万科魅力之城新年包装投射方案下.ppt

/*
* armboot - Startup Code for ARM920 CPU-core
*
* Copyright (c) 2001 Marius Gr鰃er <******@>
* Copyright (c) 2002 Alex Z黳ke <******@>
* Copyright (c) 2002 Gary Jennejohn <******@>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU 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
*/
#include <>
#include <>
/*
*************************************************************************
*
* Jump vector table as in table in [1]
*
*************************************************************************
*/
.globl _start //定义全局变量_start 为程序入口点:对应系统复位,各异常向量的跳转代码
_start: b reset
ldr pc, _undefined_instruction
ldr pc, _software_interrupt
ldr pc, _prefetch_abort
ldr pc, _data_abort
ldr pc, _not_used
ldr pc, _irq
ldr pc, _fiq
_undefined_instruction: .word undefined_instruction //ARM 规定的异常向量地址
_software_interrupt: .word software_interrupt
_prefetch_abort: .word prefetch_abort
_data_abort: .word data_abort
_not_used: .word not_used
_irq: .word irq
_fiq: .word fiq
.balignl 16,0xdeadbeef /*这句伪指令是用来占位的,使下面的程序从一个16位数的地址开始写*/
/*0xdeadbeef它的作用大概就是为内存做标记,有点儿像个小旗子,插在那里,表示从这个位置往后,就是干什么的内存,这个位置往前,禁止访问。*/
.balignw则表示第二个参数存入的内容长度为一个字长,即16位,所以一般有这样的形式出现:
.balignw 4,0x368d
因为现在填入的内容为16位了,那就存在以下几种情况