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70 lines
2.2 KiB
C
70 lines
2.2 KiB
C
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#ifndef _APPLE2_DISK_DRIVE_H
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#define _APPLE2_DISK_DRIVE_H
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/*
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* These are the possible modes a drive can be in.
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*/
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enum apple2_disk_drive_mode {
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DD_READ,
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DD_WRITE,
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};
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#define MAX_DRIVE_STEPS 70
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typedef struct {
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/*
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* Disk II drives allow the stepper to move in half-tracks, so we
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* track (pun intended) the position of the head in those
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* half-tracks rather than in full tracks.
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*
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* For example, if track_pos is 4, then the effective track is 2. If
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* the track_pos is 9, then the effective track is 4, except that
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* the head is on the half-track position.
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*
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* There are, at most, 35 tracks in a conventional disk, so there
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* would be at most 70 track positions that we can iterate to.
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*/
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int track_pos;
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/*
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* The data field is where the actual byte data for the image is
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* kept.
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*/
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vm_segment *data;
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/*
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* A disk drive may be "off" or "on", regardless of whether it's
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* been selected by the peripheral interface.
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*/
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bool online;
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/*
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* This is one of DD_READ or DD_WRITE (defined in the enum above).
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* The drive can only read or write at once, and the mode of
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* operation must be made explicit through this mechanism.
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*/
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int mode;
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/*
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* Write protection is an attribute of the disk. Back in the day, a
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* disk would have a small segment cut out of the disk on the side;
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* this would make it writeable. A disk without that would be
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* write-protected. You could take a writeable disk and make it
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* write-protected simply by putting some solid-colored tape over
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* the cut-out.
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*
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* For our purposes, write protection is a simply boolean attribute
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* that you can enable or disable on the drive.
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*/
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bool write_protect;
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} apple2_disk_drive;
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extern apple2_disk_drive *apple2_disk_drive_create();
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extern void apple2_disk_drive_free(apple2_disk_drive *);
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extern void apple2_disk_drive_step(apple2_disk_drive *, int);
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extern void apple2_disk_drive_set_mode(apple2_disk_drive *, int);
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extern void apple2_disk_drive_turn_on(apple2_disk_drive *, bool);
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extern void apple2_disk_drive_write_protect(apple2_disk_drive *, bool);
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#endif
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