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 #undef GNU_OUR_PAGESIZE
  39 #if defined (HAVE_SYSCONF) && defined (HAVE_UNISTD_H)
  40 #include <unistd.h>
  41 #ifdef _SC_PAGESIZE
  42 #define GNU_OUR_PAGESIZE sysconf(_SC_PAGESIZE)
  43 #endif
  44 #endif
  45
  46 #ifndef GNU_OUR_PAGESIZE
  47 # ifdef PAGESIZE
  48 #  define       GNU_OUR_PAGESIZE PAGESIZE
  49 # else  /* no PAGESIZE */
  50 #  ifdef        EXEC_PAGESIZE
  51 #   define      GNU_OUR_PAGESIZE EXEC_PAGESIZE
  52 #  else /* no EXEC_PAGESIZE */
  53 #   ifdef       NBPG
  54 #    define     GNU_OUR_PAGESIZE (NBPG * CLSIZE)
  55 #    ifndef     CLSIZE
  56 #     define    CLSIZE 1
  57 #    endif      /* CLSIZE */
  58 #   else        /* no NBPG */
  59 #    ifdef      NBPC
  60 #     define    GNU_OUR_PAGESIZE NBPC
  61 #    else       /* no NBPC */
  62 #     define    GNU_OUR_PAGESIZE 4096   /* Just punt and use reasonable value */
  63 #    endif /* NBPC */
  64 #   endif /* NBPG */
  65 #  endif /* EXEC_PAGESIZE */
  66 # endif /* PAGESIZE */
  67 #endif /* GNU_OUR_PAGESIZE */
  68
  69 int
  70 getpagesize ()
  71 {
  72   return (GNU_OUR_PAGESIZE);
  73 }
  74
  75 #else /* VMS */
  76
  77 #if 0   /* older distributions of gcc-vms are missing <syidef.h> */
  78 #include <syidef.h>
  79 #endif
  80 #ifndef SYI$_PAGE_SIZE  /* VMS V5.4 and earlier didn't have this yet */
  81 #define SYI$_PAGE_SIZE 4452
  82 #endif
  83 extern unsigned long lib$getsyi(const unsigned short *,...);
  84
  85 int getpagesize ()
  86 {
  87   long pagsiz = 0L;
  88   unsigned short itmcod = SYI$_PAGE_SIZE;
  89
  90   (void) lib$getsyi (&itmcod, (void *) &pagsiz);
  91   if (pagsiz == 0L)
  92     pagsiz = 512L;      /* VAX default */
  93   return (int) pagsiz;
  94 }
  95
  96 #endif /* VMS */