調試通道例子。DCC is available on ARM cores which contain EmbeddedICE logic, e.g. arm7tdmi,
ARM9TDMI, etc. DCC is accessed by the target via coprocessor 14 using the
ARM instructions MCR and MRC.
The two assembler source files provided are:
outchan.s for Target to debugger communication
inchan.s for Debugger to target communication
