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Rename to apple2dd; add read/write functions

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This commit is contained in:
Peter Evans 2017-12-14 22:14:55 -06:00
parent 58137cb2a0
commit 24e599a8fd
1 changed files with 72 additions and 10 deletions
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82
src/apple2.disk_drive.c
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@ -4,12 +4,32 @@
#include "apple2.disk_drive.h"
apple2_disk_drive *
apple2_disk_drive_create()
{
apple2_disk_drive *drive;
/*
* This is the length of a typical disk that is formatted in either DOS
* 3.3 or ProDOS.
*/
#define _140K_ 143360
drive = malloc(sizeof(apple2_disk_drive));
/*
* 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
/*
* This is the last _accessible_ sector position within a track (you can
* have 0 - 4095).
*/
#define MAX_SECTOR_POS 4095
apple2dd *
apple2dd_create()
{
apple2dd *drive;
drive = malloc(sizeof(apple2dd));
if (drive == NULL) {
log_critical("Could not malloc space for apple2 disk drive");
return NULL;
@ -21,6 +41,7 @@ apple2_disk_drive_create()
drive->data = NULL;
drive->track_pos = 0;
drive->sector_pos = 0;
drive->online = false;
drive->write_protect = true;
drive->mode = DD_READ;
@ -29,7 +50,7 @@ apple2_disk_drive_create()
}
void
apple2_disk_drive_free(apple2_disk_drive *drive)
apple2dd_free(apple2dd *drive)
{
if (drive->data) {
vm_segment_free(drive->data);
@ -39,7 +60,7 @@ apple2_disk_drive_free(apple2_disk_drive *drive)
}
void
apple2_disk_drive_step(apple2_disk_drive *drive, int steps)
apple2dd_step(apple2dd *drive, int steps)
{
drive->track_pos += steps;
@ -51,7 +72,7 @@ apple2_disk_drive_step(apple2_disk_drive *drive, int steps)
}
void
apple2_disk_drive_set_mode(apple2_disk_drive *drive, int mode)
apple2dd_set_mode(apple2dd *drive, int mode)
{
if (mode != DD_READ && mode != DD_WRITE) {
return;
@ -61,13 +82,54 @@ apple2_disk_drive_set_mode(apple2_disk_drive *drive, int mode)
}
void
apple2_disk_drive_turn_on(apple2_disk_drive *drive, bool online)
apple2dd_turn_on(apple2dd *drive, bool online)
{
drive->online = online;
}
void
apple2_disk_drive_write_protect(apple2_disk_drive *drive, bool protect)
apple2dd_write_protect(apple2dd *drive, bool protect)
{
drive->write_protect = protect;
}
static int
position(apple2dd *drive)
{
if (drive->data->size == _140K_) {
int track_offset;
track_offset = (drive->track_pos % 2) * 4096;
return track_offset + drive->sector_pos;
}
return 0;
}
vm_8bit
apple2dd_read_byte(apple2dd *drive)
{
vm_8bit byte = vm_segment_get(drive->data, position(drive));
// We may have read the very last byte in a sector; if so let's
// adjust the track_pos by two half tracks and reset the sector pos.
drive->sector_pos++;
if (drive->sector_pos > MAX_SECTOR_POS) {
drive->track_pos += 2;
drive->sector_pos = 0;
}
return byte;
}
void
apple2dd_write(apple2dd *drive, vm_8bit byte)
{
vm_segment_set(drive->data, position(drive), byte);
drive->sector_pos++;
if (drive->sector_pos > MAX_SECTOR_POS) {
drive->track_pos += 2;
drive->sector_pos = 0;
}
}