.text .global _start _start: b rest ldr pc ,  _undefine_instruction ldr pc , _software_interrrupt ldr pc , _prefetch_aport ldr pc , _data_abort ldr pc , _not_use ldr pc , _irq ldr pc , _fiq _undefine_instruction: .word undefine_instruction _software_interrrupt: .word software_interrrupt _prefetch_aport: .word prefetch_aport _data_abort:.word data_abort _not_use: .word not_use _irq: .word irq _fiq: .word fiq undefine_instruction: nop software_interrrupt: nop prefetch_aport: nop data_abort: nop not_use: nop irq: nop fiq: nop rest: bl set_svc bl disable_watchdog set_svc: mrs r0 , cpsr bic r0 , r0 ,  #0x1f orr r0 , r0 , #0x13 msr cpsr , r0 #define pWTCON 0x53000000//2440的WTCON地址 disable_watchdog: ldr r0 , =pWTCON//ldr在這裡是偽指令 mov r1 , #0x0 str r1 , [r0]  mov pc , lr