mirror of
https://github.com/cc65/cc65.git
synced 2024-11-11 01:05:25 +00:00
125 lines
4.0 KiB
Plaintext
125 lines
4.0 KiB
Plaintext
<!doctype linuxdoc system>
|
|
|
|
<article>
|
|
<title>Diskette Sector I/O Routines
|
|
<author>Christian Groessler, <htmlurl url="mailto:cpg@aladdin.de" name="cpg@aladdin.de">
|
|
<date>20-Feb-2005
|
|
|
|
<abstract>
|
|
The cc65 library provides functions to read and write raw disk sectors.
|
|
Include the dio.h header file to get the necessary definitions.
|
|
</abstract>
|
|
|
|
<!-- Table of contents -->
|
|
<toc>
|
|
|
|
<!-- Begin the document -->
|
|
|
|
<sect>Opening the disk for low level I/O<p>
|
|
|
|
Prior to using these functions a handle to the drive has to be obtained. This
|
|
is done with the <tt>dio_open</tt> function. After use, the handle should be
|
|
released with the <tt>dio_close</tt> function.
|
|
|
|
<tscreen><verb>
|
|
dhandle_t __fastcall__ dio_open (driveid_t drive_id);
|
|
</verb></tscreen>
|
|
|
|
The <tt>drive_id</tt> specifies the drive to access, with 0 being the first
|
|
disk drive, 1 the second, and so on.
|
|
|
|
<tscreen><verb>
|
|
unsigned char __fastcall__ dio_close (dhandle_t handle);
|
|
</verb></tscreen>
|
|
|
|
Closes a handle obtained by <tt>dio_open</tt>. Returns status code.
|
|
<p>
|
|
|
|
<sect>Reading and writing sectors<p>
|
|
|
|
The read and write functions are:
|
|
|
|
<tscreen><verb>
|
|
unsigned char __fastcall__ dio_read (dhandle_t handle,
|
|
sectnum_t sect_num,
|
|
void *buffer);
|
|
</verb></tscreen>
|
|
|
|
This function will read the sector specified by <tt>sect_num</tt> into the memory
|
|
location at buffer.
|
|
|
|
<tscreen><verb>
|
|
unsigned char __fastcall__ dio_write (dhandle_t handle,
|
|
sectnum_t sect_num,
|
|
const void *buffer);
|
|
</verb></tscreen>
|
|
|
|
This function will write the memory contents at buffer to the sector specified
|
|
by <tt>sect_num</tt>. No verify is performed.
|
|
|
|
<tscreen><verb>
|
|
unsigned char __fastcall__ dio_write_verify (dhandle_t handle,
|
|
sectnum_t sect_num,
|
|
const void *buffer);
|
|
</verb></tscreen>
|
|
|
|
This function will write the memory contents at buffer to the sector specified
|
|
by <tt>sect_num</tt>. A verification is performed.
|
|
<p>
|
|
|
|
Use the <tt><ref name="dio_query_sectsize" id="sectsize"></tt> function to query the size of a sector.
|
|
|
|
All these functions will return 0 for success and an OS specific error code in
|
|
case of failure.
|
|
<p>
|
|
|
|
<sect>Querying sector size<label id="sectsize"><p>
|
|
|
|
Some systems support multiple diskette formats which have different sector sizes.
|
|
The following function returns the sector size of the currently inserted disk:
|
|
|
|
<tscreen><verb>
|
|
sectsize_t __fastcall__ dio_query_sectsize(dhandle_t handle);
|
|
</verb></tscreen>
|
|
|
|
On the Atari platform, the sector size is handled specially. Please refer
|
|
to the DIO section in the <htmlurl url="atari.html" name="Atari">
|
|
specific platform documentation.
|
|
|
|
<sect>Converting sector numbers<p>
|
|
|
|
Since the read and write functions expect a sector number, for systems where
|
|
the sectors aren't addressed by a logical sector number (e.g. CBM drives),
|
|
there are 2 conversion functions. One of them converts a logical sector number
|
|
to a head/track/sector triple. The other conversion function works the other
|
|
way round.
|
|
|
|
<tscreen><verb>
|
|
unsigned char __fastcall__ dio_phys_to_log (dhandle_t handle,
|
|
const dio_phys_pos *physpos,
|
|
sectnum_t *sectnum);
|
|
</verb></tscreen>
|
|
|
|
This function converts track/head/sector to logical sector number.
|
|
|
|
<tscreen><verb>
|
|
unsigned char __fastcall__ dio_log_to_phys (dhandle_t handle,
|
|
const _sectnum_t *sectnum,
|
|
dio_phys_pos *physpos);
|
|
</verb></tscreen>
|
|
|
|
This function converts a logical sector number to track/head/sector notation.
|
|
<p>
|
|
|
|
Note, that on systems which natively use logical sector numbers (e.g. Atari),
|
|
the conversion functions are dummies. They ignore head/track
|
|
(<tt>dio_phys_to_log</tt>) or return them as zero (<tt>dio_log_to_phys</tt>).
|
|
The logical sector number is returned as physical sector and vice versa.
|
|
<p>
|
|
|
|
|
|
</article>
|
|
|
|
|
|
|