libiberty/getpagesize.c

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