223cc6685e
git-svn-id: svn://svn.compuextreme.de/Viitor/V963/Viitor_cc65@5933 504e572c-2e33-0410-9681-be2bf7408885
56 lines
1.9 KiB
HTML
56 lines
1.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<META NAME="GENERATOR" CONTENT="LinuxDoc-Tools 0.9.20">
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<TITLE>Diskette Sector I/O Routines: Converting sector numbers</TITLE>
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<LINK HREF="dio-3.html" REL=previous>
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<LINK HREF="dio.html#toc4" REL=contents>
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<H2><A NAME="s4">4.</A> <A HREF="dio.html#toc4">Converting sector numbers</A></H2>
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<P>Since the read and write functions expect a sector number, for systems where
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the sectors aren't addressed by a logical sector number (e.g. CBM drives),
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there are 2 conversion functions. One of them converts a logical sector number
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to a head/track/sector triple. The other conversion function works the other
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way round.</P>
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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unsigned char __fastcall__ dio_phys_to_log (dhandle_t handle,
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const dio_phys_pos *physpos,
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sectnum_t *sectnum);
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</PRE>
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</CODE></BLOCKQUOTE>
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</P>
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<P>This function converts track/head/sector to logical sector number.</P>
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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unsigned char __fastcall__ dio_log_to_phys (dhandle_t handle,
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const _sectnum_t *sectnum,
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dio_phys_pos *physpos);
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</PRE>
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</CODE></BLOCKQUOTE>
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</P>
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<P>This function converts a logical sector number to track/head/sector notation.</P>
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<P>Note, that on systems which natively use logical sector numbers (e.g. Atari),
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the conversion functions are dummies. They ignore head/track
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(<CODE>dio_phys_to_log</CODE>) or return them as zero (<CODE>dio_log_to_phys</CODE>).
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The logical sector number is returned as physical sector and vice versa.</P>
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