crt0.s

来自「这是TFTP 协议的最新源代码 很辛苦的」· S 代码 · 共 91 行

/*
	Copyright 2001-2004 Georges Menie (www.menie.org)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

	.title "crt0.S for m68k"

	.extern main
	.extern __stack
	.extern __text_end
	.extern __data_start
	.extern __data_end
	.extern __bss_start
	.extern __bss_end

	.global start
start:

	/* initialize the stack */
	move.l  #__stack, %sp

	/* initialize the data section */
	lea.l	__text_end,%a0
	lea.l	__data_start,%a1
	lea.l	__data_end,%a2
1:	cmpa.l  %a1,%a2
	jbeq	2f
	move.l	(%a0)+,(%a1)+
	jbra	1b
2:
	/* initialize the bss section */
	lea.l   __bss_start,%a0
	lea.l   __bss_end,%a1
1:	cmpa.l  %a0,%a1
	jbeq	2f
	move.l  #0,(%a0)+
	jbra	1b
2:
	
/*
 * call the main routine from the application to get it going.
 * main (argc, argv, environ)
 * we pass argv as a pointer to NULL.
 */

	pea     0
	pea     environ
	pea     %sp@(4)
	pea     0
	jsr	main

/*
 * Define exit to a jump to the board monitor
 */
	.global exit
exit:
	move.l	#-1,0xfffff304
	move.b	#0,0xfffff300;
	movea.l	#0x04000000,%a0;
	movea.l	0(%a0),%sp;
	movea.l	4(%a0),%a0;
	jmp	(%a0);

/*
 * Define an empty __main
 */
	.global __main
__main:
	rts

/*
 * Define an empty environment.
 */
	.data
	.align 2
environ:
	.long 0