148 lines
3.7 KiB
C
148 lines
3.7 KiB
C
/* endian.c -- A trick for determining the byte order of a machine. */
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/* Copyright (C) 1993 Free Software Foundation, Inc.
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This file is part of GNU Bash, the Bourne Again SHell.
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Bash is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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Bash is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License along
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with Bash; see the file COPYING. If not, write to the Free Software
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Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include <sys/types.h>
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#include <stdio.h>
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#include "bashansi.h"
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/* The name of this program, as taken from argv[0]. */
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char *progname;
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/* The name of the source file that this code is made from. */
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char source_name[256];
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/* The name of the define. Either "BIG_ENDIAN" or "LITTLE_ENDIAN". */
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char *endian_define;
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char string[9];
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char nstring[9];
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/* Stuff "1234" into a long, and compare it against a character string
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"1234". If the results are EQ, the machine is big endian like a 68000
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or Sparc, otherwise it is little endian, like a Vax, or 386. */
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main (argc, argv)
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int argc;
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char **argv;
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{
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#if defined (__STDC__)
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register size_t i;
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#else
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register int i;
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#endif /* !__STDC__ */
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FILE *stream = (FILE *)NULL;
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char *stream_name = "stdout";
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union {
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unsigned long l;
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char s[sizeof (long)];
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} u;
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progname = argv[0];
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for (i = strlen (progname); i > 0; i--)
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if (progname[i] == '/')
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{
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progname = progname + i + 1;
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break;
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}
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strcpy (source_name, progname);
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for (i = strlen (source_name); i > 0; i--)
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if (source_name[i] == '.')
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{
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source_name[i] = '\0';
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break;
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}
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strcat (source_name, ".c");
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if (argc == 1)
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{
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stream_name = "stdout";
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stream = stdout;
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}
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else if (argc == 2)
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{
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stream_name = argv[1];
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stream = fopen (stream_name, "w");
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}
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else
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{
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fprintf (stderr, "Usage: %s [output-file]\n", progname);
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exit (1);
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}
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if (!stream)
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{
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fprintf (stderr, "%s: %s Cannot be opened or written to.\n",
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progname, stream_name);
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exit (2);
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}
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if (sizeof (long int) == 4)
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{
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u.l = 0x04030201L;
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(void) strcpy (string, "4321");
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}
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else if (sizeof (long int) == 8)
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{
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#if defined (__GNUC__)
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unsigned long fake_out_gcc;
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fake_out_gcc = (0x08070605L << 31);
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fake_out_gcc = (fake_out_gcc << 1);
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u.l = fake_out_gcc | 0x04030201L;
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#else
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u.l = (0x08070605L << 32) | 0x04030201L;
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#endif /* !__GNUC__ */
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(void) strcpy (string, "87654321");
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}
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else
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{
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fprintf (stderr,
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"%s: sizeof (long int) = %d, which isn't handled here.\n",
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progname, sizeof (long int));
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exit (2);
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}
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for (i = 0; i < sizeof (long); i++)
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nstring[i] = u.s[i] + '0';
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nstring[i] = '\0';
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if (strcmp (nstring, string) == 0)
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endian_define = "BIG_ENDIAN";
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else
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endian_define = "LITTLE_ENDIAN";
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fprintf (stream, "/* %s - Define BIG or LITTLE endian. */\n\n", stream_name);
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fprintf (stream,
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"/* This file was automatically created by `%s'. You shouldn't\n\
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edit this file, because your changes will be overwritten. Instead,\n\
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edit the source code file `%s'. */\n\n",
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progname, source_name);
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fprintf (stream, "#if !defined (%s)\n", endian_define);
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fprintf (stream, "# define %s\n", endian_define);
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fprintf (stream, "#endif /* %s */\n", endian_define);
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if (stream != stdout)
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fclose (stream);
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exit (0);
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}
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