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[metaconfig.git] / U / compline / byteorder.U
1?RCS: $Id: byteorder.U,v 1997/02/28 15:24:55 ram Exp $
3?RCS: Copyright (c) 1991-1993, Raphael Manfredi
5?RCS: You may redistribute only under the terms of the Artistic Licence,
6?RCS: as specified in the README file that comes with the distribution.
7?RCS: You may reuse parts of this distribution only within the terms of
8?RCS: that same Artistic Licence; a copy of which may be found at the root
9?RCS: of the source tree for dist 3.0.
11?RCS: $Log: byteorder.U,v $
12?RCS: Revision 1997/02/28 15:24:55 ram
13?RCS: patch61: no longer ask the user if the test runs ok
15?RCS: Revision 1994/10/29 16:02:58 ram
16?RCS: patch36: added ?F: line for metalint file checking
18?RCS: Revision 3.0 1993/08/18 12:05:28 ram
19?RCS: Baseline for dist 3.0 netwide release.
21?MAKE:byteorder: cat Myread Oldconfig Loc Compile rm \
22 longsize crosscompile multiarch
23?MAKE: -pick add $@ %<
25?S: This variable holds the byte order. In the following, larger digits
26?S: indicate more significance. The variable byteorder is either 4321
27?S: on a big-endian machine, or 1234 on a little-endian, or 87654321
28?S: on a Cray ... or 3412 with weird order !
31?C: This symbol holds the hexadecimal constant defined in byteorder,
32?C: i.e. 0x1234 or 0x4321, etc...
33?C: If the compiler supports cross-compiling or multiple-architecture
34?C: binaries (eg. on NeXT systems), use compiler-defined macros to
35?C: determine the byte order.
36?C: On NeXT 3.2 (and greater), you can build "Fat" Multiple Architecture
37?C: Binaries (MAB) on either big endian or little endian machines.
38?C: The endian-ness is available at compile-time. This only matters
39?C: for perl, where the config.h can be generated and installed on
40?C: one system, and used by a different architecture to build an
41?C: extension. Older versions of NeXT that might not have
42?C: defined either *_ENDIAN__ were all on Motorola 680x0 series,
43?C: so the default case (for NeXT) is big endian to catch them.
44?C: This might matter for NeXT 3.0.
46?H:?%<:#if defined(CROSSCOMPILE) || defined(MULTIARCH)
47?H:?%<:# ifdef __LITTLE_ENDIAN__
48?H:?%<:# if LONGSIZE == 4
49?H:?%<:# define BYTEORDER 0x1234
50?H:?%<:# else
51?H:?%<:# if LONGSIZE == 8
52?H:?%<:# define BYTEORDER 0x12345678
53?H:?%<:# endif
54?H:?%<:# endif
55?H:?%<:# else
56?H:?%<:# ifdef __BIG_ENDIAN__
57?H:?%<:# if LONGSIZE == 4
58?H:?%<:# define BYTEORDER 0x4321
59?H:?%<:# else
60?H:?%<:# if LONGSIZE == 8
61?H:?%<:# define BYTEORDER 0x87654321
62?H:?%<:# endif
63?H:?%<:# endif
64?H:?%<:# endif
65?H:?%<:# endif
66?H:?%<:# if !defined(BYTEORDER) && (defined(NeXT) || defined(__NeXT__))
67?H:?%<:# define BYTEORDER 0x4321
68?H:?%<:# endif
70?H:?%<:#define BYTEORDER 0x$byteorder /* large digits for MSB */
71?H:?%<:#endif /* NeXT */
75?LINT:use longsize
76: check for ordering of bytes in a long
77echo " "
78case "$crosscompile$multiarch" in
80 $cat <<EOM
81You seem to be either cross-compiling or doing a multiarchitecture build,
82skipping the byteorder check.
85 byteorder=''
86 ;;
88 case "$byteorder" in
89 '')
90 $cat <<'EOM'
91In the following, larger digits indicate more significance. A big-endian
92machine like a Pyramid or a Motorola 680?0 chip will come out to 4321. A
93little-endian machine like a Vax or an Intel 80?86 chip would be 1234. Other
94machines may have weird orders like 3412. A Cray will report 87654321. If
95the test program works the default is probably right.
96I'm now running the test program...
98 $cat >try.c <<'EOCP'
99#include <stdio.h>
100int main()
102 int i;
103 union {
104 unsigned long l;
105 char c[sizeof(long)];
106 } u;
108 if (sizeof(long) > 4)
109 u.l = (0x08070605L << 32) | 0x04030201L;
110 else
111 u.l = 0x04030201L;
112 for (i = 0; i < sizeof(long); i++)
113 printf("%c", u.c[i]+'0');
114 printf("\n");
115 exit(0);
118 xxx_prompt=y
119 set try
120 if eval $compile && ./try > /dev/null; then
121 dflt=`./try`
122 case "$dflt" in
123 [1-4][1-4][1-4][1-4]|12345678|87654321)
124 echo "(The test program ran ok.)"
125 echo "byteorder=$dflt"
126 xxx_prompt=n
127 ;;
128 ????|????????) echo "(The test program ran ok.)" ;;
129 *) echo "(The test program didn't run right for some reason.)" ;;
130 esac
131 else
132 dflt='4321'
133 cat <<'EOM'
134(I can't seem to compile the test program. Guessing big-endian...)
136 fi
137 case "$xxx_prompt" in
138 y)
139 rp="What is the order of bytes in a long?"
140 . ./myread
141 byteorder="$ans"
142 ;;
143 *) byteorder=$dflt
144 ;;
145 esac
146 ;;
147 esac
148 $rm -f try.c try
149 ;;