Package org.applecommander.archive.binscii

package org.applecommander.archive.binscii

BinSCII archive format support.

BinSCII is a text-based binary encoding format for Apple II files, designed to allow binary files to be transmitted over text-only channels such as email or Usenet. It is similar in concept to uuencode, but uses a 64-character alphabet and encodes data three bytes at a time into four 6-bit ASCII characters.

Files in BinSCII format typically use the .bsc extension. The archive is divided into 12 KB segments, each beginning with a sentinel line FiLeStArTfIlEsTaRt, followed by an alphabet line defining the 64-character encoding alphabet, and a metadata line containing the file name and a 29-byte binary header structure. This header encodes ProDOS metadata including file size, segment offset, access mode, file type, auxiliary type, storage type, block size, creation and modification timestamps, segment length, and a CRC-16 checksum.

Data lines are exactly 64 characters long, each representing 48 bytes of the original file. Each segment ends with a CRC-16 checksum line for integrity verification using the polynomial X^16 + X^12 + X^5 + 1.

This package provides a FileStore implementation that parses BinSCII archives and exposes their contents through the standard AppleCommander file store API, supporting decoding of the custom alphabet encoding, metadata parsing, CRC-16 integrity verification, and extraction of archived files with full ProDOS metadata.

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