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Add documentation; plus set sector/track pos to 0 on eject
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@ -4,6 +4,11 @@
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#include "apple2.dd.h"
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/*
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* Create a new disk drive. We do not create a memory segment for the
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* drive right away, as the size of said data can be variable based on
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* the disk format.
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*/
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apple2dd *
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apple2dd_create()
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{
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@ -29,6 +34,11 @@ apple2dd_create()
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return drive;
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}
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/*
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* Insert a "disk" into the drive, such that a disk is delivered to us
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* through a FILE stream. Return an error code if the disk format is
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* something we cannot accept.
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*/
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int
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apple2dd_insert(apple2dd *drive, FILE *stream)
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{
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@ -68,6 +78,10 @@ apple2dd_insert(apple2dd *drive, FILE *stream)
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return OK;
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}
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/*
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* Return the segment position that the drive is currently at, based
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* upon track and sector position.
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*/
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int
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apple2dd_position(apple2dd *drive)
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{
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@ -90,6 +104,10 @@ apple2dd_position(apple2dd *drive)
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return 0;
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}
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/*
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* Read a single byte from the disk drive, at its current position, and
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* then shift the head by 1 byte.
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*/
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vm_8bit
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apple2dd_read(apple2dd *drive)
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{
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@ -99,6 +117,10 @@ apple2dd_read(apple2dd *drive)
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return byte;
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}
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/*
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* Here we mean to "empty" the drive, essentially freeing the segment
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* memory and resetting the head position.
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*/
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void
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apple2dd_eject(apple2dd *drive)
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{
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@ -106,8 +128,14 @@ apple2dd_eject(apple2dd *drive)
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vm_segment_free(drive->data);
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drive->data = NULL;
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}
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drive->track_pos = 0;
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drive->sector_pos = 0;
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}
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/*
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* Free the memory taken up by the disk drive.
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*/
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void
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apple2dd_free(apple2dd *drive)
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{
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@ -118,6 +146,10 @@ apple2dd_free(apple2dd *drive)
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free(drive);
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}
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/*
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* Set the disk drive mode, which is either read or write. (It can only
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* be one or the other at a time.)
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*/
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void
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apple2dd_set_mode(apple2dd *drive, int mode)
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{
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@ -128,6 +160,11 @@ apple2dd_set_mode(apple2dd *drive, int mode)
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drive->mode = mode;
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}
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/*
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* Shift the head position in the drive by the given positions, which is
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* in bytes. Pos may be a negative number; if so, the head essentially
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* moves further away from the center of the magnetic wafer.
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*/
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void
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apple2dd_shift(apple2dd *drive, int pos)
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{
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@ -143,6 +180,13 @@ apple2dd_shift(apple2dd *drive, int pos)
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}
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}
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/*
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* When you step the drive, you are essentially moving the head in
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* track positions. It's not really faster for _us_, but it's faster for
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* a mechanical drive than a bunch of shifts if you know the data is far
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* away track-wise. This function also safeguards (as the drive did!)
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* against stepping too far out or too far in.
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*/
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void
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apple2dd_step(apple2dd *drive, int steps)
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{
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@ -155,12 +199,20 @@ apple2dd_step(apple2dd *drive, int steps)
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}
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}
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/*
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* A really simple function to turn the drive "on".
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*/
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void
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apple2dd_turn_on(apple2dd *drive, bool online)
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{
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drive->online = online;
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}
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/*
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* Write a byte to the disk in the drive. This is pretty similar to the
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* read function in that, once we do what we need with the segment, we
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* shift the drive position forward by one byte.
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*/
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void
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apple2dd_write(apple2dd *drive, vm_8bit byte)
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{
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@ -168,6 +220,12 @@ apple2dd_write(apple2dd *drive, vm_8bit byte)
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apple2dd_shift(drive, 1);
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}
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/*
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* Set the write-protect status for the disk. Note that it was _disks_
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* that were write-protected in the past, sometimes by taping over a
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* chunk that was clipped out of the disk. So this function is somewhat
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* similar to just taping over or removing that tape.
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*/
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void
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apple2dd_write_protect(apple2dd *drive, bool protect)
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{
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