mirror of
https://github.com/zellyn/diskii.git
synced 2024-12-23 06:30:12 +00:00
93 lines
2.7 KiB
Go
93 lines
2.7 KiB
Go
// Copyright © 2016 Zellyn Hunter <zellyn@gmail.com>
|
|
|
|
// dsk.go contains logic for reading ".dsk" disk images.
|
|
|
|
package disk
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
"io/ioutil"
|
|
)
|
|
|
|
// DSK represents a .dsk disk image.
|
|
type DSK struct {
|
|
data []byte // The actual data in the file
|
|
sectors byte // Number of sectors per track
|
|
physicalToStored []byte // Map of physical on-disk sector numbers to sectors in the disk image
|
|
bytesPerTrack int // Number of bytes per track
|
|
tracks byte // Number of tracks
|
|
}
|
|
|
|
var _ SectorDisk = (*DSK)(nil)
|
|
|
|
// LoadDSK loads a .dsk image from a file.
|
|
func LoadDSK(filename string) (DSK, error) {
|
|
bb, err := ioutil.ReadFile(filename)
|
|
if err != nil {
|
|
return DSK{}, err
|
|
}
|
|
// TODO(zellyn): handle 13-sector disks.
|
|
if len(bb) != DOS33DiskBytes {
|
|
return DSK{}, fmt.Errorf("Expected file %q to contain %d bytes, but got %d.", filename, DOS33DiskBytes, len(bb))
|
|
}
|
|
return DSK{
|
|
data: bb,
|
|
sectors: 16,
|
|
physicalToStored: Dos33PhysicalToLogicalSectorMap,
|
|
bytesPerTrack: 16 * 256,
|
|
tracks: DOS33Tracks,
|
|
}, nil
|
|
}
|
|
|
|
// ReadPhysicalSector reads a single physical sector from the disk. It
|
|
// always returns 256 byes.
|
|
func (d DSK) ReadPhysicalSector(track byte, sector byte) ([]byte, error) {
|
|
if track >= d.tracks {
|
|
return nil, fmt.Errorf("ReadPhysicalSector expected track between 0 and %d; got %d", d.tracks-1, track)
|
|
}
|
|
if sector >= d.sectors {
|
|
return nil, fmt.Errorf("ReadPhysicalSector expected sector between 0 and %d; got %d", d.sectors-1, sector)
|
|
}
|
|
|
|
storedSector := d.physicalToStored[int(sector)]
|
|
start := int(track)*d.bytesPerTrack + 256*int(storedSector)
|
|
buf := make([]byte, 256)
|
|
copy(buf, d.data[start:start+256])
|
|
return buf, nil
|
|
}
|
|
|
|
// WritePhysicalSector writes a single physical sector to a disk. It
|
|
// expects exactly 256 bytes.
|
|
func (d DSK) WritePhysicalSector(track byte, sector byte, data []byte) error {
|
|
if track >= d.tracks {
|
|
return fmt.Errorf("WritePhysicalSector expected track between 0 and %d; got %d", d.tracks-1, track)
|
|
}
|
|
if sector >= d.sectors {
|
|
return fmt.Errorf("WritePhysicalSector expected sector between 0 and %d; got %d", d.sectors-1, sector)
|
|
}
|
|
if len(data) != 256 {
|
|
return fmt.Errorf("WritePhysicalSector expects data of length 256; got %d", len(data))
|
|
}
|
|
|
|
storedSector := d.physicalToStored[int(sector)]
|
|
start := int(track)*d.bytesPerTrack + 256*int(storedSector)
|
|
copy(d.data[start:start+256], data)
|
|
return nil
|
|
}
|
|
|
|
// Sectors returns the number of sectors on the DSK image.
|
|
func (d DSK) Sectors() byte {
|
|
return d.sectors
|
|
}
|
|
|
|
// Tracks returns the number of tracks on the DSK image.
|
|
func (d DSK) Tracks() byte {
|
|
return d.tracks
|
|
}
|
|
|
|
// Write writes the disk contents to the given file.
|
|
func (d DSK) Write(w io.Writer) (n int, err error) {
|
|
return w.Write(d.data)
|
|
}
|