[quote user="fan Linlin"]Does the compiler5 treat the first member of a struct as the MSB ,diffrent from ccs2 ?[/quote]
CCS 2.x is from many years ago. I take this to mean you are porting code from a very old ARM compiler version to the relatively recent compiler version 5.0.1. I further presume you have changed ABI from the older ti_arm9_abi to the newer EABI.
One option for restoring old behavior is to build with --abi=ti_arm9_abi.
To understand this issue better, please see the appendix titled Bit Fields in the ARM compiler EABI migration document.
Thanks and regards,
-George