请教IAR下的cstart.s79问题

只看该作者 · 2010-1-28 10:01

在IAR 给的例子中的cstart.s79下有这样一段:
;---------------------------------------------------------------
; ?RESET
; Reset Vector.
; Normally, segment INTVEC is linked at address 0.
; For debugging purposes, INTVEC may be placed at other
; addresses.
; A debugger that honors the entry point will start the
; program in a normal way even if INTVEC is not at address 0.
;---------------------------------------------------------------
  MODULE ?RESET
COMMON INTVEC:CODE:NOROOT(2)
  PUBLIC  __program_start
  EXTERN ?cstartup
  EXTERN undef_handler, swi_handler, prefetch_handler
  EXTERN data_handler, irq_handler, fiq_handler
  CODE32 ; Always ARM mode after reset
  org 0x00
__program_start
  .
  .
  .
org 0x20
               dc32 ?cstartup
  org 0x24
;             dc32 undef_handler
  org 0x28
;             dc32 swi_handler
  org 0x2c
;             dc32 prefetch_handler
  org 0x30
;             dc32 data_handler
  org 0x38
;             dc32 irq_handler
  org 0x3c
;             dc32 fiq_handler
  LTORG
;  ENDMOD __program_start

   ENDMOD

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我想请教一下我用红色标记出的2句话的意思,他们是起什么作用呢?
各位DX帮帮忙哈