HREF for next/prev links

<map name="oO">
<area shape="rect" coords="289,011,300,289" alt="next_post" href="NEED_HELP_HERE" <area shape="rect" coords="000,011,011,289" alt="prev_post" href="NEED_HELP_HERE"/>
/>
</map>

I am trying to generate the internal content for a HREF within a AREA tag for the next/prev posts. I can generate the appropriate text based links but after having trawled the codex and tinkered for a few hours I am stumped. What I need is the actual link for the next/prev posts, eg., https://asdf.com/posts/1078 . I can generate an anchor tag with the appropriate href, but I am stuck trying to generate just the href.

Any hints? As I have said, I have searched and tinkered for hours and feel like I am probably missing something simple. Thanks.