config/machine.c

   1 /*
   2     Copyright © 1995-2004, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include <stdio.h>
   7 #include <stddef.h>
   8 #include <exec/types.h>
   9 #include <aros/config.h>
  10
  11 struct __aros_longalign
  12 {
  13     char dummy;
  14     LONG offset;
  15 };
  16
  17 struct __aros_wordalign
  18 {
  19     char dummy;
  20     WORD offset;
  21 };
  22
  23 struct __aros_ptralign
  24 {
  25     char dummy;
  26     APTR offset;
  27 };
  28
  29 struct __aros_iptralign
  30 {
  31     char dummy;
  32     IPTR offset;
  33 };
  34
  35 struct __aros_doublealign
  36 {
  37     char dummy;
  38     double offset;
  39 };
  40
  41 long sub (void)
  42 {
  43     char b; /* This MUST NOT BE static ! */
  44     long adr = (long)&b;
  45
  46     return adr;
  47 }
  48
  49 int main (void)
  50 {
  51     char a;
  52     long adr1, adr2;
  53     long val;
  54     char * first_byte;
  55     int wordalign;
  56     int longalign;
  57     int ptralign;
  58     int iptralign;
  59     int doublealign;
  60     int worstalign;
  61
  62     /* Calculate the addresses of two *local* variables */
  63     adr1 = (long)&a;
  64     adr2 = sub();
  65
  66     /* If this is a normal stack, memory looks like this:
  67
  68             adr2 (b)
  69             ...
  70             adr1 (a)
  71
  72        because adr1 (a) is pushed on the stack and the stackpointer
  73        is decreased (*--sp=a). Otherwise it looks like:
  74
  75             adr1 (a)
  76             ...
  77             adr2 (b)
  78     */
  79
  80     /*
  81         The difference between big and little endian is this:
  82
  83         Big endian stores the value 0x11223344 as { 0x11, 0x22, 0x33, 0x44 }
  84         (ie. the first byte in memory is the most significant byte of the
  85         variable).
  86
  87         Little endian stores the value 0x11223344 as { 0x44, 0x33, 0x22, 0x11 }
  88         (ie. the first byte in memory is the least significant byte of the
  89         variable).
  90     */
  91
  92     val = 0x11223344;
  93
  94     first_byte = (char *)&val; /* Check if the first byte is 0x11 */
  95
  96     wordalign   = offsetof(struct __aros_wordalign,    offset);
  97     longalign   = offsetof(struct __aros_longalign,    offset);
  98     ptralign    = offsetof(struct __aros_ptralign,     offset);
  99     iptralign   = offsetof(struct __aros_iptralign,    offset);
 100     doublealign = offsetof(struct __aros_doublealign,  offset);
 101
 102     worstalign = wordalign;
 103     if (worstalign < longalign)   worstalign = longalign;
 104     if (worstalign < ptralign)    worstalign = ptralign;
 105     if (worstalign < iptralign)   worstalign = iptralign;
 106     if (worstalign < doublealign) worstalign = doublealign;
 107
 108 #if (AROS_FLAVOUR & AROS_FLAVOUR_BINCOMPAT)
 109     if (worstalign < 8) worstalign = 8;
 110 #endif
 111
 112     printf ("#define AROS_STACK_GROWS_DOWNWARDS %d /* Stack direction */\n", (adr2 < adr1));
 113     printf ("#define AROS_BIG_ENDIAN            %d /* Big or little endian */\n", (*first_byte == 0x11));
 114     printf ("#define AROS_SIZEOFULONG           %ld /* Size of an ULONG */\n", (unsigned long)sizeof (ULONG));
 115     printf ("#define AROS_WORDALIGN             %d /* Alignment for WORD */\n",   wordalign);
 116     printf ("#define AROS_LONGALIGN             %d /* Alignment for LONG */\n",   longalign);
 117     printf ("#define AROS_PTRALIGN              %d /* Alignment for PTR */\n",    ptralign);
 118     printf ("#define AROS_IPTRALIGN             %d /* Alignment for IPTR */\n",   iptralign);
 119     printf ("#define AROS_DOUBLEALIGN           %d /* Alignment for double */\n", doublealign);
 120     printf ("#define AROS_WORSTALIGN            %d /* Worst case alignment */\n", worstalign);
 121
 122     return 0;
 123 }
 124