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/* endian.c -- A trick for determining the byte order of a machine. */
/* Copyright (C) 1993 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Bash is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <sys/types.h>
#include <stdio.h>
#include "bashansi.h"
/* The name of this program, as taken from argv[0]. */
char *progname;
/* The name of the source file that this code is made from. */
char source_name[256];
/* The name of the define. Either "BIG_ENDIAN" or "LITTLE_ENDIAN". */
char *endian_define;
char string[9];
char nstring[9];
/* Stuff "1234" into a long, and compare it against a character string
"1234". If the results are EQ, the machine is big endian like a 68000
or Sparc, otherwise it is little endian, like a Vax, or 386. */
main (argc, argv)
int argc;
char **argv;
{
#if defined (__STDC__)
register size_t i;
#else
register int i;
#endif /* !__STDC__ */
FILE *stream = (FILE *)NULL;
char *stream_name = "stdout";
union {
unsigned long l;
char s[sizeof (long)];
} u;
progname = argv[0];
for (i = strlen (progname); i > 0; i--)
if (progname[i] == '/')
{
progname = progname + i + 1;
break;
}
strcpy (source_name, progname);
for (i = strlen (source_name); i > 0; i--)
if (source_name[i] == '.')
{
source_name[i] = '\0';
break;
}
strcat (source_name, ".c");
if (argc == 1)
{
stream_name = "stdout";
stream = stdout;
}
else if (argc == 2)
{
stream_name = argv[1];
stream = fopen (stream_name, "w");
}
else
{
fprintf (stderr, "Usage: %s [output-file]\n", progname);
exit (1);
}
if (!stream)
{
fprintf (stderr, "%s: %s Cannot be opened or written to.\n",
progname, stream_name);
exit (2);
}
if (sizeof (long int) == 4)
{
u.l = 0x04030201L;
(void) strcpy (string, "4321");
}
else if (sizeof (long int) == 8)
{
#if defined (__GNUC__)
unsigned long fake_out_gcc;
fake_out_gcc = (0x08070605L << 31);
fake_out_gcc = (fake_out_gcc << 1);
u.l = fake_out_gcc | 0x04030201L;
#else
u.l = (0x08070605L << 32) | 0x04030201L;
#endif /* !__GNUC__ */
(void) strcpy (string, "87654321");
}
else
{
fprintf (stderr,
"%s: sizeof (long int) = %d, which isn't handled here.\n",
progname, sizeof (long int));
exit (2);
}
for (i = 0; i < sizeof (long); i++)
nstring[i] = u.s[i] + '0';
nstring[i] = '\0';
if (strcmp (nstring, string) == 0)
endian_define = "BIG_ENDIAN";
else
endian_define = "LITTLE_ENDIAN";
fprintf (stream, "/* %s - Define BIG or LITTLE endian. */\n\n", stream_name);
fprintf (stream,
"/* This file was automatically created by `%s'. You shouldn't\n\
edit this file, because your changes will be overwritten. Instead,\n\
edit the source code file `%s'. */\n\n",
progname, source_name);
fprintf (stream, "#if !defined (%s)\n", endian_define);
fprintf (stream, "# define %s\n", endian_define);
fprintf (stream, "#endif /* %s */\n", endian_define);
if (stream != stdout)
fclose (stream);
exit (0);
}
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