Parsing integers from buffers

[owens@gargoyle.uchicago.edu (Christopher Owens)]

I need to parse integers from a buffer, lots of them.

The obvious (parse-integer (buffer-substring buf start end))
does an unnecessary copy of the string.

I wrote my own (buffer-parse-integer buf start end) but it's slow.

Does anybody have source code for an implementation of parse-integer
that they would be willing to send me so I can adapt it to this
purpose?  

Thanks,