bc000000: 01 02 03 04 05 06 07 08 ........
You would need to use the "-s offset" option of the xxd. However, there is a bug in the code that makes this options only works as the FIRST option. Otherwise, it wouldn't work.
You want to do this:
xxd -s -0xbc000000 -r -g 1 test.dump test.bin
Basically the xxd is hardcoded to look for the offset at argv[2].
Another alternative:
https://github.com/pheehs/hexdump2bin/blob/master/hexdump2bin.py
Another alternative:
https://github.com/pheehs/hexdump2bin/blob/master/hexdump2bin.py