Lex Source Code

I have an application -- awkcc -- that I've happily used for some years
in Solaris. Trying to port to Linux, there are a number of functions in
lex that are not part of flex: yybgin, yysvec, yysptr, yysbuf, yytchar,
yysptr. I'm not smart enough about flex to be able to figure out what
these things are supposed to do from just the source code and I'm
wondering, given that Solaris lex works just fine, if it's possible to
obtain the source code for lex so I can just build that and install it
(/usr/bin/lex on my Linux systems just executes "flex -l $*)?

Thanks.
[I dug it up for him out of the old 32V distribution which Caldera
released to the public some years ago.  It doesn't compile under a
modern C compiler, either, of course. -John]