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/*********************************************************************
formats/g64_dsk.c
Floppy format code for Commodore 1541 GCR disk images
*********************************************************************/
/*
TODO:
- speed zones
- writing
*/
#define XTAL_16MHz 16000000
#define XTAL_12MHz 12000000
#include "g64_dsk.h"
#include "flopimg.h"
/***************************************************************************
PARAMETERS
***************************************************************************/
#define LOG 0
#define HEADER_LENGTH 0x2ac /* standard length for 84 half tracks */
#define MAX_TRACKS 84
/***************************************************************************
TYPE DEFINITIONS
***************************************************************************/
struct g64dsk_tag
{
int version;
int heads; /* number of physical heads */
int tracks; /* number of physical tracks */
UINT16 track_size; /* size of each track */
UINT32 track_offset[MAX_TRACKS]; /* offset within data for each track */
UINT32 speed_zone_offset[MAX_TRACKS]; /* offset within data for each track */
};
/***************************************************************************
INLINE FUNCTIONS
***************************************************************************/
INLINE struct g64dsk_tag *get_tag(floppy_image_legacy *floppy)
{
return (g64dsk_tag *)floppy_tag(floppy);
}
INLINE float get_dos_track(int track)
{
return ((float)track / 2) + 1;
}
/***************************************************************************
IMPLEMENTATION
***************************************************************************/
/*-------------------------------------------------
g64_get_heads_per_disk - returns the number
of heads in the disk image
-------------------------------------------------*/
static int g64_get_heads_per_disk(floppy_image_legacy *floppy)
{
return get_tag(floppy)->heads;
}
/*-------------------------------------------------
g64_get_tracks_per_disk - returns the number
of DOS tracks in the disk image
-------------------------------------------------*/
static int g64_get_tracks_per_disk(floppy_image_legacy *floppy)
{
return get_tag(floppy)->tracks;
}
/*-------------------------------------------------
get_track_offset - returns the offset within
the disk image for a given track
-------------------------------------------------*/
static floperr_t get_track_offset(floppy_image_legacy *floppy, int head, int track, UINT64 *offset)
{
struct g64dsk_tag *tag = get_tag(floppy);
UINT64 offs = 0;
if ((track < 0) || (track >= tag->tracks))
return FLOPPY_ERROR_SEEKERROR;
offs = tag->track_offset[track];
if (offset)
*offset = offs;
return FLOPPY_ERROR_SUCCESS;
}
/*-------------------------------------------------
g64_get_track_size - returns the track size
-------------------------------------------------*/
static UINT32 g64_get_track_size(floppy_image_legacy *floppy, int head, int track)
{
/* get track offset */
UINT64 track_offset;
floperr_t err = get_track_offset(floppy, head, track, &track_offset);
if (err)
return 0;
/* read track length */
UINT8 size[2];
floppy_image_read(floppy, &size, track_offset, 2);
UINT32 track_length = (size[1] << 8) | size[0];
return track_length;
}
/*-------------------------------------------------
g64_read_track - reads a full track from the
disk image
-------------------------------------------------*/
static floperr_t g64_read_track(floppy_image_legacy *floppy, int head, int track, UINT64 offset, void *buffer, size_t buflen)
{
struct g64dsk_tag *tag = get_tag(floppy);
floperr_t err;
UINT64 track_offset;
UINT16 track_length = 0;
/* get track offset */
err = get_track_offset(floppy, head, track, &track_offset);
if (err)
return err;
if (!head && track_offset)
{
if (buflen < tag->track_size) { printf("G64 track buffer too small: %u!", (UINT32)buflen); exit(-1); }
/* read track */
floppy_image_read(floppy, buffer, track_offset + 2, tag->track_size);
}
else
{
/* set track length to 0 */
memset(buffer, 0, buflen);
}
if (LOG) LOG_FORMATS("G64 track %.1f length %u\n", get_dos_track(track), track_length);
return FLOPPY_ERROR_SUCCESS;
}
/*-------------------------------------------------
g64_write_track - writes a full track to the
disk image
-------------------------------------------------*/
static floperr_t g64_write_track(floppy_image_legacy *floppy, int head, int track, UINT64 offset, const void *buffer, size_t buflen)
{
return FLOPPY_ERROR_UNSUPPORTED;
}
/*-------------------------------------------------
FLOPPY_IDENTIFY( g64_dsk_identify )
-------------------------------------------------*/
FLOPPY_IDENTIFY( g64_dsk_identify )
{
UINT8 header[8];
floppy_image_read(floppy, header, 0, 8);
if (!strncmp((const char *)header, "GCR-1541", 8))
{
*vote = 100;
}
else
{
*vote = 0;
}
return FLOPPY_ERROR_SUCCESS;
}
/*-------------------------------------------------
FLOPPY_CONSTRUCT( g64_dsk_construct )
-------------------------------------------------*/
/*
G64 File Header Format
Bytes: $0000-0007: File signature "GCR-1541"
0008: G64 version (presently only $00 defined)
0009: Number of tracks in image (usually $54, decimal 84)
000A-000B: Size of each stored track in bytes (usually 7928, or
$1EF8 in LO/HI format.
