#@deckyard/d64

Read, write, create and format Commodore 1541 D64 disk images.

This deck is part of Deckyard, community decks for Jennifer.

A D64 is the blocks of a 5.25" disk stored back to back with no header: 683 blocks of 256 bytes on a 35-track disk. Inside them is CBM DOS 2.6 - the BAM in 18/0, a chain of 32-byte directory slots from 18/1, one linked list of blocks per file. Four BAM layouts are supported: stock 35-track Cbm and the 40-track SpeedDos, DolphinDos and PrologicDos.

#Import

use io;
import "@deckyard/d64/" as d64;

def img as d64.Image init d64.formatDisk("sample disk", "01");
$img = d64.writeText($img, "readme", d64.FileType.Seq, "hello\n");
io.printf("%s", d64.directoryText($img));
d64.save($img, "sample.d64");

The trailing slash resolves to the entry module.

#Value semantics

Every function that changes the disk returns a new Image and leaves its argument untouched:

def before as d64.Image init d64.formatDisk("work", "01");
def after as d64.Image init d64.writeText($before, "readme", d64.FileType.Seq, "hi\n");

len(d64.listFiles($before));   # 0
len(d64.listFiles($after));    # 1

The calling shape is $img = something($img, ...). An operation that fails part-way throws, and the caller's image is unchanged.

#Case

The transcoder swaps case, as petcat does: toPetscii("hello") gives the bytes a C64 shows as HELLO. Write names lower case. See PETSCII.

#Errors

Every failure is an Error with kind "d64" (ERROR_KIND).

try {
    $img = d64.writeFile($img, "toobig", d64.FileType.Prg, $huge);
} catch (e) {
    io.printf("%s\n", $e.message);
}

Thrown for, among others: a name that is empty, over 16 PETSCII characters or already on the disk, a full disk, a full directory, a track or sector outside the image, scratching a locked file, a block chain that loops, and a buffer whose length is not a D64 size.

#Contents

Runnable programs: examples/.