Hi,
why do you think that your Buf[x] is rotated through the Carry flag?
The "_cror_" function use "RR A" instruction. The "RRC A"
instruction is not used for that.
My version is V7.20 but I guess it will be same in your version.
You can use SRC directive or set it in uVision, generate assmebler source code and look at your problem.

Vaclav