1 <!doctype linuxdoc system>
4 <title>Diskette Sector I/O Routines
5 <author><url url="mailto:chris@groessler.org" name="Christian Groessler">
9 The cc65 library provides functions to read and write raw disk sectors.
10 Include the dio.h header file to get the necessary definitions.
13 <!-- Table of contents -->
16 <!-- Begin the document -->
18 <sect>Opening the disk for low level I/O<p>
20 Prior to using these functions a handle to the device has to be obtained. This
21 is done with the <tt>dio_open</tt> function. After use, the handle should be
22 released with the <tt>dio_close</tt> function.
25 dhandle_t __fastcall__ dio_open (unsigned char device);
28 The <tt>device</tt> specifies the device to access.
31 unsigned char __fastcall__ dio_close (dhandle_t handle);
34 Closes a handle obtained by <tt>dio_open</tt>. Returns status code.
37 <sect>Reading and writing sectors<p>
39 The read and write functions are:
42 unsigned char __fastcall__ dio_read (dhandle_t handle,
47 This function will read the sector specified by <tt>sect_num</tt> into the memory
51 unsigned char __fastcall__ dio_write (dhandle_t handle,
56 This function will write the memory contents at buffer to the sector specified
57 by <tt>sect_num</tt>. No verify is performed.
60 unsigned char __fastcall__ dio_write_verify (dhandle_t handle,
65 This function will write the memory contents at buffer to the sector specified
66 by <tt>sect_num</tt>. A verification is performed.
69 Use the <tt><ref name="dio_query_sectsize" id="sectsizecount"></tt> function to query
70 the size of a sector and the <tt><ref name="dio_query_sectcount" id="sectsizecount"></tt>
71 function to query the number of available sectors.
74 All these functions will return 0 for success and an OS specific error code in
78 <sect>Querying sector size and count<label id="sectsizecount"><p>
80 Some systems support multiple diskette formats which have different sector sizes
81 and/or different sector counts.
84 The following function returns the sector size of the currently inserted disk:
87 unsigned __fastcall__ dio_query_sectsize (dhandle_t handle);
90 On the Atari platform, the sector size is handled specially. Please refer
91 to the DIO section in the <url url="atari.html" name="Atari-specific
92 platform documentation">.
95 The following function returns the sector count of the currently inserted disk:
98 unsigned __fastcall__ dio_query_sectcount (dhandle_t handle);
101 <sect>Converting sector numbers<p>
103 Since the read and write functions expect a sector number, for systems where
104 the sectors aren't addressed by a logical sector number (e.g. CBM devices),
105 there are 2 conversion functions. One of them converts a logical sector number
106 to a head/track/sector triple. The other conversion function works the other
110 unsigned char __fastcall__ dio_phys_to_log (dhandle_t handle,
111 const dio_phys_pos *physpos,
115 This function converts track/head/sector to logical sector number.
118 unsigned char __fastcall__ dio_log_to_phys (dhandle_t handle,
119 const unsigned *sectnum,
120 dio_phys_pos *physpos);
123 This function converts a logical sector number to track/head/sector notation.
126 Note, that on systems which natively use logical sector numbers (e.g. Atari),
127 the conversion functions are dummies. They ignore head/track
128 (<tt>dio_phys_to_log</tt>) or return them as zero (<tt>dio_log_to_phys</tt>).
129 The logical sector number is returned as physical sector and vice versa.