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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML><HEAD> <META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.20"> <TITLE>cc65 function reference: Alphabetical function reference: em_use</TITLE> <LINK HREF="funcref-94.html" REL=next> <LINK HREF="funcref-92.html" REL=previous> <LINK HREF="funcref.html#toc3" REL=contents></HEAD><BODY><A HREF="funcref-94.html">Next</A><A HREF="funcref-92.html">Previous</A><A HREF="funcref.html#toc3">Contents</A><HR><H2><A NAME="em_use"></A> 3.52 <A HREF="funcref.html#toc3.52">em_use</A></H2><P><BLOCKQUOTE><DL><DT><B>Function</B><DD><P>Prepare an extended memory page for use.</P><DT><B>Header</B><DD><P><CODE><A HREF="funcref-15.html#em.h">em.h</A></CODE></P><DT><B>Declaration</B><DD><P><CODE>void* __fastcall__ em_use (unsigned page);</CODE></P><DT><B>Description</B><DD><P>The function maps one page of extended memory into linearmemory and returns a pointer to the page frame. This function is similar to<CODE><A HREF="funcref-90.html#em_map">em_map</A></CODE>, but will not transfer data into theactual memory window in the assumption that the existing data is wrong orwill get overwritten.</P><DT><B>Limits</B><DD><P><UL><LI>Calling <CODE>em_use</CODE> will invalidate the memory window, so if youmade any changes to the data in the window, call <CODE><A HREF="funcref-86.html#em_commit">em_commit</A></CODE> first, or the changes are lost.</LI><LI>The function is only available as fastcall function, so it may only beused in presence of a prototype.</LI><LI>The function produces undefined results if no extended memory driver isloaded.</LI></UL></P><DT><B>Availability</B><DD><P>cc65</P><DT><B>See also</B><DD><P><A HREF="funcref-86.html#em_commit">em_commit</A>,<A HREF="funcref-89.html#em_load_driver">em_load_driver</A>,<A HREF="funcref-90.html#em_map">em_map</A></P><DT><B>Example</B><DD><P>None.</P></DL></BLOCKQUOTE></P><HR><A HREF="funcref-94.html">Next</A><A HREF="funcref-92.html">Previous</A><A HREF="funcref.html#toc3">Contents</A></BODY></HTML>⌨️ 快捷键说明
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