sysdeps/unix/arm/start.c

   1 /* Special startup code for ARM a.out binaries.
   2    Copyright (C) 1998, 2004 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    In addition to the permissions in the GNU Lesser General Public
  11    License, the Free Software Foundation gives you unlimited
  12    permission to link the compiled version of this file with other
  13    programs, and to distribute those programs without any restriction
  14    coming from the use of this file. (The GNU Lesser General Public
  15    License restrictions do apply in other respects; for example, they
  16    cover modification of the file, and distribution when not linked
  17    into another program.)
  18
  19    Note that people who make modified versions of this file are not
  20    obligated to grant this special exception for their modified
  21    versions; it is their choice whether to do so. The GNU Lesser
  22    General Public License gives permission to release a modified
  23    version without this exception; this exception also makes it
  24    possible to release a modified version which carries forward this
  25    exception.
  26
  27    The GNU C Library is distributed in the hope that it will be useful,
  28    but WITHOUT ANY WARRANTY; without even the implied warranty of
  29    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  30    Lesser General Public License for more details.
  31
  32    You should have received a copy of the GNU Lesser General Public
  33    License along with the GNU C Library; if not, write to the Free
  34    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  35    02111-1307 USA.  */
  36
  37 #include <errno.h>
  38 #include <stdlib.h>
  39 #include <unistd.h>
  40 #include <sysdep.h>
  41
  42 /* The first piece of initialized data.  */
  43 int __data_start = 0;
  44 #ifdef HAVE_WEAK_SYMBOLS
  45 weak_alias (__data_start, data_start)
  46 #endif
  47
  48 extern void __libc_init (int argc, char **argv, char **envp);
  49 extern int main (int argc, char **argv, char **envp);
  50
  51 /* N.B.: It is important that this be the first function.
  52    This file is the first thing in the text section.  */
  53
  54 /* If this was in C it might create its own stack frame and
  55    screw up the arguments.  */
  56 #ifdef NO_UNDERSCORES
  57 asm (".text; .globl _start; _start: B start1");
  58 #else
  59 asm (".text; .globl __start; __start: B _start1");
  60
  61 /* Make an alias called `start' (no leading underscore, so it can't
  62    conflict with C symbols) for `_start'.  This is the name vendor crt0.o's
  63    tend to use, and thus the name most linkers expect.  */
  64 asm (".set start, __start");
  65 #endif
  66
  67 /* Fool gcc into thinking that more args are passed.  This makes it look
  68    on the stack (correctly) for the real arguments.  It causes somewhat
  69    strange register usage in start1(), but we aren't too bothered about
  70    that at the moment. */
  71 #define DUMMIES a1, a2, a3, a4
  72
  73 #ifdef  DUMMIES
  74 #define ARG_DUMMIES     DUMMIES,
  75 #define DECL_DUMMIES    int DUMMIES;
  76 #else
  77 #define ARG_DUMMIES
  78 #define DECL_DUMMIES
  79 #endif
  80
  81 /* ARGSUSED */
  82 static void
  83 start1 (ARG_DUMMIES argc, argv, envp)
  84      DECL_DUMMIES
  85      int argc;
  86      char **argv;
  87      char **envp;
  88 {
  89   /* Store a pointer to the environment.  */
  90   __environ = envp;
  91
  92   /* Do C library initializations.  */
  93   __libc_init (argc, argv, __environ);
  94
  95   /* Call the user program.  */
  96   exit (main (argc, argv, __environ));
  97 }