mirror of
https://github.com/pevans/erc-c.git
synced 2024-10-31 13:07:14 +00:00
118 lines
3.6 KiB
C
118 lines
3.6 KiB
C
#ifndef _APPLE2_DISK_DRIVE_H
|
|
#define _APPLE2_DISK_DRIVE_H
|
|
|
|
#include <stdbool.h>
|
|
#include <stdio.h>
|
|
#include <sys/stat.h>
|
|
|
|
#include "vm_bits.h"
|
|
#include "vm_segment.h"
|
|
|
|
/*
|
|
* These are the possible modes a drive can be in.
|
|
*/
|
|
enum apple2_dd_mode {
|
|
DD_READ,
|
|
DD_WRITE,
|
|
};
|
|
|
|
/*
|
|
* This is the length of a typical disk that is formatted in either DOS
|
|
* 3.3 or ProDOS.
|
|
*/
|
|
#define _140K_ 143360
|
|
|
|
/*
|
|
* And this is the length of a disk that has been formatted as a nibble
|
|
* file (*.NIB). This is not an Apple thing, exactly; it's more of an
|
|
* emulator thing, that emulators had used to try and get around copy
|
|
* protection in emulation. It does complicate disk drive operation!
|
|
*/
|
|
#define _240K_ 245760
|
|
|
|
#define MAX_DRIVE_STEPS 70
|
|
|
|
/*
|
|
* This is the last _accessible_ sector position within a track (you can
|
|
* have 0 - 4095).
|
|
*/
|
|
#define MAX_SECTOR_POS 4095
|
|
|
|
typedef struct {
|
|
/*
|
|
* Disk II drives allow the stepper to move in half-tracks, so we
|
|
* track (pun intended) the position of the head in those
|
|
* half-tracks rather than in full tracks.
|
|
*
|
|
* For example, if track_pos is 4, then the effective track is 2. If
|
|
* the track_pos is 9, then the effective track is 4, except that
|
|
* the head is on the half-track position.
|
|
*
|
|
* There are, at most, 35 tracks in a conventional disk, so there
|
|
* would be at most 70 track positions that we can iterate to.
|
|
*/
|
|
int track_pos;
|
|
|
|
/*
|
|
* This is a weirder one, because while DOS cares about sectors, we
|
|
* don't really. We just need to know how to find the right position
|
|
* to work with in the disk image.
|
|
*
|
|
* Each track has 16 sectors, and each sector has 256 bytes. We can
|
|
* then say that each track is 4k (4,096) bytes large. So while our
|
|
* track_pos can tell us which 4k chunk we're in, the sector_pos has
|
|
* to tell us where we are _within_ the track. Again -- we don't
|
|
* care about the sector number, really. So the sector_pos field is
|
|
* tracking the byte offset from the beginning of the track, such
|
|
* that 0 ≤ sector_pos < 4096.
|
|
*/
|
|
int sector_pos;
|
|
|
|
/*
|
|
* The data field is where the actual byte data for the image is
|
|
* kept.
|
|
*/
|
|
vm_segment *data;
|
|
|
|
/*
|
|
* A disk drive may be "off" or "on", regardless of whether it's
|
|
* been selected by the peripheral interface.
|
|
*/
|
|
bool online;
|
|
|
|
/*
|
|
* This is one of DD_READ or DD_WRITE (defined in the enum above).
|
|
* The drive can only read or write at once, and the mode of
|
|
* operation must be made explicit through this mechanism.
|
|
*/
|
|
int mode;
|
|
|
|
/*
|
|
* Write protection is an attribute of the disk. Back in the day, a
|
|
* disk would have a small segment cut out of the disk on the side;
|
|
* this would make it writeable. A disk without that would be
|
|
* write-protected. You could take a writeable disk and make it
|
|
* write-protected simply by putting some solid-colored tape over
|
|
* the cut-out.
|
|
*
|
|
* For our purposes, write protection is a simply boolean attribute
|
|
* that you can enable or disable on the drive.
|
|
*/
|
|
bool write_protect;
|
|
} apple2dd;
|
|
|
|
extern apple2dd *apple2_dd_create();
|
|
extern int apple2_dd_insert(apple2dd *, FILE *);
|
|
extern int apple2_dd_position(apple2dd *);
|
|
extern vm_8bit apple2_dd_read(apple2dd *);
|
|
extern void apple2_dd_eject(apple2dd *);
|
|
extern void apple2_dd_free(apple2dd *);
|
|
extern void apple2_dd_set_mode(apple2dd *, int);
|
|
extern void apple2_dd_shift(apple2dd *, int);
|
|
extern void apple2_dd_step(apple2dd *, int);
|
|
extern void apple2_dd_turn_on(apple2dd *, bool);
|
|
extern void apple2_dd_write(apple2dd *, vm_8bit);
|
|
extern void apple2_dd_write_protect(apple2dd *, bool);
|
|
|
|
#endif
|