Type Alias chd::codecs::CdZlibCodec

pub type CdZlibCodec = CdCodec<ZlibCodec, ZlibCodec>;

Available on codec_api only.

CD-ROM wrapper decompression codec (cdzl) using the Deflate codec for decompression of sector data and the Deflate codec for decompression of subcode data.

Format Details

CD-ROM compressed hunks have a layout with a header, then all compressed frame data in sequential order, followed by compressed subcode data.

[Header, Frame0, Frame1, ..., FrameN, Subcode0, Subcode1, ..., SubcodeN]

The slice of the input buffer from Frame0 to Frame1 is a single Deflate compressed stream, followed by the subcode data which is a single Deflate compressed stream.

The size of the header is determined by the number of 2448-byte sized frames that can fit into a hunk-sized buffer and the length of such buffer. First, the number of ECC bytes are calculated as (frames + 7) / 8. If the hunk size is less than 65536 (0x10000) bytes, then the length of the compressed sector data is stored as a 2 byte big-endian integer, otherwise the length is 3 bytes, stored after the number of ECC bytes in the header.

After decompression, the data is swizzled so that each frame is followed by its corresponding subcode data.

[Frame0, Subcode0, Frame1, Subcode1, ..., FrameN, SubcodeN]

After swizzling, the following CD sync header will be written to the first 12 bytes of each frame.

pub const CD_SYNC_HEADER: [u8; 12] = [
    0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00,
];

The ECC data is then regenerated throughout the sector.

Buffer Restrictions

Each compressed CDZL hunk decompresses to a hunk-sized chunk. The hunk size must be a multiple of 2448, the size of each CD frame. The input buffer must contain exactly enough data to fill the output buffer when decompressed.

Aliased Type

struct CdZlibCodec { /* private fields */ }

Trait Implementations

impl CompressionCodecType for CdZlibCodec

fn codec_type(&self) -> CodecType

Returns the known CodecType that this codec implements.

impl CompressionCodec for CdZlibCodec