYS_PARAM_H
  35 #include <sys/param.h>
  36 #endif
  37
  38 #ifdef HAVE_SYSCONF
  39 #include <unistd.h>
  40 #define GNU_OUR_PAGESIZE sysconf(_SC_PAGESIZE)
  41 #else
  42 #ifdef  PAGESIZE
  43 #define GNU_OUR_PAGESIZE PAGESIZE
  44 #else   /* no PAGESIZE */
  45 #ifdef  EXEC_PAGESIZE
  46 #define GNU_OUR_PAGESIZE EXEC_PAGESIZE
  47 #else   /* no EXEC_PAGESIZE */
  48 #ifdef  NBPG
  49 #define GNU_OUR_PAGESIZE (NBPG * CLSIZE)
  50 #ifndef CLSIZE
  51 #define CLSIZE 1
  52 #endif  /* CLSIZE */
  53 #else   /* no NBPG */
  54 #ifdef  NBPC
  55 #define GNU_OUR_PAGESIZE NBPC
  56 #else   /* no NBPC */
  57 #define GNU_OUR_PAGESIZE 4096   /* Just punt and use reasonable value */
  58 #endif /* NBPC */
  59 #endif /* NBPG */
  60 #endif /* EXEC_PAGESIZE */
  61 #endif /* PAGESIZE */
  62 #endif /* HAVE_SYSCONF */
  63
  64 int
  65 getpagesize ()
  66 {
  67   return (GNU_OUR_PAGESIZE);
  68 }
  69
  70 #else /* VMS */
  71
  72 #if 0   /* older distributions of gcc-vms are missing <syidef.h> */
  73 #include <syidef.h>
  74 #endif
  75 #ifndef SYI$_PAGE_SIZE  /* VMS V5.4 and earlier didn't have this yet */
  76 #define SYI$_PAGE_SIZE 4452
  77 #endif
  78 extern unsigned long lib$getsyi(const unsigned short *,...);
  79
  80 int getpagesize ()
  81 {
  82   long pagsiz = 0L;
  83   unsigned short itmcod = SYI$_PAGE_SIZE;
  84
  85   (void) lib$getsyi (&itmcod, (void *) &pagsiz);
  86   if (pagsiz == 0L)
  87     pagsiz = 512L;      /* VAX default */
  88   return (int) pagsiz;
  89 }
  90
  91 #endif /* VMS */