Bytes: $000C-000F: Offset to stored track 1.0 ($000002AC, in LO/HI
format, see below for more)
0010-0013: Offset to stored track 1.5 ($00000000)
0014-0017: Offset to stored track 2.0 ($000021A6)
...
0154-0157: Offset to stored track 42.0 ($0004F8B6)
0158-015B: Offset to stored track 42.5 ($00000000)
Bytes: $015C-015F: Speed zone entry for track 1 ($03, in LO/HI format,
see below for more)
0160-0163: Speed zone entry for track 1.5 ($03)
...
02A4-02A7: Speed zone entry for track 42 ($00)
02A8-02AB: Speed zone entry for track 42.5 ($00)
Bytes: $02AC-02AD: Actual size of stored track (7692 or $1E0C, in LO/HI
format)
02AE-02AE+$1E0C: Track data
*/
FLOPPY_CONSTRUCT( g64_dsk_construct )
{
struct FloppyCallbacks *callbacks;
struct g64dsk_tag *tag;
UINT8 header[HEADER_LENGTH];
UINT64 pos = 0;
int i;
if (params)
{
/* create not supported */
return FLOPPY_ERROR_UNSUPPORTED;
}
tag = (struct g64dsk_tag *) floppy_create_tag(floppy, sizeof(struct g64dsk_tag));
if (!tag) return FLOPPY_ERROR_OUTOFMEMORY;
/* version */
floppy_image_read(floppy, header, pos, 0x0c); pos += 0xc;
tag->version = header[8];
if (LOG) LOG_FORMATS("G64 version: %u\n", tag->version);
/* number of half tracks */
tag->heads = 1;
tag->tracks = header[9];
if (LOG) LOG_FORMATS("G64 tracks: %u\n", tag->tracks);
/* size of each stored half track */
tag->track_size = (header[11] << 8) | header[10];
if (LOG) LOG_FORMATS("G64 track size: %04x\n", tag->track_size);
/* data offsets */
for (i = 0; i < tag->tracks; i++)
{
floppy_image_read(floppy, header, pos, 4); pos += 4;
tag->track_offset[i] = (header[3] << 24) | (header[2] << 16) | (header[1] << 8) | header[0];
if (LOG) LOG_FORMATS("G64 track %.1f data offset: %04x\n", get_dos_track(i), tag->track_offset[i]);
}
/* speed zone offsets */
for (i = 0; i < tag->tracks; i++)
{
floppy_image_read(floppy, header, pos, 4); pos += 4;
tag->speed_zone_offset[i] = (header[3] << 24) | (header[2] << 16) | (header[1] << 8) | header[0];
if (LOG)
{
if (tag->speed_zone_offset[i] < 4) {
LOG_FORMATS("G64 track %.1f speed zone: %u\n", get_dos_track(i), tag->speed_zone_offset[i]);
} else {
LOG_FORMATS("G64 track %.1f speed zone offset: %04x\n", get_dos_track(i), tag->speed_zone_offset[i]);
}
}
}
/* set callbacks */
callbacks = floppy_callbacks(floppy);
callbacks->read_track = g64_read_track;
callbacks->write_track = g64_write_track;
callbacks->get_heads_per_disk = g64_get_heads_per_disk;
callbacks->get_tracks_per_disk = g64_get_tracks_per_disk;
callbacks->get_track_size = g64_get_track_size;
return FLOPPY_ERROR_SUCCESS;
}
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