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