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91 lines
3.0 KiB
ArmAsm
91 lines
3.0 KiB
ArmAsm
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/* Startup code compliant to the ELF m68k ABI.
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Copyright (C) 1996 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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/* This is the canonical entry point, usually the first thing in the text
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segment. The SVR4/m68k ABI says that when the entry point runs,
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most registers' values are unspecified, except for:
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%a1 Contains a function pointer to be registered with `atexit'.
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This is how the dynamic linker arranges to have DT_FINI
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functions called for shared libraries that have been loaded
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before this code runs.
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%sp The stack contains the arguments and environment:
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0(%sp) argc
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4(%sp) argv[0]
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...
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(4*argc)(%sp) NULL
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(4*(argc+1))(%sp) envp[0]
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...
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NULL
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*/
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.text
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.globl _start
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_start:
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/* Clear the frame pointer. The ABI suggests this be done, to mark
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the outermost frame obviously. */
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sub.l %fp, %fp
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/* %a1 contains the address of the shared library termination
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function, which we will register with `atexit' to be called by
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`exit'. */
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tstl %a1
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jbeq 1f
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move.l %a1, -(%sp)
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jbsr atexit
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addql #4, %sp
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1:
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/* Do essential libc initialization. In statically linked
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programs under the GNU Hurd, this is what sets up the
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arguments on the stack for the code below. */
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jbsr __libc_init_first
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/* Extract the arguments and environment as encoded on the stack
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and set up the arguments for `main': argc, argv, envp. */
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move.l (%sp)+, %d0 /* Pop the argument count. */
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lea (4,%sp,%d0*4), %a0 /* envp = &argv[argc + 1] */
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move.l %a0, _environ /* Store it in the global variable. */
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pea (%a0) /* Push third argument: envp. */
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pea 4(%sp) /* Push second argument: argv. */
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move.l %d0, -(%sp) /* Push first argument: argc. */
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/* Call `_init', which is the entry point to our own `.init'
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section; and register with `atexit' to have `exit' call
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`_fini', which is the entry point to our own `.fini' section. */
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jbsr _init
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move.l #_fini, -(%sp)
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jbsr atexit
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addq.l #4, %sp
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/* Call the user's main function, and exit with its value. */
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jbsr main
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move.l %d0, (%sp)
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1: jbsr exit /* This should never return. */
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jbra 1b /* Try again if somehow it does return. */
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/* Define a symbol for the first piece of initialized data. */
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.data
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.globl __data_start
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__data_start:
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.long 0
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.weak data_start
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data_start = __data_start
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