[TUHS] cross reference tool for pre-K&R C

[nao]

Hi,

I really enjoy hacking ancient unix rather seriously and want a cross
reference tools for them. Since some of them are written in pre-K&R C,
modern tools are not very useful. Is there any cross reference tool
for pre-K&R C source codes?

BTW, early UNIX assembler document has bugs which state '>>' and '<<'
are shift operators despite that really '\>' and '\<' are. I wonder
where these bugs came from...

Cheers,
- nao