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Diffstat (limited to 'sysdeps/m68k/elf/start.S')
| -rw-r--r-- | sysdeps/m68k/elf/start.S | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/sysdeps/m68k/elf/start.S b/sysdeps/m68k/elf/start.S new file mode 100644 index 0000000000..1b622d6e08 --- /dev/null +++ b/sysdeps/m68k/elf/start.S @@ -0,0 +1,90 @@ +/* Startup code compliant to the ELF m68k ABI. +Copyright (C) 1996 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C Library is free software; you can redistribute it and/or +modify it under the terms of the GNU Library General Public License as +published by the Free Software Foundation; either version 2 of the +License, or (at your option) any later version. + +The GNU C Library 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 +Library General Public License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +/* This is the canonical entry point, usually the first thing in the text + segment. The SVR4/m68k ABI says that when the entry point runs, + most registers' values are unspecified, except for: + + %a1 Contains a function pointer to be registered with `atexit'. + This is how the dynamic linker arranges to have DT_FINI + functions called for shared libraries that have been loaded + before this code runs. + + %sp The stack contains the arguments and environment: + 0(%sp) argc + 4(%sp) argv[0] + ... + (4*argc)(%sp) NULL + (4*(argc+1))(%sp) envp[0] + ... + NULL +*/ + + .text + .globl _start +_start: + /* Clear the frame pointer. The ABI suggests this be done, to mark + the outermost frame obviously. */ + sub.l %fp, %fp + + /* %a1 contains the address of the shared library termination + function, which we will register with `atexit' to be called by + `exit'. */ + tstl %a1 + jbeq 1f + move.l %a1, -(%sp) + jbsr atexit + addql #4, %sp +1: + + /* Do essential libc initialization. In statically linked + programs under the GNU Hurd, this is what sets up the + arguments on the stack for the code below. */ + jbsr __libc_init_first + + /* Extract the arguments and environment as encoded on the stack + and set up the arguments for `main': argc, argv, envp. */ + move.l (%sp)+, %d0 /* Pop the argument count. */ + lea (4,%sp,%d0*4), %a0 /* envp = &argv[argc + 1] */ + move.l %a0, _environ /* Store it in the global variable. */ + pea (%a0) /* Push third argument: envp. */ + pea 4(%sp) /* Push second argument: argv. */ + move.l %d0, -(%sp) /* Push first argument: argc. */ + + /* Call `_init', which is the entry point to our own `.init' + section; and register with `atexit' to have `exit' call + `_fini', which is the entry point to our own `.fini' section. */ + jbsr _init + move.l #_fini, -(%sp) + jbsr atexit + addq.l #4, %sp + + /* Call the user's main function, and exit with its value. */ + jbsr main + move.l %d0, (%sp) +1: jbsr exit /* This should never return. */ + jbra 1b /* Try again if somehow it does return. */ + +/* Define a symbol for the first piece of initialized data. */ + .data + .globl __data_start +__data_start: + .long 0 + .weak data_start + data_start = __data_start |